Hydrocarbon abundance and distribution in the vicinity of the … · Figure 10. Consolidated plot...

Shell/INPEX Applied Research Program Shell Contract No. U124206

INPEX Contract No. 800950

Shell/INPEX ARP2 Milestone Report #5a

Hydrocarbon abundance and distribution in

the vicinity of the Prelude/Ichthys fields of

the Browse Basin

Prepared by CSIRO

October 2017

Document Details

AIMS Document No: ARP2/CSIRO/AIMS/RT/043

Rev Date: Prepared by: Authorised by: Date: Approved

by: Date:

0 October 2017 Andrew Ross et al AIMS Project Manager December 2017 AIMS Project

Manager December 2017

1 October 2017 Andrew Ross et al AIMS Project Manager March 2018 AIMS Project

Manager March 2018

Hydrocarbon abundance and distribution in the vicinity of the Prelude/Ichthys fields of the Browse Basin | i

Hydrocarbon abundance and distribution in the vicinity of the Prelude/Ichthys fields of the Browse Basin Applied Research Program Project 2 Task 5a Report

Andrew Ross, Charlotte Stalvies, Asrar Talukder, Christine Trefry, Mederic Mainson, Leif Cooper,

May Yuen, Julian Palmer

October 2017

A report prepared for Australian Institute of Marine Science for Shell Australia Pty Ltd (Shell) and

INPEX Operations Australia Pty Ltd (INPEX)

Commercial-in-confidence

CSIRO

Applied Research Program Project 2 Task 5a Report | i

Citation

Ross, A., Stalvies, C., Talukder, A., Trefry, C., Mainson, M., Cooper, L., Yuen, M., Palmer, J. (2017)

Hydrocarbon abundance and distribution in the vicinity of the Prelude/Ichthys fields of the Browse

Basin. Applied Research Program Project 2 Task 5a Report. CSIRO confidential report EP177989. Pp

118.

Copyright

© Commonwealth Scientific and Industrial Research Organisation 2017. To the extent permitted

by law, all rights are reserved and no part of this publication covered by copyright may be

reproduced or copied in any form or by any means except with the written permission of CSIRO.

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therefore be made on that information without seeking prior expert professional, scientific and

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mailto:[email protected]

CSIRO ARP2-5 MILESTONE REPORT REV 1 OCTOBER 2017

Applied Research Program Project 2 Task 5a Report | i

Foreword

This report and associated data transmission are the deliverable for task 5 of the baseline

hydrocarbon survey in the Browse Basin, Project 2 of the Applied Research Program. This

deliverable pertains to the subcontract to the agreement between AIMS and Shell Development

(Australia) Pty Ltd (No.UI24206) and INPEX Operations Australia Pty Ltd (No.800950).


ii | Applied Research Program Project 2 Task 5a Report

Contents

Foreword ................................................................................................................................ i

Acknowledgments ......................................................................................................................... viii

Executive summary ......................................................................................................................... ix

1 Introduction ........................................................................................................................ 1

2 Marine survey design .......................................................................................................... 2

2.1 Survey designs ....................................................................................................... 2

2.2 Analytical program and data processing ............................................................. 17

3 Results and discussion ...................................................................................................... 22

3.1 ARP2 Trip 6184 operations and sampling ........................................................... 22

3.2 ARP 5 MV Empress trip November 2016 operations and sampling .................... 32

3.3 ARP 7 Trip 6578 operations and sampling .......................................................... 33

3.4 Water column profile data .................................................................................. 36

3.5 Water column chemistry ..................................................................................... 60

3.6 Sediment chemistry ............................................................................................. 76

3.7 Summary of findings from geochemical analyses ............................................... 86

4 Conclusions and future work ............................................................................................ 87

5 References ........................................................................................................................ 89


Applied Research Program Project 2 Task 5a Report | iii

Figures

Figure 1. ARP2 Trip 6184 survey design overlain on survey area with INPEX focal areas, known

seepage and SAR anomalies marked. ............................................................................................. 4

Figure 2. Browse Island, potential seep areas A, B, C and F, Echuca Shoal and Heywood Shoal

focal areas with sampling station locations marked. ..................................................................... 5

Figure 3. Site investigation decision tree for potential seeps ........................................................ 6

Figure 4. ARP5 M/V Empress survey design overlain on survey area with known seepage and

SAR anomalies marked. .................................................................................................................. 8

Figure 5. ARP7 Trip 6578 survey design overlain on survey area with known seepage and SAR

anomalies marked. .......................................................................................................................... 9

Figure 6. ARP7 Trip 6578 survey design in each area focal area. ................................................. 10

Figure 7. RV Solander (left), augmented CTD profiler (middle) and Smith McIntyre grab

(right). ............................................................................................................................................ 11

Figure 8 CTD sampling depths overview. OB = off bottom, FS = from surface, TC =

Thermocline. ................................................................................................................................. 13

Figure 9 Samples taken from each type of sampling gear ............................................................ 15

Figure 10. Consolidated plot of all salinity data from each water column profile (upper panel)

and consolidated histogram of sensor response (lower panel) collected during the ARP 2 - 6184

and ARP 7 – 6578 trips. BBS signifies Browse Basin Station location numbers............................ 37

Figure 11. Heat map of salinity for all water column profiles collected during the ARP 2-6184

and ARP 7- 6578 trips. The warmer colours represent higher repeatability across the profiles.

The heat map of salinity is overlain by the mean and standard deviation of the collated data

from each voyage. Note that the standard errors (not shown) are larger at depth due to

decreased sampling frequency. .................................................................................................... 38

Figure 12. Map of study area showing salinity ranges at each station for ARP 2 trip 6184 and

ARP 7 trip 6578. ............................................................................................................................ 39

Figure 13. Indian Ocean Dipole Index Time Series 2013-2017. .................................................... 41

Figure 14. Consolidated plot of all temperature data from each water column profile (upper

panel) and consolidated histogram of sensor response (lower panel) collected during the ARP 2

- 6184 and ARP 7 – 6578 trips. BBS signifies Browse Basin Station location numbers. ............... 42

Figure 15. Heat map of temperature for all water column profiles collected during the ARP 2-

6184 and ARP 7- 6578 trips. The warmer colours represent higher repeatability across the

profiles. The heat map of temperature is overlain by the mean and standard deviation of the

collated data from each voyage. Note that the standard errors (not shown) are larger at depth

due to decreased sampling frequency. ......................................................................................... 43

Figure 16. Consolidated plot of all dissolved oxygen concentration data from each water column

profile (upper panel) and consolidated histogram of sensor response (lower panel) collected


iv | Applied Research Program Project 2 Task 5a Report

during the ARP 2 - 6184 and ARP 7 – 6578 trips. BBS signifies Browse Basin Station location

numbers. ....................................................................................................................................... 44

Figure 17. Heat map of dissolved oxygen concentration for all water column profiles collected

during the ARP 2-6184 and ARP 7- 6578 trips. The warmer colours represent higher

repeatability across the profiles. The heat map of oxygen is overlain by the mean and standard

deviation of the collated data from each voyage. Note that the standard errors (not shown) are

larger at depth due to decreased sampling frequency. ................................................................ 45

Figure 18. Consolidated plot of chlorophyll concentration data from each water column profile

(upper panel) and consolidated histogram of sensor response (lower panel) collected during the

ARP 2 - 6184 and ARP 7 – 6578 trips. BBS signifies Browse Basin Station location numbers. ..... 46

Figure 19. Heat map of chlorophyll concentration for all water column profiles collected during

the ARP 2-6184 and ARP 7- 6578 trips. The warmer colours represent higher repeatability

across the profiles. The heat map of chlorophyll is overlain by the mean and standard deviation

of the collated data from each voyage. Note that the standard errors (not shown) are larger at

depth due to decreased sampling frequency. .............................................................................. 47

Figure 20. Map of study area showing stations where profiles had anomalously high chlorophyll

concentrations >0.1 µg/l) when compared with the other data collected during the ARP 2

hydrocarbon seeps and baseline survey – Trip 6184. The figure map underlay also shows

regional MODIS-derived chlorophyll-a mg/m3 OC3 concentrations for the 16th May

2015(http://oceancurrent.imos.org.au/MODIScomp/2015051604.gif). ..................................... 48

Figure 21. Map of study area showing stations where profiles had anomalously high chlorophyll

concentrations >0.1 µg/l) when compared with the other data collected during the ARP 7 trip

6578. The figure map underlay also shows regional MODIS-derived chlorophyll-a mg/m3 OC3

concentrations for the November 21/24 2016. ............................................................................ 48

Figure 22. Consolidated plot of turbidity data from each water column profile (upper panel) and

consolidated histogram of sensor response (lower panel) collected during the ARP 2 - 6184 and

ARP 7 – 6578 trips. BBS signifies Browse Basin Station location numbers................................... 50

Figure 23. Heat map of turbidity for all water column profiles collected during the ARP 2-6184

and ARP 7- 6578 trips. The warmer colours represent higher repeatability across the profiles.

The heat map of turbidity is overlain by the mean and standard deviation of the collated data

from each voyage. Note that the standard errors (not shown) are larger at depth due to

decreased sampling frequency. .................................................................................................... 51

Figure 24. Consolidated plot of refined hydrocarbon (CHR) or polycyclic aromatic hydrocarbons

(PAH) data from each water column profile (upper panel) and consolidated histogram of sensor

response (lower panel) collected during the ARP 2 - 6184 and ARP 7 – 6578 trips. BBS signifies

Browse Basin Station location numbers. ...................................................................................... 53

Figure 25. Heat map of refined hydrocarbon (CHR) or polycyclic aromatic hydrocarbons (PAH)

data for all water column profiles collected during the ARP 2-6184 and ARP 7- 6578 trips. The

warmer colours represent higher repeatability across the profiles. The heat map of CHR is

overlain by the mean and standard deviation of the collated data from each voyage. Note that

the standard errors (not shown) are larger at depth due to decreased sampling frequency. .... 54


Applied Research Program Project 2 Task 5a Report | v

Figure 26. Map of study area showing CHR or polycyclic aromatic hydrocarbon concentrations

at each station for ARP 2 trip 6184 and ARP 7 trip 6578. ............................................................. 55

Figure 27. Consolidated plot of crude hydrocarbons (CHC) or coloured dissolved organic matter

(CDOM) data from each water column profile (upper panel) and consolidated histogram of

sensor response (lower panel) collected during the ARP 2 - 6184 and ARP 7 – 6578 trips. BBS

signifies Browse Basin Station location numbers. ........................................................................ 57

Figure 28. Heat map of crude hydrocarbons (CHC) or coloured dissolved organic matter (CDOM)

data for all water column profiles collected during the ARP 2-6184 and ARP 7- 6578 trips. The

warmer colours represent higher repeatability across the profiles. The heat map of CHC is

overlain by the mean and standard deviation of the collated data from each voyage. Note that

the standard errors (not shown) are larger at depth due to decreased sampling frequency. .... 58

Figure 29. Example LISST profile data from station 11 showing mean particle size and standard

deviation (µm) (left), and total volume concentration (µL/L) (right), with depth through the

water column. ............................................................................................................................... 59

Figure 30. GC-FID chromatogram of ChemCentre sample 14B0708/090 (water sample

COA/001414), showing weathered diesel fuel and heavier waxes. ............................................. 61

Figure 31. Map of study area showing stations with the highest concentrations of total PAHs in

the water column collected during the ARP 2 trip 6184, ARP 5 and ARP 7 Trip 6578 after

removal of contamination outliers. .............................................................................................. 62

Figure 32. Example GC-FID chromatogram: water sample 14B0708/225 – Station 46, CTD_164,

50m unusual distribution of unidentified compounds attributed to a biogenic origin or plant

waxes. ............................................................................................................................................ 63

Figure 33. Map of study area showing stations highest concentrations of quantified alkanes

(excluding UCM) from TPH analyses in the water column from ARP 2 trip 6184, ARP 5 and ARP 7

Trip 6578 after removal of contamination outliers. ..................................................................... 65

Figure 34. Whisker plot showing variance in individual parent and alkylated PAH compound

concentrations from 245 ARP 2, 45 ARP 5 and 54 ARP 7 water column profile water samples

unaffected by contamination plotted on the same scale. Limits of reporting for the parent PAH

compounds were 0.001 ug/L and the *number above each compound is the number of samples

not included in the analysis of variance due to that compound being below limits of reporting.

The whiskers describe the total range in variance, whilst the upper box represents the 2nd

quartile the lower box represents the 3rd quartile and bar in the centre represents the median

concentration of the compound. .................................................................................................. 66

Figure 35. Whisker plot showing variance in quantified alkane and UCM concentrations from

245 ARP 2, 45 ARP 5 and 54 ARP 7 water column profile water samples. Limits of reporting for

the compounds were 0.001 µg/L. The *number above each compound is the number of

samples not included in the analysis of variance due to that compound being below limits of

reporting. The whiskers describe the total range in variance, whilst the upper box represents

the 2nd quartile the lower box represents the 3rd quartile and bar in the centre represents the

median concentration of the compound. ..................................................................................... 67


vi | Applied Research Program Project 2 Task 5a Report

Figure 36. Map of study area showing stations highest concentrations of total parent and

alkylated PAH in sediments collected from ARP 2 trip 6184, ARP 5 and ARP 7 Trip 6578 after

removal of contamination outliers. .............................................................................................. 78

Figure 37. GC-FID chromatogram for ARP 2 station 38 (SMG 132). Inset A shows full

chromatogram and TPH compound profile. Inset B shows a close-up view of the chromatogram

showing odd over even n-alkane predominance indicative of terrestrially derived plant

waxes. ............................................................................................................................................ 79

Figure 38. Map of study area showing stations with the highest concentrations of quantified

alkanes from THP analyses in the sediments from ARP 2 trip 6184, ARP 5 and ARP 7 Trip 6578

after removal of contamination outliers. ..................................................................................... 81

Figure 39. Whisker plot showing variance in individual parent and alkylated PAH concentrations

from 61 ARP 2, 13 ARP 5 and 24 ARP 7 sediment samples collected during the ARP 2

hydrocarbon seep and baseline survey –Trip 6184. Limits of reporting for the compounds were

0.001 mg/kg and the *number above each compound is the number of samples not included in

the analysis of variance due to that compound being below limits of reporting. The whiskers

describe the total range in variance, whilst the upper box represents the 2nd quartile the lower

box represents the 3rd quartile and bar in the centre represents the median concentration of

the compound. .............................................................................................................................. 82

Figure 40. Whisker plot showing variance in in quantified alkane and UCM concentrations

from61 ARP 2, 13 ARP 5 and 24 ARP sediment samples collected during the ARP2 hydrocarbon

seep and baseline survey –Trip 6184. Limits of reporting for the compounds were 0.001 mg/kg

and the *number above each compound is the number of samples not included in the analysis

of variance due to that compound being below limits of reporting. The whiskers describe the

total range in variance, whilst the upper box represents the 2nd quartile the lower box

represents the 3rd quartile and bar in the centre represents the median concentration of the

compound. .................................................................................................................................... 83

Tables

Table 1 Survey trips undertaken and sampling operations conducted (inclusive of all voyages up

until the end of 2016). Note that further ARP 7 voyages have been undertaken or are planned in

2017................................................................................................................................................. 2

Table 2. Example sampling matrix for each ARP 2 sampling station (Mercury and metals samples

not shown as these were additional samples and analysis collected outside the scope of ARP

2) ................................................................................................................................................... 16

Table 3. Operations undertaken and samples collected during the ARP 2 hydrocarbon seeps and

baseline survey - trip 6184. ........................................................................................................... 22

Table 4. Operations undertaken and samples collected during the ARP 5 survey. ARP7 Trip 6578

operations and sampling ............................................................................................................... 32

Table 5. Operations undertaken and samples collected during the ARP 7 survey - trip 6578. .... 34


Applied Research Program Project 2 Task 5a Report | vii

Table 6. Average daily river flows for Ord and Fitzroy Rivers during 2015 ARP 2 and 2016 ARP 7

trips. .............................................................................................................................................. 40

Table 7. Interpretation of source of hydrocarbons (HC) within water samples collected during

the ARP 2 hydrocarbon seeps and baseline survey – Trip 6184. HC source includes: PW = Plant

Wax, Bio = Biogenic origin, LL = low level hydrocarbon concentration, contam = contamination

(unspecified), Kero (contam) = Kerosene contamination, Contam (poly) = plastic contamination,

Contam (IFO) = Intermediate fuel oil contamination, Petr = petrogenic source. Profile A = see

interpretation below. .................................................................................................................... 68


the ARP 5 survey. HC source includes: PW = Plant Wax, Bio = Biogenic origin, LL = low level

hydrocarbon concentration, contam = contamination (unspecified), Kero (contam) = Kerosene

contamination, Contam (poly) = plastic contamination, Contam (IFO) = Intermediate fuel oil

contamination, Petr = petrogenic source. Profile A = see interpretation below. ........................ 74


the ARP 7 survey – Trip 6578. HC source includes: PW = Plant Wax, Bio = Biogenic origin, LL =

low level hydrocarbon concentration, contam = contamination (unspecified), Kero (contam) =

Kerosene contamination, Contam (poly) = plastic contamination, Contam (IFO) = Intermediate

fuel oil contamination, Petr = petrogenic source. Profile A = see interpretation below. ............ 75

Table 10. Interpretation of the source of hydrocarbons in sediment samples. HC sources

include: PW = Plant Wax, Bio = Biogenic origin,contam = contamination (unspecified), Kero

(contam) = Kerosene contamination. ........................................................................................... 84

Table 11. List of ARP 2 sample stations and associated CTD data files ........................................ 90

Table 12. List of ARP 7 sample stations and associated CTD data files ........................................ 93


viii | Applied Research Program Project 2 Task 5a Report

Acknowledgments

This work is the result of the combined operational efforts of scientists and staff from the Commonwealth

Scientific and Industrial Research Organisation (CSIRO), the Australian Institute of Marine Science (AIMS),

ChemCentre, Shell and INPEX. In particular the shipboard party of RV Solander voyages 6184 (ARP 2), 6578

(ARP 7) and ARP 5 MV Empress voyage are thanked for their work in the collection of data and samples

which have been subsequently analysed and interpreted to generate this report. The authors and CSIRO

would also like to acknowledge funding from Shell and INPEX-operated Ichthys LNG Project, via AIMS to

support this research.


Applied Research Program Project 2 Task 5a Report | ix

Executive summary

The objective of Applied Research Program Project 2 (ARP 2) is to characterise the thermogenic

hydrocarbon content of waters and sediments in the vicinity of the Prelude and Ichthys development fields.

The study aims to determine baseline hydrocarbon concentrations at a variety of sites including areas close

to Browse Island, Echuca Shoal and other potential, and known, natural seep locations.

This report seeks to interpret the data collected during the ARP 2 program across the Browse Basin in the

context of understanding the hydrocarbon baseline conditions prior to production activities at the Prelude

and Ichthys fields. This report integrates both water column profile data along with geochemical data

derived from water column and sediment samples collected during the ARP 2 6184, ARP 5 M/V Empress

and ARP 7 6578 trips conducted between March 2015 and December 2016.

This report comprises the task 5 (first revision) deliverable of ARP 2 as part of the subcontract to the

agreement between the Australian Institute of Marine Science (AIMS) and Shell Development (Australia)

Pty Ltd (No. UI24206) and INPEX Operations Australia Pty Ltd (No. 800950).

Prior to the ARP 2 6184 trip there were no known records of water profiles collecting a suite of chemical

and physical data in this area. Collection of 88 water column profiles incorporating a large number of

chemical and physical measurements represents the first systematic baseline data collection across the

Browse Basin.

Water column profile data show systematic spatial trends across the basin, as well as interdependency

between responses. The inclusion of a suite of measurements enabled the identification of linkages which

may otherwise not have been revealed, which in turn may have led to erroneous interpretations. The

trends in the data are related to oceanographic processes, such as the halocline and thermocline, tidal

processes and different water mass properties. There are significant differences in the data collected from

the ARP 2 6184 and ARP 7 6578 trips which are attributable to changing oceanographic and biological

processes. Variance between the data collected from each trip demonstrates the wide range in natural

variability in the Browse Basin water column.

The large differences in in inferred crude hydrocarbon (CHR) and refined hydrocarbon (CHC) concentrations

between the ARP 2 and ARP 7 trips shows that the natural range of variability in the waters of the Browse

Basin has yet to be fully characterised. This reduces the capability to correctly identify, and understand the

spatial distribution of, entrained hydrocarbons in the water column in the unlikely event of an unintended

hydrocarbon release. Further data collection is required to reduce these uncertainties and more fully

characterise the natural variability observed in the study area. This will be partly addressed through

analysis of samples from the April 2017 ARP7 survey and the forthcoming ARP7 trip in December 2017

which will collect repeat measurements at the Browse Island, Heywood Shoal, and Echuca Shoal study

areas.

Graphical tools such as heat maps of sensor responses plotted as side-by-side water column profiles have

allowed simple incorporation of additional baseline data from the ARP 7 trip. These visual approaches have

permitted the identification of anomalous data and will be a valuable tool in the event of an unintended

hydrocarbon release into the marine environment in the study area.

The collection and analysis of 1413 geochemical water and sediment samples is a considerable extension to

existing sediment chemistry data holdings in the Browse Basin study area, the collation of which represents

a pre-development hydrocarbon baseline. As such the results of this study meet the extended ARP 2

objectives to develop a hydrocarbon baseline in the vicinity of the Ichthys development fields.


x | Applied Research Program Project 2 Task 5a Report

Generally, the abundance of benzene, toluene, ethylbenzene and xylene isomers (BTEX) and higher

molecular weight polycyclic aromatic hydrocarbons (PAH) is low, to very low. Where observed, such

compounds are identified as pyrogenic in origin, likely the products of wildfires, either from the Australian

mainland or regionally. There are enhanced water column PAH concentrations in samples collected during

the ARP 5 trip which is tentatively assigned to enhanced bush fire activity at the time of sample collection,

although further studies are required to affirm this interpretation.

In the event of an incident, the low baseline concentrations recorded during this study would permit the

BTEX compounds and PAHs introduced during the incident to be distinguished from background

concentrations. Alkane compounds were found to be more prevalent than PAHs and the provenance of

these compounds was assigned to an origin from plant waxes and biogenic sources, such as marine algal

and microbial populations.

The use of the whisker plot has permitted further sample data to be readily integrated and compared,

enabling assessment of range of variation in PAH and Total Petroleum Hydrocarbon (TPH) concentrations in

the study area. This approach will allow rapid identification of anomalous sample concentrations in the

event of a hydrocarbon spill in the study area.

The data presented here will be augmented with further data sets collected during the ARP 7 project which

will collect further temporal data during reoccupation of sites visited during the ARP 2 field campaign.


Applied Research Program Project 2 Task 5a Report | 1

1 Introduction

The objective of Applied Research Program Project 2 (ARP 2) is to characterise the petrogenichydrocarbon

content of waters and sediments near the Prelude and Ichthys development fields. The study aims to

determine baseline hydrocarbon concentrations at a variety of sites including areas close to Browse Island,

Echuca Shoal and other potential, and known, natural seep locations. The project will provide a reference

dataset of thermogenic hydrocarbon concentrations at discrete locations that could be referred to in the

event of an unintended hydrocarbon release at the Prelude and Ichthys developments. The results

obtained during this study will provide contextual data to support projects 5 and 7 of the ARP.

The Browse Basin is the best known area of natural hydrocarbon seepage in the marine environment in

Australia (Logan et al., 2010). In particular, the Cornea field, 135 km from the Prelude and Ichthys fields and

originally discovered by Shell (Permit 342-P), is overlain by a vigorous hydrocarbon seep field. In addition,

the area contains a number of pristine environments with no known petroleum hydrocarbon signature in

the waters or sediments.

The purpose of this report is to interpret the data collected during the ARP 2, ARP 5 and ARP 7 programs

across the Browse Basin to understand the hydrocarbon baseline conditions prior to production activities

commencing at the Prelude and Ichthys fields. This report forms a companion report to Ross et al. (2017a)

and Ross et al. (2017 b) which provide a more detailed description of multidisciplinary results from areas of

potential seepage and a focussed report on ARP 2 data. This report integrates both water column profile

data along with geochemical analysis data derived from water column and sediment samples collected

during the ARP 2 6184, ARP 5 M/V Empress and ARP 7 6578 trips. As such the report augments the ARP 2.1

and ARP 2.2 reports delivered as part of this project (Trefry et al., 2015; Gresham et al., 2015).

This report is the task 5 (first revision) deliverable of ARP 2 as part of the subcontract to the agreement between AIMS and Shell Development (Australia) Pty Ltd (No. UI24206) and INPEX Operations Australia Pty Ltd. (No. 800950).


2 | Applied Research Program Project 2 Task 5a Report

2 Marine survey design

Through the Applied Research Program, the ARP 2 project has collected marine survey data and samples for hydrocarbon analysis from a dedicated seeps survey aboard the RV Solander during trip 6184 and also through collaboration with other ARP projects, namely ARP 5 and ARP 7 (Table 1).

Collaboration with the other ARP projects predominantly involves the reoccupation of water profiling, surface water and sediment sampling locations. This was undertaken to establish temporal variability of water and sediment properties across a number of seasons and years.

The survey design of the ARP 2, ARP 5 and ARP 7 are summarised below. Detailed voyage plans and post voyage trip reports can be found in:

ARP 2 - Trefry et al., 2015; Stalvies et al., 2015

ARP 5 - Tonks, 2016a; Tonks, 2016b

ARP 7 – Heyward & Case, 2016.

For the ARP 5 and 7 surveys only, the geochemical characterisation and water and sediment sampling activities are discussed in this report.

Table 1. Survey trips undertaken and sampling operations conducted (inclusive of all voyages up until the end of

2016). Note that further ARP 7 voyages have been undertaken or are planned in 2017.

ARP Main Survey ARP 2 repeat stations

ARP Trip Vessel Duration

Dates Sites Operations CTD casts

Water bottles

fired

Grab samples

Sites Operatio

ns CTD casts

Water bottles

fired

Grab samples

2 6184 RV Solander

10.2 days

7 to 16 May 2015

56 195 66 257 66

5 MV Empress

18 days

22 Nov to 9 Dec 2015

9 158 9* 27 7 7 29 7* 21 6

7 6578 RV Solander

14 days

27 Nov to 10 Dec 2016

1 119 8 16 40 22 18

* CTD data not reported here as only comprises CTD measurements.

2.1 Survey designs

2.1.1 ARP2 hydrocarbon seeps and baseline survey – Trip 6184

The aims of the ARP 2 hydrocarbon seeps and baseline survey (ARP 2 Hydrocarbons Trip ARP2 6184) were

to collect baseline water and sediment geochemical data across a large area of the Browse Basin that could

potentially be impacted during a worst-case spill scenario at the Prelude or Ichthys developments. To

achieve an understanding of baseline conditions, areas of potential seepage were also targeted for study.

The ARP 2 survey comprised the predominant water quality monitoring activities for the ARP program. The

water quality and sediment monitoring data provide contextual data for the other ARP projects, and record

baseline conditions before hydrocarbon production was initiated within the Browse Basin. One intention of

the survey design for ARP 2 was to facilitate the collection of further water quality monitoring data and



geochemical samples through the reoccupation of selected sites by other ARP project surveys with the

intention of establishing the temporal variability of water and sediment properties across a number of

seasons and years.

The field work was predominantly conducted around the Prelude and Ichthys field locations across an area

likely to experience hydrocarbon impacts in the event of an incident at either development. The survey

plan comprised eight survey transects arranged in a radial pattern with ~45 degree spacing around a central

25 km diameter ring at the centre of the survey. This approach was used by the Joint Advisory Group after

the Macondo Incident in the Gulf of Mexico in 2010. The area within the 25 km ring was not sampled due

to ongoing SIMOPS considerations and other proprietary activities being undertaken at the time.

Modelling results have shown that in the event of an incident, those areas closest to the field would expect

to be most impacted, with the modelled plume extending in a south-southwest to east-north-easterly

direction. For this reason, the distribution of sampling sites proposed during ARP 2 was weighted towards

sites closer to the focal point. As shown in Figure 15, a circular exclusion zone around the fields formed the

inner boundary of the proposed survey track. From this boundary, sampling sites were distributed thus:

0 km from the boundary of the central ring

a nominal distance, X, from the boundary, where X = 5.8 km

2X from the boundary, where 2X = 11.6 km

4X from the boundary, where 4X = 23.2 km

8X from the boundary, where 8X = 46.4 km.

As the spill modelling suggests a SSW-ENE spread of surface hydrocarbons resulting from an incident, two

far field sampling stations were also included in the survey design, located 230 km SSW and 203 km ENE

from of the centre of the survey area.

In addition to the main survey area, several focal points for more detailed study were included within the

survey design. These comprised waters offshore Browse Island and waters near to Echuca Shoal and

Heywood Shoal. The sampling stations at these locations were sited to the north, east, south and western

sides of the island and shoals. Around Echuca Shoal and Heywood Shoal, sampling stations visited during

the 2011 Montara studies were re-visited to build on the data gathered from these surveys:

http://www.environment.gov.au/system/files/pages/bcefac9b-ebc5-4013-9c88-a356280c202c/files/2011-

offshore-banks-assessment-survey.pdf.

Eight other focal areas within the survey design included: five areas based on the identification of potential

seeps by INPEX and CSIRO from geophysical data (Figure 1, Areas A, B, C, D, E); one area of synthetic

aperture radar (SAR) anomaly (slick) (Figure 1, Area F), as well as a transit through an area of known

seepage close to the Cornea field in order to reoccupy sampling locations from previous Montara and

Geoscience Australia seep surveys (Figure 1, Area G, H). Time was allocated within the schedule to obtain

opportunistic samples at these sites where sampling stations were not predefined in the sampling plan.

Opportunistic sampling was determined based on the site investigation decision tree for potential seeps

shown in Figure 3.

The operations on board the RV/Solander where broken into two primary tasks. The first task was acoustic

surveying of the water column, seafloor and shallow sub-surface using an EM 2040 multibeam system

operating at 200-400 kHz (see description below). This instrumentation, when used during transect

operations, permitted the collection of seabed bathymetry as well as water column backscatter data. The

data collected can indicate possible hydroacoustic flares within the water column and bathymetric

http://www.environment.gov.au/system/files/pages/bcefac9b-ebc5-4013-9c88-a356280c202c/files/2011-offshore-banks-assessment-survey.pdf

http://www.environment.gov.au/system/files/pages/bcefac9b-ebc5-4013-9c88-a356280c202c/files/2011-offshore-banks-assessment-survey.pdf



morphologies caused by gas seeps. Once again, if potential seeps were encountered during transects the

sampling decision tree (Figure 3) was utilised to effectively characterise and sample the potential seep.

The second task was the collection of water and sediment samples from predefined or opportunistic

sampling stations (as discussed above). At each sampling station, surface waters were collected. This was

followed by the deployment of a conductivity temperature depth (CTD) profiler with water sampling Niskin

bottle rosette, attached to which was an array of sensors, tuned to monitor the chemical and physical

properties of the water column. The CTD and associated apparatus was lowered through the water column

to a depth just above the seabed to firstly characterise, and secondly, collect samples from, the water

column. After recovery of the CTD, a Smith McIntyre sediment grab was deployed to sample surficial

seafloor sediments. The detailed sampling plan and equipment used is outlined below.

The dates allocated for the survey included time for mobilisation, steaming to and from site and

demobilisation. The schedule was based on 24-hour operations and a 24hour weather contingency was

factored into the plan to allow for delays caused by inclement weather. Further flexibility was incorporated

through the prioritisation of the sites to maximise outcomes should poor weather have resulted in

diminished time available for planned survey activities. The ARP 2 6184 was successfully completed as

planned between 07/05/2015-18/05/2015, visiting all 56 of the planned sampling sites.

Figure 1. ARP2 Trip 6184 survey design overlain on survey area with INPEX focal areas, known seepage and SAR

anomalies marked.



Figure 2. Browse Island, potential seep areas A, B, C and F, Echuca Shoal and Heywood Shoal focal areas with

sampling station locations marked.



Figure 3. Site investigation decision tree for potential seeps



2.1.2 ARP 5 Establishing the basis to evaluate the effects of an oil spill on commercially important demersal fishes - MV Empress trip November 2015

The objectives of this ARP 5 trip were to:

a) To deliver improved baseline understanding of the status and spatial variability in populations of

commercially and ecologically important finfish of the Browse Basin region, centred on the

Prelude/ Ichthys development. The target species include Goldband snapper, Red emperor,

Spangled emperor and Saddletail snapper.

b) Quantify baseline levels of biochemical markers and indicators of hydrocarbon exposure for key

commercial species at the selected sampling sites, providing an improved understanding of spatial

variation in these indicators in areas surrounding the Prelude and Ichthys developments, and

increased ability to detect point source impacts in that region.

To achieve these objectives at each of the designated ARP5 sites (SL1-SL9, Figure 4) it was intended that sampling equipment was deployed in order to examine the demersal fish communities and water/ sediment chemistry, physical properties and water column profiles.

At each site the fishing director located appropriate fish trap and baited remote underwater video (BRUV)

sites within 2.5 nm radius of the actual ARP5 site coordinates. The fish and BRUV sites were selected based

on bottom structure and fish life detected on a fish echo sounder in order to target fish habitat. Fishing

activity was planned so that soak times of fish traps would be at least 3 hours around the slack tide.

Therefore, the first trap was to be set about 1.5 hours before and retrieved about 1.5 hours after slack tide.

Fish traps and BRUVs were to be deployed alternately until all seven traps and seven BRUVS were set. The

distance between deployed fish traps and BRUVs was to be at least 0.15 nm (250 m) and traps were to be

set cross current from each other so that a level of independence was maintained.

At completion of trap/ BRUV deployments, water/ sediment sampling was conducted near the actual site

coordinates, and up-current at a distance of at least 0.3 nm from trap/ BRUV sites. This ensured that water

chemistry samples were not affected by pilchard bait, fuel etc. Furthermore, the sampling was timed near

the slack tide so that the water/ sediment sampling equipment was set at appropriate depths without

being affected by the strong currents that are characteristic of this region. Once a water/sediment site was

determined, the secchi disk, CTD, niskin bottles (set at three depths – 5 m from surface, mid water and 10

m from the bottom) and sediment grab were deployed.

At completion of water/ sediment sampling the vessel returned to the first trap to begin retrieval of traps/

BRUVs. As traps were retrieved, fish were measured and photographed, and non-target species returned to

the water as soon as possible, using necessary measures to ensure fish were returned to water in optimum

condition. The target species required for toxicology assessment were either processed immediately or

placed into a 1000 L live tank for processing at a later stage. Once fish tissue was taken for toxicology

samples, the ear bones (otoliths) were removed, labelled and stored for WA Fisheries.

At completion of the trip the water, sediment and fish toxicology samples were returned to Perth by air,

with scientific staff ensuring that sample integrity was maintained.

Collection of water and sediment samples from ARP2 sites that were on or near the transit routes between

ARP5 sites were sampled where time permitted.



Figure 4. ARP5 M/V Empress survey design overlain on survey area with known seepage and SAR anomalies

marked.

2.1.3 ARP7 Reefs survey – Trip 6578

Objectives of this field trip were to:

a) Establish initial survey sites for benthic habitats and fish communities at Browse Island, with a focus

on reef crest, shallow reef slope and deeper reef apron areas around the island.

b) Collect samples of water and sediment at Heywood, Echuca Shoal and around Browse Island in

support of ARP2 hydrocarbon baseline studies (Figure 5 and Figure 6).

The voyage supported collection of water and sediment samples to compliment previous sampling for ARP2

near shoals and reefs. Samples from Heywood and Echuca Shoal were collected for that program en-route

to Browse Island, with additional samples also collected around the island during the course of the voyage.

Some additional shallow reef slope and intertidal beach sediments were collected for the first time this trip.

The focus of work while at Browse Island was to establish survey sites for benthos and fish, in three depth

zones, at multiple locations around the island. The approach for the benthic and fish survey around Browse

Island consisted of sampling with hand deployed drop cameras and BRUVS from auxiliary boats, in reef flat

and shallow reef slope habitats, and using larger towed camera gear and stereo BRUVS from RV Solander in

depths greater than 10 m. Benthic habitat sampling focussed on establishing four groups of three reef flat

/crest locations (12 locations), four groups of three reef slope locations (12 locations) and 20 transects of

the deeper reef apron around the island.



The reef crest and shallow slope benthic communities were sampled with drop cameras. Fish communities

were sampled using small single camera BRUVS in the shallow slope habitat. The deeper apron of reef

around Browse Island was not well known and satellite imagery does not penetrate deep enough to reveal

any habitat patterns along the western side. In order to provide an initial description and inform the final

survey design, the deeper reef zone was surveyed from RV Solander using towed video in the early part of

the cruise. This enabled a more targeted sampling design within key habitats during the second half of the

voyage with towed video and stereo BRUVS from RV Solander.

During the 2016 survey sampling of reef crest and shallow reef slope, sites were repeated up to three times

at representative sites, to enable an analysis of the variability these non-diver methods introduce into the

data.

Figure 5. ARP7 Trip 6578 survey design overlain on survey area with known seepage and SAR anomalies marked.



Figure 6. ARP7 Trip 6578 survey design in each area focal area.



2.1.4 Survey equipment for seafloor and water column characterisation and sampling

For the ARP 5 and ARP 7 (Trip 6578) surveys there was a suite of equipment used to achieve the survey

objectives which are discussed in Tonks, 2016a and Heyward & Case, 2016. For the identification of seeps

and collection of water a subset of equipment was used.

The ARP2 6184 and ARP 7 6578 trip utilised the RV Solander (Figure 7). Water column characterisation and

water sampling were conducted using an augmented conductivity temperature depth (CTD) profiler rosette

with additional integrated chemical and physical sensors (Figure 7). Sediments were collected using a Smith

McIntyre sediment grab. For the ARP2 6184 trip a multibeam echo sounder was also fitted to the vessel for

seafloor and water column acoustic characterisation.

The ARP 5 trip utilised the MV Empress (Empress Marine). Water column characterisation used a hand

deployed CTD lowered through the water column and water sampling occurred through the deployment of

a Niskin bottle line which was lowered through the water column to near the seabed. Niskin bottles were

primed and attached to a deployment line at desired depths and closure triggered by a messenger weight

(Tonks 2016a). Sediments were collected using a Smith McIntyre sediment grab.

Figure 7. RV Solander (left), augmented CTD profiler (middle) and Smith McIntyre grab (right).

Multibeam Echosounder System (MBES)

For the ARP 2 6184 trip, a Kongsberg EM 2040 multibeam echosounder system (MBES) was used for

bathymetric mapping. The portable, single head system with a working frequency of 200-400 kHz was

mounted through the moon pool shaft of the RV Solander on a retractable carriage. After the setup, a

standard calibration was completed prior to the start of the survey. The optimum speed for the MBES

survey is 6 knots, although the MBES was also operated during times when the vessel was transiting at

higher speeds.

In addition to bathymetric swathing, the EM 2040 system is also capable of simultaneously recording water

column back scatter data. The water column back scatter recording module was run during bathymetric

mapping to detect the presence of hydroacoustic fares indicative of active gas seeps in the area.

While the MBES operations did not require a marine mammal observer or special permits (due to much

higher frequency of operation when compared to seismic operations), a cetacean policy was adopted in

order to minimise noise exposure to cetaceans in the vicinity of the vessel.



Sediment Sampler

For each of the three trips reported here either an AIMS or CSIRO Smith McIntyre grab sampler was used

for the collection of seabed sediments. The grab sampling was carried out at the predetermined sampling

stations as well as at the stations of interest defined by real-time acoustic observation during the ARP 2

6184 survey.

Instrumented Conductivity Temperature Depth profiler (CTD)

The CTD used on the RV Solander during the ARP2 6184 and ARP 7 6578 marine surveys comprised a

complex package of sensor instrumentation and a water sampling bottle array. The core of this system was

a Sea Bird Electronics SBE 25plus CTD, used to record conductivity, temperature and depth during the

deployments, which were carried out at speeds of 1 m/s. The system was augmented with an 8 bottle (10 L

each) water sampling carousel. The CTD system was interfaced with additional sensors to measure a large

number of chemical and physical parameters through the water column which included:

SBE3T, temperature sensor

SBE4C, conductivity sensor

Pressure sensor

Refined hydrocarbons or polycyclic aromatic hydrocarbon concentration (Chelsea Technologies UV

AquaTracka, CHR/PAH)

Crude hydrocarbons (CHC) or coloured dissolved organic matter concentration (CDOM) (Chelsea

Technologies UV AquaTracka)

Chlorophyll concentration (Chelsea Technologies AquaTracka III, CHL)

Turbidity (Chelsea Technologies AquaTracka III, nephelometer)

Dissolved oxygen concentration (JFE Advantech RINKO3 DO and Temperature)

Dissolved methane concentration (CONTROS, CH4 or Franatech Laser Methane sensor)

Particle size distribution and volume concentration (Sequoia LISST-Deep).

All sensors used were rated for the water depths investigated. Due to the high power consumption of these

multiple instruments and sensors, an external battery pack able to supply the additional power was

required. All data were collected at 24 Hz. The dissolved methane concentration sensor has a response

longer than 1 second, however, changes in response can be detected within 5 seconds.

The use of a live-wire configuration permitted live display of the sensor data as the array descended

through the water column. This enabled the observation of the sensor data from the vessel control room,

and hence the collection of opportunistic water samples if any sensor anomaly was detected within the

water column.

All data from the CTD were processed for quality assurance and control using the IMOS toolbox

(https://github.com/aodn/imos-toolbox/wiki) and CSIRO developed Matlab scripts for other sensor data.

The collection of water samples collection was performed on the up cast of the CTD system permitting

review of the water column sensor data. This included sampling from predetermined water depths or

particular water column features (Figure 8). Flexibility was retained within the sampling approach to collect

samples from depths with hydrocarbon anomalies. The exact depths of water sample collection was

determined in consultation with the ship’s crew, to determine the practical operating depths of the CTD

and observation of depths of potential interest during downcast operations.

https://github.com/aodn/imos-toolbox/wiki



Figure 8 CTD sampling depths overview. OB = off bottom, FS = from surface, TC = Thermocline.

CTD data collected from ARP 5 will not be presented here as the purpose of the deployment of the CTD

during ARP 5 was to only measure basic water column physical properties.

2.1.5 Sampling approach

Where possible within the operational constraints of the ARP surveys, water and sediment sampling for

geochemical samples has been standardised and standard operating procedures have been used. The

sampling approach attempted to collect samples which, upon analysis, would reliably enable the

determination of hydrocarbons of environmental concern. In addition, samples for metals analysis

including mercury were also collected as these are often associated with discharged waters from producing

oil and gas fields and thus a baseline characterisation of these chemical species is required. Data from these

samples and subsequent analyses are not reported here as they were not the focus of the ARP2 study.

2.1.6 Sampling plan summary

The sampling plan for each sampling station is summarised in Figure 9 and Table 2. The sampling plan for each ARP included:



Collection of surface waters using 350 mL wide-mouth glass jars, stored at 4°C. These samples were

analysed to assess the background levels of dissolved hydrocarbons in surface waters.

Water column samples collected Niskin bottles were sampled for:

o Dissolved hydrocarbons (PAH/TPH) - These waters were collected in 1 L amber glass

bottles; no preservative was added.

o Benzene, toluene, ethylbenzene and xylenes (BTEX) - Samples (in duplicate) were collected

in pre-acidified 40 mL volatile organic analyte (VOA) vials.

o Mercury - Water from the Niskin bottles was filtered through an Acrodisc PSF Ion Chrom

0.45 µm filter before being collected into 100 mL amber glass bottles, pre-filled with an

aliquot of the preservative dichromate.

o Other metals - Waters from Niskin bottles were passed through an Acrodisc PSF Ion Chrom

45 µm filter before being collected in 125 mL plastic bottles, pre-filled with an aliquot of

nitric acid to act as a preservative.

Collection of sediments using grabs. Sediments were collected for organic geochemical analysis and

headspace gas analysis, with the intention of investigating the background thermogenic

hydrocarbon signature present. Sediments were collected in 250 mL glass jars (organic

geochemistry) and 500 mL IsoPak bags (headspace gas samples). Samples were stored at -20

degrees Celsius (for organic geochemistry) and -80 degrees Celsius (headspace gas samples).

Due to the nature of the underlying geology of the survey area, it was anticipated that natural hydrocarbon

seeps may be observed. Where this manifested as surface slicks or sheens, additional samples were to be

collected using two Teflon nets (known as GO nets), to be stored at 4°C. These samples were to be analysed

for the organic geochemical signature of the oil captured using standard GC-MS techniques by ChemCentre

using methods described below.



Figure 9 Samples taken from each type of sampling gear



Table 2. Example sampling matrix for each ARP 2 sampling station (Mercury and metals samples not shown as these were additional samples and analysis collected outside the

scope of ARP 2)

Sheen or Slick Oil BTEXDissolved

HydrocarbonsHeadspace Gas

PAHs, Biomarkers,

TOC, Rock-Eval

Destination Lab ChemCentre ChemCentre ChemCentre ChemCentre ChemCentre

Total samples per station 2 per station

2 per depth sampled

(max of 10 plus

anomaly samples)

4 plus samples from

anomalous sensor

readings

1 1

Sampler

TypeDepth Interval

Wide mouth

jarsSurface water Y Y Y 350

10 m from bottom Y 40 Y 40

Below thermocline Y 40 Y 40

Above thermocline Y 40 Y 40

5 m from surface Y 40 Y 40

On sighting sensor anomaly Y 40 Y 40

10 m from bottom Y 1000 Y 1000

Below thermocline Y 1000 Y 1000

Above thermocline Y 1000 Y 1000

5 m from surface Y 1000

On sighting sensor anomaly Y 1000 Y 1000

250 ml sediment from lower

seds recoveredY 250 Y

500 (max vol

of IsoPak)

125 ml sediment from grab

sediment recoveredY 125 Y 250

Type of container/vesselStorage volume requirements per

individual sample/aliquot(ml)

Smith-

McIntyre

grab

Type of sample

Quantity of each

sample/aliquot (ml)4 (fridge

volume

required)

-20 -80

Niskin

bottles

40 ml VOA vial350 ml clear

glass jar

1 L amber

glass

bottle

IsoPak

250 ml

clear glass

jar

If any sites of seepage are encountered, additional samples will be collected.



2.2 Analytical program and data processing

2.2.1 Acoustic data processing from ARP 2

In the set up and calibration of the Kongsberg EM 2040C multibeam system an initial patch test was

conducted at Anzac Shoal. Updated sound velocity profiles (SVPs) were applied periodically throughout the

survey to maintain depth calibrations. A depth check was conducted on arrival in Darwin as it had not been

possible to conduct an accurate test in Broome due to strong tidal currents. The results of the depth check

indicated a problem, and the Z-offset to the transducer face was re-measured, and an error found.

Consequently, a correction of 0.109 m was applied in post-processing.

Acquisition

The EM 2040C was run continuously upon departure from Broome. Data collected prior to the patch test

being conducted at Anzac Shoal was post-processed to correct for the calibration values determined.

Due to warm water conditions and seabed geomorphology, the EM 2040C would ‘lose’ the bottom earlier

than expected and/or provide extremely noisy data at depths past approximately 250 m. Therefore, there

were areas of the survey where no bathymetric data were collected due to the depths exceeding the

capabilities of the system.

The EM 2040C system was set to acquire data between 200 kHz and 300 kHz depending on the depth, with

the pulse width set to ‘automatic mode’. Filters and gains were set at the Kongsberg recommended default

settings.

SVPs were conducted before acquisition each day and when the profiles surface sound speed varied by

more than 2m/s from the sound speed acquired at the multibeam transducer in real-time. All sound

velocity corrections were applied in real-time within the acquisition software.

The soundings were motion corrected in real-time within the acquisition software. Acquisition was

undertaken by Stuart Edwards and Matt Boyd from CSIRO.

Processing

Processing of the multibeam data was undertaken using CARIS HIPS/SIPS v8.1.7 software.

Swath bathymetry profiles were examined within CARIS HIPS to remove erroneous beams/profiles. A

summary of the processing steps undertaken is given below.

Manual swath editing to review the quality of the bathymetric data and remove outliers closer to

the seabed

Application of tides

Generation and review of the mean depth surfaces followed by subset editing

Generation of final gridded surfaces for ASCII XYZ data export and GeoTIFF creation.

All processing of data was carried out by Stuart Edwards.



Product creation

The processed bathymetry was used to create some standard products. This included:

Bathymetry and backscatter GeoTIFFs

Bathymetry and backscatter xyzs

Generic sensor format (GSF) files for all lines within the sampling area.

2.2.2 Chemical sensor data processing from ARP 2 and ARP 7

Before chemical sensor data processing was undertaken, each of the sensors was recalibrated using both

manufacturer and CSIRO standard operating procedures as discussed below. The calibration certificates are

included in Appendix A2.

UV AquaTracka (PAH or refined hydrocarbon, and CDOM or crude hydrocarbon)

UV AquaTracka instruments were calibrated based on a CSIRO calibration method described in the UV

AquaTracka handbook HB151 V1.2. In order to limit the instrument measurement offset, the method was

adapted to replicate field deployment conditions. To do so, the sensor head was completely immersed in a

2 L beaker of water and subjected to serial additions of calibrant seawater solution. While this calibration

approach mitigates any offset observed between laboratory and field deployments, it does not completely

negate it. It is common for fluorimeters to record baseline values in synthetic seawater used in laboratory

calibrations above those encountered in the field and it is likely that there is very minor florescence

quenching/suppression within seawater at particularly excitation/emission wavelengths that cannot be

recreated in the laboratory. Whilst the data can simply manually re-zeroed after each trip our approach

here is not to do so. If we were to manually re-zero after each trip we would be assuming that the

minimum response obtained in the field from that trip was the same for all trips which it is not and

therefore the data would incorporate artificial baseline shifts/bias for each data set. Hence, in this report,

the data has not been re-zeroed and therefore negative concentrations have been reported.

AquaTracka III

The chlorophyll sensor and nephelometer were calibrated using the method described in the AquaTracka III

HB101 handbook. However, calibration of the nephelometer sensor was calibrated using the 2 L beaker

serial calibration method described above, whereas for the UV AquaTracka a calibration cell was used, as

the optical window of the sensor can be damaged by the acetone used for cleaning.

RINKO3 DO

The Rinko3 DO sensor was calibrated in-house using the manufacturer’s procedure from JFE Advantech available on request.

SBE3T, SBE4C and Pressure Sensor

Temperature, conductivity and pressure sensors were calibrated at the CSIRO calibration facility in Hobart as per IMOS standards.

CONTROS CH4/Franatech Laser Methane Sensor

During Trip 6184 the CONTROS CH4 sensor failed after a few deployments and the instrument became flooded with seawater. For this reason, the CONTROS data have not been included in this report. During Trip



6578 a Franatech laser methane sensor was used for methane detection as this has built in algorithms which enable rapid response times (<30 seconds) and higher methane sensitivities than the CONTROS CH4

sensor.

This instrument was calibrated prior to use on the 6578 trip by Franatech. During this trip a 3 millivolt loading was observed on the analogue channel caused by interference from the altimeter on the CTD analogue circuit on detection of the seafloor. This shows that the input on the CTD is not fully isolated, this issue has been raised with Seabird (CTD manufacturer) and they are working on a solution. In order to avoid this issue in the future the altimeter has now been placed on the last CTD analogue input. As the interference between analogue channels has been identified this can be post processed in the data to remove the artefact. This has not been completed for the trip 6578 data as no methane was detected.

LISST-Deep

High background noise was noticed on this instrument before the trip 6184 mobilisation. Advice was sought from Sequoia Scientific (manufacturer), and the instrument was deemed to be deployable. The instrument was recalibrated after the voyage by Sequoia Scientific and subsequently successfully deployed with no issues during trip 6578.

2.2.3 Analytical methods for water and sediment samples

The samples were returned to Perth using chain-of-custody protocols whereupon they were analysed by

ChemCentre. All samples were received within their recommended holding times.

Water samples

BTEX

Water samples were analysed for BTEX compounds directly using purge-and-trap gas chromatography mass spectrometry (P&T GC-MS). Samples were prepared and analysed using ChemCentre method ORG002WL2 - Low level volatile organic compounds (VOCs) by P&T GC-MS.

PAHs

Water samples underwent liquid-liquid extraction with dichloromethane (DCM). The DCM extracts were chemically dried with sodium sulphate, and concentrated by rotary evaporator. The concentrated solvent extracts underwent clean-up to remove interfering polar compounds using a silica gel flash chromatography column. Deuterated internal standards were added, and the extracts were then analysed by GC-MS. The inlet was a programmed temperature vaporising (PTV) injector with large volume injection. The mass spectrometer was operated in selected ion monitoring (SIM) mode. The ChemCentre methods used for preparation and analysis were ORG020WL - PAH in water by GC-MS with low limits of reporting (LOR), and ORG020WLA - Alkylated PAH homologues in water with low LOR.

TPH - Alkanes and unresolved complex mixture (UCM)

The hydrocarbon extracts from above were re-analysed by gas chromatography flame ionisation detection (GC-FID), using PTV large volume injection. Preparation and analysis used the ChemCentre method ORG007WL n-Alkanes in Water with low detection limits.

All processed geochemical data can be found in the ChemCentre analytical reports:

14B0708 – Bulk water column samples

14B0710 – Surface water samples

14B0711 – Daily BTEX field blank samples.



Metals

Filtered water samples were acidified with nitric acid and analysed by inductively coupled plasma optical emission spectrometry/mass spectrometry (ICP-OES/MS) for silver (Ag), aluminium (Al), arsenic (As), barium (Ba), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), molybdenum (Mo), nickel (Ni), lead (Pb), antimony (Sb), tin (Sn), titanium (Ti), vanadium (V) and zinc (Zn). Metals were prepared and analysed using a combination of the ChemCentre methods iMET1WCICP - Total dissolved metals by inductively coupled plasma atomic emission spectroscopy (ICP-AES), and iMET1WCMS - Total dissolved metals by inductively coupled plasma mass spectrometry (ICPMS). Mercury was determined by cold vapour atomic absorption spectroscopy (AAS) using a CETAC autoanalyser, using the ChemCentre method iHGL1WCVG Dissolved mercury in water by digestion, cold vapour atomic absorption spectroscopy (CV-AAS).

Sediment samples

Methane

IsoPak bags were warmed to room temperature, and a portion of the headspace was analysed directly by GC-FID. Preparation and analysis followed ChemCentre method ORG512 - Analysis of air by gas chromatography thermal conductivity detection flame ionisation detection (GC/TCD/FID).

BTEX

Sediments were extracted with methanol, and a portion of methanol was diluted in ultra-pure water, and analysed by P&T GC-MS. Samples were prepared and analysed using the ChemCentre method ORG002SL - BTEX in soil with low LOR.

PAHs

A sub-sample of sediment was extracted using three aliquots of 1:1 DCM/methanol. The extracts were combined and partitioned in water to remove the methanol and any excess water from the sample. The solvent extracts were chemically dried with sodium sulphate, and concentrated by rotary evaporator. The concentrated solvent extracts underwent clean-up to remove interfering polar compounds using a silica gel flash chromatography column. Deuterated internal standards were added, and the extracts were then analysed by GC-MS. The inlet was a PTV injector with large volume injection. The mass spectrometer was operated in SIM mode. The ChemCentre methods used for preparation and analysis were ORG020SL - PAHs in soil by GC-MS with low LOR, and ORG020SLA - Alkylated PAH homologues in soil with low LOR.

TPH - Alkanes and UCM

The PAH extracts were re-analysed by GC-FID, using PTV with large volume injection. Preparation and analysis used the ChemCentre method ORG007SL - n-Alkanes in soil with low LOR.

All processed geochemical data can be found in the ChemCentre analytical reports:

14B0709 – Sediment samples.

Metals

Sediment was dried and ground and then digested by microwave with nitric and hydrochloric acids. A diluted portion of the digest was analysed by ICP-OES/MS for silver (Ag), aluminium (Al), arsenic (As), barium (Ba), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), molybdenum (Mo), nickel (Ni), lead (Pb), antimony (Sb), tin (Sn), titanium (Ti), vanadium (V) and zinc (Zn). Metals were prepared and analysed using a combination of the ChemCentre methods iMET2SAICP - Acid digestible metals (dry wt basis) by digestion and ICPAES, and iMET2SAMS - Acid digestible metals (dry weight basis) by ICPMS. Mercury was determined by cold vapour AAS using a CETAC autoanalyser using the ChemCentre method iHG2STVG - Mercury (dry basis) in soil/sediments based on USEPA 3051A digestion and CV-AAS.



3 Results and discussion

3.1 ARP2 Trip 6184 operations and sampling

The ARP 2 hydrocarbon seeps and baseline survey - trip 6184 - took place 7th May and 18th May 2015 during

which 56 stations were visited. 195 operations were undertaken during the survey and 1247 samples were

collected for subsequent analysis. Table 3 summarises the operations and samples collected during each

operation.

The primary purpose of the voyage was to establish baseline physical and geochemical properties of the

water column and sediments across the Browse Basin. The data collected from the water column profiling

instruments and analyses on samples collected from the water column and seabed sediments are

summarised in sections 3.4, 3.5 and 3.6 below.

Table 3. Operations undertaken and samples collected during the ARP 2 hydrocarbon seeps and baseline survey -

trip 6184.

ST

AT

ION

LO

CA

L

DA

TE/T

IME

LN

GX

LA

TY

SA

MP

LE

TY

PE

OP

ER

AT

ION

DE

PT

H (M

)

BT

EX

/ VO

LA

TIL

E

OR

GA

NIC

S

HE

AD

SP

AC

E G

AS

ME

RC

UR

Y

ME

TA

LS

PA

H/T

PH

UN

SP

EC

IFE

D

1 9/05/2015 1:57 -15.7668 122.0364 Water CTD_001 5 1

1 1 1

1 9/05/2015 1:57 -15.7668 122.0364 Water CTD_001 64 1

1 1 1

1 9/05/2015 2:37 -15.7674 122.0361 Sediment SMG_002 74

1

1

1 9/05/2015 2:42 -15.7669 122.0362 Water SWAT_003 0

1

2 9/05/2015 13:42 -14.7345 123.6245 Water CTD_004 5 1

1 1 1

2 9/05/2015 13:42 -14.7345 123.6245 Water CTD_004 25 1

1 1 1

2 9/05/2015 13:42 -14.7345 123.6245 Water CTD_004 80 1

1 1 1

2 9/05/2015 14:15 -14.7338 123.6247 Water CTD_005 5 1

1 1 1

2 9/05/2015 14:15 -14.7338 123.6247 Water CTD_005 25 1

1 1 1

2 9/05/2015 14:15 -14.7338 123.6247 Water CTD_005 80 1

1 1 1

2 9/05/2015 14:27 -14.7348 123.6230 Sediment SMG_006 90

1

1

2 9/05/2015 14:40 -14.7345 123.6249 Sediment SMG_007 90

1

1

2 9/05/2015 14:50 -14.7339 123.6226 Water SWAT_008 0

1

2 9/05/2015 14:52 -14.7298 123.6208 Water SWAT_009 0

1

3 9/05/2015 17:44 -14.3463 123.4208 Water CTD_010 5 1

1 1 1

3 9/05/2015 17:44 -14.3463 123.4208 Water CTD_010 60 1

1 1 1

3 9/05/2015 17:44 -14.3463 123.4208 Water CTD_010 80 1

1 1 1

3 9/05/2015 17:44 -14.3463 123.4208 Water CTD_010 115 1

1 1 1

3 9/05/2015 18:10 -14.3475 123.4193 Sediment SMG_011 122

1

1

3 9/05/2015 18:11 -14.3473 123.4187 Water SWAT_012 0

1

4 9/05/2015 19:47 -14.1598 123.3239 Water CTD_013 5 1

1 1 1

4 9/05/2015 19:47 -14.1598 123.3239 Water CTD_013 60 1

1 1 1

4 9/05/2015 19:47 -14.1598 123.3239 Water CTD_013 145 1

1 1 1



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4 9/05/2015 19:47 -14.1598 123.3239 Water CTD_013 172 1

1 1 1

4 9/05/2015 20:22 -14.1588 123.3229 Sediment SMG_014 180

1

1

4 9/05/2015 20:30 -14.1590 123.3226 Water SWAT_015 0

1

5 9/05/2015 22:14 -14.0601 123.2722 Water CTD_016 5 1

1 1 1

5 9/05/2015 22:14 -14.0601 123.2722 Water CTD_016 50 1

1 1 1

5 9/05/2015 22:14 -14.0601 123.2722 Water CTD_016 100 1

1 1 1

5 9/05/2015 22:14 -14.0601 123.2722 Water CTD_016 200 1

1 1 1

5 9/05/2015 22:14 -14.0601 123.2722 Water CTD_016 250 1

1 1 1

5 9/05/2015 22:39 -14.0601 123.2717 Sediment SMG_017 260

1

1

5 9/05/2015 22:50 -14.0606 123.2711 Water SWAT_018 0

1

6 9/05/2015 23:15 -14.0137 123.2477 Water CTD_019 5 1

1 1 1

6 9/05/2015 23:15 -14.0137 123.2477 Water CTD_019 50 1

1 1 1

6 9/05/2015 23:15 -14.0137 123.2477 Water CTD_019 200 1

1 1 1

6 9/05/2015 23:15 -14.0137 123.2477 Water CTD_019 230 1

1 1 1

6 9/05/2015 23:15 -14.0137 123.2477 Water CTD_019 263 1

1 1 1

6 9/05/2015 23:34 -14.0156 123.2470 Water SWAT_020 0

1

6 9/05/2015 23:41 -14.0137 123.2480 Sediment SMG_021 273

1

1

7 10/05/2015 3:18 -13.6429 123.1551 Water CTD_022 5 1

1 1 1

7 10/05/2015 3:18 -13.6429 123.1551 Water CTD_022 50 1

1 1 1

7 10/05/2015 3:18 -13.6429 123.1551 Water CTD_022 73 1

1 1 1

7 10/05/2015 3:18 -13.6429 123.1551 Water CTD_022 255 1

1 1 1

7 10/05/2015 3:18 -13.6429 123.1551 Water CTD_022 315 1

1 1 1

7 10/05/2015 3:45 -13.6442 123.1553 Sediment SMG_023 325

1

1

7 10/05/2015 4:01 -13.6426 123.1530 Water SWAT_024 0

1

8 10/05/2015 5:37 -13.4535 123.0730 Water CTD_025 5 1

1 1 1

8 10/05/2015 5:37 -13.4535 123.0730 Water CTD_025 60 1

1 1 1

8 10/05/2015 5:37 -13.4535 123.0730 Water CTD_025 80 1

1 1 1

8 10/05/2015 5:37 -13.4535 123.0730 Water CTD_025 200 1

1 1 1

8 10/05/2015 5:59 -13.4524 123.0697 Sediment SMG_026 384

1

1

8 10/05/2015 6:18 -13.4474 123.0722 Water SWAT_027 0

1

9 10/05/2015 9:21 -13.0576 122.8994 Water CTD_028 54 1

1 1 1

9 10/05/2015 9:21 -13.0576 122.8994 Water CTD_028 224 1

1 1 1

9 10/05/2015 9:21 -13.0576 122.8994 Water CTD_028 430 1

1 1 1

9 10/05/2015 9:49 -13.0572 122.8996 Sediment SMG_029 440

1

1

9 10/05/2015 9:59 -13.0570 122.9005 Water SWAT_030 0

1

9 10/05/2015 10:29 -13.0556 122.9028 Water CTD_031 5 1

1 1 1

9 10/05/2015 10:29 -13.0556 122.9028 Water CTD_031 48 1

1 1 1

10 10/05/2015 14:14 -13.3780 122.5052 Water CTD_032 5 1

1 1 1

10 10/05/2015 14:14 -13.3780 122.5052 Water CTD_032 60 1

1 1 1

10 10/05/2015 14:14 -13.3780 122.5052 Water CTD_032 100 1

1 1 1

10 10/05/2015 14:14 -13.3780 122.5052 Water CTD_032 200 1

1 1 1

10 10/05/2015 14:14 -13.3780 122.5052 Water CTD_032 460 1

1 1 1



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10 10/05/2015 14:16 -13.3780 122.5050 Water SWAT_033 0

1

10 10/05/2015 14:41 -13.3762 122.5038 Sediment SMG_034 479

1

1

11 10/05/2015 17:33 -13.6279 122.8552 Water CTD_035 5 1

1 1 1

11 10/05/2015 17:33 -13.6279 122.8552 Water CTD_035 60 1

1 1 1

11 10/05/2015 17:33 -13.6279 122.8552 Water CTD_035 70 1

1 1 1

11 10/05/2015 17:33 -13.6279 122.8552 Water CTD_035 280 1

1 1 1

11 10/05/2015 17:33 -13.6279 122.8552 Water CTD_035 388 1

1 1 1

11 10/05/2015 17:35 -13.6273 122.8548 Water SWAT_036 0

1

11 10/05/2015 17:59 -13.6293 122.8566 Sediment SMG_037 406

1

1

12 10/05/2015 19:44 -13.7459 123.0207 Water CTD_038 5 1

1 1 1

12 10/05/2015 19:44 -13.7459 123.0207 Water CTD_038 50 1

1 1 1

12 10/05/2015 19:44 -13.7459 123.0207 Water CTD_038 160 1

1 1 1

12 10/05/2015 19:44 -13.7459 123.0207 Water CTD_038 240 1

1 1 1

12 10/05/2015 19:44 -13.7459 123.0207 Water CTD_038 319 1

1 1 1

12 10/05/2015 20:00 -13.7440 123.0200 Water SWAT_039 0

1

12 10/05/2015 20:01 -13.7439 123.0200 Water SWAT_040 0

1

12 10/05/2015 20:05 -13.7453 123.0209 Sediment SMG_041 339

1

1

12 10/05/2015 20:20 -13.7472 123.0218 Sediment SMG_042 339

1

1

12 10/05/2015 20:43 -13.7474 123.0226 Water CTD_043 5 1

1 1 1

12 10/05/2015 20:43 -13.7474 123.0226 Water CTD_043 50 1

1 1 1

12 10/05/2015 20:43 -13.7474 123.0226 Water CTD_043 160 1

1 1 1

12 10/05/2015 20:43 -13.7474 123.0226 Water CTD_043 240 1

1 1 1

12 10/05/2015 20:43 -13.7474 123.0226 Water CTD_043 319 1

1 1 1

13 10/05/2015 21:54 -13.8082 123.1080 Water SWAT_045 0

1

13 10/05/2015 21:55 -13.8083 123.1079 Water CTD_044 5 1

1 1 1

13 10/05/2015 21:55 -13.8083 123.1079 Water CTD_044 40 1

1 1 1

13 10/05/2015 21:55 -13.8083 123.1079 Water CTD_044 140 1

1 1 1

13 10/05/2015 21:55 -13.8083 123.1079 Water CTD_044 220 1

1 1 1

13 10/05/2015 21:55 -13.8083 123.1079 Water CTD_044 285 1

1 1 1

13 10/05/2015 22:16 -13.8085 123.1080 Sediment SMG_046 306

1

1

14 10/05/2015 23:27 -13.7397 123.1964 Water CTD_047 5 1

1 1 1

14 10/05/2015 23:27 -13.7397 123.1964 Water CTD_047 40 1

1 1 1

14 10/05/2015 23:27 -13.7397 123.1964 Water CTD_047 200 1

1 1 1

14 10/05/2015 23:27 -13.7397 123.1964 Water CTD_047 250 1

1 1 1

14 10/05/2015 23:27 -13.7397 123.1964 Water CTD_047 280 1

1 1 1

14 10/05/2015 23:41 -13.7403 123.1979 Water SWAT_048 0

1

14 10/05/2015 23:47 -13.7407 123.1977 Sediment SMG_049 283

1

1

15 11/05/2015 0:24 -13.7865 123.2174 Water CTD_050 5 1

1 1 1

15 11/05/2015 0:24 -13.7865 123.2174 Water CTD_050 47 1

1 1 1

15 11/05/2015 0:24 -13.7865 123.2174 Water CTD_050 65 1

1 1 1

15 11/05/2015 0:24 -13.7865 123.2174 Water CTD_050 231 1

1 1 1

15 11/05/2015 0:24 -13.7865 123.2174 Water CTD_050 260 1

1 1 1



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15 11/05/2015 0:34 -13.7854 123.2164 Water SWAT_051 0

1

15 11/05/2015 0:45 -13.7850 123.2200 Sediment SMG_052 274

1

1

16 11/05/2015 1:45 -13.8401 123.1535 Water CTD_053 5 1

1 1 1

16 11/05/2015 1:45 -13.8401 123.1535 Water CTD_053 66 1

1 1 1

16 11/05/2015 1:45 -13.8401 123.1535 Water CTD_053 101 1

1 1 1

16 11/05/2015 1:45 -13.8401 123.1535 Water CTD_053 156 1

1 1 1

16 11/05/2015 1:45 -13.8401 123.1535 Water CTD_053 273 1

1 1 1

16 11/05/2015 2:03 -13.8378 123.1571 Sediment SMG_054 284

1

1

16 11/05/2015 2:05 -13.8372 123.1573 Water SWAT_055 0

1

17 11/05/2015 3:14 -13.9276 123.1424 Water CTD_056 5 1

1 1 1

17 11/05/2015 3:14 -13.9276 123.1424 Water CTD_056 61 1

1 1 1

17 11/05/2015 3:14 -13.9276 123.1424 Water CTD_056 79 1

1 1 1

17 11/05/2015 3:14 -13.9276 123.1424 Water CTD_056 200 1

1 1 1

17 11/05/2015 3:14 -13.9276 123.1424 Water CTD_056 258 1

1 1 1

17 11/05/2015 3:22 -13.9264 123.1434 Water SWAT_057 0

1

17 11/05/2015 3:35 -13.9250 123.1443 Sediment SMG_058 274

1

1

18 11/05/2015 4:24 -13.9423 123.0894 Water CTD_059 5 1

1 1 1

18 11/05/2015 4:24 -13.9423 123.0894 Water CTD_059 54 1

1 1 1

18 11/05/2015 4:24 -13.9423 123.0894 Water CTD_059 77 1

1 1 1

18 11/05/2015 4:24 -13.9423 123.0894 Water CTD_059 232 1

1 1 1

18 11/05/2015 4:24 -13.9423 123.0894 Water CTD_059 255 1

1 1 1

18 11/05/2015 4:34 -13.9411 123.0909 Water SWAT_060 0

1

18 11/05/2015 4:41 -13.9404 123.0906 Sediment SMG_061 272

1

1

19 11/05/2015 6:06 -13.9719 122.9857 Water CTD_062 5 1

1 1 1

19 11/05/2015 6:06 -13.9719 122.9857 Water CTD_062 53 1

1 1 1

19 11/05/2015 6:06 -13.9719 122.9857 Water CTD_062 64 1

1 1 1

19 11/05/2015 6:06 -13.9719 122.9857 Water CTD_062 222 1

1 1 1

19 11/05/2015 6:06 -13.9719 122.9857 Water CTD_062 268 1

1 1 1

19 11/05/2015 6:26 -13.9716 122.9856 Sediment SMG_063 282

1

1

19 11/05/2015 6:26 -13.9716 122.9856 Water SWAT_064 0

1

20 11/05/2015 8:59 -14.0271 122.7724 Water CTD_065 5 1

1 1 1

20 11/05/2015 8:59 -14.0271 122.7724 Water CTD_065 52 1

1 1 1

20 11/05/2015 8:59 -14.0271 122.7724 Water CTD_065 72 1

1 1 1

20 11/05/2015 8:59 -14.0271 122.7724 Water CTD_065 232 1

1 1 1

20 11/05/2015 8:59 -14.0271 122.7724 Water CTD_065 338 1

1 1 1

20 11/05/2015 9:17 -14.0248 122.7713 Water SWAT_066 0

1

20 11/05/2015 9:23 -14.0313 122.7767 Sediment SMG_067 351

1

1

21 11/05/2015 13:29 -14.1417 122.3751 Water CTD_069 5 1

1 1 1

21 11/05/2015 13:29 -14.1417 122.3751 Water CTD_069 65 1

1 1 1

21 11/05/2015 13:29 -14.1417 122.3751 Water CTD_069 140 1

1 1 1

21 11/05/2015 13:29 -14.1417 122.3751 Water CTD_069 280 1

1 1 1

21 11/05/2015 13:29 -14.1417 122.3751 Water CTD_069 430 1

1 1 1



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21 11/05/2015 14:21 -14.1406 122.3775 Water SWAT_070 0

1

21 11/05/2015 14:36 -14.1442 122.3746 Sediment SMG_071 444

1

1

22 11/05/2015 20:21 -14.7172 122.8486 Water CTD_072 5 1

1 1 1

22 11/05/2015 20:21 -14.7172 122.8486 Water CTD_072 45 1

1 1 1

22 11/05/2015 20:21 -14.7172 122.8486 Water CTD_072 105 1

1 1 1

22 11/05/2015 20:35 -14.7184 122.8508 Sediment SMG_073 117

1

1

22 11/05/2015 20:35 -14.7184 122.8508 Water SWAT_074 0

1

23 12/05/2015 0:01 -14.3320 123.0364 Water CTD_075 5 1

1 1 1

23 12/05/2015 0:01 -14.3320 123.0364 Water CTD_075 80 1

1 1 1

23 12/05/2015 0:01 -14.3320 123.0364 Water CTD_075 90 1

1 1 1

23 12/05/2015 0:11 -14.3336 123.0361 Water SWAT_076 0

1

23 12/05/2015 0:16 -14.3315 123.0362 Sediment SMG_077 107

1

1

24 12/05/2015 2:05 -14.1391 123.1290 Water CTD_078 5 1

1 1 1

24 12/05/2015 2:05 -14.1391 123.1290 Water CTD_078 44 1

1 1 1

24 12/05/2015 2:05 -14.1391 123.1290 Water CTD_078 64 1

1 1 1

24 12/05/2015 2:05 -14.1391 123.1290 Water CTD_078 130 1

1 1 1

24 12/05/2015 2:05 -14.1391 123.1290 Water CTD_078 270 1

1 1 1

24 12/05/2015 2:17 -14.1408 123.1293 Water SWAT_079 0

1

24 12/05/2015 2:28 -14.1433 123.1294 Sediment SMG_080 285

1

1

25 12/05/2015 3:54 -14.0426 123.1748 Water CTD_081 5 1

1 1 1

25 12/05/2015 3:54 -14.0426 123.1748 Water CTD_081 55 1

1 1 1

25 12/05/2015 3:54 -14.0426 123.1748 Water CTD_081 68 1

1 1 1

25 12/05/2015 3:54 -14.0426 123.1748 Water CTD_081 241 1

1 1 1

25 12/05/2015 3:54 -14.0426 123.1748 Water CTD_081 265 1

1 1 1

25 12/05/2015 3:57 -14.0427 123.1747 Water SWAT_082 0

1

25 12/05/2015 4:17 -14.0423 123.1756 Sediment SMG_083 280

1

1

25 12/05/2015 4:45 -14.0423 123.1749 Water CTD_084 5 1

1 1 1

25 12/05/2015 4:45 -14.0423 123.1749 Water CTD_084 63 1

1 1 1

25 12/05/2015 4:45 -14.0423 123.1749 Water CTD_084 82 1

1 1 1

25 12/05/2015 4:45 -14.0423 123.1749 Water CTD_084 237 1

1 1 1

25 12/05/2015 4:45 -14.0423 123.1749 Water CTD_084 265 1

1 1 1

25 12/05/2015 4:45 -14.0423 123.1749 Water SWAT_085 0

1

25 12/05/2015 5:03 -14.0426 123.1751 Sediment SMG_086 280

1

1

26 12/05/2015 5:59 -13.9981 123.1966 Water CTD_087 5 1

1 1 1

26 12/05/2015 5:59 -13.9981 123.1966 Water CTD_087 61 1

1 1 1

26 12/05/2015 5:59 -13.9981 123.1966 Water CTD_087 82 1

1 1 1

26 12/05/2015 5:59 -13.9981 123.1966 Water CTD_087 180 1

1 1 1

26 12/05/2015 5:59 -13.9981 123.1966 Water CTD_087 260 1

1 1 1

26 12/05/2015 6:03 -13.9980 123.1966 Water SWAT_088 0

1

26 12/05/2015 6:20 -13.9985 123.1962 Sediment SMG_089 276

1

1

27 12/05/2015 9:26 -13.7792 123.3221 Water CTD_090 5 1

1 1 1

27 12/05/2015 9:26 -13.7792 123.3221 Water CTD_090 46 1

1 1 1



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27 12/05/2015 9:26 -13.7792 123.3221 Water CTD_090 64 1

1 1 1

27 12/05/2015 9:26 -13.7792 123.3221 Water CTD_090 210 1

1 1 1

27 12/05/2015 9:26 -13.7792 123.3221 Water CTD_090 240 1

1 1 1

27 12/05/2015 9:28 -13.7790 123.3220 Water SWAT_091 0

1

27 12/05/2015 9:56 -13.7770 123.3226 Sediment SMG_092 263

1

1

28 12/05/2015 10:34 -13.7488 123.3292 Water CTD_093 5 1

1 1 1

28 12/05/2015 10:34 -13.7488 123.3292 Water CTD_093 55 1

1 1 1

28 12/05/2015 10:34 -13.7488 123.3292 Water CTD_093 65 1

1 1 1

28 12/05/2015 10:34 -13.7488 123.3292 Water CTD_093 204 1

1 1 1

28 12/05/2015 10:34 -13.7488 123.3292 Water CTD_093 246 1

1 1 1

28 12/05/2015 10:40 -13.7481 123.3290 Water SWAT_094 0

1

28 12/05/2015 10:56 -13.7473 123.3306 Sediment SMG_095 263

1

1

29 12/05/2015 13:24 -13.6458 123.3573 Water CTD_096 5 1

1 1 1

29 12/05/2015 13:24 -13.6458 123.3573 Water CTD_096 70 1

1 1 1

29 12/05/2015 13:24 -13.6458 123.3573 Water CTD_096 200 1

1 1 1

29 12/05/2015 13:24 -13.6458 123.3573 Water CTD_096 225 1

1 1 1

29 12/05/2015 13:24 -13.6458 123.3573 Water CTD_096 270 1

1 1 1

29 12/05/2015 13:29 -13.6456 123.3549 Water SWAT_097 0

1

29 12/05/2015 13:52 -13.6459 123.3555 Sediment SMG_098 284

1

1

30 12/05/2015 15:40 -13.4434 123.4050 Water SWAT_100 0

1

30 12/05/2015 15:40 -13.4434 123.4050 Water CTD_099 5 1

1 1 1

30 12/05/2015 15:40 -13.4434 123.4050 Water CTD_099 50 1

1 1 1

30 12/05/2015 15:40 -13.4434 123.4050 Water CTD_099 65 1

1 1 1

30 12/05/2015 15:40 -13.4434 123.4050 Water CTD_099 200 1

1 1 1

30 12/05/2015 15:40 -13.4434 123.4050 Water CTD_099 320 1

1 1 1

30 12/05/2015 16:04 -13.4441 123.4053 Sediment SMG_101 337

1

1

31 12/05/2015 19:32 -13.0212 123.5091 Water CTD_102 5 1

1 1 1

31 12/05/2015 19:32 -13.0212 123.5091 Water CTD_102 60 1

1 1 1

31 12/05/2015 19:32 -13.0212 123.5091 Water CTD_102 140 1

1 1 1

31 12/05/2015 19:32 -13.0212 123.5091 Water CTD_102 230 1

1 1 1

31 12/05/2015 19:32 -13.0212 123.5091 Water CTD_102 340 1

1 1 1

31 12/05/2015 19:34 -13.0213 123.5090 Water SWAT_103 0

1

31 12/05/2015 19:59 -13.0212 123.5089 Sediment SMG_104 357

1

1

32 13/05/2015 1:20 -13.4879 124.0295 Water CTD_105 5 1

1 1 1

32 13/05/2015 1:20 -13.4879 124.0295 Water CTD_105 55 1

1 1 1

32 13/05/2015 1:20 -13.4879 124.0295 Water CTD_105 96 1

1 1 1

32 13/05/2015 1:24 -13.4881 124.0291 Water SWAT_106 0

1

32 13/05/2015 1:32 -13.4897 124.0285 Sediment SMG_107 107

1

1

33 13/05/2015 2:39 -13.4385 123.9856 Water CTD_108 5 1

1 1 1

33 13/05/2015 2:39 -13.4385 123.9856 Water CTD_108 55 1

1 1 1

33 13/05/2015 2:39 -13.4385 123.9856 Water CTD_108 101 1

1 1 1

33 13/05/2015 2:45 -13.4392 123.9857 Water SWAT_109 0

1



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GX

LA

TY

SA

MP

LE

TY

PE

OP

ER

AT

ION

DE

PT

H (M

)

BT

EX

/ VO

LA

TIL

E

OR

GA

NIC

S

HE

AD

SP

AC

E G

AS

ME

RC

UR

Y

ME

TA

LS

PA

H/T

PH

UN

SP

EC

IFE

D

33 13/05/2015 2:53 -13.4395 123.9856 Sediment SMG_110 112

1

1

34 13/05/2015 3:53 -13.4030 124.0437 Water CTD_111 5 1

1 1 1

34 13/05/2015 3:53 -13.4030 124.0437 Water CTD_111 54 1

1 1 1

34 13/05/2015 3:53 -13.4030 124.0437 Water CTD_111 82 1

1 1 1

34 13/05/2015 3:53 -13.4030 124.0437 Water CTD_111 97 1

1 1 1

34 13/05/2015 3:57 -13.4029 124.0436 Water SWAT_112 0

1

34 13/05/2015 4:04 -13.4030 124.0431 Sediment SMG_113 110

1

1

35 13/05/2015 4:59 -13.4431 124.0882 Water CTD_114 5 1

1 1 1

35 13/05/2015 4:59 -13.4431 124.0882 Water CTD_114 65 1

1 1 1

35 13/05/2015 4:59 -13.4431 124.0882 Water CTD_114 81 1

1 1 1

35 13/05/2015 5:04 -13.4435 124.0878 Water SWAT_115 0

1

35 13/05/2015 5:10 -13.4436 124.0872 Sediment SMG_116 91

1

1

36 13/05/2015 6:17 -13.5609 124.1053 Water CTD_117 5 1

1 1 1

36 13/05/2015 6:17 -13.5609 124.1053 Water CTD_117 70 1

1 1 1

36 13/05/2015 6:17 -13.5609 124.1053 Water CTD_117 94 1

1 1 1

36 13/05/2015 6:28 -13.5591 124.1049 Sediment SMG_118 104

1

1

36 13/05/2015 6:30 -13.5588 124.1048 Water SWAT_119 0

1

36 13/05/2015 22:54 -13.5585 124.1047 Sediment SMG_126 103

1

1

36 13/05/2015 22:54 -13.5585 124.1047 Water SMG_126 103

1 1

36 13/05/2015 23:16 -13.5581 124.1034 Sediment SMG_127 103

1

1

36 13/05/2015 23:16 -13.5581 124.1034 Water SMG_127 103

1 1

36 13/05/2015 23:32 -13.5572 124.1040 Sediment SMG_128 101

1

1

36 13/05/2015 23:32 -13.5572 124.1040 Water SMG_128 101

1 1

36 13/05/2015 23:54 -13.5574 124.1046 Water CTD_129 10 1

1 1 1

36 13/05/2015 23:54 -13.5574 124.1046 Water CTD_129 65 1

1 1 1

37 13/05/2015 16:05 -13.7011 123.6968 Water SWAT_121 0

1

37 13/05/2015 16:06 -13.7010 123.6968 Water CTD_120 5 1

1 1 1

37 13/05/2015 16:06 -13.7010 123.6968 Water CTD_120 75 1

1 1 1

37 13/05/2015 16:06 -13.7010 123.6968 Water CTD_120 120 1

1 1 1

37 13/05/2015 16:06 -13.7010 123.6968 Water CTD_120 185 1

1 1 1

37 13/05/2015 16:10 -13.7007 123.6965 Water SWAT_122 0

1

37 13/05/2015 16:25 -13.7024 123.6972 Sediment SMG_123 198

1

1

37 13/05/2015 16:34 -13.7020 123.6960 Sediment SMG_124 198

1

1

37 13/05/2015 16:50 -13.7010 123.6968 Water CTD_125 5 1

1 1 1

37 13/05/2015 16:50 -13.7010 123.6968 Water CTD_125 75 1

1 1 1

37 13/05/2015 16:50 -13.7010 123.6968 Water CTD_125 120 1

1 1 1

37 13/05/2015 16:50 -13.7010 123.6968 Water CTD_125 185 1

1 1 1

38 14/05/2015 5:12 -13.7894 123.5057 Water CTD_130 5 1

1 1 1

38 14/05/2015 5:12 -13.7894 123.5057 Water CTD_130 69 1

1 1 1

38 14/05/2015 5:12 -13.7894 123.5057 Water CTD_130 80 1

1 1 1

38 14/05/2015 5:12 -13.7894 123.5057 Water CTD_130 164 1

1 1 1

38 14/05/2015 5:12 -13.7894 123.5057 Water CTD_130 241 1

1 1 1



ST

AT

ION

LO

CA

L

DA

TE/T

IME

LN

GX

LA

TY

SA

MP

LE

TY

PE

OP

ER

AT

ION

DE

PT

H (M

)

BT

EX

/ VO

LA

TIL

E

OR

GA

NIC

S

HE

AD

SP

AC

E G

AS

ME

RC

UR

Y

ME

TA

LS

PA

H/T

PH

UN

SP

EC

IFE

D

38 14/05/2015 5:16 -13.7886 123.5060 Water SWAT_131 0

1

38 14/05/2015 5:34 -13.7899 123.5055 Sediment SMG_132 256

1

1

39 14/05/2015 6:42 -13.8332 123.4083 Water CTD_133 5 1

1 1 1

39 14/05/2015 6:42 -13.8332 123.4083 Water CTD_133 67 1

1 1 1

39 14/05/2015 6:42 -13.8332 123.4083 Water CTD_133 88 1

1 1 1

39 14/05/2015 6:42 -13.8332 123.4083 Water CTD_133 165 1

1 1 1

39 14/05/2015 6:42 -13.8332 123.4083 Water CTD_133 220 1

1 1 1

39 14/05/2015 6:58 -13.8299 123.4107 Water SWAT_134 0

1

39 14/05/2015 7:23 -13.8335 123.4089 Sediment SMG_135 243

1

1

40 14/05/2015 8:08 -13.8543 123.3602 Water CTD_136 5 1

1 1 1

40 14/05/2015 8:08 -13.8543 123.3602 Water CTD_136 62 1

1 1 1

40 14/05/2015 8:08 -13.8543 123.3602 Water CTD_136 77 1

1 1 1

40 14/05/2015 8:08 -13.8543 123.3602 Water CTD_136 150 1

1 1 1

40 14/05/2015 8:08 -13.8543 123.3602 Water CTD_136 221 1

1 1 1

40 14/05/2015 10:11 -13.8511 123.3661 Water SWAT_137 0

1

40 14/05/2015 10:17 -13.8552 123.3604 Sediment SMG_138 141

1

1

41 15/05/2015 21:33 -13.9507 123.3560 Water SWAT_167 0

1

41 15/05/2015 21:33 -13.9507 123.3560 Water CTD_166 5 1

1 1 1

41 15/05/2015 21:33 -13.9507 123.3560 Water CTD_166 70 1

1 1 1

41 15/05/2015 21:33 -13.9507 123.3560 Water CTD_166 115 1

1 1 1

41 15/05/2015 21:33 -13.9507 123.3560 Water CTD_166 235 1

1 1 1

41 15/05/2015 21:58 -13.9503 123.3558 Sediment SMG_168 250

1

1

42 15/05/2015 22:41 -13.9761 123.3996 Water CTD_169 5 1

1 1 1

42 15/05/2015 22:41 -13.9761 123.3996 Water CTD_169 70 1

1 1 1

42 15/05/2015 22:41 -13.9761 123.3996 Water CTD_169 100 1

1 1 1

42 15/05/2015 22:41 -13.9761 123.3996 Water CTD_169 155 1

1 1 1

42 15/05/2015 22:41 -13.9761 123.3996 Water CTD_169 220 1

1 1 1

42 15/05/2015 22:44 -13.9758 123.3997 Water SWAT_170 0

1

42 15/05/2015 23:00 -13.9736 123.3989 Sediment SMG_171 242

1

1

43 16/05/2015 0:13 -14.0299 123.4922 Water CTD_172 5 1

1 1 1

43 16/05/2015 0:13 -14.0299 123.4922 Water CTD_172 70 1

1 1 1

43 16/05/2015 0:13 -14.0299 123.4922 Water CTD_172 85 1

1 1 1

43 16/05/2015 0:13 -14.0299 123.4922 Water CTD_172 150 1

1 1 1

43 16/05/2015 0:13 -14.0299 123.4922 Water CTD_172 210 1

1 1 1

43 16/05/2015 0:17 -14.0295 123.4923 Water SWAT_173 0

1

43 16/05/2015 0:33 -14.0290 123.4926 Sediment SMG_174 224

1

1

44 15/05/2015 15:48 -14.0626 123.5525 Water SWAT_154 0

1

44 15/05/2015 15:49 -14.0626 123.5526 Water CTD_153 5 1

1 1 1

44 15/05/2015 15:49 -14.0626 123.5526 Water CTD_153 75 1

1 1 1

44 15/05/2015 15:49 -14.0626 123.5526 Water CTD_153 150 1

1 1 1

44 15/05/2015 15:49 -14.0626 123.5526 Water CTD_153 175 1

1 1 1

44 15/05/2015 16:04 -14.0617 123.5521 Sediment SMG_155 194

1

1



ST

AT

ION

LO

CA

L

DA

TE/T

IME

LN

GX

LA

TY

SA

MP

LE

TY

PE

OP

ER

AT

ION

DE

PT

H (M

)

BT

EX

/ VO

LA

TIL

E

OR

GA

NIC

S

HE

AD

SP

AC

E G

AS

ME

RC

UR

Y

ME

TA

LS

PA

H/T

PH

UN

SP

EC

IFE

D

45 15/05/2015 16:40 -14.1066 123.4934 Water SWAT_157 0

1

45 15/05/2015 16:41 -14.1065 123.4936 Water CTD_156 5 1

1 1 1

45 15/05/2015 16:41 -14.1065 123.4936 Water CTD_156 75 1

1 1 1

45 15/05/2015 16:41 -14.1065 123.4936 Water CTD_156 120 1

1 1 1

45 15/05/2015 16:41 -14.1065 123.4936 Water CTD_156 145 1

1 1 1

45 15/05/2015 17:01 -14.1071 123.4964 Sediment SMG_158 159

1

1

46 15/05/2015 17:33 -14.1484 123.5621 Water CTD_159 5 1

1 1 1

46 15/05/2015 17:33 -14.1484 123.5621 Water CTD_159 90 1

1 1 1

46 15/05/2015 17:33 -14.1484 123.5621 Water CTD_159 110 1

1 1 1

46 15/05/2015 17:38 -14.1487 123.5629 Water SWAT_160 0

1

46 15/05/2015 18:07 -14.1477 123.5609 Sediment SMG_162 123

1

1

46 15/05/2015 18:23 -14.1484 123.5638 Water CTD_164 5 1

1 1 1

46 15/05/2015 18:23 -14.1484 123.5638 Water CTD_164 50 1

1 1 1

46 15/05/2015 18:23 -14.1484 123.5638 Water CTD_164 110 1

1 1 1

46 15/05/2015 18:40 -14.1502 123.5714 Water SWAT_165 0

1

47 16/05/2015 4:13 -14.1024 123.6186 Water CTD_175 5 1

1 1 1

47 16/05/2015 4:13 -14.1024 123.6186 Water CTD_175 58 1

1 1 1

47 16/05/2015 4:13 -14.1024 123.6186 Water CTD_175 75 1

1 1 1

47 16/05/2015 4:13 -14.1024 123.6186 Water CTD_175 135 1

1 1 1

47 16/05/2015 4:16 -14.1022 123.6189 Water SWAT_176 0

1

47 16/05/2015 4:27 -14.1013 123.6199 Sediment SMG_177 149

1

1

48 16/05/2015 5:12 -14.1347 123.6795 Water CTD_178 5 1

1 1 1

48 16/05/2015 5:12 -14.1347 123.6795 Water CTD_178 50 1

1 1 1

48 16/05/2015 5:12 -14.1347 123.6795 Water CTD_178 110 1

1 1 1

48 16/05/2015 5:16 -14.1351 123.6799 Water SWAT_179 0

1

48 16/05/2015 5:25 -14.1362 123.6801 Sediment SMG_180 121

1

1

48 16/05/2015 5:25 -14.1362 123.6801 Sediment SMG_180 121

1

1

49 16/05/2015 10:09 -14.3467 124.0517 Water CTD_181 5 1

1 1 1

49 16/05/2015 10:09 -14.3467 124.0517 Water CTD_181 68 1

1 1 1

49 16/05/2015 10:09 -14.3467 124.0517 Water CTD_181 86 1

1 1 1

49 16/05/2015 10:09 -14.3467 124.0517 Water CTD_181 96 1

1 1 1

49 16/05/2015 10:23 -14.3454 124.0514 Water SWAT_182 0

1

49 16/05/2015 10:24 -14.3453 124.0513 Sediment SMG_183 104

1

1

50 15/05/2015 10:20 -13.9380 123.9250 Water CTD_139 5 1

1 1 1

50 15/05/2015 10:20 -13.9380 123.9250 Water CTD_139 60 1

1 1 1

50 15/05/2015 10:20 -13.9380 123.9250 Water CTD_139 90 1

1 1 1

50 15/05/2015 10:20 -13.9380 123.9250 Water CTD_139 120 1

1 1 1

50 15/05/2015 10:23 -13.9373 123.9249 Water SWAT_140 0

1

50 15/05/2015 10:34 -13.9363 123.9267 Sediment SMG_141 131

1

1

51 15/05/2015 13:28 -13.8998 123.8724 Water SWAT_151 0

1

51 15/05/2015 13:29 -13.8995 123.8725 Water CTD_150 5 1

1 1 1

51 15/05/2015 13:29 -13.8995 123.8725 Water CTD_150 50 1

1 1 1



ST

AT

ION

LO

CA

L

DA

TE/T

IME

LN

GX

LA

TY

SA

MP

LE

TY

PE

OP

ER

AT

ION

DE

PT

H (M

)

BT

EX

/ VO

LA

TIL

E

OR

GA

NIC

S

HE

AD

SP

AC

E G

AS

ME

RC

UR

Y

ME

TA

LS

PA

H/T

PH

UN

SP

EC

IFE

D

51 15/05/2015 13:29 -13.8995 123.8725 Water CTD_150 100 1

1 1 1

51 15/05/2015 13:29 -13.8995 123.8725 Water CTD_150 132 1

1 1 1

51 15/05/2015 13:41 -13.8989 123.8723 Sediment SMG_152 149

1

1

52 15/05/2015 12:05 -13.8779 123.9252 Water SWAT_146 0

1

52 15/05/2015 12:19 -13.8756 123.9229 Water CTD_147 8 1

1 1 1

52 15/05/2015 12:19 -13.8756 123.9229 Water CTD_147 50 1

1 1 1

52 15/05/2015 12:19 -13.8756 123.9229 Water CTD_147 132 1

1 1 1

52 15/05/2015 12:30 -13.8744 123.9209 Water SWAT_148 0

1

52 15/05/2015 12:39 -13.8734 123.9214 Sediment SMG_149 142

1

1

53 15/05/2015 11:08 -13.9126 123.9647 Water CTD_142 5 1

1 1 1

53 15/05/2015 11:08 -13.9126 123.9647 Water CTD_142 65 1

1 1 1

53 15/05/2015 11:08 -13.9126 123.9647 Water CTD_142 86 1

1 1 1

53 15/05/2015 11:08 -13.9126 123.9647 Water CTD_142 115 1

1 1 1

53 15/05/2015 11:14 -13.9114 123.9640 Water SWAT_143 0

1

53 15/05/2015 11:25 -13.9095 123.9638 Sediment SMG_144 128

1

1

54 16/05/2015 19:14 -13.6538 124.7111 Water CTD_184 5 1

1 1 1

54 16/05/2015 19:14 -13.6538 124.7111 Water CTD_184 55 1

1 1 1

54 16/05/2015 19:14 -13.6538 124.7111 Water CTD_184 80 1

1 1 1

54 16/05/2015 19:15 -13.6539 124.7110 Water SWAT_185 0

1

54 16/05/2015 19:25 -13.6552 124.7110 Sediment SMG_186 88

1

1

55 16/05/2015 22:03 -13.4125 124.7007 Water CTD_187 5 1

1 1 1

55 16/05/2015 22:03 -13.4125 124.7007 Water CTD_187 45 1

1 1 1

55 16/05/2015 22:03 -13.4125 124.7007 Water CTD_187 95 1

1 1 1

55 16/05/2015 22:04 -13.4124 124.7007 Water SWAT_188 0

1

55 16/05/2015 22:15 -13.4129 124.7009 Sediment SMG_189 110

1

1

55 16/05/2015 22:23 -13.4121 124.7003 Sediment SMG_190 110

1

1

55 16/05/2015 22:26 -13.4118 124.7001 Water SWAT_191 0

1

55 16/05/2015 22:36 -13.4103 124.6998 Water CTD_192 5 1

1 1 1

55 16/05/2015 22:36 -13.4103 124.6998 Water CTD_192 25 1

1 1 1

55 16/05/2015 22:36 -13.4103 124.6998 Water CTD_192 95 1

1 1 1

56 17/05/2015 2:35 -13.3051 125.1490 Water CTD_193 5 1

1 1 1

56 17/05/2015 2:35 -13.3051 125.1490 Water CTD_193 68 1

1 1 1

56 17/05/2015 2:58 -13.3030 125.1450 Sediment SMG_194 79

1

1

56 17/05/2015 3:04 -13.3047 125.1440 Water SWAT_195 0

1



3.2 ARP 5 MV Empress trip November 2016 operations and sampling

The ARP 5 MV Empress trip took place between the 22nd November and 9th December 2015. During the

voyage 14 water and sediment sampling stations were visited and 62 water and sediment sampling

operations occurred which resulted in 62 samples being collected for subsequent analysis. Table 4

summarises the operations and samples collected during each operation. The chemical analysis data

collected from the water and sediment samples collected during this voyage are summarised in sections 3.5

and 3.6 below.

Table 4. Operations undertaken and samples collected during the ARP 5 survey.

Station

Local Date/T

ime

LngX

LatY

Sam

ple Type

Operation

Depth (m

)

BT

EX

/ Volatile

Organics

Headspace G

as

Mercury

Metals

PA

H/T

PH

TP

H B

iomarkers

1 29/11/2015 6:30 124.51629 -12.77525 Water SL1_CTD_001 5 1

1 1 1

1 29/11/2015 6:30 124.51629 -12.77525 Water SL1_CTD_001 40 1

1 1 1

1 29/11/2015 6:30 124.51629 -12.77525 Water SL1_CTD_001 70 1

1 1 1

1 7/12/2015 16:10 123.41987 -14.34968 Sediment STN1_VGRAB_001 75 1 1

1

1 7/12/2015 16:10 123.41987 -14.34968 Water STN1_CTD_001 5 1

1 1 1

1 7/12/2015 16:10 123.41987 -14.34968 Water STN1_CTD_001 30 1

1 1 1

1 7/12/2015 16:10 123.41987 -14.34968 Water STN1_CTD_001 65 1

1 1 1

2 30/11/2015 7:20 123.97634 -13.41638 Water SL2_CTD_001 5 1

1 1 1

2 30/11/2015 7:20 123.97634 -13.41638 Water SL2_CTD_001 50 1

1 1 1

2 30/11/2015 7:20 123.97634 -13.41638 Water SL2_CTD_001 90 1

1 1 1

3 1/12/2015 7:52 124.04736 -13.56232 Water SL3_CTD_001 5 1

1 1 1

3 1/12/2015 7:52 124.04736 -13.56232 Water SL3_CTD_001 60 1

1 1 1

3 1/12/2015 7:52 124.04736 -13.56232 Water SL3_CTD_001 115 1

1 1 1

3 1/12/2015 8:31 124.04778 -13.56092 Sediment SL3_VGRAB_001 125 1 1

1


1

3 5/12/2015 14:50 123.41987 -14.34968 Water STN3_CTD_001 5 1

1 1 1

3 5/12/2015 14:50 123.41987 -14.34968 Water STN3_CTD_001 60 1

1 1 1

3 5/12/2015 14:50 123.41987 -14.34968 Water STN3_CTD_001 105 1

1 1 1

4 2/12/2015 8:19 124.35618 -13.56563 Water SL4_CTD_001 5 1

1 1 1

4 2/12/2015 8:19 124.35618 -13.56563 Water SL4_CTD_001 45 1

1 1 1

4 2/12/2015 8:19 124.35618 -13.56563 Water SL4_CTD_001 80 1

1 1 1

4 2/12/2015 8:45 124.35724 -13.56485 Sediment SL4_SMG_001 90 1 1

1

5 3/12/2015 8:21 123.62534 -14.17834 Water SL5_CTD_001 5 1

1 1 1

5 3/12/2015 8:21 123.62534 -14.17834 Water SL5_CTD_001 50 1

1 1 1

5 3/12/2015 8:21 123.62534 -14.17834 Water SL5_CTD_001 90 1

1 1 1


1

6 4/12/2015 8:48 123.45354 -14.19261 Water SL6_CTD_001 5 1

1 1 1

6 4/12/2015 8:48 123.45354 -14.19261 Water SL6_CTD_001 50 1

1 1 1

6 4/12/2015 8:48 123.45354 -14.19261 Water SL6_CTD_001 95 1

1 1 1


1

7 5/12/2015 9:20 123.66037 -14.27808 Water SL7_CTD_001 5 1

1 1 1



Station

Local Date/T

ime

LngX

LatY

Sam

ple Type

Operation

Depth (m

)

BT

EX

/ Volatile

Organics

Headspace G

as

Mercury

Metals

PA

H/T

PH

TP

H B

iomarkers

7 5/12/2015 9:20 123.66037 -14.27808 Water SL7_CTD_001 50 1

1 1 1

7 5/12/2015 9:20 123.66037 -14.27808 Water SL7_CTD_001 94 1

1 1 1


1

8 6/12/2015 6:32 122.89087 -14.506 Water SL8_CTD_001 5 1

1 1 1

8 6/12/2015 6:32 122.89087 -14.506 Water SL8_CTD_001 50 1

1 1 1

8 6/12/2015 6:32 122.89087 -14.506 Water SL8_CTD_001 90 1

1 1 1


1

9 7/12/2015 7:08 122.23089 -14.84778 Water SL9_CTD_001 5 1

1 1 1

9 7/12/2015 7:08 122.23089 -14.84778 Water SL9_CTD_001 50 1

1 1 1

9 7/12/2015 7:08 122.23089 -14.84778 Water SL9_CTD_001 85 1

1 1 1


1


1

32 1/12/2015 14:40 124.32379 -13.49046 Water STN32_CTD_001 5 1

1 1 1

32 1/12/2015 14:40 124.32379 -13.49046 Water STN32_CTD_001 70 1

1 1 1

32 1/12/2015 14:40 124.32379 -13.49046 Water STN32_CTD_001 100 1

1 1 1

33 30/11/2015 18:30 123.9892 -13.43978 Water STN33_CTD_001 5 1

1 1 1

33 30/11/2015 18:30 123.9892 -13.43978 Water STN33_CTD_001 70 1

1 1 1

33 30/11/2015 18:30 123.9892 -13.43978 Water STN33_CTD_001 90 1

1 1 1


1

45 4/12/2015 15:08 123.49275 -14.10783 Water STN45_CTD_002 5 1

1 1 1

45 4/12/2015 15:08 123.49275 -14.10783 Water STN45_CTD_002 80 1

1 1 1

45 4/12/2015 15:08 123.49275 -14.10783 Water STN45_CTD_002 150 1

1 1 1


1

46 3/12/2015 14:15 123.55455 -14.15042 Water STN46_CTD_002 5 1

1 1 1

46 3/12/2015 14:15 123.55455 -14.15042 Water STN46_CTD_002 60 1

1 1 1

46 3/12/2015 14:15 123.55455 -14.15042 Water STN46_CTD_002 110 1

1 1 1

53 28/11/2015 15:00 123.9644 -13.9132 Sediment STN53_SMG_001 120 1 1

1

53 28/11/2015 15:00 123.9644 -13.9132 Water STN53_CTD_001 5 1

1 1 1

53 28/11/2015 15:00 123.9644 -13.9132 Water STN53_CTD_001 70 1

1 1 1

53 28/11/2015 15:00 123.9644 -13.9132 Water STN53_CTD_001 90 1

1 1 1

53 28/11/2015 15:00 123.9644 -13.9132 Water STN53_CTD_001 110 1

1 1 1

3.3 ARP 7 Trip 6578 operations and sampling

The ARP 7 6578 trip took place between the 27th November and 10th December 2016. During the voyage 18

water and sediment sampling stations were visited and 104 water and sediment sampling operations

occurred which resulted in 89 samples being collected for subsequent analysis. Table 5 summarises the

operations and stations visited. The data collected from the water column profiling instruments and



analyses on samples collected from the water column and seabed sediments are summarised in sections

3.4, 3.5 and 3.6 below.

Table 5. Operations undertaken and samples collected during the ARP 7 survey - trip 6578.

Statio

n

Lo

cal Date/T

ime

Ln

gX

LatY

Sam

ple T

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1 8/12/2016 12:00 122.0356 -15.766 Water STN1_CTD_002 5 1 1 1 1

1 8/12/2016 12:00 122.0356 -15.766 Water STN1_CTD_002 40 1 1 1 1

1 8/12/2016 12:00 122.0356 -15.766 Water STN1_CTD_002 71 1 1 1 1

1 8/12/2016 12:00 122.0356 -15.766 Water STN1_SW_001 0 1

1 8/12/2016 12:00 122.0364 -15.7676 Sediment STN1_SMG_002 74 1 1 1 1 1

9 5/12/2016 12:00 123.5462 -14.1079 Sediment BRWISB_HAND_W_001 0 1 1 1 1 1

9 5/12/2016 12:00 123.5492 -14.1059 Sediment BRWISB_HAND_N_001 0 1 1 1 1 1

9 5/12/2016 12:00 123.55 -14.1112 Sediment BRWISB_HAND_S_001 0 1 1 1 1 1

9 5/12/2016 12:00 123.5505 -14.1081 Sediment BRWISB_HAND_E_001 0 1 1 1 1 1

10 5/12/2016 12:00 123.5435 -14.1 Sediment BRWIS_PGRAB_N_001 6.7 1 1 1 1 1

10 5/12/2016 12:00 123.5499 -14.1212 Sediment BRWIS_PGRAB_S_001 8 1 1 1 1 1

10 5/12/2016 12:00 123.5527 -14.1032 Sediment BRWIS_PGRAB_NE_001 10.3 1 1 1 1 1

10 5/12/2016 12:00 123.5577 -14.111 Sediment BRWIS_PGRAB_E_001 9.8 1 1 1 1 1

32 28/11/2016 12:00 124.0297 -13.4881 Water STN32_SW_002 0 1

32 28/11/2016 12:00 124.0297 -13.488 Water STN32_SW_003 0 1

32 28/11/2016 12:00 124.0297 -13.488 Water STN32D_CTD_001 5 2 2 2 2

32 28/11/2016 12:00 124.0297 -13.488 Water STN32D_CTD_001 61 1 1 1 1

32 28/11/2016 12:00 124.0297 -13.488 Water STN32D_CTD_001 70 1 1 1 1

32 28/11/2016 12:00 124.0297 -13.488 Water STN32D_CTD_001 103 1 1 1 1

32 28/11/2016 12:00 124.0297 -13.488 Water STN32D_CTD_001 106 1 1 1 1

32 28/11/2016 12:00 124.0337 -13.4862 Sediment STN32D_SMG_001 108 2 2 2 2 2

33 28/11/2016 12:00 123.986 -13.4384 Water STN33_CTD_002 5 1 1 1 1

33 28/11/2016 12:00 123.986 -13.4384 Water STN33_CTD_002 80 1 1 1 1

33 28/11/2016 12:00 123.986 -13.4384 Water STN33_CTD_002 102 1 1 1 1

33 28/11/2016 12:00 123.986 -13.4384 Water STN33_SW_004 0 1

33 28/11/2016 12:00 123.9895 -13.4369 Sediment STN33_SMG_001 108 1 1 1 1 1

34 28/11/2016 12:00 124.0451 -13.4028 Water STN34_CTD_001 5 1 1 1 1

34 28/11/2016 12:00 124.0451 -13.4028 Water STN34_CTD_001 80 1 1 1 1

34 28/11/2016 12:00 124.0451 -13.4028 Water STN34_CTD_001 103 1 1 1 1

34 28/11/2016 12:00 124.0451 -13.4028 Water STN34_SW_005 0 1

34 28/11/2016 12:00 124.0492 -13.4019 Sediment STN34_SMG_001 110 1 1 1 1 1

35 28/11/2016 12:00 124.0888 -13.4443 Water STN35_CTD_001 5 1 1 1 1

35 28/11/2016 12:00 124.0888 -13.4443 Water STN35_CTD_001 50 1 1 1 1

35 28/11/2016 12:00 124.0888 -13.4443 Water STN35_CTD_001 85 1 1 1 1

35 28/11/2016 12:00 124.0888 -13.4443 Water STN35_SW_006 0 1

35 28/11/2016 12:00 124.0918 -13.4486 Sediment STN35_SMG_001 90 1 1 1 1 1

36 28/11/2016 12:00 124.1051 -13.5608 Water STN36_CTD_001 5 1 1 1 1



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36 28/11/2016 12:00 124.1051 -13.5608 Water STN36_CTD_001 20 1 1 1 1

36 28/11/2016 12:00 124.1051 -13.5608 Water STN36_CTD_001 100 1 1 1 1

36 28/11/2016 12:00 124.1051 -13.5608 Water STN36_SW_007 0 1

36 28/11/2016 12:00 124.1085 -13.558 Sediment STN36_SMG_001 106 1 1 1 1 1

44 1/12/2016 12:00 123.5527 -14.06 Water STN44_CTD_001 5 1 1 1 1

44 1/12/2016 12:00 123.5527 -14.06 Water STN44_CTD_001 92 1 1 1 1

44 1/12/2016 12:00 123.5527 -14.06 Water STN44_CTD_001 190 1 1 1 1

44 1/12/2016 12:00 123.5527 -14.06 Water STN44_SW_008 0 1

44 1/12/2016 12:00 123.5527 -14.0588 Sediment STN44_SMG_001 196 1 1 1 1 1

45 1/12/2016 12:00 123.4927 -14.1068 Sediment STN45_SMG_001 164 1 1 1 1 1

45 1/12/2016 12:00 123.4927 -14.1061 Water STN45_CTD_001 5 1 1 1 1

45 1/12/2016 12:00 123.4927 -14.1061 Water STN45_CTD_001 115 1 1 1 1

45 1/12/2016 12:00 123.4927 -14.1061 Water STN45_CTD_001 157 1 1 1 1

45 1/12/2016 12:00 123.4927 -14.1061 Water STN45_SW_009 0 1

46 1/12/2016 12:00 123.5613 -14.1481 Water STN46_CTD_001 5 1 1 1 1

46 1/12/2016 12:00 123.5613 -14.1481 Water STN46_CTD_001 76 1 1 1 1

46 1/12/2016 12:00 123.5613 -14.1481 Water STN46_CTD_001 115 1 1 1 1

46 1/12/2016 12:00 123.5613 -14.1481 Water STN46_SW_011 0 1

46 1/12/2016 12:00 123.5624 -14.1487 Water STN46_SW_010 0 1

46 1/12/2016 12:00 123.5624 -14.1487 Water STN46D_CTD_001 5 1 1 1 1

46 1/12/2016 12:00 123.5624 -14.1487 Water STN46D_CTD_001 52 1 1 1 1

46 1/12/2016 12:00 123.5624 -14.1487 Water STN46D_CTD_001 116 1 1 1 1

46 1/12/2016 12:00 123.563 -14.1461 Sediment STN46_SMG_001 123 1 2 1 1 1

47 5/12/2016 12:00 123.6168 -14.1059 Sediment STN47_SMG_001 152 1 1 1 1 1

47 5/12/2016 12:00 123.6185 -14.1027 Water STN47_CTD_001 5 1 1 1 1

47 5/12/2016 12:00 123.6185 -14.1027 Water STN47_CTD_001 92 1 1 1 1

47 5/12/2016 12:00 123.6185 -14.1027 Water STN47_CTD_001 145 1 1 1 1

47 5/12/2016 12:00 123.6185 -14.1027 Water STN47_SW_012 0 1

48 5/12/2016 12:00 123.678 -14.1355 Sediment STN48_SMG_001 125 1 1 1 1 1

48 5/12/2016 12:00 123.6792 -14.1345 Water STN48_CTD_001 5 1 1 1 1

48 5/12/2016 12:00 123.6792 -14.1345 Water STN48_CTD_001 60 1 1 1 1

48 5/12/2016 12:00 123.6792 -14.1345 Water STN48_CTD_001 119 1 1 1 1

48 5/12/2016 12:00 123.6792 -14.1345 Water STN48_SW_013 0 1

50 28/11/2016 12:00 123.9249 -13.9383 Water STN50_CTD_001 5 1 1 1 1

50 28/11/2016 12:00 123.9249 -13.9383 Water STN50_CTD_001 70 1 1 1 1

50 28/11/2016 12:00 123.9249 -13.9383 Water STN50_CTD_001 126 1 1 1 1

50 7/12/2016 12:00 123.925 -13.9381 Water STN50_CTD_002 5 1 1 1 1

50 7/12/2016 12:00 123.925 -13.9381 Water STN50_CTD_002 127 1 1 1 1

50 7/12/2016 12:00 123.925 -13.9381 Water STN50_SW_014 0 1

50 7/12/2016 12:00 123.9258 -13.9354 Sediment STN50_SMG_001 130 1 1 1 1 1

51 28/11/2016 12:00 123.8725 -13.8998 Water STN51_CTD_001 5 1 1 1 1

51 28/11/2016 12:00 123.8725 -13.8998 Water STN51_CTD_001 60 1 1 1 1



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51 28/11/2016 12:00 123.8725 -13.8998 Water STN51_CTD_001 144 1 1 1 1

51 7/12/2016 12:00 123.8725 -13.8992 Water STN51_CTD_002 5 1 1 1 1

51 7/12/2016 12:00 123.8725 -13.8992 Water STN51_CTD_002 144 1 1 1 1

51 7/12/2016 12:00 123.8725 -13.8992 Water STN51_SW_015 0 1

51 7/12/2016 12:00 123.8739 -13.8973 Sediment STN51_SMG_001 145 1 1 1 1 1

52 28/11/2016 12:00 123.9261 -13.8784 Water STN52_CTD_001 5 1 1 1 1

52 28/11/2016 12:00 123.9261 -13.8784 Water STN52_CTD_001 70 1 1 1 1

52 28/11/2016 12:00 123.9261 -13.8784 Water STN52_CTD_001 100 1 1 1 1

52 28/11/2016 12:00 123.9261 -13.8784 Water STN52_CTD_001 140 1 1 1 1

52 7/12/2016 12:00 123.9254 -13.8738 Sediment STN52_SMG_001 144 1 1 1 1 1

52 7/12/2016 12:00 123.9257 -13.8784 Water STN52_CTD_002 5 1 1 1 1

52 7/12/2016 12:00 123.9257 -13.8784 Water STN52_CTD_002 140 1 1 1 1

52 7/12/2016 12:00 123.9257 -13.8784 Water STN52_SW_016 0 1

53 28/11/2016 12:00 123.965 -13.9082 Sediment STN53_SMG_002 128 1 1 1 1 1

53 28/11/2016 12:00 123.9651 -13.9118 Water STN53_CTD_003 5 1 1 1 1

53 28/11/2016 12:00 123.9651 -13.9118 Water STN53_CTD_003 120 1 1 1 1

53 28/11/2016 12:00 123.9651 -13.9118 Water STN53_SW_017 0 1

53 7/12/2016 12:00 123.9649 -13.912 Water STN53_CTD_002 5 1 1 1 1

53 7/12/2016 12:00 123.9649 -13.912 Water STN53_CTD_002 63 1 1 1 1

53 7/12/2016 12:00 123.9649 -13.912 Water STN53_CTD_002 121 1 1 1 1

57 27/11/2016 12:00 127.1953 -13.3646 Sediment STN57_SMG_001 93 1 1 1 1 1

57 27/11/2016 12:00 127.1973 -13.3674 Water STN57_CTD_001 5 1 1 1 1

57 27/11/2016 12:00 127.1973 -13.3674 Water STN57_CTD_001 60 1 1 1 1

57 27/11/2016 12:00 127.1973 -13.3674 Water STN57_CTD_001 90 1 1 1 1

57 27/11/2016 12:00 127.1973 -13.3674 Water STN57_SW_018 0 1

3.4 Water column profile data

Water column profiling collected a wide range of sensor data including temperature, salinity, dissolved

oxygen, chlorophyll, PAH (or CHR), CDOM (or CHC), turbidity and particle size distribution.

A total of 66 casts were collected during the ARP 2 Trip 6184, 64 of which passed the initial quality control

criteria during post-voyage data processing. These cast data were supplemented by data from a further 25

casts collected during ARP 7 Trip 6578, all of which passed initial quality control criteria during post-voyage

data processing. The raw file names can be found in Appendix A - Table 11 and Table 12. Due to the

number of water column profiles, these profiles will not be individually described. Furthermore, the data

are more informative when considered and compared between trips.

The data for each type of measurement are reported below. Where further explanation is required, the

data are discussed in relation to other measurement results.



3.4.1 Salinity

When the cast data is considered side-by-side (Figure 10) there are clear differences between salinity data

collected in May 2015 (ARP 2 trip 6184) and December 2016 (ARP 7 trip 6578). While all data presented has

passed quality control criteria, two casts recorded data with high variance (BBS40 trip 6184 and BBS32 trip

6578) (Figure 10). More detailed interrogation of the BBS40 data revealed many spikes within this data

which were clearly attributable to temperature sensor spikes, and it is highly probable that they are due to

a pump malfunction during this specific CTD cast. The single spike in the BBS32 cast cannot be attributed

and its origin is unknown.

The salinity data histogram (Figure 10) which combines data from both trips, shows a tri-modal distribution

which is dominated by the data collected during the ARP 2 6184 trip. The first mode (34.46 practical salinity

units (PSU)) shows the occurrence of lower salinity values in the top layer of the water column in the ARP 2

6184 trip data (as indicated by the colour of the vertical bars in Figure 10). The second mode is a higher

salinity value (34.62 PSU), which corresponds to deeper within the water column in the ARP 2 6184 trip

data (Figure 10). The third mode represents relatively high salinities (34.9 PSU) which correspond to the

higher salinities encountered in the casts to 196 m collected during the ARP 7 6578 trip data.

Figure 10. Consolidated plot of all salinity data from each water column profile (upper panel) and consolidated

histogram of sensor response (lower panel) collected during the ARP 2 - 6184 and ARP 7 – 6578 trips. BBS signifies

Browse Basin Station location numbers.



When salinity is plotted with depth (Figure 11), the differences between data collected during each trip are

pronounced. For data collected during the ARP 2 6184 trip, salinity increases with depth through the

halocline from 34.46 PSU to 34.62 PSU, while during the ARP 7 6578 trip, salinity decreases from 34.9 PSU

to 34.62 PSU with depth. These differences are ~0.5 PSU and suggest that there are differences between

the dominant oceanographic processes affecting the study area between measurement periods.

Figure 11. Heat map of salinity for all water column profiles collected during the ARP 2-6184 and ARP 7- 6578 trips.

The warmer colours represent higher repeatability across the profiles. The heat map of salinity is overlain by the

mean and standard deviation of the collated data from each voyage. Note that the standard errors (not shown) are

larger at depth due to decreased sampling frequency.

The maximum salinity for the whole water column, when displayed geographically (Figure 12) shows

distinct geographic distributions in salinity data for ARP 2 trip 6184 showing a population of cast data with

salinities that are distinctly lower than those from the rest of the trip (Figure 12). Stations 10 to 13, 16 to 19

and 24 to 26 exhibited salinity values lower than the value at the top of the halocline recorded at the rest

of the stations visited during the trip. When plotted by location (Figure 12) these data cluster to the

northwest, west and southwest of the centre of the survey area. This response could represent a distinct,

slightly less saline water mass compared with the surrounding waters. When the salinity data are plotted

for the ARP 7 6578 trip, which has a limited geographic extent when compared to the ARP 2 extent, shows

higher salinity maxima in the vicinity of Browse Island, Heywood Shoal and Echuca Shoal when compared to

ARP 2. This is more pronounced to the north of the study area in the vicinity of Echuca Shoal.



Figure 12. Map of study area showing salinity ranges at each station for ARP 2 trip 6184 and ARP 7 trip 6578.



There are a number of potential factors contributing to the variance in salinity measurements between the

consecutive years of the two trips. The period over which the trips were undertaken coincides with the dry

season in northern Australia, with the December ARP 7 6578 trip occurring just before the tropical wet

season and May ARP 2 6184 trip occurring after the tropical wet season. To understand if freshwater inputs

into the coastal and shelfal environment could explain the observed differences in salinity between trips,

river flow from the two largest rivers (Fitzroy and Ord) in the Kimberly region of Western Australia were

compared between the periods of the trips (Table 6). River flow data shows that there are minor additional

freshwater flows from the Fitzroy River during the 2015 ARP 2 survey period, however this was offset by

reduced flows from the controlled releases from the Ord River. Previous 2015 ARP 2 survey flows from the

Fitzroy River and Ord Rivers were steadily declining from a maximum daily peak flow of 151,484 ML in

January 2015 and 11053 ML March respectively

(http://kumina.water.wa.gov.au/waterinformation/telem/stage.cfm). During the 2016 ARP 7 survey period

there were no flows from the Fitzroy River, however there were enhanced controlled flows from the Ord

River. From September 2016 through to the ARP 7 6578 trip the Fitzroy River had no flows while the Ord

River controlled water release averaged 6452 ML per day

(http://kumina.water.wa.gov.au/waterinformation/telem/stage.cfm). These flows and the river flows

proceeding the survey period could suggest that freshwater discharge could be having a minor effect on the

salinity data between trips, however this is unlikely to significant.

Table 6. Average daily river flows for Ord and Fitzroy Rivers during 2015 ARP 2 and 2016 ARP 7 trips.

River 7th May - 16th May 2015

(megalitres per day)

27th November – 10th December

2016 (megalitres per day)

Fitzroy (Willare, site 802008) 291 0

Ord (Tarrara Bar, site 809339) 5,408 5,913

Source - http://kumina.water.wa.gov.au/waterinformation/telem/stage.cfm

The differences in salinity may also be considered in terms large scale oceanographic processes.

Throughout the period of the two trips, El Niño conditions were observed across the Pacific and therefore

the differences between salinities between trips cannot be easily attributed to this event. Between trips

there were, however differences in the Indian Ocean Dipole Index (IOD)

(http://www.bom.gov.au/climate/iod/), which is a measure of the difference of sea surface temperatures

between the tropical western and eastern Indian Ocean. Prior to the ARP 2 trip 6184 the IOD was slightly

positive to neutral (Figure 13), whereas just prior to the ARP 7 6578 trip the IOD was strongly negative. A

relatively neutral IOD response preceding the 2015 survey would lead to normal weather patterns.

However, the strongly negative IOD preceding the 2016 survey in combination with a persistent El Niño

condition, are likely to have led to warmer sea-surface temperatures, increase evaporative losses from the

ocean surface and increased salinities. The combination of low river flows combined with negative IOD and

persistent El Niño conditions could therefore explain the enhanced salinities observed during the ARP 7

6578 trip.

http://www.bom.gov.au/climate/iod/



Figure 13. Indian Ocean Dipole Index Time Series 2013-2017.

3.4.2 Temperature

When the cast data is considered side-by-side (Figure 14) there are clear differences between surface water

temperature data collected in May 2015 (ARP 2 trip 6184) and December 2016 (ARP 7 trip 6578). The

temperature data histogram (Figure 14) which combines data from both trips shows a skewed unimodal

distribution (Figure 14), with higher water temperatures observed within the surface waters, as expected.

The average temperature of the top mixed layer is around 28.5 °C. ARP 2 data shows that the start of the

thermocline is generally around 60 m below sea surface, but ranges from 30 to 80 m (Figure 14 and Figure

15). There is no pronounced thermocline observed in the ARP 7 data. Temperature decays rapidly through

the water column to 14 °C at approximately 200 m and then decays more slowly to a minimum of circa 8 °C

at the deepest sites. The differences between surface water temperatures between the two trips can be

seen most clearly in the temperature depth profiles (Figure 15). ARP 7 6578 trip data shows higher surface

water temperatures (>30 oC). The differences between water temperatures between years are due to the

different periods of the year over which the measurements were taken and reflect higher sea surface

temperatures in December when compared with May in the Kimberly region.



Figure 14. Consolidated plot of all temperature data from each water column profile (upper panel) and consolidated





Figure 15. Heat map of temperature for all water column profiles collected during the ARP 2-6184 and ARP 7- 6578

trips. The warmer colours represent higher repeatability across the profiles. The heat map of temperature is

overlain by the mean and standard deviation of the collated data from each voyage. Note that the standard errors

(not shown) are larger at depth due to decreased sampling frequency.

3.4.3 Dissolved oxygen

Dissolved oxygen (DO) data considered side-by-side shows minor differences between the ARP 2 and ARP 7

trips (Figure 16). Within each trip the data is relatively consistent, however of note are the BBS002 and

BBS055 station profiles collected during the ARP 2 trip which have slightly different properties, with lower

concentrations of DO through the water column (Figure 16). Both of these sampling stations are located in

shallow waters close to the edge of the continental shelf. They have high chlorophyll concentrations (Figure

18) and elevated turbidity (Figure 22).The DO data histogram (Figure 16) shows a bimodal in oxygen

concentration reflecting upper and lower water column DO end member concentrations (Figure 17).

When plotted by depth the ARP 2 DO data typically describe well-mixed oxygen rich surface waters with

about 230 µmol of oxygen. This concentration rapidly decays with depth below the thermocline, starting at

approximately 60 m through to 200 m water depth, after which the decay curve is more moderate. This

trend is also observed within the ARP 7 data, however from an initial DO concentration of 190 µmol

concentrations increase to 200 µmol before rapidly decreasing with depth. The ARP 7 data also show a

minor depletion of DO throughout the water column profiles when compared to ARP 2 data. The increased

DO in the upper water column within the ARP 7 data coincides with the water column chlorophyll maxima



and may reflect increased oxygen production. The lower DO measurements throughout the ARP 7 profiles

may reflect an increased uptake of DO in the water column by marine biota in the water column.

Figure 16. Consolidated plot of all dissolved oxygen concentration data from each water column profile (upper

panel) and consolidated histogram of sensor response (lower panel) collected during the ARP 2 - 6184 and ARP 7 –

6578 trips. BBS signifies Browse Basin Station location numbers.



Figure 17. Heat map of dissolved oxygen concentration for all water column profiles collected during the ARP 2-

6184 and ARP 7- 6578 trips. The warmer colours represent higher repeatability across the profiles. The heat map of

oxygen is overlain by the mean and standard deviation of the collated data from each voyage. Note that the

standard errors (not shown) are larger at depth due to decreased sampling frequency.

3.4.4 Chlorophyll

When the cast data from both the ARP 2 and ARP 7 trips are considered side-by-side (Figure 18) there is

significant variance in chlorophyll concentration between casts within trips, and between trips. While the

data collected during the ARP 2 BBS56 cast passed initial quality control, the anomalously high data values

suggest that that this data is spurious. This is also likely for part of the BBS45 cast collected during the ARP

7 trip where very high chlorophyll concentrations were observed. The chlorophyll concentration data

histogram (Figure 18) which combines data from both trips shows a skewed unimodal distribution with the

majority of data displaying a low concentration typical of upper and lower water column.

The summed chlorophyll concentrations plotted with depth for each trip show similar trends in the data

with depth between each trip, although concentrations are distinctly different (Figure 19). The data for

both trips shows increasing chlorophyll concentration through the surface waters to the base of the

thermocline or top of halocline between 60 - 80 m. after which there is a rapid decrease in chlorophyll

concentration to very low levels at 150 m depth. For both the ARP 2 and ARP 7 data there is a wide range in

chlorophyll concentrations with depth, however peak chlorophyll concentrations are higher for the ARP 7



data. This is indicative of higher primary productivity in the study area at the time of the ARP 7 trip when

compared to the ARP 2 trip.

Figure 18. Consolidated plot of chlorophyll concentration data from each water column profile (upper panel) and

consolidated histogram of sensor response (lower panel) collected during the ARP 2 - 6184 and ARP 7 – 6578 trips.

BBS signifies Browse Basin Station location numbers.

When the ARP 2 6184 trip data are compared spatially (Figure 20) typically chlorophyll concentrations are

elevated in many of the shallower sites visited, these include sampling stations BBS001, 002, 032, 033, 034,

035, 036, 044, 045, 046, 047, 048, 049, 050, 051, 052, 053, 055 and 056. These stations are associated with

the shelf break as well as the north-eastern quadrant of the survey area. These data correlate well with

ocean colour data which shows distinct areas of elevated chlorophyll concentration along the shelf break

and within these areas during the period of the survey (Figure 20). These areas represent a different water

mass when compared with the rest of the survey stations, with the surface waters to the west of the survey

area more likely to be oligotrophic.

The ARP 7 6578 trip data also show spatial correlation with ocean colour data collected just prior to the trip

(Figure 21). However due to the limited geographic extent of the trip it is not possible to test if areas of

lower OC3 concentration in ocean colour data correlated with lower chlorophyll concentrations at depth in

the water column.



Figure 19. Heat map of chlorophyll concentration for all water column profiles collected during the ARP 2-6184 and

ARP 7- 6578 trips. The warmer colours represent higher repeatability across the profiles. The heat map of

chlorophyll is overlain by the mean and standard deviation of the collated data from each voyage. Note that the

standard errors (not shown) are larger at depth due to decreased sampling frequency.



Figure 20. Map of study area showing stations where profiles had anomalously high chlorophyll concentrations >0.1

µg/l) when compared with the other data collected during the ARP 2 hydrocarbon seeps and baseline survey – Trip

6184. The figure map underlay also shows regional MODIS-derived chlorophyll-a mg/m3 OC3 concentrations for the

16th May 2015(http://oceancurrent.imos.org.au/MODIScomp/2015051604.gif).

Figure 21. Map of study area showing stations where profiles had anomalously high chlorophyll concentrations >0.1

µg/l) when compared with the other data collected during the ARP 7 trip 6578. The figure map underlay also shows

regional MODIS-derived chlorophyll-a mg/m3 OC3 concentrations for the November 21/24 2016.

http://oceancurrent.imos.org.au/MODIScomp/2015051604.gif



3.4.5 Turbidity

The turbidity measurements obtained during the ARP 2 and ARP 7 data show a similar sensor response

pattern across both trips (Figure 22). Typically, surface waters have low turbidity however in many casts

towards the seafloor, turbidity increases. The histogram of turbidity data shows a skewed unimodal

distribution of turbidity with the majority of data 0-0.1 NTU.

Within the shallow waters of the continental shelf, higher values of turbidity are encountered in the water

column. This could represent higher primary productivity (i.e. higher numbers of algal cells) and is partly

corroborated when compared with the chlorophyll data. Enhanced turbidity in these areas can also be

attributed to higher energy mixing within the water column permitting re-suspension of fine-grained

sediment in the water column.

Towards the base of many of the column profiles, turbidity values were high (Figure 22 and Figure 23). This

represents re-suspension of fine grained sediments and detrital material from the seafloor into the

overlying water column, as a result of high seafloor shear stress imparted by the large tidal range in the

basin.

It is important to note that the re-suspension of materials from the seafloor includes organic material. This

has a confounding effect on CHR/PAH and CHC/CDOM sensor response (see below). It is an important

consideration in the context of an incident as it could comprise a pathway for hydrocarbon materials to

become incorporated into sediments, through the interaction of inorganic and organic particles with water

column entrained or chemically dispersed hydrocarbons. The movement of these materials in the deeper

waters may not be captured effectively in oil spill trajectory models.

When the data from the ARP 2 and ARP 7 trips are compared, the ARP 7 data has elevated turbidity values

between 100 and 150 m. It is unlikely that this can be attributed to tidal re-suspension alone. Rather the

high primary productivity in the waters from 60 - 100 m and associated grazing fauna in combination with

re-suspension of sediment contribute to this elevated turbidity.



Figure 22. Consolidated plot of turbidity data from each water column profile (upper panel) and consolidated





Figure 23. Heat map of turbidity for all water column profiles collected during the ARP 2-6184 and ARP 7- 6578 trips.

The warmer colours represent higher repeatability across the profiles. The heat map of turbidity is overlain by the

mean and standard deviation of the collated data from each voyage. Note that the standard errors (not shown) are

larger at depth due to decreased sampling frequency.

3.4.6 CHR/PAH

CHR sensor response is often also considered as PAH response. It should be noted that the chlorophyll,

refined hydrocarbons and crude hydrocarbon concentrations are derived from fluorometer readings, which

record fluorescence responses after excitation at a particular range of wavelengths, and record responses

over a narrow fluorescence emission band. In the natural environment there are compounds and organic

matter which have overlapping responses within these bands. For example, the CHC response is also used

for the determination of CDOM (gelbstoff) released into the marine environment from terrestrial run off

(Section 3.1.7). Therefore, the response of these sensors needs to be carefully interpreted in the context of

the environment in which the data is collected. Typically, when interpreting sensor responses related to

dissolved hydrocarbons, it is expected that both the CHR and CHC sensors will respond concurrently.

When considering a refined hydrocarbon response, it is therefore important to consider that the data can

represent naturally occurring hydrocarbons. The data collected during the ARP 2 and ARP 7 trips represent

the natural variability in the baseline conditions in the basin.

When the CHR cast data are considered side-by-side they show considerable differences between the ARP

2 and ARP 7 trip results (Figure 24). Gaps in data in the upper water column of APR 7 data set are the result



of data not meeting quality control criteria and therefore these data have been excluded. The cause of the

data quality issues was sunlight interference with the sensors, which was particularly acute during this trip.

Notwithstanding these issues the remaining ARP 7 data are consistently higher than those collected during

the ARP 2 trip. Typically, the data shows increases in CHR concentration with depth. The histogram of data

from both trips shows a trimodal distribution dominated by the data collected during the ARP 2 trip (peaks

at 0.07 µg/L and 0.13µg/L). The third histogram peak (0.33 µg/L) is associated with data collected during

ARP 7.

Cumulative depth plots highlight the major differences between CHR concentrations between the two trips

(Figure 25). ARP 2 trip data show relatively stable concentrations of CHR through the upper 50 m of the

water column although there is some variance in concentrations as evidenced by the standard deviations of

the data. A peak correlating with the chlorophyll peak at the thermocline is then observed, this peak has a

maximum value of 0.20 to 0.25 µg/L. However, as opposed to the chlorophyll water column profile, higher

concentrations of refined hydrocarbons are maintained with depth, with values of around 0.15 µg/L slowly

diminishing with depth to approximately 0.1 µg/L at 175 m and below. The ARP 7 data shows higher surface

water concentrations (0.16 µg/L), albeit derived from a limited dataset, which rapidly climb to 0.33 µg/L at

75 m. This depth correlates with the chlorophyll maxima observed in the ARP 7 data. Below this depth the

concentration decreases to 0.31 µg/L at the deepest cast site of 190 m.

When plotted spatially (Figure 26) the higher CHR/PAH response observed in the ARP 2 data is the same as

that observed within the chlorophyll data, and is interpreted as consistent with the data describing a

different water mass when compared with the rest of the survey stations. This is also likely to be the case

for the ARP 7 data however the limited spatial extent of the data set limits this interpretation.

The derived CHR response reflects the dissolved organic matter (DOM) in the water column released into

the water column by organic matter decay and/or activity by higher trophic level organisms (e.g.

zooplankton). There is no evidence from the chemical analysis data (discussed below) of enhanced

PAH/TPH concentrations in samples collected during the ARP 7 trip.



Figure 24. Consolidated plot of refined hydrocarbon (CHR) or polycyclic aromatic hydrocarbons (PAH) data from

each water column profile (upper panel) and consolidated histogram of sensor response (lower panel) collected

during the ARP 2 - 6184 and ARP 7 – 6578 trips. BBS signifies Browse Basin Station location numbers.



Figure 25. Heat map of refined hydrocarbon (CHR) or polycyclic aromatic hydrocarbons (PAH) data for all water

column profiles collected during the ARP 2-6184 and ARP 7- 6578 trips. The warmer colours represent higher

repeatability across the profiles. The heat map of CHR is overlain by the mean and standard deviation of the

collated data from each voyage. Note that the standard errors (not shown) are larger at depth due to decreased

sampling frequency.



Figure 26. Map of study area showing CHR or polycyclic aromatic hydrocarbon concentrations at each station for

ARP 2 trip 6184 and ARP 7 trip 6578.



3.4.7 CHC/CDOM

As discussed above, the CHC sensor response can also be used to determine CDOM and sensor response can be affected by other factors (discussed above). Once again, gaps in data in the upper water column of APR 7 data set are the result of data not meeting quality control criteria due to sunlight interference. As with the CHR data the side by side comparison of cast data shows considerable differences between the ARP 2 and ARP 7 trip results (Figure 27), with ARP 7 CHC concentrations elevated with respect to ARP 2.

For both datasets an increase in CHC concentration is observed with depth although this is much more pronounced in the ARP 7 data. The histogram of concentration data from both trips shows a bimodal distribution, dominated by the data collected during the ARP 2 trip with the greatest sample counts around 0.5 µg/L. The second broad peak at 4.5 µg/L describes the CHC concentrations associated with the ARP 7 trip (Figure 27).

Cumulative depth plots once again highlight the major differences in water column properties between the ARP 2 and ARP 7 trip (Figure 28). For the ARP 2 trip typically, the lowest values encountered were in the surface waters above the thermocline (approximately 0.4 µg/L). Inferred concentrations show a stepwise increase at the thermocline and then gradually increase throughout the rest of the water column to around 0.5 µg/L. The ARP 7 data shows higher surface water concentrations (2 µg/L) which rapidly increase to 4.5 µg/L at 75 m and very gradually increase to 190 m.

As with the CHR sensor response, it is likely that the CHC sensor response describes dissolved hydrocarbons released into the water column by organic matter decay and/or the activity of higher trophic level organisms (e.g. zooplankton). Some of the variability encountered in the lower sections of the ARP 2 profiles can also be attributed to the enhanced turbidity and the re-suspension of organic matter from sediments. There is no evidence from the chemical analysis data (discussed below) of enhanced PAH/TPH concentrations in samples collected during the ARP 7 trip.

The large differences in CHR and CHC concentrations between trips shows that the natural range of variability in the waters of the Browse Basin has yet to be fully characterised. This reduces the capability to correctly identify, and understand the spatial distribution of entrained hydrocarbons in the water column in the unlikely event of an unintended hydrocarbon release. Further data collection is required to reduce these uncertainties and more fully characterise the natural variability observed in the study area. This will be partly addressed through analysis of samples from the April 2017 ARP7 survey and the forthcoming ARP7 trip in December 2017 which will collect repeat measurements at the Browse Island, Heywood Shoal, and Echuca Shoal study areas.



Figure 27. Consolidated plot of crude hydrocarbons (CHC) or coloured dissolved organic matter (CDOM) data from

each water column profile (upper panel) and consolidated histogram of sensor response (lower panel) collected

during the ARP 2 - 6184 and ARP 7 – 6578 trips. BBS signifies Browse Basin Station location numbers.



Figure 28. Heat map of crude hydrocarbons (CHC) or coloured dissolved organic matter (CDOM) data for all water

column profiles collected during the ARP 2-6184 and ARP 7- 6578 trips. The warmer colours represent higher

repeatability across the profiles. The heat map of CHC is overlain by the mean and standard deviation of the

collated data from each voyage. Note that the standard errors (not shown) are larger at depth due to decreased

sampling frequency.

3.4.8 Particle size analyser (LISST-Deep) data

For each sampling station, LISST data provided the following information:

Total volume concentration

Mean size

Standard deviation

Particle size fractiles: 'D10', 'D16', 'D50', 'D60', 'D84', 'D90'.

The Hazen uniformity coefficient (D60/D10)

Surface area in cm2/L

Silt density

Silt volume concentration.

An example of the mean particle size, standard deviation and total volume concentration through the

water column is shown for station 11 in Figure 29 below. The data required detailed interpretation, but the

utility of the data is that plots such as those shown in Figure 23 permit the deconvolution of different



contributions of particles in the water column. Typically, different size fractions are attributed to different

processes, for example, larger particle size fractions are attributed to algal cells, whilst smaller size fractions

can be attributed to suspended sediments. During their entrainment, droplets of oil from mechanical or

chemical dispersion also have characteristic size fractions. It is therefore important to collect baseline data

to avoid misinterpretation of the size fraction data, particularly if such data are to be used in a spill

response situation.

Figure 29. Example LISST profile data from station 11 showing mean particle size and standard deviation (µm) (left),

and total volume concentration (µL/L) (right), with depth through the water column.

3.4.9 Water column profile summary findings

Prior to the ARP 2 hydrocarbon seeps and baseline survey – Trip 6184, there were no known records of

water column profiles which had collected a suite of chemical and physical data in this area. This dataset

has been significantly augmented by the addition of the ARP 7 6578 trip data. As such, the collection of 88

water column profiles incorporating a large number of chemical and physical parameters represents a

baseline dataset across the Browse Basin.

The data show systematic spatial trends across the basin, as well as interdependency between responses.

The inclusion of a suite of measurements enabled the identification of linkages which may otherwise not

have been revealed, which in turn may have led to erroneous interpretations. The trends in the data are

related to oceanographic processes, such as the halocline and thermocline, tidal processes and different



water mass properties. There are significant differences in the data collected from the ARP 2 6184 and ARP

7 6578 trips which are attributable to changing oceanographic processes and biological processes. Variance

between the data collected from each trip demonstrates that the natural variability within the Browse

Basin water column physical and chemical properties, has yet to be fully characterised and this warrants

further investigation.

Graphical tools such as the heat maps of sensor responses plotted as side-by-side water column profiles

have now shown their utility in the ability to incorporate additional field data from other voyages within

the APR program (e.g. ARP 7). Visual approaches such as this will also permit rapid identification of

anomalous data (as outliers) in the event of an unintended hydrocarbon release into the marine

environment in the study area.

3.5 Water column chemistry

328 water samples were collected during the ARP 2 6184 trip and these were complemented with a further

49 water samples from the ARP 5 Empress trip and 81 samples from the ARP 7 6578 trip. The samples were

collected either from surface waters or from Niskin bottles on the CTD water sampling rosette. These

samples were subsampled for a suite of analyses described in Section 2.2.3., which composed 1114

individual analyses including metal analyses which are not reported here.

3.5.1 BTEX

A total of 366 (262 - ARP2, 49- ARP 5 and 55 – ARP 7) samples were collected from the water bottle rosette

for analysis for analysis for BTEX. With the exception of three ARP 2 samples and 36 samples from ARP 5, all

of the other analyses returned null results with no data above limits of reporting (B, T, E, and o-xylene <0.1

µg/L, and m- + p-xylene <0.2 µg/L). The three ARP 2 samples with responses above limits of reporting were

encountered at station 7 (2 samples, 50 and 70 m) and station 9 (48 m) with 0.2, 0.1 and 0.2 µg/L toluene

respectively. Only toluene was above limits of reporting in the 36 samples from ARP 5 and ranged from 0.1-

0.4 µg/L. For both ARP 2 and ARP 5 these concentrations are very low and close to limits of reporting. There

was no consistency in location or water depth in the samples which had elevated toluene concentrations.

As they were single compound responses, and were not associated with elevated responses for higher

molecular weight PAHs or TPHs they most likely reflect low-level contamination of toluene introduced

either during sampling or during subsequent transport and analysis.

3.5.2 PAH

456 (327 –ARP2, 49 –ARP5 and 80 – ARP 7) samples collected from surface waters and throughout the

water column were analysed for a suite of 38 poly aromatic and alkylated polycyclic aromatic

hydrocarbons. None of the 66 surface water samples collected during ARP 2 nor the 18 samples collected

during ARP 7 had PAH concentrations above the limits of reporting. For the 261 ARP 2, 49 ARP 5 and 62 ARP

7 water column samples, total concentrations of PAHs were low, typically below 1µg/L. Interpretations of

the compound distribution and concentration identified 15, 3, and 7 samples that were affected by

contamination from ARP 2, ARP 5 and ARP 7 respectively. These contaminants were either intermediate

fuel oil (IFO), kerosene or plastics (Table 7, Table 8 and Table 9).



Three water samples (COA001237, COA001414, and COA001582) collected during the ARP 2 trip gave an

unusual GC-FID chromatographic profile (Figure 30). This unusual profile appears to be a weathered diesel

fuel, supplemented by higher molecular weight waxes. The diesel is unlikely to be from sampling or

laboratory contamination, as there is evidence of weathering given the concentration of unresolved

complex mixture (UCM) relative to the alkanes. The origin of the waxes is unclear and may be related to

either contamination or a thermogenic source.

Removal of samples with contamination from the data set permits the determination of baseline

concentration distributions of naturally occurring PAHs across the study area (Figure 31). There are no clear

trends in total PAH concentration data with location (Figure 31) although where PAHs were present in

samples from the ARP 5 trip, concentrations were elevated relative to those from the ARP 2 and 7 trips.

Figure 30. GC-FID chromatogram of ChemCentre sample 14B0708/090 (water sample COA/001414), showing

weathered diesel fuel and heavier waxes.



Figure 31. Map of study area showing stations with the highest concentrations of total PAHs in the water column

collected during the ARP 2 trip 6184, ARP 5 and ARP 7 Trip 6578 after removal of contamination outliers.

When the distribution of individual compounds for the water column samples are considered (Figure 34),

after the removal of contaminated sample data, it is apparent that the majority of PAHs in most samples



are below limits of reporting. Where PAH compounds are present, the concentrations of the compounds

are usually less than one order of magnitude above limits of reporting. The naphthalene and alkylated

naphthalenes are the most abundant class of PAHs in the samples. The presence of these compounds is

attributed to pyrogenic compounds from bush fires in the surrounding region (Peters et al. 2005). The

upper range of compound concentrations is determined by very few samples and these have a maximum

concentration of 0.23, 0.71 and 0.033 µg/L total single PAH for ARP 2, 5 and 7 respectively.

The whisker plot which summarises these data (Figure 34) clearly highlights the differences between the

trip results, and where PAHs are present in the ARP 5 samples they occur at levels which are significantly

different from ARP 2 and 7 data. The reason for this difference is not clear, however the dry period prior to

summer rains in late December is bush fire season in the Kimberly region.

3.5.3 TPH

456 (327 –ARP2, 49 –ARP5 and 80 – ARP 7) were analysed for TPH. Interpretations of the compound

distribution and concentration identified 15, 3, and 7 samples that were affected by contamination from

ARP 2, ARP 5 and ARP 7 respectively. These contaminants were either intermediate fuel oil (IFO), kerosene

or plastics (Table 7, Table 8 and Table 9). The alkane distributions in uncontaminated samples are

attributed to being of biogenic origin (Figure 32) or terrestrial plant waxes (Peters et al. 2005). After

removal of contaminated sample data, total concentrations of alkanes quantified in the samples were

higher than PAH concentrations with values ranging from 0 to 280 µg/L (237 µg/L - ARP 2, 280 µg/L - ARP 5,

153 µg/L – ARP 7).

Figure 32. Example GC-FID chromatogram: water sample 14B0708/225 – Station 46, CTD_164, 50m unusual

distribution of unidentified compounds attributed to a biogenic origin or plant waxes.

After removal of both contaminated sample data and the UCM quantification, the spatial distribution

shows elevated alkane concentrations are present at stations 5 and 12 (Figure 33). Overall alkane

1 0 . 0 0 1 5 . 0 0 2 0 . 0 0 2 5 . 0 0 3 0 . 0 0 3 5 . 0 0 4 0 . 0 0

5 0 0 0 0 0

1 0 0 0 0 0 0

1 5 0 0 0 0 0

2 0 0 0 0 0 0

2 5 0 0 0 0 0

3 0 0 0 0 0 0

3 5 0 0 0 0 0

4 0 0 0 0 0 0

4 5 0 0 0 0 0

T i m e

R e s p o n s e _

S ig n a l: L L _ T R H _ 0 7 2 . D \ F I D 1 A . c h



concentrations were higher in samples collected during the ARP 2 trip when compared to ARP 5 and ARP 7

data. There are no spatial trends apparent in the data (Figure 33).

When the distribution of individual alkanes in the water column samples are considered (Figure 35), it is

apparent that alkane compounds were detected in most of the ARP 2 samples. Few samples from the ARP 5

and 7 trips contained detectable alkanes. The range of alkane concentrations detected in the ARP 2

samples extended beyond five orders of magnitude above the limits of reporting. Where alkanes were

detected in the ARP 5 and 7 samples these results fell within the variance of the ARP 2 results, with the

majority of compound concentrations falling within the second quartile of the ARP 2 data.

The data show that there is no significant difference in alkane concentration between trips. This also

suggests that, as with the PAH water column results, that elevated inferred CHR and CHC concentrations

observed from water column profiles during the ARP 7 trip are derived from non-hydrocarbon sources,

such as CDOM, and do not represent elevated hydrocarbon concentrations in the water column. The

combination of both arrayed sensor and analytical chemical data demonstrates the value of the use of a

multiple lines of evidence approach to enhance understanding of the water column chemistries and

processes.

3.5.4 Metals

Analysis was undertaken to understand baseline metal concentrations for future produced water studies.

As such the data generated are not directly related to the aims and objectives of the ARP 2 study and not

reported here. Detailed results can be found in ChemCentre report 14B0708.



Figure 33. Map of study area showing stations highest concentrations of quantified alkanes (excluding UCM) from

TPH analyses in the water column from ARP 2 trip 6184, ARP 5 and ARP 7 Trip 6578 after removal of contamination

outliers.



Figure 34. Whisker plot showing variance in individual parent and alkylated PAH compound concentrations from 245 ARP 2, 45 ARP 5 and 54 ARP 7 water column profile water samples

unaffected by contamination plotted on the same scale. Limits of reporting for the parent PAH compounds were 0.001 ug/L and the *number above each compound is the number of

samples not included in the analysis of variance due to that compound being below limits of reporting. The whiskers describe the total range in variance, whilst the upper box represents

the 2nd quartile the lower box represents the 3rd quartile and bar in the centre represents the median concentration of the compound.



Figure 35. Whisker plot showing variance in quantified alkane and UCM concentrations from 245 ARP 2, 45 ARP 5 and 54 ARP 7 water column profile water samples. Limits of reporting

for the compounds were 0.001 µg/L. The *number above each compound is the number of samples not included in the analysis of variance due to that compound being below limits of

reporting. The whiskers describe the total range in variance, whilst the upper box represents the 2nd quartile the lower box represents the 3rd quartile and bar in the centre represents

the median concentration of the compound.



Table 7. Interpretation of source of hydrocarbons (HC) within water samples collected during the ARP 2

hydrocarbon seeps and baseline survey – Trip 6184. HC source includes: PW = Plant Wax, Bio = Biogenic origin, LL =

low level hydrocarbon concentration, contam = contamination (unspecified), Kero (contam) = Kerosene

contamination, Contam (poly) = plastic contamination, Contam (IFO) = Intermediate fuel oil contamination, Petr =

petrogenic source. Profile A = see interpretation below.

LabID SampleID Station Water depth HC Source

14B0708/001 COA/001001 1 64 PW

14B0708/002 COA/001005 1 5 Bio

14B0708/005 COA/001012 2 80

14B0708/004 COA/001016 2 25 Bio

14B0708/003 COA/001020 2 5 Bio

14B0708/008 COA/001024 2 80 PW

14B0708/007 COA/001028 2 25 LL, PW

14B0708/006 COA/001032 2 5 LL

14B0708/011 COA/001042 3 115 Bio, PW

14B0708/010 COA/001046 3 80 Bio, PW

14B0708/009 COA/001050 3 60 Bio, PW

14B0708/012 COA/001054 3 5 Bio, PW

14B0708/013 COA/001061 4 172 PW

14B0708/014 COA/001065 4 145 Bio, PW

14B0708/015 COA/001069 4 60 Bio, PW

14B0708/016 COA/001073 4 5 Bio, PW

14B0708/017 COA/001080 5 250 PW

14B0708/018 COA/001084 5 200 PW

14B0708/019 COA/001088 5 100 Bio, PW

14B0708/020 COA/001092 5 50 LL

14B0708/021 COA/001096 5 5 Bio

14B0708/022 COA/001103 6 263 LL

14B0708/023 COA/001107 6 230 LL

14B0708/024 COA/001111 6 200 Bio, PW

14B0708/025 COA/001115 6 50 LL

14B0708/026 COA/001119 6 5 LL

14B0708/027 COA/001126 7 315 Bio

14B0708/028 COA/001130 7 255 LL

14B0708/029 COA/001134 7 73 LL

14B0708/030 COA/001138 7 50 Bio

14B0708/031 COA/001142 7 5 LL

14B0708/032 COA/001149 8 200 LL

14B0708/033 COA/001153 8 80 LL

14B0708/034 COA/001157 8 60 PW

14B0708/035 COA/001161 8 5 LL

14B0708/036 COA/001168 9 430 LL

14B0708/037 COA/001172 9 224 PW

14B0708/038 COA/001176 9 54 LL, contam

14B0708/039 COA/001180 9 48 LL

14B0708/040 COA/001184 9 5 Bio, PW



14B0708/041 COA/001192 10 460 LL

14B0708/042 COA/001196 10 200 LL

14B0708/043 COA/001200 10 100 LL

14B0708/044 COA/001204 10 60 PW

14B0708/045 COA/001208 10 5 PW

14B0708/046 COA/001214 11 388 Bio, PW

14B0708/047 COA/001218 11 280 PW

14B0708/048 COA/001222 11 70 PW

14B0708/049 COA/001226 11 60 PW

14B0708/050 COA/001230 11 5 PW

14B0708/051 COA/001237 12 319 Profile A

14B0708/052 COA/001241 12 240 LL

14B0708/053 COA/001245 12 160 PW

14B0708/054 COA/001249 12 50 PW

14B0708/055 COA/001253 12 5 PW

14B0708/056 COA/001263 12 319 PW

14B0708/057 COA/001267 12 240 PW

14B0708/058 COA/001271 12 160 PW

14B0708/059 COA/001275 12 50 LL

14B0708/060 COA/001279 12 5 PW

14B0708/061 COA/001283 13 285 LL

14B0708/062 COA/001287 13 220 PW

14B0708/063 COA/001291 13 140 Kero (contam)

14B0708/064 COA/001295 13 40 LL

14B0708/065 COA/001299 13 5 Petr, PW

14B0708/066 COA/001306 14 280 Bio

14B0708/067 COA/001310 14 250 PW

14B0708/068 COA/001314 14 200 PW

14B0708/069 COA/001318 14 40 PW

14B0708/070 COA/001322 14 5 LL

14B0708/071 COA/001329 15 260 PW

14B0708/072 COA/001333 15 231 PW

14B0708/073 COA/001337 15 65 LL

14B0708/074 COA/001341 15 47 Contam (poly)

14B0708/075 COA/001345 15 5 Bio

14B0708/076 COA/001352 16 273 LL

14B0708/077 COA/001356 16 156 Bio

14B0708/078 COA/001360 16 101 LL

14B0708/079 COA/001364 16 66 PW

14B0708/080 COA/001368 16 5 PW

14B0708/081 COA/001375 17 258 Bio

14B0708/082 COA/001379 17 200 Bio

14B0708/083 COA/001383 17 79 PW

14B0708/084 COA/001387 17 61 PW

14B0708/085 COA/001391 17 5 Bio



14B0708/086 COA/001398 18 255 Bio

14B0708/087 COA/001402 18 232 Kero (contam)

14B0708/088 COA/001406 18 77 LL

14B0708/089 COA/001410 18 54 Bio

14B0708/090 COA/001414 18 5 Profile A

14B0708/091 COA/001421 19 268 Bio

14B0708/092 COA/001425 19 222 Bio

14B0708/093 COA/001429 19 64 Bio

14B0708/094 COA/001433 19 53 PW

14B0708/095 COA/001437 19 5 Bio

14B0708/096 COA/001444 20 338 Bio

14B0708/097 COA/001448 20 232 PW

14B0708/098 COA/001452 20 72 LL

14B0708/099 COA/001456 20 52 Petr, Bio

14B0708/100 COA/001460 20 5 PW

14B0708/101 COA/001467 21 430 Bio

14B0708/102 COA/001471 21 280 Bio

14B0708/103 COA/001475 21 140 Contam (poly)

14B0708/104 COA/001479 21 65 Bio

14B0708/105 COA/001483 21 5 LL

14B0708/106 COA/001490 22 105 Unk

14B0708/107 COA/001494 22 45 LL

14B0708/108 COA/001498 22 5 LL

14B0708/109 COA/001505 23 90 LL

14B0708/110 COA/001509 23 80 LL

14B0708/111 COA/001513 23 5 Bio

14B0708/112 COA/001520 24 270 Bio, PW

14B0708/113 COA/001524 24 130 LL

14B0708/114 COA/001528 24 64 LL

14B0708/115 COA/001532 24 44 LL

14B0708/116 COA/001536 24 5 LL

14B0708/117 COA/001543 25 265 LL

14B0708/118 COA/001547 25 241 LL

14B0708/119 COA/001551 25 68 Bio

14B0708/120 COA/001555 25 55 PW

14B0708/121 COA/001559 25 5 Bio

14B0708/122 COA/001566 25 265 PW

14B0708/123 COA/001570 25 237 PW

14B0708/124 COA/001574 25 82 Bio

14B0708/125 COA/001578 25 63 Bio

14B0708/126 COA/001582 25 5 Profile A

14B0708/127 COA/001589 26 260 PW

14B0708/128 COA/001593 26 180 PW

14B0708/129 COA/001597 26 82 Bio

14B0708/130 COA/001601 26 61 LL

14B0708/131 COA/001605 26 5 LL



14B0708/132 COA/001612 27 240 LL

14B0708/133 COA/001616 27 210 LL

14B0708/134 COA/001620 27 64 Bio

14B0708/135 COA/001624 27 46 Unk

14B0708/136 COA/001628 27 5 PW

14B0708/137 COA/001635 28 246 Bio

14B0708/138 COA/001639 28 204 PW

14B0708/139 COA/001643 28 65 Bio

14B0708/140 COA/001647 28 55 Bio

14B0708/141 COA/001651 28 5 PW

14B0708/142 COA/001658 29 270 PW

14B0708/143 COA/001662 29 225 LL

14B0708/144 COA/001666 29 200 LL

14B0708/145 COA/001670 29 70 Contam (IFO)

14B0708/146 COA/001674 29 5 Contam (IFO)

14B0708/147 COA/001682 30 320 Contam (IFO)

14B0708/148 COA/001686 30 200 Contam (IFO)

14B0708/149 COA/001690 30 65 Contam (IFO)

14B0708/150 COA/001694 30 50 Contam (IFO)

14B0708/151 COA/001698 30 5 Contam (IFO)

14B0708/152 COA/001704 31 340 Contam (IFO)

14B0708/153 COA/001708 31 230 PW

14B0708/154 COA/001712 31 140 Bio

14B0708/155 COA/001716 31 60 LL

14B0708/156 COA/001720 31 5 PW

14B0708/157 COA/001727 32 96 PW

14B0708/158 COA/001731 32 55 PW

14B0708/159 COA/001735 32 5 PW

14B0708/160 COA/001742 33 101 PW

14B0708/161 COA/001746 33 55 Bio

14B0708/162 COA/001750 33 5 PW

14B0708/163 COA/001757 34 97 PW

14B0708/164 COA/001761 34 82 LL

14B0708/165 COA/001765 34 54 Bio

14B0708/166 COA/001769 34 5 PW

14B0708/167 COA/001776 35 81 LL

14B0708/168 COA/001780 35 65 LL

14B0708/169 COA/001784 35 5 LL

14B0708/170 COA/001791 36 94 Bio

14B0708/171 COA/001795 36 70 Bio

14B0708/172 COA/001799 36 5 Bio

14B0708/173 COA/001806 37 185 Bio

14B0708/174 COA/001810 37 120 Bio

14B0708/175 COA/001814 37 75 LL

14B0708/176 COA/001818 37 5 PW



14B0708/177 COA/001828 37 185 Petr, PW

14B0708/178 COA/001832 37 120 Kero (contam)

14B0708/179 COA/001836 37 75 Bio, PW

14B0708/180 COA/001840 37 5 Bio, PW

14B0708/181 COA/001856 36 65 LL

14B0708/182 COA/001860 36 10 LL

14B0708/183 COA/001864 38 241 LL

14B0708/184 COA/001868 38 164 Petr, PW

14B0708/185 COA/001872 38 80 LL

14B0708/186 COA/001876 38 69 LL

14B0708/187 COA/001880 38 5 LL

14B0708/188 COA/001887 39 220 LL

14B0708/189 COA/001891 39 165 LL

14B0708/190 COA/001895 39 88 LL

14B0708/191 COA/001899 39 67 LL

14B0708/192 COA/001903 39 5 Petr, Bio

14B0708/193 COA/001910 40 221 PW

14B0708/194 COA/001914 40 150 LL

14B0708/195 COA/001918 40 77 LL

14B0708/196 COA/001922 40 62 Petr, Bio

14B0708/197 COA/001926 40 5 LL

14B0708/198 COA/001933 50 120 LL

14B0708/199 COA/001937 50 90 LL

14B0708/200 COA/001941 50 60 PW

14B0708/201 COA/001945 50 5 LL

14B0708/202 COA/001952 53 115 LL

14B0708/203 COA/001956 53 86 PW

14B0708/204 COA/001960 53 65 PW

14B0708/205 COA/001964 53 5 PW

14B0708/206 COA/001972 52 132 Bio

14B0708/207 COA/001976 52 50 PW

14B0708/208 COA/001980 52 8 PW

14B0708/209 COA/001988 51 132 LL

14B0708/210 COA/001992 51 100 PW

14B0708/211 COA/001996 51 50 LL

14B0708/212 COA/002000 51 5 Bio, PW

14B0708/213 COA/002007 44 175 Contam, PW

14B0708/214 COA/002011 44 150 LL

14B0708/215 COA/002015 44 75 LL

14B0708/216 COA/002019 44 5 Bio

14B0708/217 COA/002025 45 145 PW

14B0708/218 COA/002029 45 120 PW

14B0708/219 COA/002033 45 75 PW

14B0708/220 COA/002037 45 5 LL

14B0708/221 COA/002045 46 110 LL

14B0708/222 COA/002049 46 90 LL



14B0708/223 COA/002053 46 5 Bio

14B0708/224 COA/002059 46 110 LL

14B0708/225 COA/002063 46 50 LL

14B0708/226 COA/002067 46 5 LL

14B0708/227 COA/002072 41 235 LL

14B0708/228 COA/002076 41 115 LL

14B0708/229 COA/002080 41 70 PW

14B0708/230 COA/002084 41 5 PW

14B0708/231 COA/002092 42 220 LL

14B0708/232 COA/002096 42 155 Bio

14B0708/233 COA/002100 42 100 Bio

14B0708/234 COA/002104 42 70 Petr, PW

14B0708/235 COA/002108 42 5 Bio

14B0708/236 COA/002114 43 210 LL

14B0708/237 COA/002118 43 150 PW

14B0708/238 COA/002122 43 85 LL

14B0708/239 COA/002126 43 70 PW

14B0708/240 COA/002130 43 5 PW

14B0708/241 COA/002137 47 135 LL

14B0708/242 COA/002141 47 75 LL

14B0708/243 COA/002145 47 58 Bio

14B0708/244 COA/002149 47 5 LL

14B0708/245 COA/002156 48 110 LL

14B0708/246 COA/002160 48 50 LL

14B0708/247 COA/002164 48 5 LL

14B0708/248 COA/002173 49 96 Bio

14B0708/249 COA/002177 49 86 LL

14B0708/250 COA/002181 49 68 LL

14B0708/251 COA/002185 49 5 LL

14B0708/252 COA/002192 54 80 LL

14B0708/253 COA/002196 54 55 Bio

14B0708/254 COA/002200 54 5 Bio

14B0708/255 COA/002207 55 95 LL

14B0708/256 COA/002211 55 45 Kero (contam)

14B0708/257 COA/002215 55 5 LL

14B0708/258 COA/002225 55 95 LL

14B0708/259 COA/002229 55 25 PW

14B0708/260 COA/002233 55 5 LL

14B0708/261 COA/002237 56 68 LL

14B0708/262 COA/002241 56 5 Petr, PW, Bio



Table 8. Interpretation of source of hydrocarbons (HC) within water samples collected during the ARP 5 survey. HC

source includes: PW = Plant Wax, Bio = Biogenic origin, LL = low level hydrocarbon concentration, contam =

contamination (unspecified), Kero (contam) = Kerosene contamination, Contam (poly) = plastic contamination,

Contam (IFO) = Intermediate fuel oil contamination, Petr = petrogenic source. Profile A = see interpretation below.

SampleID Station Depth (m) HC source

15S1341/001 53 110 LL

15S1341/002 53 90 LL

15S1341/003 53 70 LL

15S1341/004 53 5 Bio

15S1341/005 1 70 Bio

15S1341/006 1 40 Bio

15S1341/007 1 5 Bio

15S1341/008 2 90 LL

15S1341/009 2 50 Petr, Bio

15S1341/010 2 5 LL

15S1341/011 33 90 Kero (contam)

15S1341/012 33 70 Kero (contam)

15S1341/013 33 5 Bio

15S1341/014 3 115 LL

15S1341/015 3 60 LL

15S1341/016 3 5 LL

15S1341/017 32 100 PW

15S1341/018 32 70 LL

15S1341/019 32 5 LL

15S1341/020 4 80 Kero (contam)

15S1341/021 4 45 LL

15S1341/022 4 5 LL

15S1341/023 5 90 LL

15S1341/024 5 50 LL

15S1341/025 5 5 LL

15S1341/026 46 110 LL

15S1341/027 46 60 Bio

15S1341/028 46 5 LL

15S1341/029 6 95 LL

15S1341/030 6 50 LL

15S1341/031 6 5 LL

15S1341/032 45 150 LL

15S1341/033 45 80 Petr

15S1341/034 45 5 LL

15S1341/035 7 94 Petr

15S1341/036 7 50 LL

15S1341/037 7 5 LL

15S1341/038 3 105 LL

15S1341/039 3 60 LL

15S1341/040 3 5 LL

15S1341/041 8 90 LL

15S1341/042 8 50 LL

15S1341/043 8 5 LL



SampleID Station Depth (m) HC source

15S1341/044 9 85 Bio

15S1341/045 9 50 LL

15S1341/046 9 2 Bio, PW

15S1341/047 1 65 LL

15S1341/048 1 30 LL

15S1341/049 1 5 Bio, PW

Table 9. Interpretation of source of hydrocarbons (HC) within water samples collected during the ARP 7 survey –

Trip 6578. HC source includes: PW = Plant Wax, Bio = Biogenic origin, LL = low level hydrocarbon concentration,

contam = contamination (unspecified), Kero (contam) = Kerosene contamination, Contam (poly) = plastic

contamination, Contam (IFO) = Intermediate fuel oil contamination, Petr = petrogenic source. Profile A = see

interpretation below.

Sample_ID Station

Water depth

HC Source

16S1375/063 1 5 Bio

16S1375/062 1 40 Bio

16S1375/061 1 71 Bio

16S1375/009 32 5 Bio

16S1375/012 32 5 Bio

16S1375/008 32 61 Bio

16S1375/011 32 70 Contam (poly)

16S1375/007 32 103 Bio

16S1375/010 32 106 Bio

16S1375/015 33 5 Bio

16S1375/014 33 80 Bio

16S1375/013 33 102 Bio

16S1375/018 34 5 Bio

16S1375/017 34 80 Bio

16S1375/016 34 103 Bio

16S1375/003 35 5 Contam (poly)

16S1375/002 35 50 Contam (poly)

16S1375/001 35 85

16S1375/021 36 5 Contam (poly)

16S1375/020 36 20 Petr, Bio

16S1375/019 36 100 Petr, Bio

16S1375/037 44 5 Bio

16S1375/036 44 92 Petr, Bio

16S1375/035 44 190 Petr, Bio

16S1375/040 45 5 LL

16S1375/039 45 115 Bio

16S1375/038 45 157 Bio

16S1375/043 46 5 LL

16S1375/046 46 5 LL

16S1375/045 46 52 Kero (contam)

16S1375/042 46 76 LL

16S1375/041 46 115 LL

16S1375/044 46 116 LL



Sample_ID Station

Water depth

HC Source

16S1375/049 47 5 LL

16S1375/048 47 92 LL

16S1375/047 47 145 LL

16S1375/052 48 5 Bio

16S1375/051 48 60 Bio

16S1375/050 48 119 Bio

16S1375/024 50 5 unk

16S1375/054 50 5 LL

16S1375/023 50 70 Bio

16S1375/022 50 126 Bio

16S1375/053 50 127 Bio

16S1375/027 51 5 PW

16S1375/056 51 5 Bio

16S1375/026 51 60 PW

16S1375/025 51 144 PW

16S1375/055 51 144 Bio

16S1375/058 52 5 LL

16S1375/031 52 5 Bio

16S1375/030 52 70 Bio

16S1375/029 52 100 Bio, PW

16S1375/057 52 140 Bio

16S1375/028 52 140 Bio, PW

16S1375/034 53 5 Bio

16S1375/060 53 5 Contam (poly)

16S1375/033 53 63 Bio

16S1375/059 53 120 Contam (poly)

16S1375/032 53 121 Bio

16S1375/006 57 5 Bio

16S1375/005 57 60 Bio

16S1375/004 57 90 LL

3.6 Sediment chemistry

65 sediment samples were collected during the ARP 2 6184 trip and these were complemented with a

further 13 sediment samples from the ARP 5 Empress trip and 26 samples from the ARP 7 6578 trip. These

samples were collected by sediment grab were subsampled for a suite of analyses described in Section

2.2.3., which comprised 1114 individual analyses including metal analyses not reported here.

3.6.1 Methane

A total of 97 (65 - ARP 2, 13 – ARP 5, 19 – ARP 7) headspace gas samples were collected and analysed for

methane. 94 samples returned methane concentrations below the limits of reporting (<15 ppm). The three



samples from the ARP 2 trip from station 15 (SMG 052), station 16 (SMG 053) and station 27 (SMG 092) had

concentrations of 25, 17 and 26 ppm, respectively. These data are intriguing because although these

concentrations of methane are very low, the positive responses all overly the subsurface extent of the

Prelude and Ichthys fields, suggesting low level gas seepage. This is partially supported by the presence of

pock marks and other fluid escape features observed in multibeam data from mapping of the seafloor over

the Prelude field conducted by Shell. However, elevated methane concentrations may also be the product

of anaerobic biodegradation of organic matter in the sediments.

3.6.2 BTEX

103 (65 - ARP 2, 13 – ARP 5, 25 – ARP 7) sediment samples were analysed for BTEX. 48, 1 and 25 ARP 2, 5

and 7 sediment samples respectively had BTEX concentrations below the limits of reporting (B, T, E, o-

Xylene <0.02 mg/kg and m+p-Xylene <0.04 mg/kg). Toluene was the only compound present in the

remaining 17 ARP 2 and 12 ARP 5 samples. These concentrations were either at the limits of reporting (0.02

mg/kg) or slightly above (0.04 mg/kg). As these concentrations were single compound responses, and were

not associated with elevated higher molecular weight PAH or TPH concentrations, they are interpreted to

be low level contamination introduced either during sampling or in subsequent transport and analysis.

3.6.3 PAH

103 (65 - ARP 2, 13 – ARP 5, 25 – ARP 7) sediment samples were analysed for 38 parent and alkylated PAH.

Interpretations of the compound distribution and concentration identified 4 ARP 2 and 1 ARP 7 samples

that were affected by contamination. These contaminants were either intermediate fuel oil (IFO), kerosene

or plastics (Table 7, Table 8 and Table 9). None of the remaining samples analysed had total PAH

concentrations above 0.796 mg/kg. The majority of the remaining sediment samples had very low total

concentrations of PAH (below 0.01 mg/kg). Total PAH concentration data, when displayed geographically,

shows that there are no clear spatial trends in total PAH concentration data with location (Figure 36) either

within trips or between trips.

When the distribution of individual PAH for the sediments are considered after removing contaminated

sample data (Figure 39), it is apparent that the majority of PAH in all samples are below limits of reporting.

Where PAH are present, the majority of concentrations are close to or less than one order of magnitude

above the limits of reporting. As with the water samples, the naphthalene and alkylated naphthalenes

represent the most abundant class of PAH in the samples. The presence of these compounds is attributed

to pyrogenic compounds from bush fires in the surrounding region (Peters et al. 2005). The upper range of

compound concentrations is determined by very few samples and these have a maximum concentration of

0.61, 0.18 and 0.014 mg/kg total single PAH for ARP 2, 5 and 7 respectively. The summary whisker plot

shows that while the individual PAH compound data is sparse they are generally consistent between trips.



Figure 36. Map of study area showing stations highest concentrations of total parent and alkylated PAH in

sediments collected from ARP 2 trip 6184, ARP 5 and ARP 7 Trip 6578 after removal of contamination outliers.



3.6.4 TPH

103 (65 - ARP 2, 13 – ARP 5, 25 – ARP 7) sediment samples were analysed for TPH. As with the PAH

samples, interpretation of the compound distribution and concentration identified 4 ARP 2 and 1 ARP 7

samples that were affected by contamination. These contaminants were either intermediate fuel oil (IFO),

kerosene or plastics (Table 7, Table 8 and Table 9). As with the prior interpretations, the alkane

distributions in the uncontaminated samples are attributed to being of biogenic origin or terrestrial plant

waxes (Figure 37). After removal of contaminated sample data, total concentrations of alkanes quantified in

the samples were higher than PAH concentrations with values ranging from 0 to 25 mg/kg (25 mg/kg - ARP

2, 9.5 mg/kg - ARP 5, 9.5 mg/kg – ARP 7).

Figure 37. GC-FID chromatogram for ARP 2 station 38 (SMG 132). Inset A shows full chromatogram and TPH

compound profile. Inset B shows a close-up view of the chromatogram showing odd over even n-alkane

predominance indicative of terrestrially derived plant waxes.



When plotted by location there was no obvious spatial pattern in the data (Figure 38) within trips or

between trips. The distribution of individual compounds (Figure 40), after removing contaminated sample

data, show that in the majority of samples a complete suite of alkanes was detected. The range of alkane

concentration extended to four orders of magnitude above the limits of reporting, although the majority of

the data is within three orders of magnitude of reporting limits. The data shows that between trips the

range in individual compound abundance was similar.

3.6.5 Metals

Analysis was undertaken to understand baseline concentrations of metals for future produced water

studies and as such is not directly related to the aims and objectives of the ARP2 study and these data have

not been reported here. Detailed results can be found in ChemCentre report 14B0709.



Figure 38. Map of study area showing stations with the highest concentrations of quantified alkanes from THP

analyses in the sediments from ARP 2 trip 6184, ARP 5 and ARP 7 Trip 6578 after removal of contamination outliers.



Figure 39. Whisker plot showing variance in individual parent and alkylated PAH concentrations from 61 ARP 2, 13 ARP 5 and 24 ARP 7 sediment samples collected during the

ARP 2 hydrocarbon seep and baseline survey –Trip 6184. Limits of reporting for the compounds were 0.001 mg/kg and the *number above each compound is the number of

samples not included in the analysis of variance due to that compound being below limits of reporting. The whiskers describe the total range in variance, whilst the upper box

represents the 2nd quartile the lower box represents the 3rd quartile and bar in the centre represents the median concentration of the compound.



Figure 40. Whisker plot showing variance in in quantified alkane and UCM concentrations from 61 ARP 2, 13 ARP 5 and 24 ARP sediment samples collected during the ARP2

hydrocarbon seep and baseline survey –Trip 6184. Limits of reporting for the compounds were 0.001 mg/kg and the *number above each compound is the number of samples

not included in the analysis of variance due to that compound being below limits of reporting. The whiskers describe the total range in variance, whilst the upper box

represents the 2nd quartile the lower box represents the 3rd quartile and bar in the centre represents the median concentration of the compound.



Table 10. Interpretation of the source of hydrocarbons in sediment samples. HC sources include: PW = Plant Wax,

Bio = Biogenic origin, contam = contamination (unspecified), Kero (contam) = Kerosene contamination.

Lab IDe SampleID Station Water Depth HC source

14B0709/001 COA/001009 1 74 PW

14B0709/002 COA/001036 2 90 PW

14B0709/003 COA/001038 2 90 PW

14B0709/004 COA/001058 3 122 PW

14B0709/005 COA/001077 4 180 PW

14B0709/006 COA/001100 5 260 PW, Bio

14B0709/007 COA/001124 6 273 PW

14B0709/008 COA/001146 7 325 PW, Bio

14B0709/009 COA/001165 8 384 PW

14B0709/010 COA/001188 9 440 PW

14B0709/011 COA/001212 10 479 PW, Bio

14B0709/012 COA/001235 11 406 PW

14B0709/013 COA/001259 12 339 PW, contam

14B0709/014 COA/001261 12 339 PW

14B0709/015 COA/001304 13 306 PW

14B0709/016 COA/001327 14 283 PW

14B0709/017 COA/001350 15 274 PW

14B0709/018 COA/001372 16 284 PW, Bio

14B0709/019 COA/001396 17 274 PW, Bio

14B0709/020 COA/001419 18 272 PW, Bio

14B0709/021 COA/001441 19 282 PW, Bio

14B0709/022 COA/001465 20 351 PW, Bio

14B0709/023 COA/001488 21 444 PW, Bio

14B0709/024 COA/001502 22 117 PW, Bio

14B0709/025 COA/001518 23 107 PW, Bio

14B0709/026 COA/001541 24 285 PW, Bio

14B0709/027 COA/001564 25 280 PW, Bio

14B0709/028 COA/001587 25 280 PW, Bio

14B0709/029 COA/001610 26 276 PW, Bio

14B0709/030 COA/001633 27 263 PW, Bio

14B0709/031 COA/001656 28 263 PW, contam

14B0709/032 COA/001679 29 284 PW

14B0709/033 COA/001702 30 337 PW

14B0709/034 COA/001725 31 357 Kero (contam?), PW

14B0709/035 COA/001739 32 107 PW

14B0709/036 COA/001755 33 112 PW

14B0709/037 COA/001774 34 110 PW

14B0709/038 COA/001789 35 91.1 PW

14B0709/039 COA/001803 36 104 PW

14B0709/040 COA/001824 37 198 PW

14B0709/041 COA/001826 37 198 PW, Bio

14B0709/063 COA/001844 36 103 PW



14B0709/064 COA/001848 36 103 PW

14B0709/065 COA/001852 36 101 PW

14B0709/042 COA/001885 38 256 PW, Bio

14B0709/043 COA/001908 39 243 PW, Bio

14B0709/044 COA/001930 40 141 PW

14B0709/045 COA/001950 50 131 PW

14B0709/046 COA/001969 53 128 PW

14B0709/047 COA/001985 52 142 PW

14B0709/048 COA/002004 51 149 PW

14B0709/049 COA/002023 44 194 PW

14B0709/050 COA/002042 45 159 PW

14B0709/051 COA/002057 46 123 PW

14B0709/052 COA/002089 41 250 PW

14B0709/053 COA/002112 42 242 PW, contam

14B0709/054 COA/002135 43 224 PW

14B0709/055 COA/002154 47 149 PW

14B0709/056 COA/002168 48 121 PW

14B0709/057 COA/002170 48 121 PW

14B0709/058 COA/002190 49 104 PW

14B0709/059 COA/002205 54 88 PW

14B0709/060 COA/002220 55 110 PW

14B0709/061 COA/002222 55 110 PW

14B0709/062 COA/002245 56 79.1 PW



3.7 Summary of findings from geochemical analyses

The hydrocarbon chemistry data collected during the ARP 2 6184 trip, subsequently supplemented by

samples from the ARP 5 M/V Empress and ARP 7 6578 trips represents a water column baseline and a

considerable extension to existing sediment chemistry data holdings in the Browse Basin study area. As

such the results of this study meet the ARP2 objectives to develop a hydrocarbon baseline in the vicinity of

the Ichthys development fields.

Generally, the abundance of BTEX and higher molecular weight PAH compounds is low to very low, and

where observed, such compounds have been attributed to being of pyrogenic origin, likely from wildfires,

either from the Australian mainland or regionally.


identification of BTEX and PAH compounds introduced during an incident to be distinguished from

background concentrations.

Alkane compounds were found to be more prevalent than PAHs and based on their specific components,

the provenance of these compounds was assigned to an origin from plant waxes and biogenic sources, such

marine algal and microbial populations.

The inclusion of data from samples collected during other ARP projects in the whisker plots presented here

has allowed the variation expected in samples collected during different time periods to be determined.

Particularly the variance in water column PAHs during the ARP 5 Empress trip show that the range in

natural conditions may not have been fully characterised to date. TPH concentrations and the sediment

PAH concentrations were consistent across trips and this suggests that the natural variance in the study

area has been adequately characterised. This approach will permit rapid identification of anomalous

sample concentrations in the event of a hydrocarbon spill within the study area.

The approaches used to describe the hydrocarbon geochemistry data will permit a first level of

determination of variance from baseline concentrations. However, in the event of an incident such

approaches are unlikely to permit rapid and semi-automated determination of source – as a minimum this

will require careful consideration of the compound distributions and compound abundances to determine

the source of hydrocarbons. It is likely that more detailed forensic analyses, such as saturated biomarker

analysis (e.g. hopanes and steranes), would be required in the determination of hydrocarbon source in

more ambiguously sourced samples. Biomarker plots comparing the ratios of weathering resistant

compounds derived from the spilled hydrocarbons with samples collected from the field have been used

elsewhere to determine the source of hydrocarbons with more certainty.

In the case of fixed discharge scenarios where sources are known, it is recommended that this work be

undertaken in advance of an incident so that a rapid assessment of the hydrocarbon source could be

undertaken in the event of an incident.



4 Conclusions and future work

The objective of this report was to interpret the sensor and hydrocarbon analysis data collected during the

ARP 2, ARP5 and ARP 7 trips across the Browse Basin. This research was undertaken with a view to

establishing an understanding of the hydrocarbon baseline conditions prior to production activities at the

Prelude and Ichthys development fields. This report integrates water column profile data along with

geochemical analysis data on water column and sediment samples collected during the ARP 2 6184 trip,

ARP 5 Empress trip and ARP 7 6578 trip.

This report is the task 5 deliverable of ARP 2 as part of the subcontract to the agreement (No.UI24206)

between AIMS and Shell Development (Australia) Pty Ltd (No.UI24206) and INPEX Operations Australia Pty

Ltd (No.800950).

Prior to the ARP 2 Trip 6184 there were no known records of water column profiles collecting a suite of

chemical and physical data in this area. As such, the collection of 88 water column profiles incorporating a

large number of chemical and physical water column measurements represents a water column baseline.

The sediment chemistry data collected also is a considerable extension to existing sediment chemistry data

holdings in the Browse Basin study area, the collation of which represents a pre-development hydrocarbon

baseline. Therefore, the results of this study meet the extended ARP2 objectives to develop a hydrocarbon

baseline in the vicinity of the Ichthys development fields.

The data show systematic spatial trends across the basin, as well as interdependency between responses.

The inclusion of a suite of measurements enabled the identification of linkages which may otherwise not

have been revealed, which in turn may have led to erroneous interpretations. The trends in the data are

related to oceanographic processes, such as the halocline and thermocline, tidal processes and different

water mass properties. There are significant differences in the data collected from the ARP 2 6184 and ARP

7 6578 trips which are attributable to changing oceanographic processes and biological processes. Variance

between the data collected from each trip demonstrates that the natural variability within the Browse

Basin water column physical and chemical properties, has yet to be fully characterised and this warrants

further investigation.

In particular, the differences in salinity may also be considered in terms large scale oceanographic

processes. For example, differences in the Indian Ocean Dipole Index (IOD)

(http://www.bom.gov.au/climate/iod/), from slightly positive during ARP 2 trip 6184 to strongly negative

just prior to the ARP 7 6578 trip, are likely to have led to the warmer sea-surface temperatures and

increased salinities observed in the ARP 7 data.

As with the CHR sensor response, it is likely that the CHC sensor response describes dissolved hydrocarbons

released into the water column by organic matter decay and/or the activity of higher trophic level

organisms (e.g. zooplankton). Some of the variability encountered in the lower sections of the ARP 2

profiles can also be attributed to the enhanced turbidity and the re-suspension of organic matter from

sediments. There is no evidence from the chemical analysis data of enhanced PAH/TPH concentrations in

samples collected during the ARP 7 trip.

The large differences in CHR and CHC concentrations between trips shows that the natural range of

variability in the waters of the Browse Basin has yet to be fully characterised. This reduces the capability to

correctly identify, and understand the spatial distribution of entrained hydrocarbons in the water column in

the unlikely event of an unintended hydrocarbon release. Further data collection is required to reduce

these uncertainties and more fully characterise the natural variability observed in the study area. This will

be partly addressed through analysis of samples from the April 2017 ARP7 survey and the forthcoming

http://www.bom.gov.au/climate/iod/



ARP7 trip in December 2017 which will collect repeat measurements at the Browse Island, Heywood Shoal,

and Echuca Shoal study areas.

Graphical tools such as heat maps of sensor responses plotted as side-by-side water column profiles have

allowed simple incorporation of additional baseline data from the ARP 7 trip. These visual approaches have

permitted the identification of anomalous data and will be a valuable tool in the event of an unintended

hydrocarbon release into the marine environment in the study area.

As for the water column sensor data, the water and sediment hydrocarbon chemistry data collected during

the ARP 2 6184 trip, ARP 5 Empress trip and ARP 7 6578 trips provide a considerable increase in baseline

chemistries in the Browse Basin and study area. Generally, the abundance of BTEX and higher molecular

weight PAH compounds is low to very low, and where observed, such compounds are identified as

pyrogenic in origin, likely the products of wildfires, either from the Australian mainland or regionally. There

are enhanced water column PAH concentrations in samples collected during the ARP 5 trip which is

tentatively assigned to enhanced bush fire activity at the time of sample collection. Although further

studies are required to affirm this interpretation.


BTEX compounds and PAHs introduced during the incident to be distinguished from background

concentrations. Alkane compounds were found to be more prevalent than PAHs. Based on their specific

components, the provenance of these compounds was assigned to an origin from plant waxes and biogenic

sources, such marine algal and microbial populations.

The use of the whisker plot has permitted further sample data to be readily integrated and compared,

enabling assessment of the range of variation in PAH and TPH concentrations in the study area. This

approach will allow rapid identification of anomalous sample concentrations in the event of a hydrocarbon

spill in the study area.

The approaches used to describe the hydrocarbon geochemistry data will permit a first level of

determination of variance from baseline concentrations. However, in the event of an incident such

approaches are unlikely to permit rapid and semi-automated determination of source – as a minimum this

will require careful consideration of the compound distributions and the compound abundance to

determine the source of hydrocarbons. It is likely that more detailed forensic analyses, such as saturate

biomarker analysis, would be required in the determination of hydrocarbon source in more ambiguously

sourced samples. Biomarker plots comparing the ratios of weathering resistant compounds derived from

the spilled hydrocarbons with samples collected from the field have been used elsewhere to determine the

source of hydrocarbons with more certainty.

In the case of fixed discharge scenarios where sources are known, it is recommended that this work be

undertaken in advance of an incident so that a rapid assessment of the hydrocarbon source could be

undertaken in the event of an incident. This could be achieved through additional sample collection during

forthcoming ARP field trips.



5 References

Gresham, M., and Ross, A. (2015) Synthetic Aperture Radar data collection in the vicinity of the Prelude and Icthys developments, Browse Basin, Australia. CSIRO report EP154316. pp. 74.

Heyward, A., Case, M. (2016) AIMS Cruise Report # 6578 (ARP 7 Reefs - 2016). AIMS confidential report. Report number ARP7/AIMS/AIMS/RT/033. Pp 16.

Logan, G.A., Jones, A.T., Ryan, G.J., Wettle, M., Thankappan, M., Groesjean, E., Rollet, N., Kennard J.M. (2010) Review of Australian Offshore Natural Hydrocarbon Seepage Studies. Geoscience Australia Record: 2008/17.

Peters, K.E., Walters, C.C., Moldowan, J.M. (2005) The Biomarker Guide, Cambridge University Press, ISBN 0 521 78158 2, pp 1155.

Ross, A., Stalvies, C., Talukder, A., Trefry, C., Mainson, M., Cooper, L., Palmer, J., Yuen, M., Gresham, M., Edwards, S. and Boyd, M. (2017a) Occurrence of Natural seeps in the vicinity of the Prelude/Ichthys fields - Applied Research Program project 2 task 4 report. CSIRO confidential report EP173371. Pp 90.

Ross, A., Stalvies, C., Talukder, A., Trefry, C., Mainson, M., Cooper, L., Yuen, M., Palmer, J. (2017b) Interpretive geochemical data report on samples obtained during ARP 2 Trip 6184, May 2015. Applied Research Program project 2 task 3 report -CSIRO confidential report EP173371. Pp 96.

Stalvies, C., Trefry, C., Talukder, T., Mainson, M. (2015) Shell/INPEX ARP Trip Report 6184 (ARP 2). CSIRO confidential report. Report number ARP2/CSIRO/AIMS/RT/001. Pp15.

Tonks, M. (2016a) ARP5 –Demersal Fish Trip Plan: November 2015. Pp93.

Tonks, M. (2016b) Shell/INPEX ARP Trip Report (ARP 5) 2015. CSIRO confidential report. Report number ARP5/AIMS/CSIRO/RT/023. Pp83.

Trefry, C., Ross, A., Stalvies, C. (2015) Data collation and development of hydrocarbon baseline survey and sampling plans in the vicinity of the Prelude and Ichthys developments, Browse Basin, Australia. CSIRO report EP-154824. pp.90.



A.1 CTD sample stations

Table 11. List of ARP 2 sample stations and associated CTD data files

BBS Day (UTC) Time (UTC)

Depth

LISST Files SB25plus Files

1 8/5/2015 17:54:00 74 na IMOS_CSIRO_CDEKORSTUZ_20150508T175659Z_BBS001_FV01_Profile-SBE25plus_C-20160601T035544Z.nc

2 9/5/2015 5:42:00 92 L1290544.DAT IMOS_CSIRO_CDEKORSTUZ_20150509T054406Z_BBS002_FV01_Profile-SBE25plus_C-20160527T060638Z.nc








































54 16/5/2015 11:21:00 90 L1361115.DAT na






Table 12. List of ARP 7 sample stations and associated CTD data files

BBS Day (UTC) Time (UTC) Depth LISST Files SB25plus Files

1 8/12/2016 22:41:27 75

IMOS_CSIRO_CDEKORSTUZ_20161208T224127Z_BBS001_FV01_Profile-SBE25plus_C-20170622T035446Z.nc

32 29/11/2016 1:51:11 109 L3340153 IMOS_CSIRO_CDEKORSTUZ_20161129T015111Z_BBS032_FV01_Profile-SBE25plus_C-20170622T052507Z.nc










47 6/12/2016 5:41:39 152


48 6/12/2016 6:26:02 124




50 8/12/2016 1:40:26



51 8/12/2016 3:07:25 150




52 8/12/2016 2:35:24



53 8/12/2016 2:07:20 126



58 2/12/2016 1:54:42

L3370156 IMOS_CSIRO_CDEKORSTUZ_20161202T015442Z_BBS058_FV01_Profile-SBE25plus_C-20170622T070858Z.nc

58 2/12/2016 23:40:35

L3372343 IMOS_CSIRO_CDEKORSTUZ_20161202T234035Z_BBS058_FV01_Profile-SBE25plus_C-20170622T070858Z.nc



A.2 Sensor calibration certificates



Annex 1 Calibration Certificate UV AQUATRACKA SN107629-001



Annex 2 Calibration Certificate UV AQUATRACKA SN10-7776-001



Annex 3 Calibration Certificate AQUATRACKA MK# SN11-8199-001



Annex 4 Calibration Certificate AQUATRACKA MK# SN11-8141-001



Annex 5 Calibration Rinko 77



Annex 6 Rinko3 Correction formula for temperature and pressure



Annex 7 SB25plus Calibration Certificate Temperature



Annex 8 SB25plus Calibration Certificate Conductivity



Annex 9 SB25plus Calibration Certificate Pressure



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