LINKING SEDIMENT GEOCHEMISTRY IN THE FRASER...

LINKING SEDIMENT GEOCHEMISTRY IN THE FRASER RIVER

INTERTIDAL REGION TO METAL BIOACCUMULATION IN

MACOMA BALTHZCA

by

Christine A. Thomas

B.Sc. Simon Fraser University, 1994

THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE

in the Department

Biological Sciences

O Christine A. Thomas 1997

SIMON FRASER UNIVERSITY

August, 1997

All rights reserved. This work may not be reproduced in whole or in part, by photocopy or other means, without permission of the author.

APPROVAL

Name: Christine Anne Thomas

Degree: MASTER OF SCIENCE

Title of Thesis:

Linlung Sediment Geochemistry in the Fraser River Intertidal Area to Metal Bioaccumulation in Macoma balthica

Examining Committee:

Chair: Dr. B. Honda, Assohte Professor

Lbr. L: ~ e n d d n o u n g , Assistant Frofessor, Senior ~udervisor Department of Biological Sciences, S.F.U.

son, Professor of Oceanography and Botany, U.B.C.

Dr. E. B. Hartwick, ~ssdciate Professor Department of Biological Sciences, S.F.U.

- - - Dr. R. Elner, Research Scientist Canadian Wildlife Services

Dr. I C H W 6 f e s b r and Assistant Director Westwaterantre, U.B.C. Public Examiner

Date Approved: -. .

ll

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Title of Thesis/Project/Extended Essay

Author: (signature)

, (date)

ABSTRACT

Porewater, surficial sediment and biota samples were collected from 26 locations in the

intertidal region of the Fraser River estuary. Sediment samples were collected in May

and July of 1995 and porewater and biota samples were only collected in July. Porewater

samples were analysed for dissolved iron and manganese to assess the contribution of

diagenesis to concentrations of iron and manganese oxides at the sediment-water

interface. Surficial sediment samples were geochemically characterized by a simultaneous

extraction procedure that separated trace metals among three 'biologically relevant'

sediment components; organic matter, reducible iron (iron oxides) and easily reducible

manganese (manganese oxide). Each sediment fraction was then analysed for cadmium,

copper, lead, nickel, zinc and mercury. Benthic samples of Macoma balthica, a deposit

feeding bivalve, were also collected. Bivalve samples were separated into shell and tissue

and analysed for trace metals. An R~ MAX procedure was applied to determine if

differences in the concentration of trace metals in the shell and tissue of M. balthica were

related to sediment geochemistry using sediment geochemistry as the independent variable

and bivalve metal concentrations as the dependent variable.

Porewater profiles revealed that concentrations of iron and manganese oxides at the

surface could be attributed to a combination of two factors; diagenetic processes and

influence from the Fraser River. The relative importance of each factor was highly

element specific; for iron, diagenesis was more important relative to the Fraser River, while

for manganese, both of these factors contributed to the amount of oxides recovered at the

sediment-water interface. The combination of these two factors in contributing to the

amounts of iron and manganese oxides at the various sampling locations resulted in a

spatially heterogeneous environment in regards to these two elements. In contrast, the

temporal variation (May vs July) was insignificant. Heterogeneity was also reflected in

the partitioning of trace metals, where partitioning was location dependent i.e., contingent

on surrounding geochemistry. This in turn, lead to differences in metal uptake by M.

balthica that were related to sediment geochemistry. The relationships with tissues were

highly significant (p10.001), except for mercury (p10.05), with sediment geochemistry

accounting for 31 % of the variability for cadmium, 39% for zinc, 5 1 % for copper and 54

% for lead. For shells, sediment geochemistry explained 12% of the variation for mercury,

15% for zinc, 21% for nickel and 43% for copper. Overall, metal levels in the tissue and

shell of M. balthica seem to best relate to the concentration of easily reducible metal (i.e.,

metal recovered in the easily reducible phase).

These findings have implications considering that monitoring programs often characterize

large areas based on only a few sample sites, with the assumption being that the area is

fairly homogeneous. However, this was not the case in the present study. Given that

physical, chemical and biological differences in an estuary can occur on a scale of

centimeters to kiIometers (Shine et al. & Sewall, 1996) extrapolation of resuIts to an

entire estuary can be misleading. Therefore, these results underscore the necessity of

comprehensive multicomponent studies that consider the processes influencing the fate and

effects of metals in an estuarine environment.

ACKNOWLEDGMENTS

I have been extremely fortunate in having been surrounded by helpful, kind and

knowledgeable people throughout this study. I thank my senior supervisor, Leah Bendell-

Young, for her guidance, encouragement and freedom she allowed me in my studies. I

would also like to thank my sister, Katherine Thomas, for all the technical advice and

support she provided throughout my degree. Many thanks also go out to everyone I

dragged out to help me in the field and in the lab: Laura Barjaktarovic, Leanne Hariss,

Zainal Arifin, Leah Bendell-Young, Pierre Stecko, Rupinder Bagri, Bill Nicholson and

Jason Giles. In addition, without the co-operation of the Canadian Coastguard, accessing

sampling sites on Sturgeon Bank would have been extremely difficult.

I am also extremely grateful to the Pacific Environmental Science Center, Environment

Canada, without whose help the analysis of all my samples would not have been possible.

I am especially grateful to Henry Quon, Maria Araujo and Ron Leary who worked with

me month after month until all my samples were run.

TABLE OF CONTENTS

. . Approval Page ...................................................................................................... 11

... Abstract .................................................................................................................. 111

Acknowledgments ................................................................................................. v

.................................................................................................... Table of Contents vi

List of Tables ...................................................................................................... ix

......................................................................................................... List of Figures x

CHAPTER 1: INTRODUCTION ....................................................................... 1

1.0 Diagenesis as Measured Through Porewaters ........................ 3

2.0 Sediment Geochemistry ....................................................... 4

3.0 Metal Uptake by Biota .......................................................... 4

4.0 Objectives ............................................................................ 6

CHAPTER 2: METHODS ................................................................................... ............................................................................ 1.0 Study Area

................................................................ 1.1 Study Sites

............................................................. 2.0 Porewater Chemistry

3.0 Sediment Geochemistry ......................................................... 3.1 Trace Metal Analysis .................................................

. . ............................................... 3.2 Matrix Detemnatlons . . 3.3 Gram Slze ..................................................................

4.0 Tissue Chemistry ................................................................... 5.0 Statistical Analyses ................................................................

CHAPTER 3: THE ROLE OF POREWATERS IN CONTRIBUTING ............ 18

TO THE SEDIMENT MATRIX

1.0 Results ................................................................................. 18

1.1 Porewaters ................................................................. 18

vii

1.2 Sediment Geochemistry ............................................. 35

1.2.1 Iron and Manganese Oxides ............................ 35

1.2.2 Organic Matter ............................................... 43

1.2.3 Grain Size ...................................................... 43

1.2.4 Relationships Between Sediment Matrix ......... 45 Parameters

Discussion .......................................................................... 46

..................................................... 2.1 Porewater Profiles 46

2.1.1 Diagenetic Processes ..................................... 48

2.1.2 Biological Processes ....................................... 49

2.2 Riverine Input versus Diagenetic Processes ................ 49

............................. 2.3 Implications of Porewater Cycling 51

2.4 SedimentGeochemistry ............................................. 51

........................... 2.4.1 Iron and Manganese Oxides 51

............................................... 2.4.2 Organic Matter 52 . .

2.4.3 Grain Size ...................................................... 53

......... CHAPTER 4: LINKING SEDIMENT GEOCHEMISTRY TO METAL 55 BIOACCUMULATION

.................................................................................. Results 55

1.1 Metal Concentrations and Partitioning ........................ 55

1.1.1 General Trends .............................................. 55

............................................... 1.1.2 Specific Metals 56

........................................... 1.1.3 Metal Partitioning 63

...................................................... 1.2 Grain Size Effects 69

....................................... 1.3 Metals in Macoma balthica 69

Discussion ........................................................................... 74 . . . ...................................................... 2.1 Metal Partitioning 74

............... 2.2 Metal Concentrations Relative to Sediment 76 Quality Guidelines

................ 2.3 Status of the Fraser River Intertidal Region 78

viii

2.3.1 Relative to Other Studies Within the Estuary .. 78

............................. 2.3.2 Relative to Other Estuaries 80

Linking Sediment Geochemistry to Tissue and Shell .. 80 Levels

.................... 2.4.1 General Trends In Bivalve Metal 81 Concentrations

................................................ 2.4.2 Specific Metals 81

Implications of Metals in Macoma balthica ................ 83

2.5.1 Tissue versus Shell ........................................ 83

2.5.2 Relative to Other Studies Within the Estuary .. 84

............................. 2.5.3 Relative to Other Estuaries 85

........................................... CHAPTER 5: SUMMARY AND IMPLICATIONS 87

............................................................................. CHAPTER 6: REFERENCES 91

................................................................ APPENDIX I: Instrument Theory 100

APPENDIX II: Detection Limits and Dilution Factors ................................... 102

APPENDIX m: Quality AssuranceIQuality Control ....................................... 104

APPENDIX IV: Sediment Matrix Attributes ................................................... 106

APPENDIX V: . . . .

Gram Size Charactenstlcs ..................................................... 107

APPENDIX VI: Trace Metals in Deposit Sediments ....................................... 108

APPENDIX VII: Trace Metals in Macoma balthica ........................................ 114

LIST OF TABLES

Chapter 3 Table I:

Table 11:

Table 111:

Table N:

Table V:

Table VI:

Table VII:

Chapter 4

Table I:

Table 11:

Table III:

Table N:

Table V:

Table VI:

Table VII:

Table VIII:

Table IX:

Table X:

Salinity measurements taken at depth 0, 6 and 20 cm from ............... 35 various sampling locations

Three-way GLM for RED Fe concentrations .................................... 40

Three-way GLM for ER Mn concentrations ................................... 43

Three-way GLM for organic content .............................................. 43

Three-way GLM for grain size .......................................................... 45

Correlations between sediment matrix parameters ............................ 46

Comparison of actual measured concentrations of metals versus ...... 54 those calculated after grain size normalization

Three-way GLM on metal concentrations in the different sediment ... 60 fractions

Multiple comparison tests for differences in metal concentrations.. .... 6 1 between months and among sites

The percent metal partitioned in the easily reducible (ER), reducible 64 (RED) and residual (RES) fractions

Three-way GLM on metal partitioning in the different sediment ........ 67 fractions

Multiple comparison tests for differences in metal partitioning ... ...... 68 between seasons and among sites

Average concentration, range and coefficient of variation for tissue.. 70 and shell metal concentrations

Partial regression coefficients, coefficients of multiple determination 72 and related statistics of predictions of trace metal levels in the tissue of Macoma balthica using multiple linear regression ( R ~ MAX)

Partial regression coefficients, coefficients of multiple determination 73 and related statistics of predictions of trace metal levels in the shell of Macoma balthica using multiple linear regression ( R ~ MAX)

Summary of maximum concentrations of metal in the aqua regia ...... 77 extract and labile fraction (ER+RED+ORG), as well as the site and location at which this value was observed.

Ranges of total trace metal concentrations in various estuarine ... . ..... 79

surface sediments

Table XI: Ranges of trace metal concentrations in the tissues of Macoma ......... 86 balthica in various estuaries

LIST OF FIGURES

Figure 1.1

Figure 2.1

Figure 2.2

Figure 3.1

Figure 3.2

Figure 3.3

Figure 3.4

Figure 3.5

Figure 3.6

Figure 3.7

Figure 3.8

Figure 3.9

Figure 3.10

Figure 3.1 1

Figure 4.1

General overview of factors contributing to metal bioavailability ...... 2 in a deposit feeding bivalve in an estuarine intertidal region

Location of sample sites ..................................................................... 8

Simultaneous extraction procedure used for the partitioning of ........ 13 metals

Porewater profiles for Sturgeon Bank ................................................. 19

Porewater profiles for Roberts Bank ................................................... 25

Porewater profiles for Boundary Bay. .................. .................. . . .......... 3 1

Correlation of iron recovered from the RED fraction of the ............... 36 sediment and the corresponding sub-surface maximum of ~ e ~ + in the porewater

Correlation of manganese recovered from the ER fraction of the....... 37 sediment and the corresponding sub-surface maximum of ~ n ~ ' in the porewater

Concentrations of matrix features in surficial sediment from the.. . .. .. .3 8 intertidal region, May 1995

Concentrations of matrix features in surficial sediment from the ........ 39 intertidal region, July 1995

Partitioning of iron among the ER, RED, ORG and RES fractions, ... 41 May and July 1995

Partitioning of manganese among the ER, RED, ORG and RES ........ 42 fractions, May and July 1995

Particle size of sediments, May and July 1995 .................................... 44

Schematic representation of profile shapes of dissolved Fe and Mn ... 47 at a the sediment-water interface

Concentrations of metals in the different sediment fractions,. .. .......... 57 May 1995

Figure 4.2 Concentrations of metals in the different sediment fractions , ............. 58 July 1995

Figure 4.3 Correlation between Hg in the sediment and organic matter .............. 62

Figure 4.4 Partitioning of metals in the different sediment fractions , .................. 65 May 1995

Figure 4.5 Partitioning of metals in the different sediment fractions , ................... 66 July 1995

CHAPTER 1: INTRODUCTION

Estuarine sediments are a major reservoir of trace metals, both of anthropogenic and natural

origins (Bryan, 1980; Langston, 1982). Once in the sediment, these metals can be

accumulated by benthic-dwelling organisms which live and feed on the sediment (Engel &

Fowler, 1979; Bryan & Langston, 1992; Tessier et al., 1994). Considering that benthic

organisms are primary prey items for several higher trophic levels (shorebirds, waterfowl,

fish, etc.), transfer of metals to the next trophic level can occur over time (Braune, 1987;

Young et al., 1987; Miller et al., 1992; Ferns & Anderson, 1994). In addition, elevated

tissue concentrations of metals can lead to adverse effects in biota (Kemp & Swartz, 1988;

Roesijadi, 1992; Luoma et al., 1995). Concerns regarding trace metals in an estuarine

environment have changed from the focus of just measuring total levels to understanding

the processes and controls on metal behavior. This study addresses the processes and

controls on metal bioavailability such that further insight can be gained in the prediction of

trace metal uptake in organisms. Figure 1.1 provides a general overview of the processes

investigated that contribute to metal bioaccumulation in a deposit feeding bivalve.

The Fraser River estuary is one of the most extensive and productive biological systems in

Canada (Kennett & McPhee, 1988; FRAP, 1995). It is also Canada's third largest urban

region, with the basin area containing one-half of the population of British Columbia

(Environment Canada, 1992). The above conflicting demands on the Fraser River make

proper management and monitoring of this system essential. Through various monitoring

programs within the Fraser River intertidal area, levels of metals have been measured

sporadically and in isolated areas; however, no studies have addressed the geochemistry of

metals across the entire intertidal region as related to metal availability.

This thesis considers the origin and characteristics of sediment geochemistry and how it

influences trace metal partitioning and metal uptake in the intertidal area of the Fraser River

estuary. Chapter 1.0 provides an introduction and rationale for the research, Chapter 2.0

provides a detailed summary of the methods used throughout the study. Chapter 3.0

Figure 1.1 General overview of factors contributing to metal bioaccumulation in a deposit feeding bivalve in an estuarine intertidal region. Most metals released into the Fraser fiver will be transported downriver associated with the iron and manganese oxides and organic matter present in the suspended particulate matter. These three components are considered key geochemical components in the binding of trace metals in the sediment. In addition to the Fraser River, the sub-surface sediments can also contribute to the supply of iron and manganese oxides at the sediment-water interface as a result of the natural redox cycling of both of these elements. Organisms that feed on the deposit sediment will ingest these components and any trace metals associated with them. In tum, bioavailability will be related to the metal's associations with these three geochemical components.

o verlying water

FeOx I*> MnOx + M+

river OM

+ I. e n sediment- water

FeOx - M +

r M n 0 x - M + j

balthica

subsurface sediments

presents and discusses the findings on the role of porewaters in contributing to sediment

geochemistry at the sediment-water interface. Chapter 4.0 considers the role of sediment

geochemistry on trace metal partitioning/distribution and its role in metal uptake in a deposit

feeding bivalve. Chapter 5.0 synthesizes the findings, summarizes conclusions and considers

the rmplications of the findings.

1.0 Diagenesis as Measured Through Porewaters

Diagenesis refers to the chemical, physical and mineralogical changes that occur in the

sediments during and after deposition. The primary driving mechanism for diagenesis is the

decomposition of organic matter through oxidation. As a result of oxidation, oxygen is

depleted and oxidizing species of nitrogen, manganese, iron, sulfur and carbon are used in

sequence, as terminal electron acceptors. Therefore, iron and manganese will undergo a

natural cycling in the porewaters as a result of diagenesis. The natural cycling of both of these

elements occurs when iron and manganese oxyhydroxides (referred to from now on as oxides)

exposed to reducing conditions, become reduced to form dissolved iron (l?e23 and manganese

(hIn23 at depth in the porewaters. From here they can either diffuse towards the surface to be

oxidized again or be scavenged from solution to remain at depth (Klinkharnmer, 1980; Balzer,

1982). The dissolution of iron and manganese oxides in the sediment will also result in the

release of any metals and nutrients associated with them into the porewaters.

In view of the role the sediment matrix plays in metal bioavailability, it is essential to determine

the relative importance of factors contributing to the matrix. The sediment matrix is influenced

by a combination of two factors: overlying water column processes and diagenetic processes.

The relative contribution of each combines together to define the existing matrix at the

sediment-water interface. For example, Bendell-Young & Harvey (1992) found that in lakes,

diagenesis could account for the manganese oxides in the sediments; however, for iron,

processes in the overlying water column were more important. In an estuarine environment,

the role of diagenetic processes versus overlying water column processes in contributing to the

sediment matrix are unknown. Both of these processes were investigated with an integrated

study of porewater chemistry (I?e2+ and MI?) and particulate phase composition (iron and

4

manganese oxides at the surface). The role porewaters play in contributing to the geochemical

matrix throughout an entire intertidal area have yet to be addressed.

2.0 Sediment Geochemistry

Aquatic sediments are composed of several different geochemical phases that can act as

potential sinks for metals entering an estuarine system. These phases include clay, silt, sand,

organic material, oxides of iron, manganese, aluminium and silica, carbonates and sulphide

complexes (Shea, 1988). Of these components, oxides of iron and manganese and organic

matter are considered the most important geochemical components controlling rnetal binding in

the oxidized portion of estuarine sedment (Jenne, 1968; Luoma & Bryan, 198 1; Davies-

Colley, 1984). Considering that metal availability is affected by the metal's association within

one or more of these sediment components, total metal concentrations provide little

information about potential interactions between the abiotic and biotic environments.

Therefore, knowledge of the partitioning of a particular metal among these three sediment

components is useful in providing a better estimate of metal bioavailability.

Selective extraction procedures that partition metals into 'biologically relevant' fractions are

usefbl in improving the correlation between tissue levels in an organism and levels in the

sediment (Tessier et al., 1984; Samant et al., 1990; Bendell-Young et al., 1994). Problems

with this procedure are associated with the nonselectivity of extractants; therefore, the results

obtained are operationally defined, i.e., the forms of metals are defined by the determination of

extractable elements using a given procedure (Martin et al., 1987; Kheboian & Bauer, 1987).

However, several experiments have verified their specificity (Tessier & Campbell, 1988;

Belzile, 1989). The advantage of selective extraction procedures is that they furnish details

about the origin, mode of occurrence, and most importantly for this study, biological

availability of trace metals.

3.0 Metal Uptake by Biota

Straightforward relationships between trace metal levels in organisms and total levels of metals

in the sediment are seldom encountered. Considering that the distribution of a metal among the

5

geochemical components present will affect the passage of a metal fiom sediment to organism,

partial extraction techniques that partition trace metals into 'biologically relevant7 fiactions in

sediments have been more successful. Some studies suggest that it is metals associated with

the iron and manganese oxides in the sediment that are most available to deposit feeding

organisms. Luoma et al. (1995) found that the concentration of silver associated with the iron

and manganese oxides was a reasonably good predictor of silver bioavailability to Macoma

balthica in estuarine sediments. Bendell-Young & Harvey (1994) also showed that zinc and

copper concentrations in chironomids correlated with zinc and copper concentrations

associated with the manganese oxide portion as modified by amounts of organic matter.

Macoma balthica, a deposit feeding bivalve which is found throughout the Fraser River

estuary, has been used frequently to monitor the levels of bioavailable metals in the sediment

(Bryan et al., 1980; Langston, 1982). Specifically, M. balthica has been used as an indicator of

metal contamination for mercury, lead, silver and arsenic in several estuaries (Bryan &

Hummerstone, 1977; Langston, 1982;1985; Bordin et al., 1992). Because the bivalves are in

intimate contact with the sediments and feed mainly on the surficial sediments (they will

occasionally filter feed) (Luorna & Harvey, 1 985), their tissue concentrations tend to reflect

levels of bioavailable metals in the sedment. By correlating levels of metals found in the

different sediment fractions to tissue levels in M. balthica, an indication of the primary source

of metal contamination, as well as interactions between geochemical components that inhibit or

promote the uptake of metals can be obtained.

A question often raised in studies involving bivalves as indicators of metal contamination is

whether or not the bivalve shell should be analysed in addition to their tissue. In most cases,

only tissues are used, as they respond faster to changes in the environment and tend to have

higher metal concentrations than shells (Koide et al., 1982; Walsh et al., 1995). However,

there is little information relating metal concentrations in the soft tissue to those in shell of

bivalves. Metal ions can become incorporated into the crystalline structure of the shell by

replacing calcium in the carbonate complex or by association with the organic component of

the shell (Babukutty & Chacko, 1992). Previous studies have shown that the analysis of shell

6

material along with tissues complements one another, given that tissues have an inherently

higher variability in their trace metal contents due to factors such as season, age, size and

weight (Cain & Luoma, 1990; Soto et al., 1995).

4.0 Objectives

This thesis considered the factors which govern the availability and accumulation of trace

metals in an estuarine intertidal region. Specifically, the objectives of the present thesis were:

(1) to assess the role of diagenesis in contributing to the sediment matrix (i.e. as defined by

oxides of iron and manganese and organic matter) at the sediment-water interface in the

estuarine intertidal region,

(2) to contrast the geochemistry of the trace metals, cadmium, copper, nickel, lead, zinc and

mercury at three sites within the intertidal region of the Fraser River estuary, and

(3) to relate these differences in trace metal geochemistry to metal availability in Macoma

balthica.

CHAPTER 2: METHODS

1.0 Study Area

For the purpose of this study, the boundaries of the lower Fraser River estuary are those

defined by Kennet and McPhee (1988). The area extends north to Point Grey and south to

the international boundary, including Boundary Bay. The three study sites are Sturgeon

Bank, Roberts Bank and Boundary Bay (Figure 2.1). Sites and locations along the lower

Fraser River estuary intertidal zone were chosen to reflect a range of conditions such as,

influence from the Fraser River, grain size and percent composition of organic matter in the

sediment. These differences all have implications with regards to metal partitioning and

availability. Sediment samples were collected during May and July of 1995, while

porewater and biota samples were only collected in July of that year. The sampling design

allowed for a broad survey of the existing conditions at one point in time across this

extensive area.

The Fraser River is the largest river in British Columbia, extending 1,378 km in length and

draining an area approximately 230,OO km2 or 25% of the land mass of British Columbia.

Each year along its course to the ocean, the Fraser River picks up approximately 20 million

tonnes of clay, silt, sand and gravel (Millman, 1980 & Kennett & McPhee, 1988). Most of

the lighter sand and silt particles remain in suspension until they settle on the delta and

intertidal flats further downstream. Discharge tends to be fairly seasonal, with peak

discharge usually occurring in May through July and accounting for 80% of the yearly run-

off. Tidal cycles are also major factors influencing processes within the Fraser River

intertidal area.

Approximately 25 km upstream from the mouth, the river bifurcates into the North Arm

and the South Arm (Figure 2.1). The North Arm, which carries ca. 16% of the total river

discharge, bifurcates again at Richmond where ca. 30% of the flow (ca. 5% of the total

Fraser River flow) exits via the Middle Arm onto Sturgeon Bank while the remaining 70%

(9% of the total flow) exits just north of Sturgeon Bank (Feeney, 1995). The South Arm

carries the majority of the flow and exits onto Roberts Bank (Kennet & McPhee, 1988).

Boundary Bay does not receive direct input from the Fraser River, but rather via three

smaller rivers; the Nicomekl, Serpentine, and Little Campbell.

1.1 Study Sites

Three sites within the intertidal region were sampled (Figure 2.1). 1) The most northerly

site, Sturgeon Bank, receives ca. 5% of the total flow of the Fraser River and is estimated to

receive ca. 15% of the industrial and municipal wastes discharged into the Fraser River

(Fraser River Estuary Study, 1979 & Feeney, 1995). Before 1988, Sturgeon Bank received

primary treated sewage from the Iona Island Sewage Treatment Plant (STP) directly onto its

foreshore. The discharge from the Iona Island STP amounts to the largest single municipal

sewage discharge in B.C.. Among other things, sewage effluent contains trace metals, such

as copper, iron, lead, mercury, nickel and zinc (Tevendale & Eng, 1984). In 1988 a new

deep-sea outfall was completed which diverted the discharge of sewage into the Strait of

Georgia, 90 m below the surface. The outfall ended the direct discharge of sewage effluent

onto Sturgeon Bank, allowing the banks to slowly rehabilitate, with rehabilitation being

closely monitored. Eight sampling locations on Sturgeon Bank were chosen to compliment

pre-existing data (Bendell-Young et al., 1997 in press). Sites closer to shore were labelled

'A' whereas sites farther offshore were labelled with a 'W'. 2) To the south of Sturgeon

Bank lies Roberts Bank, which is strongly influenced by the South Arm of the Fraser River.

Roberts Bank receives ca. 80% of the total flow of the Fraser River but is estimated to

receive 60% of the municipal and industrial effluent discharged into the Fraser River (Fraser

River estuary Study, 1979). 3) At the southern end of the estuary lies Boundary Bay, which

receives little freshwater input compared to the other two sites. Swain and Holms (1988)

suggest that water quality within Boundary Bay may be influenced by Puget Sound water

entering during flood tides from the Blaine area. Water quality is also influenced via

outflows from three freshwater rivers, the Serpentine, Nicomekl and Little Campbell. In

addition, the areas surrounding Boundary Bay are zoned and utilized for agricultural

purposes and drainage from these areas enters Boundary Bay from five land pump stations

(Swain & Walton, 1993). The pump stations are located along the west and north shores of

the Bay. Both Roberts Bank and Boundary Bay had nine sampling locations per site,

whereas Sturgeon Bank had eight.

2.0 Porewater Chemistry

Glass and plastic containers were pre-soaked in 10% HN03 for 24 h to leach trace metals

and then rinsed 5 times with distilled-deionized water @I H20) before use. All reagents

used were J.T. Baker Instra Analysed grade.

Porewaters were collected during the month of July and were taken within 3 m from where

sediment samples were taken. At each sampling location, porewaters were sampled in

duplicate, approximately 1 m apart and facing each other. Porewater samples were not

obtained from locations 4,5 & 6 at Boundary Bay as Plexiglas peepers were missing upon

retrieval.

Porewater peepers are used to obtain profiles of total dissolved iron and manganese in the

interstitial water. Porewater composition was obtained by the use of "in situ" dialysis (i.e.

porewater peepers) after the methods of Hesslein (1976) and Carignan et al., (1985). The

peepers were made from Plexiglas sheets into which wells that held 4 mL were machined 1

cm apart. Each peeper was approximately 50 cm long and 8 cm wide. Prior to deploying

in the field, each compartment was filled with NanopureQ water and covered with a 0.2 pm

pore size polysulfone filtration membrane (Gelman HT-200). The membrane was held in

place by an additional piece of Plexiglas that had apertures matching the bottom chamber

and was fastened to the main body of the peeper with stainless steel screws (nylon screws

were too fragile and stainless steel screws have been used previously without any detectable

contamination) (Carignan et al., 1985). After the peepers were fully assembled, they were

inserted into an anaerobic chamber which was continuously bubbling nitrogen through

deionized water for 24-36 h. Since salinity may be an important factor governing the

availability of metals, it was measured in representative porewater samples at the sediment-

water interface by a refractometer. In the top 5 cm, the interstitial salinity reflects average

conditions in the overlying water during the previous few days (Bryan & Uysal, 1978).

After deaeration, the peepers were doubled bagged and taken out into the field. At each

site, peepers were inserted vertically in the sediment to a depth of 36 - 40 cm and left to

equilibrate for 13-15 days. After the equilibration period, the peepers were removed and

immediately sampled in the field. Initially, peepers were rinsed with DI H20 to remove any

extraneous sediment. Porewater was removed by directly puncturing the membrane with

acid washed glass pipets and immediately placed in pre-acidified vials (100 pL of 1N

HN03). In order to prevent cross-contamination between sample wells, new pipets were

used for each well. All porewater samples were then stored at 4OC until analysis by

Inductively Coupled Plasma Atomic Emission Spectrophotometry (ICP-AES) (Appendix I).

Preliminary results revealed high levels of sodium and other cations indicative of saline

conditions. Salinity measured on a range of porewater samples varied from 4-36 ppt. In

order to overcome matrix interferences, porewater samples were diluted 20-100 times

according to their salinities before analysis for iron and manganese. The dilution factors

and corresponding detection limits for each site are provided in Appendix II (Table 1). The

recovery of known additions was used to check that final dilutions were adequate in

reducing matrix interferences. In all cases, greater than 90% recovery was recorded.

Internal reference standards were used to check instrument accuracy and precision.


Sediment samples from all sites were collected during May and July of 1995. At each

sampling location, sediment samples were collected in triplicate by skimming the oxidized

top centimeter of the sediment with a plastic scoop into 50 rnL centrifuge tubes. Only the

oxic portion of the sediment (top 1 -5 mm) was sampled as this represents the fraction of

sediment that provides the greatest source of available metals to organisms (Luoma &

Davis, 1983), as well as being the biologically relevant portion of the sediment i.e. the

majority of organisms live and feed in this fraction (Luoma & Bryan, 198 1).

12

After collection, sediments were immediately taken to the laboratory and centrifuged at

6500 rpm for 30 min at which time the porewater was pipetted off (Rapin et. al, 1986). To

minimize microbial alteration, sediments were kept at 4OC until processing (always within

48 hrs after removal from the sediment).

Sediment samples were subjected to the simultaneous extraction procedure of Bendell-

Young et al. (1992) (Figure 2.2). The procedure estimates the concentration of metals

partitioned onto operationally defined geochemical components of the sediment: easily

reducible (associated with manganese oxide phase); reducible (associated with manganese

and iron oxide phase); organic (organically bound); and aqua regia (near total digest). The

easily reducible extraction removes metals bound to manganese oxides and all easily

extractable components including phosphates, carbonates and reactive iron. The reducible

extract removes easily reducible metals (those bound to manganese oxides) and the

reducible metals (those bound to iron oxides) (Tessier et. al, 1979). The actual reducible

metals are determined after analysis by subtracting the easily reducible fraction from the

reducible fraction. Considering that this procedure uses separate subsamples from the

sediment, it is possible to get negative concentration values in the reducible phase.

Decomposition methods that employ strong acids such as HI? are the only digests that

completely dissolve the silicate lattices and release all the associated metals such as

aluminium, iron and lithium (Loring & Rantala, 1992). Digestions such as aqua regia (3: 1

HC1:HNO3) are considered 'near total' digests of the sediment and dissolve most of the

heavy metals in the fine grained sediments, including cadmium, copper, lead, mercury,

silver and zinc. Elements that are not recovered completely by this method include iron,

aluminium, manganese, chromium and nickel (Puget Sound Water Quality Authority,

1995). The amount of metal in the residual phase was estimated as aqua regia minus the

other three phases.

Sediment subsamples of 2 g each (wet weight) were weighed into 50 mL centrifuge tubes

and subjected to the treatments as outlined in Figure 2.2. To each subsample, 30 mL of

Figure 2.2 Simultaneous extraction procedure used for the partitioning of metals.

Sediment Subsamples

Wet/Dry Easily Reducible Reducible Organic Aqua Regia Dried at 60•‹C 0.1 N m 0 H HCl 0.1 N NH20H HCl 1 N W 0 H 3:l mixture for 24 h in 0.01 N HN03 in 25% HOAc for 1 wk cHCl:cHN03

for 0.5 h at 95•‹C for 6 h at 70•‹C for 8 h

Dry w t Mn oxides Mn + Fe oxides Organic Acid Extractable 600•‹C for 1 h

4 Centrifuge at 6500 RPM % LOI Pipet off supernatant /

reagent was added (15: 1 so1ution:solid extractant ratio). After digestion under the

appropriate conditions, the supernatants were pipetted off after centrifugation at 6500 rpm

for 30 min (Tessier et. al, 1979). The supernatant extracts were stored in glass vials at 4OC

until analysis. Theory and principles regarding the different analytical instruments

employed in the analysis of metals in the various substrates are provided in Appendix I.

3.1 Trace Metal Analysis

Chemical analyses for metals associated with the different sediment components was

carried out in collaboration with the Pacific Environmental Science Center, North

Vancouver. The analysis for iron, manganese, zinc, copper and nickel was done by

Inductively Coupled Plasma-Atomic Emission Spectrophotometry (ICP-AES). Only the

easily reducible fraction was analysed without dilution; the other three extracts required

1/10 dilutions to reduce matrix interferences. Standards were matrix matched for each

extract to account for matrix quenching. Cadmium and lead were analysed by graphite

furnace atomic absorption spectrophotometry (GF-AAS) and were diluted as required (115,

1/10) (Appendix Q. Only the aqua regia extract was analysed for mercury using Cold

Vapour Atomic Absorption Spectrophotometry (CV-AAS) (ASL labs).

Quality assurance/quality control (QNQC) was maintained by the analysis of reference

sediment (MESS-2), and reagent blanks, as well as lab replicates (Appendix Dl, Table 1).

QNQC results for all parameters analysed demonstrated that precision and accuracy met

acceptance criteria. Detection limits and dilutions used for each analytical instrument are

provided in Appendix It (Table 2).

3.2 Matrix Determinations

In addition to the above trace metal determinations, determinations of the sediment matrix

parameters was done. This included wetldry sediment sample weights, %LOI, iron and

manganese oxides and particle size. Wetldry weight ratio was determined by drying a 2 g

subsarnple (wet weight) of sediment at 60•‹C for 24 h (previously determined as the

appropriate time for a 2 g subsample to dry to a constant weight). The wetldry weight ratio

15

was then calculated and used to standardise concentrations to dry weight. Loss on ignition

was performed on the dried sediment samples following calculation of wetldry weight by

heating the sample for 1 hr at 600OC in an ash furnace, effectively burning off all organic

matter. The sample was weighed before and after treatment to obtain the percent organic

and inorganic material.

Iron oxide concentrations (RED Fe) were determined from the concentration of iron in the

reducible phase minus the concentration of iron recovered in the easily reducible phase.

Manganese oxide concentrations were determined as the concentration of manganese in the

easily reducible phase (ER Mn). Henceforth, these fractions will be referred to as ER Mn

and RED Fe.

3.3 Grain Size

Particle size was determined by hydrometer (Methods of Soil Analysis, 1982). This method

separates the mineral part of the soil into different size fractions (sand at 0.05-2.00 mm, silt

at 0.002-0.05 mrn and clay at < 0.002 mm). The relative proportion of these fractions was

determined by sedimentation based on Stokes' Law which relates the radius of the particles

to the velocity of sedimentation. Particle size analysis was undertaken on a composite

sample of the three sediment samples taken at each site. Measurements on the hydrometer

were taken at standard intervals of time known to correspond to settling velocities of

different size fractions. Percentages of sand, silt and clay were calculated based on these

results.

4.0 Tissue Chemistry

A comprehensive sample of benthic invertebrates was obtained during the July of 1995.

Benthic samples were taken in triplicate by box core (20 cm x 20 cm x 10 cm) at the same

sampling stations where sediment and porewaters were taken. Benthic samples were

bagged and taken back to the lab where they were sieved and sorted. Everything retained by

an 800 pm mesh was kept and sorted through for M. balthica. Sieving was always

completed within 48 h after removal from the sediment and sorting was done in the

following 3 days. M. balthica specimens were frozen until further analysis.

After removal from the freezer, M. balthica were rinsed thoroughly with DI H20 to remove

any adhered sediment. Specimens were then separated into two size classes, 2-6 mm and

6.1- 13 mm. Clams were dissected and the shell was separated from the body. Tissues were

dried to a constant weight at 50•‹C in a drying oven (usually for around 24 h). For the 2-6

rnm size class of M. balthica, concentrations of trace metals in the shell and tissue fell

below detection. Therefore, only results for the 6.1- 13 mm size class are presented. Dried

tissue and shell samples were weighed directly into test tubes used for the digestion

procedure. Samples were cold digested with 1.0 rnL HN03 for 3 h and then heated in a

digestor at 1 10•‹C for 4-6 h. After heating, the test tubes were allowed to cool for a

minimum of 30 rnin, at which point samples were transferred back to the digestor where 0.5

rnL of 30% H202 was added and heated again for 1 h. This last step was repeated once

again to ensure the complete breakdown of all lipids. During the entire digestion process,

test tubes were capped with tuttle covers to reduce contamination and loss of volatile

elements. After cooling, samples were bulked to a volume of 10.0 mL and stored at 4OC

until analysis. To account for metals associated with sediment in the gut of M. balthica,

sediment remaining in test tubes after digestion was weighed and back calculated to

determine the concentration of associated metal. In all cases, concentrations were negligible

relative to tissue concentrations. Biota samples were analysed for cadmium, copper, nickel,

lead and zinc by Inductively Coupled Plasma Mass Spectrophotometry (ICP-MS) and

mercury was analysed by CV-AAS. Detection limits (pgg dry weight) of metals in each

sediment extract are included in Appendix I1 (Table 3).

In some cases the amount of sample exceeded the dry weight recommended for the above

digestion process. In this case, samples were digested using a CEM MDS-2000 microwave.

The program used to digest the samples was the CEM method for clam puree (CEM, 1991).

The method involved an initial cold digestion phase where 6.0 mL FINO3, 1.0 mL HC1 and

1.0 mL H202 was added to the samples and left overnight. The following day, samples

were microwaved for 30 rnin, cooled and then bulked to 30 rnL with NanopureB water.

Samples were analysed for cadmium, copper, nickel, lead and zinc by ICP-AES.

To ensure QAIQC, biota reference material (1 566a and TORT- 1) and method blanks were

analysed throughout the procedure (Appendix EI, Table 2'3). Results for all parameters met

acceptance criteria for precision and accuracy. Detection limits are presented in Appendix

11.

5.0 Statistical Analyses

Statistical analyses were carried out using SAS v.6.11. For all analyses, concentrations

were log10 transformed and percentages were arcsin transformed prior to inclusion into

statistical models (SAS, 1988). Due to the unbalanced nature of the sampling design, a

general linear model (GLM) was used for comparisons of sediment and tissue

concentrations among locations and sites and between months (May vs July). In cases

where a difference was detected, Tukey7s multiple comparison tests were carried out on the

main factors in the analysis. For Tukey's, the experiment wise probability level was 0.05.

An R~ MAX procedure was used to determine the relationship between sediment

geochemistry and metal levels in the tissue and shells of M. balthica. For this procedure,

metal levels in M. balthica were used as the dependent variable and sediment matrix

components and the corresponding metal concentrations in each of the fractions was applied

to identify which components of the sediment geochemistry correlated with M. balthica

metal concentrations. The R~ MAX procedure attempts to find the best one-variable model,

two-variable model, and so forth with the largest coefficient of determination ( R ~ ) (SAS,

1988).

18

CHAPTER 3: THE ROLE OF POREWATERS IN CONTRIBUTING TO THE SEDIMENT MATRIX

1.0 RESULTS

1.1 Porewaters

In general, porewater profiles of Fe2+ and Mn2+ from all sites were of two generalized types:

A) a typical profile of a redox sensitive species with a sub-surface maxima; B) low

concentrations with linear profiles (Figures 3.1 - 3.3). Concentrations of Fe2+ and ~ n ~ +

above the sediment water interface were usually low or below detection, indicative of

concentrations in the overlying water. Differences in duplicate peepers were attributed to

horizontal inhomogeneity as they were placed 1 m apart (Emerson et al., 1984).

Most of the profiles taken from Sturgeon (Figure 3.1 a, b, c) and Roberts Bank (Figure 3.2

a, b, c) displayed type A) profiles; reduced Fe2+ and Mn2+ formed at depth, diffused in both

an upward and downward direction, following a high to low concentration gradient. The

majority of profiles taken from Boundary Bay (Figure 3.3 a, b) exhibited type B) linear

profiles with low concentrations. In addition, at several locations at Boundary Bay,

porewater concentrations fell below detection. Considering that concentrations of iron and

manganese oxides at the sediment-water interface were much lower at Boundary Bay than

the other two sites, one would expect to see porewater cycling of these elements but on a

much smaller scale. However, the large dilution factor (100 times) that was required to

reduce the matrix interferences caused by high salinity values (32-36%0) may have resulted

in levels below the detection limit (Table I).

To determine the relative contribution of the Fraser River versus diagenesis to the

concentrations of iron and manganese oxides recovered at the sediment-water interface,

oxide concentrations were correlated with concentrations ~e~~ and ~ n ~ + in porewaters.

The correlation for iron was significant ( ~ 0 . 8 0 , p<0.0001), indicating that high

concentrations of Fe2+ in the porewater correlated to high concentrations of iron oxides at

Figure 3.1 a) Porewater profiles for total dissolved Fe and Mn (mg/L) taken in duplicate from sites AO, A10 and A12 on Sturgeon Banks during July. Solid bar at depth = 0 (i.e. sediment-water interface) is the average concentration + S.D. of RED Fe (mglg) and ER Mn (pglg) recovered from the sediment.

Figure 3.1 b) Porewater profiles for total dissolved Fe and Mn (mg/L) taken in duplicate from sites W6, W7 and W8 on Sturgeon Banks during July. Solid bar at depth = 0 (i.e. sediment-water interface) is the average concentration + S.D. of RED Fe (mglg) and ER Mn (p&) recovered from the sediment.

Figure 3.1 c) Porewater profiles for total dissolved Fe and Mn (mg/L) taken in duplicate from sites W9 and W10 on Sturgeon Banks during July. Solid bar at depth = 0 (i.e. sediment-water interface) is the average concentration + S.D. of RED Fe (mglg) and ER Mn (pglg) recovered from the sediment.

Figure 3.2 a) Porewater profiles for total dissolved Fe and Mn (mg/L) taken in duplicate from sites A14, A14a and A14b on Roberts Bank during July. Solid bar at depth = 0 (i.e. sediment-water interface) is the average concentration a S.D. of RED Fe (mglg) and ER Mn (pglg) recovered from the sediment.

Figure 3.2 b) Porewater profiles for total dissolved Fe and Mn (mg/L) taken in duplicate from sites WI-1, WI-2 and W1-3 on Roberts Bank during July. Solid bar at depth = 0 (i.e. sediment-water interface) is the average concentration + S.D. of RED Fe (mg/g) and ER Mn (pg/g) recovered from the sediment.

Figure 3.2 c) Porewater profiles for total dissolved Fe and Mn (mg/L) taken in duplicate from sites BPt-1, BPt-2 and BPt-3 on Roberts Bank during July. Solid bar at depth = 0 (i.e. sediment-water interface) is the average concentration k S.D. of RED Fe (mglg) and ER Mn (pglg) recovered from the sediment.

Figure 3.3 a) Porewater profiles for total dissolved Fe and Mn (mg/L) taken in duplicate from sites BB- 1, BB-2 and BB-3 on Boundary Bay during July. Solid bar at depth = 0 (i.e. sediment-water interface) is the average concentration + S.D. of RED Fe (mglg) and ER Mn (pglg) recovered from the sediment.

Figure 3.3 b) Porewater profiles for total dissolved Fe and Mn (mg/L) taken in duplicate from sites BB-7, BB-8 and BB-9 on Boundary Bay during July. Solid bar at depth = 0 (i.e. sediment-water interface) is the average concentration 2 S.D. of RED Fe (mg/g) and ER Mn (pg/g) recovered from the sediment.

35

the sediment-water interface (Figure 3.4). The correlation for manganese was also

significant; however, not as strong as observed for iron ( d . 6 6 , p4.0006) (Figure 3.5).

Table I Salinity (%a) measurements taken from porewaters at depths 0 ,6 and 20 cm in the sediment at various sampling locations.

Salinity (%a) Sturaeon Bank Roberts Bank Boundarv Bav

Depth (cm) A0 A12 W9 A14 WI-1 BPt-1 BB-1 BB-4


From Figures 3.6 and 3.7 it is evident that sediment geochemistry in the intertidal area of

the Fraser River Estuary is extremely heterogeneous (Appendix IV). To determine whether

locations could be pooled based on site or month, a three-way GLM was performed that

investigated differences between months and among sites and locations and the interaction

between month and location. Results indicated that locations could not be pooled based on

site or month and that there was a significant interaction between month and location.

Hence, each location was treated independently of other locations.

1.2.1 Iron and Manganese Oxides

Operationally defined concentrations of manganese oxides (ER Mn) and iron oxides (RED

Fe) were determined using the simultaneous chemical extraction procedure of Bendell-

Young et al. (1992). Of the three sediment matrix components, iron was recovered

primarily in the RED fraction of the sediment with the ER fraction and ORG fraction

accounting for substantially less (Figure 3.8). The maximum concentration of RED Fe was

observed at Brunswick Point (15,291 pglg at BR-2) and the minimum at Boundary Bay

(1,636 pg/g at BB-4). A GLM performed on log transformed RED Fe data revealed

statistically significant differences between months, among sites and locations and a

significant interaction between location and month (Table It). Results of Tukey's multiple

Figure 3.4 Correlation of iron recovered from the RED fraction of the sediment and the corresponding sub-surface maximum of ~ e ~ ' in the porewater (r=0.80, n=26).

18

WI1

16 - Roberts Bank B R l

0 2 4 6 8 10 12 14 16 18

Iron oxides (mglg)

Figure 3.5 Correlation of manganese recovered from the ER fraction of the sediment the corresponding sub-surface maximum of ~ n " in the porewater (r=0.66, n=26) Boundary Bay sites are labelled as 1,2, 3, 7, 8, 9.

16 Sturgeon Bank w13

14 - Boundary Bay aw

0 20 40 60 80 1 00 120 140 160

Manganese Oxides (pglg)

3 8

Figure 3.6 Concentration of sediment matrix features in surficial sediment from the intertidal region, May 1995. Values are means of three repicates, + 1 S.D.

Easily Reducible Manganese (vglg) 250 1

o o m a a m o w m n r m o y m q r c y q p y q y y ? 4 ; ; ~ 2 3 3 ~ ~ ~ L L L c h m m m m m m m m 4 2 ; 3 3 3 $ 6 $ m m m m m m m m m

Reducible Iron (pg/g) 24000 1

a m o w m n ~ m o y m q - c y q p y q y y ? 9 : : 2 2 2 2 5 ; : : f=$fh&h m m m m m m u + m m d m m m m m m m m

Loss on Ignition (%)

a m o w m n y q q - m o y c y q p q q ~ ~ ? q 3 2 3 3 g ; Z Z s s s f f f g g g g g g g g g

39

Figure 3.7 Concentrations of sediment matrix features in surficial sediment from the intertidal region, July 1995. Values are means of three replicates, * 1 S.D.

Easily Reducible Manganese (pglg) 250

o o m a m m o w m n y q y - - m o y q y p y q ~ y q ~ 4 2 2 3 2 3 3 5 F 2 f y g y & & & m m i n m m m m m m m m m m m m m m m

Reducible Iron (pg/g) 24000 1

T

m m m m m m m m m

Loss on Ignition (%) 8 7 6

5

4

3

2

1

y q y p y q ~ y w ~ m m m m m m m m m

m m m m m m m m m m m m

40

comparison test revealed that all three sites were significantly different from one another in

regards to the RED Fe concentrations (p<O.OS).Roberts Bank was higher than Sturgeon

Bank and Boundary Bay was the lowest overall, with concentrations of RED Fe 2-4 times

lower than the other sites. Overall concentrations of RED Fe in the July sampling period

were higher than those in May ( ~ ~ 0 . 0 5 ) .

Table II: Three-way GLM for RED Fe concentrations

Manganese was primarily recovered in the RED fraction of the sediment with the ER

fraction accounting for slightly less; however, concentrations of ER Mn were on average an

order of magnitude lower than concentrations of RED Fe (Figure 3.9). Little manganese

partitioned into the organic fraction, consistent with a weak affinity for organics. The

maximum and minimum concentrations of ER Mn were 227 pg/g and 1.5 pg/g found at

Sturgeon Banks (A 12) and Boundary Bay (BB-2) respectively. Results of the GLM

performed on log transformed ER Mn concentrations are summarized in Table III. No

statistical difference was found between months; however, strong statistical differences

were found among sites, locations and the interaction between month and location.

Subsequent multiple comparison tests indicated that Roberts and Sturgeon Bank were not

significantly different from one another whereas Boundary Bay had significantly lower

concentrations than the other two sites (p<0.05).

N=156 site location(site) month

The ER fraction also includes those metals associated with carbonates as well as

exchangeable metals. However, it is assumed that the majority of metals recovered from the

ER fraction is primarily associated with oxides of manganese (Bendell-Young et al., 1992).

Although the carbonate component of the sediment can account for a major fraction of the

sediment, it is not considered a key substrate for metal binding. In estuarine sediments, the

df 2 23 1

F 30.25 7.76 6.53

P 0.0001 0.0001 0.0171

Figure 3.8 Partitioning of iron among ER, RED, ORG and RES fractions, May and July 1995.

May 1995

n n a m m m m m m m m m m m m

July 1995

ER T I RED v7A ORG

RES

RED r A ORG

RES

Figure 3.9 Partitioning of manganese among ER, RED, ORG and RES fractions, May and July 1995.

O O N w W r n O W a n ~ m O ~ m O r N O W r n D b W r n Y ~ ~ w ~ ~ ~ ~ a a m m m m m m m m m a ~ ~ s z g g 3 a z z g g 3 a a a m m m m m m m m m m m m

July 1995

May 1995

wV RES

ER 1-1 RED

ORG RES

a a a a a m m m m m m m m m m m m

43

carbonate fraction is mostly biogenic in origin and occurs as relatively large shell fragments

with low specific surface areas and thus account for only a small fraction of metal binding

(Davies-Colley et al., 1984; Samant et al., 1990). -

Table III: Three-way GLM for ER Mn concentrations

N=156 site location(site)

1.2.2 Organic Matter

Organic content in the sediment of the lower Fraser River Estuary is summarized in Figures

3.6 and 3.7. Overall, locations varied in organic matter from 1.5 to 7.0%. A GLM

performed on arcsine transformed %LO1 data revealed no significant difference between

months. However, the GLM did indicate statistically significant differences among sites,

locations and the interaction between month and location (Table IV). Results from Tukey's

multiple comparison test revealed that Boundary Bay and Sturgeon Bank were not

significantly different in regards to their organic content (p>0.05), whereas Roberts Bank

had a significantly higher percentage of organic matter than the other two sites (~~0 .05) .

-- -

month month *location(site)

Table IV: Three-way GLM for organic content

df 2 23 1 23

1.2.3 Grain Size

Deposited sediments were characterized as the percent clay ( 4 . 0 pm), silt (2.0-50.0 pm)

and sand (>50.0 pm). Locations in the intertidal area fell into two texture categories; i) fine

silt and loam (50-100% silt and clay), and ii) very coarse sand (0-35% silt and clay), with

F 39.43 8.32

P 0.0001 0.0001

1.9 1 4.8 1

P 0.0257 0.0001 0.9750 0.0002

0.1785 0.0001

F 4.3 1 27.51 0.001 2.7 1

N=156 site location(site) month month *location(site)

df 2 23 1 23

A1 4

b W

I-I

WI-

I W

I-2

45

the majority of sites falling into the latter category (Figure 3.10). Only one measure of grain

size was obtained per location as it was performed on a composite of three taken from each

location, but note the reproducibility between months (Figure 3.10). The fine fraction of the

sediment,(<50 pm, percent clay and silt), was also calculated. Further calculations were

done using the fine fraction to normalize metal concentrations according to gain size.

A GLM performed on arcsine transformed percent grain size revealed that the percentage

was site and location dependent but independent of month (Table V). Tukey's multiple

comparison indicated that all three sites were significantly different from one another in

regards to the percent clay, sand and clay and silt together (p4.05). However, for percent

silt, Boundary Bay and Sturgeon Bank were not significantly different, whereas Roberts

Bank had a significantly higher percentage of silt (p4.05).

Table V: Three-way GLM for grain size

1 .Z.4 Relationships between sediment matrix parameters

The relationships between sediment matrix parameters are displayed in Table VI. For the

purpose of this test, all of the data were pooled. In all cases, except for between ER Mn and

LOI, a significant correlation was found among the parameters. The strongest correlations

were found between LO1 and the different grain size fractions. The percent sand was

negatively correlated with all three sediment parameters.

Table VI: Correlations between sediment matrix parameters

2.0 DISCUSSION

2.1 Porewater profiles

The two general types of porewater profiles observed in this study are depicted in Figure 3.11;

A) classic profile of a redox sensitive element with high concentrations of iron and manganese

oxides at the sediment-water interface, and B) profiles with low concentrations of dissolved

iron and manganese coupled with low concentrations of iron and manganese oxides at the

surface. Type A) profiles were observed at Sturgeon and Roberts Bank while Boundary Bay

exhibited type B) profiles

N=52

RED Fe % LO1 % clay & silt

% clay % silt % sand

Iron and manganese are both involved in early diagenetic processes, i.e., the natural cycling of

elements that occurs in recently deposited sediments due to the oxidation of organic matter.

Considering they are both redox sensitive elements, they will respond similarly to a changed

redox potential in the sedment (Davison, 1982), resulting in similar profile shapes. The redox

cycling of these two elements will contribute to the formation and dissolution of iron and

manganese oxides at the sediment-water interface. Suspended particulate material (SPM)

transported down and deposited in estuarine sediments via the Fraser River can also contribute

to the supply of iron and manganese oxides at the sediment-water interface. The proximity of

the Fraser River to sample locations can influence the amounts of iron and manganese oxides at

the surface which in turn can be incorporated into the porewater cycling that occurs.

LOI r

0.946 0.917 0.934 -0.946

P

0.0001 0.000 1 0.0001 0.0001

ER Mn RED Fe r

0.680 0.173 0.292 0.326 0.285 -0.292

r

0.733 0.776 0.789 0.75 1 -0.776

P 0.0001 0.2208 0.0360 0.01 83 0.0403 0.0360

P

0.0001 0.0001 0.0001 0.0001 0.0001

Figure 3.1 1 Schematic representation of profile shapes of dissolved Fe and Mn at the sediment-water interface; A) classic profile of a redox sensitive element, and B) linear profiles with low concentrations.

anoxic /

sediment-water interface

Concentration -

48

Therefore, the conspicuous differences in the profiles can be explained by a combination of

these two factors, with the relative importance of both being element specific.

2.1.1 Diagenetic Processes

Profile A: Profiles representative of type A were observed at Sturgeon and Roberts Bank.

Profiles from these sites had subsurface maxima of Fe2' and MI? usually occurring within the

top 5 cm of the sediment. Thereafter, concentrations of Fe2+ and Mn2+ decreased with depth in

the sediment. The sub-surface maxima are a result of the reductive dissolution of iron and

manganese oxides that occurs when exposed to anoxic conditions (Williamson & Parnell, 1994;

Song & Muller, 1995). Organic matter, H2S and microbes are the main mechanisms by

which this reduction occurs (Santschi et al., 1990). Khkhammer (1980) and Barbanti et al.

(1995) have found that the diffusion of ~ e ~ ' and Mn2+ in a downward direction depends on the

presence of sulfide and carbonate pools at depth, which will combine with both of these

elements to form insoluble precipitates such as FeS, MnS and MnCO3. Most of the iron and

manganese that complexes to form these insoluble precipitates will remain permanently bound

in the sediment. Dissolved iron and manganese that are generated can also diffuse towards the

surface where it can be consumed by downward diffusing oxygen to reform oxides or escape

into the overlying water column, both of which contribute to the natural cycling that occurs

within the sediment. The slower oxidation rate of manganese compared to iron (50 times)

facilitates the release of manganese into the overlying water column during diagenesis

(Davison, 1982). In contrast, most of the iron which reaches the sediment tends to become

permanently incorporated. .e oxidation of h4n2' occurs primarily on the surface of particles

via oxidizing bacteria, while the oxidation of Fe2' is primarily accomplished without the

mediation of organisms (Egeberg et al., 1988; Santschi et al., 1990).

Profile B: Most of the locations at Boundary Bay exhibited proiiles with low concentrations of

Fe2' and M.n2+in the porewater, as well as low concentrations of oxides at the sedirnent-water

interface. Occasionally, concentrations in porewaters fell below detection (0.10 mgL for h4n2'

and 0.5 1 mgL for Fe23, making it difficult to resolve the true profile shape. Previous studies

have shown iron and manganese cycling to occur at levels much lower than the above detection

49

limits, indicative of diagenesis on a much smaller scale (Gaillard et al., 1984; Song & Muller,

1995). Low porewater concentrations can also be are a result of the organic content in

sediments being low enough to be oxidized by oxygen and nitrate alone; hence, precluding the

reduction of irodmanganese oxides (van Hoogstraten & Nolting, 1991). Given that organic

matter was between 2-3% at the sediment-water interface and decreased with depth (Gaillard

et al., 1984; Barbanti et al., 1990; Santschi et al., 1990), it is possible that this is the controlling

process at these sites.

2.1.2 Biological Processes

Other subsurface peaks (positive or negative) could be attributed to the biological activity of

bentluc organisms (Emerson et al., 1984; Tessier et al. 1994). Through the ventilation of

burrows, benthic organisms can either introduce oxic overlying water to deeper sediments or

expose oxidized compounds to deeper anoxic sediments. Considering that all of these sites are

nearshore environments where the biological and physical activity is high, such processes could

contribute to the distribution and movement of iron and manganese.

2.2 Riverine input versus cliagenetic processes

In the overlying water column, iron and manganese exist in both the dissolved and the

particulate phase. In the dissolved phase, ~ e ~ + a n d Mn2+ is essentially limiting, with the

concentration of Mn2+ around 0.2-5.0 nmoYkg and ~ e ~ " is basically undetectable in aerobic

estuarine waters (Kennish, 1986). In contrast, riverine input of SPM has been shown to be an

important contributor to the quantity of particulate iron and manganese in estuarine deposit

sediments (Benoit et al., 1994). More specifically, Stecko & Bendell-Young (1997) have

found that SPM in the Fraser River is an important vector for the transportation and deposition

of iron and manganese oxides in estuarine sediments.

Most of the locations on Sturgeon and Roberts Bank which displayed type A porewater

profiles had concurrently high concentrations of irodmanganese oxides at the sediment-water

interface. In addition, both of these sites receive direct input from the Fraser River, via the

North and South Arm respectively. This riverine contribution could conceivably lead to the

50

elevated concentrations of irodmanganese oxides observed at the sediment-water interface. In

contrast, profiles at Boundary Bay were classified as type B, with low concentrations of

dissolved irodmanganese in porewaters coupled with low concentrations of iron and

manganese oxides at the surface. In addition, Boundary Bay is not directly influenced by the

Fraser River and, therefore, does not have an external supply of iron and manganese to the

sediment. As a result, the diminished supply of iron and manganese oxides to the sediment

reduced the contribution of these elements to the natural cycling that occurs within the

sediment.

In Figure 3.5, the correlation for manganese becomes progressively weaker when locations

influenced by the Fraser River are included. However, locations where the Fraser River is not

a factor (i.e., Boundary Bay), a stronger relationship occurred. As previously noted, these sites

receive little riverine input, indicating that porewater processes are the major contributor to

manganese oxides at these locations. Locations closer in proximity to the Fraser River seem to

be influenced by a combination of porewater processes and input from the Fraser River. At

locations with low concentrations of h4n2+ and high manganese oxides, it appears that the

contribution of manganese oxides from the Fraser River exceeds the ability of porewaters to

incorporate this manganese (i.e., through reduction of deposited manganese oxides) into the

subsurface cycling that occurs. Conversely, porewater processes seem to play a greater role in

integrating manganese oxides from the sedment-water interface at locations characterized by

high concentrations of manganese in the porewaters and in the sediment.

According to Figure 3.4, the contribution of the Fraser River to the concentration of iron

oxides at the sediment-water interface is not overwhelming the contribution from the

porewaters. This is validated by the observation that locations heavily influenced by the Fraser

River do not have the highest concentrations of iron oxides. Instead, locations with limited

riverine input had the highest concentrations of iron oxides, indicating that their source of iron

must be from the porewaters. Therefore, the strong correlation observed for iron, suggests

that porewaters are the major contributor of iron oxides to the sediment-water interface (Figure

3.4).

2.3 Implications of porewater cycling

Understanding the diagenesis of iron and manganese as inferred fiom their porewater chemistry

is important in understanding the cycling of trace elements. Iron and manganese oxides can

adsorb or incorporate trace elements, thereby coupling the fate of these trace elements to that

of iron and manganese in the porewaters (Klinkhammer et al., 1982; Santschi et al., 1990;

Peterson at al., 1995). The reductive dissolution of iron and manganese oxides at depth in the

sediment will release any trace metals associated with them into the porewater. Conversely,

the formation of oxides will bind up dissolved metals in the porewater.


In the present study, the sediment matrix was defined by concentrations of ER Mn, RED Fe

and organic matter expressed as %LOI. These matrix attributes have been found to be of

paramount importance in processes of metal transport, distribution and bioavailability (Luoma

& Bryan, 198 1 ; Davies-Colley et al., 1984; Rule & Alden, 1996).

The heterogeneous nature of the Fraser River intertidal area was confirmed by statistical tests

(three-way GLM) that revealed that sediment matrix attributes varied widely among the

different study sites and locations. However, variability is not an uncommon phenomenon in

estuaries (Luoma & Bryan, 1981; Langston, 1985; Morse et al., 1993). It is not unusual to

see metal concentrations as well as concentrations of the various geochemical components vary

by 1-3 orders of magnitude, both within and among estuaries. Only for RED Fe was a

difference between the months detected, with higher concentrations in July than May.

f Similarly, Stecko & Bendell-Young (1997) found that components of the deposit sediment in i

the midestuarine region of the Fraser River showed little seasonality except for RED Fe.

2.4.1 Iron and munganese oxides

The majority of iron and manganese recovered in the ER and RED fractions is assumed to

occur predominately in the oxide form (Tessier et al., 1979; Balistrieri & Murray, 1986). As

indicated by the porewater profiles, it appears that porewater processes as well as input fiom

52

the Fraser River contribute to the iron and manganese oxides observed at the sediment-water

interface. Both iron and manganese oxides were positively correlated with the fine fraction of

the sediment; with the correlation for manganese oxides being much weaker (Table VI). The

strong correlation for iron is not surprising considering that oxides occur as coatings on various

particles; hence, it is expected that they will be correlated and under the control of available

surface area (Jenne, 1968). In regards to manganese, other studies have found a lack of

correlation between manganese oxides in estuarine deposit sediments and the h e fraction of

the m n t (Luoma & Davis, 1983; Stecko & Bendell-Young, 1997). This could in part be

explained by the association of manganese oxides with carbonates (Vasconcelos et al., 1995).

Carbonates, which are linked to coarser particles, can play an important role in the distribution

of manganese in estuarine systems as they are important nucleation centers for manganese

oxides (Dassenakis et al., 1995). Consequently, carbonates play a similar role as clays by

acting as a carrier for the metal binding substrate (manganese oxides) but do not strongly bind

metals themselves; therefore, acting more as a dilutant in the latter case (Campbell et al., 1988).

2.4.2 Organic Matter

Organic matter declined in concentration from the mouth of the estuary to the foreslope in

most transects as well as at those areas clearly influenced by marine processes, such as

Boundary Bay and W sites at Sturgeon Bank (Figures 3.6 and 3.7). At Sturgeon Bank,

locations A0 and W6 had higher levels of organic matter, most likely as a result of their

proximity to the Iona Island STP. The percentage of organic matter was highly correlated with

the fine fraction of the sediment. In aquatic environments, organic material can occur as

coatings on sediment particles or as discrete particles, thereby facilitating the relationship with

grain size (Horowitz and Elrick, 1987). In addition, the strong correlation between organic

matter and iron oxides can partly be attributed to a similar dependence of extractable iron and

organic matter upon particle size distributions, since concentrations of both correlated

sigmficantly with the proportion of fine particles in the sediment (Table VI).

53

2.4.3 Grain Size

The correlations between grain size and all three geochemical components (positively for clay

and silt and negatively for sand) suggest that these components are associated with the finer

fraction of the sediment, with %LO1 having the strongest association and ER Mn the weakest.

Grain size is considered one of the most significant factors controlling the capacity of sediments

for collecting and concentrating trace metals. As grain size decreases, surface area increases,

as does the concentration of many of the known trace element concentrating geochemical

phases such as iron and manganese oxides, organic matter and clay minerals (Horowitz and

Elrick, 1987). Considering the observed spatial variability of grain size in the Fraser River

estuary intertidal area, interpretation of trace metal levels in sediment becomes difficult.

Normalization procedures are often useful in clanfylng trends but often produce over or

underestimates of metal concentration. However, this is especially true when the selected

grain-size accounts for less than 50-60% of the samples. Mathematical normalization of bulk

chemical data also assumes that all, or a majority of the constituents of interest are

concentrated in a limited grain size range. Previous work has shown that the effect of

decreasing grain size is an increase in metal concentration; however, the increases differ from

element to element and location to location (Horowitz & Elrick, 1988, Morse et al., 1993).

Table VII compares actual measured concentrations of metals to the concentration of metals

normalized to the < 50 pm fiaction. The table illustrates the potential discrepancy between

measured and calculated concentrations of trace metals in sediments when normalizing to

sediments of varying textures. Normalization of metals to grain size at the various locations

was not undertaken because of this discrepancy.

Table VII. Comparison of actual measured concentrations of metals versus those calculated after normalization to the <SO pm fraction of the sediment in selected samples.

--

Percent ~9/9

Location < 50pm Cu Cd N i Pb Zn WI-3 1.2 actuala 13.9 0.018 25.0 1.6 34.5

calculatedt 1154.0 1.53 2083.3 133.6 2877.8 66-1 10 actual 1.9 0.1 3 5.3 0.8 11.7

calculated 19.0 1.3 53.3 7.9 1 13.7 88-7 25.4 actual 3.8 0.043 7.3 1.9 22.8

calculated 15.0 0.1 71 26.5 7.5 89.8 W6 35.7 actual 12.5 0.037 19.2 6 :9 39.7

calculated 34.9 0.104 53.8 19.5 111.2 A1 4b 61.6 actual 13.2 0.041 19.7 3.5 29.4

calculated 21.4 0.067 32.0 5.7 47.7 BPt-3 87.2 actual 17.8 0.028 22.5 5.1 43.5

calculated 20.4 0.032 25.9 5.8 49.9 BPt-1 96 actual 10.1 0.079 19.0 6.8 28.6

calculated 10.6 0.082 19.8 7.0 29.8 a actual measured value in the RED phase t determined by multiplying the bulk chemical concentration by a normalization factor obtained from the following equation: 100/(% < 50pm)

CHAPTER 4: LINKING SEDIMENT GEOCHEMISTRY TO METAL BIOACCUMULATION

1.0 RESULTS

1 . Metal concentrations and partitioning

The concentration and percent partitioning of metals cadmium, copper, nickel, lead and zinc

were measured in each of the operationally defined sediment fractions; ER Mn, RED Fe, ORG

and 'near total' and are summarized in Figures 4.1 to 4.2 (metal concentrations) and 4.4 to 4.5

(metal partitioning) and Appendix VI. Concentrations of metals in the ORG phase were below

detection at most sampling locations; therefore, only results for metals in the ER, RED and

RES phases are discussed. The amount of metal in the residual phase was estimated as aqua

regia minus the other three phases. Residual refers to the fraction of metals that are bound

tightly within the lattice framework of the sediment and are considered unavailable for uptake

by an organism Mercury was only measured in the 'near total' phase.

A three-way GLM was used to determine if there were differences in the concentration and

partitioning of metals in the different fractions between months, among sites and locations and

the interaction between month and location. In addition, Tukey's multiple comparison test was

used to determine the significance of any differences among the three sites.

1.1.1 General Trends

Tables I , II, ID, IV and V summarize statistical results for metal concentrations and

partitioning. Spatial and temporal variability within the estuary, in regards to the concentration

and partitioning of metals was high. However, the general trends were: i) higher

concentrations of metals at Roberts and Sturgeon Bank than Boundary Bay, except for

cadmium for which the reverse was true; ii) concentrations in the RES phase were higher in

May rather than July, while metals in the RED phase were higher in July than May; and iii) for

most metals the percent partitioned in the labile fraction (ER + RED) was greater than 50%.

1. I .2 Speczjic Metals

Cadmium

Cadmium concentrations in the sediment was measured in all four extracts by GF-AAS.

Cadmium was primarily recovered in the RED and ER fractions with the RES fiaction

accounting for very little. The distriiution of cadmium was unique because during the July

sampling period the highest overall levels of cadmium were measured at Boundary Bay

(p4.05). However, during May higher cadmium concentrations at Boundary Bay were not as

evident. A three-way GLM was employed to determine if there were differences in the

concentrations of cadmium partitioned between months and among sites and locations. Only

the ER and RED fractions were used in this analysis. Results indicated that only the interaction

term between month and location was significant for ER cadmium Reducible cadmium

concentrations were sigrufcantly Merent among sites and locations and the interaction term

between month and location. Tukey's multiple comparison test revealed that all three sites had

sigdicantly different RED cadmium concentrations, with Boundary Bay having the highest

concentrations and Sturgeon Bank the lowest (p4.05).

Copper

Copper was predominately recovered in the RED and RES fractions of the sediment.

Concentration of copper in the ER phase was always well above the detection limit but at an

order of magnitude lower than the other two phases. A three-way GLM on the ER, RED and

RES fractions revealed that copper concentrations at each of the sites were sigdicantly

different. For the ER and RES phase, Sturgeon Bank had the highest copper concentrations

and Boundary Bay the lowest (pd.05). In contrast, Roberts Bank had the highest

concentrations of RED copper and again Boundary Bay had the lowest (~4 .05 ) . Also, the

ER fraction was found to differ sigmficantly among locations and there was a signdicant

interaction between month and location. The effect of month and the interaction between

month and location was sigmficant far concentrations of both RED and RES copper; however,

only the RES phase revealed an effect of location. Concentrations of copper in the RED

phase were greater during the July months and the opposite was true for the RES phase.

Figure 4.1 Metal concentrations of Zn, Cu, Ni, Cd and Pb in surficial sediments from all sampling locations at each of the three sites, May 1995 (pglg). Values are means of three measures.

Sturgeon Bank Roberts Bank Boundary Bay E R Z ~ rn RED Zn OORG Zn RES ~n

- Sturgeon Bank Roberts Bank Boundary Bay

ER Ni rn RED Ni RES Ni

" Sturgeon Bank Roberts Bank Boundary Bay

E R ~ bZ9~a,m O O R G ~ ~ R E S ~

- Sturgeon Bank Roberts Bank Boundary Bay

ER Cu RED Cu 0 ORG Cu RES Cu

" Sturgeon Bank Roberts Bank Boundary Bay

E R W ~ ~ R E O W OORGW ~ R E S W

Figure 4.2 Metal concentrations of Zn, Cu, Ni, Cd, Pb and Hg in surficial sediments from all sampling locations at each of the three sites, July 1995 (pglg). Values are means of three measures.

- - - -

80 50

40 60

30 40

20

20 10

0 0 Sturgeon Bank Roberts Bank Boundary Bay Sturgeon Bank Roberts Bank Boundary Bay

E R Z ~ RED ~n 0 ORG Zn RES ~n IERCU ~ R E D C I I OORGCU ~ R E S C I I

" - Sturgeon Bank Roberts Bank Boundary Bay Sturgeon Bank Roberts Bank Boundary Bay

ER Ni 69 RED Ni RES Ni E R C ~ ~ R E D C ~ OORGC~ ~ R E S C ~

0.2 15

0.15

10 0.1

5 0.05

0 0 Sturgeon Bank Roberts Bank Boundary Bay Sturgeon Banks Roberts Bank Boundary Bay

E R P ~ RED^ OORGP~ ~ R E S P ~ RES ng

59

Lead

Sediment lead concentrations were measured in the different fractions by GF-AAS. Lead

was recovered predominately in the RED and RES Eractions with concentrations in the ER

fraction an order of magnitude lower than measured in the other two fractions. As with

other metals, lead concentrations in May and July were lowest at Boundary Bay. A three-

way G I N revealed that concentrations of lead in the ER, RED and RES phases were

significantly different between months and among sites and locations as well as a significant

interaction term between month and location. Lead concentrations in the ER, RED and

RES phases were significantly different at each of the sites, with Sturgeon Bank having the

highest and Boundary Bay the lowest concentrations (p<O.O5). Lead concentrations were

significantly higher during May in the ER and RES phases; however, in the RED phase

concentrations were higher in July ( ~ ~ 0 . 0 5 ) .

Nickel

Nickel was analysed by ICP-AES in all four extracts. Nickel was recovered predominately

in the RED and RES fractions with the ER fraction accounting for very little. A three-way

GLM on nickel concentrations partitioned in each phase revealed that all three phases (ER,

RED and RES) had significant differences among sites. A Tukey multiple comparison test

was applied for each phase and found that all three sites were significantly different,

Roberts Bank having the highest concentrations and Boundary Bay the lowest. In

addition, the interaction term between month and location was significant for the ER and

RED phase. Both the RED and RES phase revealed a significant difference between

months, with concentrations higher in July for RED and in May for RES. The

concentration of nickel partitioned in the RES phase was also shown to vary significantly

among locations.

Zinc

Zinc concentrations followed a similar pattern as previous metals with the RED and RES

fractions accounting for the majority of zinc recovered. A three-way GLM revealed that for

the ER phase, zinc concentrations were significantly different among locations and there

60

was a significant interaction between month and location. For the RED phase, only the

difference among sites was significant; however, for the RES phase, significant differences

were found among sites and the interaction between month and location. Tukey's multiple

comparison test revealed that Roberts and Sturgeon Bank were not significantly different

from one another in regards to their RED and RES zinc concentrations, but that Boundary

Bay was significantly lower than these two sites ( ~ ~ 0 . 0 5 ) . No differences among the

months were observed.

Table I. Three-way GLM on metal concentrations in the different sediment fractions (p<0.05).

1 comer T - W m i u m 1 Nickel I . . I I

I ER I RED I RES 1 ER I RED I ER I RED I RES I I I I I I I I

site I J I J I J I n s I J I J I J I J

site location(site)

location(site)

month

mbnth*location(site)

month *location(site) I 4

Lead RED

J

ns J

I Zinc I Mercury

ns J

J significant at the 95% confidence level ns not significant at the 95% confidence level - no comparison possible

RES J

4

J

J

Mercury

Mercury analysis was only done on the aqua regia extracts from the July sampling period

J

4

by CV-AAS. The maximum concentration of mercury was 0.215 f 0.019 vg/g and was

measured at station A0 on Sturgeon Bank which is closest to the Iona Island STP.

ns

ns J

total J

J

- -

ER ns J

ns J

Correlating mercury concentrations with organic content in the sediment revealed a

correlation coefficient of 0.63 (n=26) (Figure 4.3). This correlation was improved ( d . 9 1 ,

n=26) when station A0 was excluded from the calculation. A two-way GLM on log

J

ns J

RED J

ns

ns

ns

RES J

ns

ns J

ns

ns J

ns 4

4

4

4

ns

Table II. Multiple comparison tests for differences in metal concentrations between months (May and July) and among sites (Sturgeon Bank=SB, Roberts Bank=RB, Boundary Bay=BB) ( ~ 4 . 0 5 ) .

Metal Phase Month Site May vs July

Cadmium ER ns ns RED ns BB>RB>SB

Copper ER ns SB>RB>BB RED July > May RB>SB>BB RES May > July RB/SB>BB

Nickel ER ns RB>SB>BB RED July>May RB>SB>BB RES May> July RB>SB>BB

Lead ER May > July SB>RB>BB RED July>May SB>RB>BB RES May > July SB>RB>BB

Zinc ER ns ns RED ns RB/SB>BB RES ns RB/SB>BB

Mercury AR - RB>SB>BB

ns no signtficant difference > sigmficantly greater than based on a 95% confidence level / not sigmficantly Merent from one another based on a 95% confidence level - no comparison possible

Figure 4.3 Correlation of Hg and % LO1 (organic matter) with (a) site A0 included in the correlation and (b) with site A0 removed.

Sturgeon + Roberts Boundary

Sturgeon + Roberts Boundary

transformed mercury concentrations revealed significant differences among sites and

locations. A Tukey's multiple comparison test revealed that all three sites were

significantly different, with Roberts Bank having the highest concentrations of mercury and

Boundary Bay the lowest ( ~ 4 . 0 5 ) .

1.1.3 Metal Partitioning

Cadmium

For the ER and RED phases, a significant difference in cadmium partitioning was found

among sites as well as a significant interaction between month and location; however, no

significant difference was observed among locations and between months. Tukey's

multiple comparison test revealed that the percentage of cadmium in the ER phase was

significantly lower at Boundary Bay than Roberts and Sturgeon Bank (pc0.05). In the RED

phase, the percentage of cadmium partitioned was significantly different at all three sites,

with the highest percentage at Boundary Bay and the lowest at Sturgeon Bank (pc0.05).

Copper

All three sites were found to be significantly different from one another, with Sturgeon

Bank having the highest percentage of copper partitioned into the ER phase and Boundary

Bay the lowest (p<0.05). For the RED phase, the interaction between month and location

was significant, as well as the difference between months, with a greater percentage of

copper in the RED phase in July than May. In the RES phase, differences among sites,

month and the interaction between month and location were significant. The proportion of

RES copper was significantly lower at Boundary Bay with no significant difference between

the other two sites (pc0.05). In addition, the percentage of RES copper was higher during

May than July.

Lead

A GLM with multiple comparison tests (Tukey) was employed to determine if differences

in the partitioning among the three phases occurred for lead. For all three phases the

interaction term between month and location was significant. Lead partitioning in the ER

64

fraction was significantly different among sites and locations. A Tukey's multiple

comparison test revealed that all three sites were significantly different from one another

with Boundary Bay having the highest proportion of lead and Roberts Bank the lowest. The

percentage of lead partitioned in both the RED and RES fractions was significantly different

among sites and months; however, different trends were observed for both. Boundary Bay

was found to have a significantly lower percentage of RED lead than either Sturgeon or

Roberts Bank (p<0.05), while the percentage of RES lead was highest at Boundary Bay

with no significant differences found between Sturgeon and Roberts Bank ( ~ 4 . 0 5 ) . In

addition, the percentage of lead partitioned in the RED phase was greatest in the July while

the opposite was found for RES lead (p<0.05).

Table III. The percent metal partitioned in the easily reducible (ER), reducible (RED), residual (RES) and labile (ER+RED) fractions. Values are averaged from all sampling locations and times.

Metal ER RED RES labile Cadmium 32.2 47.3 20.2 79.5 Copper 4.1 37.3 58.8 41.4 Lead 7.3 42.3 50.8 49.6 Nickel 2.6 48.6 52.8 51.2 Zinc 5.3 48.9 44.8 54.2

Nickel

A three-way GLM revealed that the proportion of nickel in the ER phase was significantly

different among sites, months and the interaction term between month and location.

Boundary Bay had a significantly lower percentage of nickel in the ER phase than Roberts

or Sturgeon Bank (p<0.05). In addition, the percentage of nickel partitioned in the ER

phase was greater in May than July (p4.05). For the RED phase, the interaction between

month and location was significant, as well as the difference among locations and month.

The proportion of nickel in the RED phase was greater in July versus May (p<0.05). In the

RES phase, the interaction term between month and location was significant as well as the

difference between months, with higher proportions of nickel in May (p4.05).

Figure 4.4 Partitioning of metals Zn, Cu, Ni, Cd and Pb among four phases in the surficial sediment from all sampling locations at each of the three sites, May 1995 (pglg).

Sturgeon Bank Roberts Bank Boundary Bay E R Zn RED zn OORG zn ~ R E S Zn

Sturgeon Bank Roberts Bank Boundary Bay ER Ni blP RED Ni RES Ni

Sturgeon Bank Roberts Bank Boundary Bay E R C U ~ R E D C U OORGCU ~ R E S C U

- .- Sturgeon Bank Roberts Bank Boundary Bay

E R W E ~ R E D C ~ OORGW ~ R E S C ~

Sturgeon Bank Roberts Bank Boundary Bay E R ~ ~ ~ P F I E D ~ OORGB E ~ ~ R E s ~

Figure 4.5 Partitioning of metals Zn, Cu, Ni, Cd and Pb among four phases in the surficial sediment from a3 sampling locations at each of the three sites, July 1995 (pglg).


E R ~n =RED Zn OORG Zn ~ R E S ~ n

V N

Sturgeon Bank Roberts Bank Boundary Bay ER ~i rn RED Ni RES Ni


E R P ~ ~ R E D P ~ OOROP~ E B R E S ~

Sturgeon Bank Roberts Bank Boundary Bay E R C U W R E D C u [ ~ O R G C I I ~ R E S C ~

Sturgeon Bank Roberts Bank Boundw Bay

E R C ~ ~ R E D W OORGW EZ~RESW

67

Zinc

Zinc partitioning in the ER fraction was significantly different among sites and locations.

Tukey's multiple comparison test revealed that all three sites were significantly different

from one another, with Boundary Bay having the highest proportion of ER zinc and Roberts

Bank the lowest (p<0.05). The percentage of zinc partitioned in the RED fraction was

significantly different among sites and months. Further analysis revealed that Boundary

Bay had a significantly higher percentage of RED zinc than either Sturgeon or Roberts Bank

( ~ 4 . 0 5 ) with the highest percentage in July versus May. With regards to the percentage of

RES zinc, a significant difference was found among sites. Application of Tukey's multiple

comparison test revealed that all three sites were significantly different from one another

with Roberts Bank having the highest percentage of RES zinc and Boundary Bay the lowest

(pc0.05). For all three phases the interaction term between month and location was

significant.

Table IV. Three-way GLM on metal partitioning among the different sediment fractions (p<0.05).

I I Lead I Zinc I

J significant at the 95% confidence level ns not significant at the 95% confidence level

site

location(site)

month

month*location(site)

ER

J

ns J

RED

ns 4

J

RES

ns 4

J

ER J J J J J J

J

ns ns

RED

ns 4

J

RES

ns nsJ

Table V. Multiple comparison tests for differences in metal partitioning between months (May and July) and among sites (Sturgeon Bank=SB, Roberts Bank=RB and Boundary Bay=BB) (p<0.05).

Metal P h e Month Site May vs July

Cadmium ER RB/SB>BB RED

Copper ER RED RES

Nickel ER RED RES

Lead ER RED RES

Zinc ER RED RES

ns ns ns July > May May > July May > July July > May May > July May > July July > May May > July ns July > May ns

ns no signrficant difference > sigrzlficantly greater than based on a 95% confidence level / not signrficantly different fiom one another based on a 95% confidence level

1.2 Grain Size Effects

Mathematical normalization to eliminate the effect of grain size was attempted by

multiplying the bulk chemical concentration, by a normalization factor obtained from the

following equation: 100/(% fine fraction). Table VII (Chapter 3) shows the results of

normalizing trace metal data at locations with varying grain sizes. This table illustrates the

unrealistic concentration values mathematical normalization can produce when the fine

fraction of the sediment represents less than 60% of the sediment. Horowitz and Elrick

(1988) suggest that grain size normalization should only take place when the fine fraction of

the sediment represents at least 50-60% of the sample. Therefore, grain size normalization

for bulk trace metal data was not performed.

1.3 Metals in Macoma balthica

Relationships between sediment geochemistry and metal levels in bivalves were determined

using an R~ MAX procedure with bivalve metal concentrations as the dependent variable

and the following as independent variables: ER Mn, RED Fe, %LOI, ER M, RED M, ORG

M and Total (where M= metal). The R~ MAX procedure was used to evaluate the

significance of the contribution of each of the variables to the prediction of trace metals in

the bivalve. The procedure was performed individually on metals in both the tissue and

shell, except for cadmium where all values were below detection in the shell. Average

concentration, the range and the coefficient of variation is presented in Table VI for each

metal in the tissue and shell. Tables VII and VIII summarize for each of the metals the

independent variables selected, partial regression coefficients and standard error and

relevant statistics. All intercorrelated independent variables which were accepted into a

model are designated as intercorrelated in tables. In all cases, concentrations in the tissue

were greater than those in the shell.

Cadmium: The R~ MAX procedure indicated that tissue cadmium concentrations were

correlated negatively with RED Fe and positively with ER cadmium (cadmium recovered in

the ER fraction). The initial entrance of RED Fe into the analysis produced an R~ value of

0.12 (pc0.0145) while further addition of ER cadmium improved the R~ value to 0.31

70

(~4.0003). Entrance of further independent variables into the R2 MAX procedure resulted

in only minimal improvement in the R2 value (i.e., only 10%).

Table VI. Average concentration (avg _+ SE), range and coefficient of variation for tissue and shell metal concentrations (pglg).

Cadmium Copper Lead Nickel Zinc Mercury

Tissue n=48 n=45 n=48 n=45 n 4 9 n=16 average 0.65 k 0.36 84.8 +. 72.8 2.8 2.9 12.9 -+ 5.1 287 + 142 0.214 k 0.480 range 0.15-1.5 9.5-308.4 0.5-13.5 4.2-26.9 86-527 0.148 - 0.265 CV' 55.3% 85.8% 102.9% 39.8% 49.3 22.4%

Shells n=42 n=42 n=49 n 4 5 n=35 average bd 13.1k8.1 0.6820.51 1.7k1.8 16+23 0.015k0.014 range - 2.0 - 46.9 0.20 - 1.8 0.11 - 11.5 0.9 - 121 0.009 - 0.036 CV - 61.4% 75.4% 108.5% 138.7% 92.6%

Coefficient of variation (standard errorlaverage) xlOO bd concentrations below detection

Copper: The R2 MAX procedure indicated that copper concentrations in tissues correlated

positively with ER and RED copper. The amount of copper recovered in the RED phase

(RED copper) accounted for 38% of the variability in tissue levels (p<0.0001). Further

addition of ER copper improved the R2 value to 0.5 1 (p<0.0001). Copper concentrations in

shells also correlated positively with ER and RED copper, accounting for 43% of the

variability in shell concentrations. The initial entrance of RED copper into the analysis

produced an R2 value of 0.33 (p<0.0001), while the further addition of ER copper improved

the R2 value to 0.43 (p<0.0001). The further addition of remaining independent variables

only improved the R2 values by 2%. ER copper and RED copper were intercorrelated,

."

Nickel: The R2 MAX procedure indicated that there were no significant correlations for i

nickel in the tissues. However, nickel in the shells correlated positively with %LO1 and

negatively with total nickel resulting in an R2 MAX of 0.21 (p<0.0039). The initial

entrance of %LO1 into the R2 MAX procedure generated an R2 value of 0.17 (p<0.0032),

7 1

while further addition of total nickel improved the R~ value to 0.2 1 (~4.0039) . Both of

these variables were significantly intercorrelated; %LO1 and ER nickel, d . 4 7 , p4.0006.

Lead: The R' MAX procedure indicated that ER lead correlated strongly with tissue

concentrations of lead (lX2 MAX of 0.54, p4.0001). Entrance of ER Mn and then %LO1

into the analysis improved the R' MAX from 0.57 (p<0.0001) to 0.61 (p4.0001),

respectively. Intercorrelations were observed for ER Mn and ER lead, d . 6 5 , p<0.000 1

and ER lead and %LOI, r=-0.28, p<0.0400. Addition of further variables only improves the

R2 value by 2%. In contrast, no significant correlation was found between lead in the

tissues and the three sediment components, as well as the four measures of lead recovered

from the sediment.

Zinc: The R' MAX procedure indicated that there was a strong correlation between tissue

concentrations of zinc and concentrations of ER Mn in the sediment ( ~ ~ = 0 . 3 9 , p4.0001).

Addition of further variables into the R2 MAX procedure resulted in minor improvement

(i.e., 6%). ER Mn was also intercorrelated with RED Fe, ER zinc, RED zinc and total zinc

concentrations. Zinc concentrations in shell samples correlated positively with ER Mn

(R2=0. 15, p<0.0086). Easily reducible manganese (ER Mn) accounted for the majority of

the variation with 15%, while further addition of ER zinc, which was intercorrelated with

ER Mn (r=0.40, p<0.0024), improved the R~ by 6%.

Mercury: An R2 MAX procedure of the three major sediment components, plus the total

concentration of mercury in the sediment (mercury was only measured in the aqua regia

extract) indicated that concentrations of mercury in the shell correlated significantly with

ER Mn in the sediment (d. 12, p<0.0436). Entrance of further independent variables into

the R~ MAX resulted in the deterioration of the p-value. An R' MAX was not performed

on tissue mercury as there were insufficient data.

Table VII. Partial regression coefficients, coefficients of multiple determination and related statistics of prediction of trace metal levels in the tissue of Macoma balthica using multiple linear regression (R~ MAX ).

Variable prc x + SE F P

log Cd in tissue constant a,, 3.19 A 0.80 16.01 0.0002 N=48 log RED Fe a, -0.74 A 0.18 15.92 0.0002

log ER Cd a2 0.41 A 0.12 11.92 0.0012 R2=0.3 1 F=9.95 p<0.0003 r=.55

log Cu in tissue constant a0 0.94 + 0.24 14.72 0.0004 N=45 log RED Cua a, 0.85 + 0.23 10.89 0.0020

log ER Cua a2 0.47 + 0.14 13.78 0.0006 ~ ~ = 0 . 5 1 F=2 1.54 p<0.0001 r=O.7 1

log Pb in tissue constant a0 0.70 + 0.07 102.83 0.0001 N=48 log ER Pb al 0.83 & 0.11 53.30 0.0001

R2=0.54 F=53.30 p<0.0001 r=0.73

log Zn in tissue constant a0 1.79 A 0.12 239.35 0.000 1 N=49 log ER Mn a, 0.34 A 0.06 29.82 0.0001

~ ~ d I . 3 9 F=29.82 p<0.0001 r=0.62

prc - partial regression coefficient x k SE - estimate of prc and standard error " or - intercorrelated variables in equation.

Table Vm. Partial regression coefficients, coefficients of multiple determination and related statistics of prediction of trace metal levels in the shell of Macoma balthica using multiple linear regression (It2 MAX ).

Variable prc x + SE F P

log Cu in shell N=42

log Ni in shell N=49

log Zn in shell N=45

log Hg in shell N=35

constant a0 log RED Cua a, log ER Cua a2

constant a0 arcsine LOIa a1 log total Nia a2

constant a0 log ER Mn a1

constant a0 log total Hg

prc - partial regression coefficient x 2 SE - estimate of prc and standard error a or - intercorrelated variables in equation.

2.0 DISCUSSION

Various environmental and biological processes influence the availability of metals to

organisms. Determining the geochemical associations of metals provides useful

information concerning the origin, absolute levels, mobilization, mode of occurrence and

biological availability of a metal. On the other hand, measuring tissue levels in organisms

has the advantage of directly measuring the bioavailable fraction. However, only

measuring tissue levels does not provide information regarding the processes controlling

metal uptake. Combining these two techniques allows for a more holistic approach, one

that considers the processes influencing bioavailability as well as a direct measure of the

bioavailable fraction, with the aim of providing a scientific background for managing

ecological systems. For example, if a monitoring program was in place to measure

concentrations of metals in M. balthica, areas of higher metal bioavailability could be

identified. However, the processes contributing to these higher tissue concentrations would

not be understood.

2.1 Metal Partitioning

Partitioning of copper, nickel, lead and zinc in the surficial sediment all followed the same

pattern. The RED and RES fractions accounted for the majority of metal binding with the

RES fraction accounting for slightly more in all cases except copper. Previous studies have

also found iron oxides (RED phase) to dominate the partitioning of many metals in an

estuarine environment (Grieve & Fletcher, 1976; Luoma & Bryan, 1981). However, direct

comparison of results with other studies is not always useful considering that different

physicochemical factors in different areas will regulate the partitioning of a metal. This was

illustrated in the present study, as differences in sediment geochemistry, partitioning and

metal concentrations precluded pooling of sample locations.

Flow related events may also have influenced the phase distribution of metals. Except for

cadmium, RED metals were always higher in July as compared to May, while RES metals

were higher in May than July. Geesey et al. (1983) noted that the Fraser River had higher

75

concentrations of reactive metals during periods of decreased flow (July) and higher

concentrations of non-reactive metals during periods of high flow (May). They suggest that

this is a result of flow characteristics which influenced sediment redox potentials and

particle movement. A factor that was not alluded to in the study by Geesey et al. (1983), but

can influence the phase distribution of metals is temperature. As temperature increases,

metal partitioning to the particulate phase will increase (Byrne et al., 1988). For example,

in July, higher temperatures could have favoured increased partitioning of metals into the

RED Fe phase.

Concentrations of copper, nickel, lead and zinc were always lowest at Boundary Bay and

highest at Sturgeon or Roberts Bank. However, if sites A0 and W6 (both influenced by the

Iona Island STP) are excluded, the highest overall levels of each of the above metals are

found at Roberts Bank. Considering that Roberts Bank is estimated to receive 60% of the

municipal and industrial effluent discharged into the Frases River (Kennet & McPhee,

1988), this implies that the Fraser River is an important source of trace metals to the

estuary.

In contrast to the behavior of the other metals measured, cadmium partitioning and

distribution was atypical. A major finding was that the majority of cadmium was recovered

in the ER and RED phase, with little recovered in the RES phase. Previous studies have

also found that in an estuarine environment very little cadmium partitions into the RES

fraction and that the reducible phase serves as an important reservoir for cadmium (Davies-

Colley et al., 1984; Kersten & Forstner, 1987). In comparison with other metals, cadmium

is characteristically enriched in the more mobile fraction (ER and RED) and, therefore, may

be more of a concern from this respect. Given the biological accessibility of ER and RED

metals versus RES metals, the existence of cadmium entirely in the labile fraction of the

sediment could represent a risk to any exposed organism.

The highest overall levels of cadmium were observed at Boundary Bay and it was the only

metal that had higher concentrations at this site than the other two sites. Swain and Walton

76

(1990) noted higher cadmium concentrations in crabs taken from Boundary Bay than those

from Burrard Inlet and suggested that the source of this cadmium was from the use of

cadmium as a fungicide, primarily on golf course greens. Cadmium chloride, the active

ingredient in these fungicides was registered with Agriculture and Agri-Food Canada until

1990 (Environment Canada, 1996). Given that there are several golf courses in the vicinity

of Boundary Bay, as well as agricultural fields, this may be a valid source of cadmium to

this area.

With respect to mercury, highest overall levels were at measured at Roberts Bank when site

A0 was excluded. Levels of mercury at Sturgeon Bank have decreased from previous years

when levels near the Iona Island STP were up to 0.89 pg/g in 1979 (McGreer, 1981) and

0.28 pg/g in 1992 (Levings & Bravender, 1993). The results for mercury agree with several

other studies that have shown a high affinity for organic matter in the oxic surficial

sediment (Lindberg & Hariss, 1974; Langston, 1982).

2.2 Metal Concentrations Relative to Sediment Quality Guidelines

For comparative purposes only, the maximum total concentration of each metal in May and

July has been presented to assess the condition of the estuary relative to provincial sediment

quality guidelines (Table IX). In addition, the maximum concentration of each metal in the

labile fraction (ER+RED+ORG) is presented to illustrate the discrepancy in some cases

between what is potentially available to an organism and total metal. Considering that

salinity is an important factor governing the availability of metals (Engel & Fowler, 1979;

Zarnuda & Sunda, 1982; Luoma, 1983) and that salinity varied from freshwater levels (3%0

nearest the outflow of the Fraser River) to marine levels (32%0 Boundary Bay and sites

farthest offshore), sediment quality guidelines for both marine and freshwater systems are

also presented. For example, copper did not exceed the criterim for marine systems, but

exceeded that for freshwater systems by two times. The corresponding salinities at these

locations were 10%0 i-e., characteristic of a freshwater environment, indicating that

freshwater criteria would be more appropriate in this situation.

Table IX. Summary of maximum comntrations of metals in the aqua rega extract and labile fraction (ER+RED+ORG) in May and July, as well as the site and location at which the maximum occurred. Corresponding salinities for each location are presented in parentheses.

Metal Month Maximum Region Maximum Region LOEL 'total ' labile (I-%%) (P&) @dg) marine fresh

Copper May

July

Cadmium May

July

Nickel May

July

Lead May

July

Zinc May

July

SB-A0 (10%0)

RB-BPt-2 (10%0) SB-A0 (10%0)

BB-BB-9 (32%0) RB*

(3-10%0) RB-BPt-2

(lrno) SB-A0 (10%0) SB-A0 (10%0) SB-A0 (10%~)

RB-BPt-2 (1Woo)

Hg July 0.215 SB-A0 - - 0.15 0.2 (10%0)

SB Sturgeon Banks RB Roberts Bank BB Boundary Bay LOEL Lowest Observable Effects Level (Nagpal, 1995) * found at several locations

7 8

Nickel and copper were the only metals that exceeded sediment quality guidelines at more

than one location (mercury exceeded guideline values at one location). Concentrations of

nickel at over half of the sampling locations exceeded both the marine and freshwater

sediment quality guidelines, while copper exceeded freshwater criteria at 18 of 26 locations.

Brewer et al. (1997, in press) found that chromium, manganese, iron, nickel and copper

exceeded the provincial criteria at all upriver reference sites, indicating that background

levels of these metals are naturally high. However, both of these metals are also released as

a consequence of several anthropogenic activities, such as battery manufacturing, sewage

effluent, storm water run off and wood preservatives, indicating that inputs from industrial

and municipal activities plus high background levels may be contributing to the elevated

levels measured.

2.3 Status of the Fraser River Estuary Intertidal Region

Direct comparison of these results to previous studies was difficult for two reasons: i) total

levels of metals were used as an indication of contamination; and ii) results from sampling

sites were often averaged across the entire estuary. Therefore, for comparative purposes

only, average total concentrations of metals, as well as range, was presented. The amount

of metal recovered in the aqua regia digest is an appropriate approximation of total metal, as

the amount of cadmium, copper, nickel, lead, zinc and mercury recovered in this digest was

always around 90% of the certified value for total levels of these metals in reference

sediment (Appendix III, Table 1). Note however, the heterogeneity observed in the Fraser

River intertidal area tends to overwhelm the summarization of conditions within an estuary

with an average concentration for each metal, as indicated by coefficients of variations

ranging from 40% for zinc to 89% for cadmium. Table X shows the range of total trace

metal concentrations measured in this study, as well as in other estuarine systems.

2.3.1 Relative to other studies within the estuary

Based on the few studies that have measured metal contamination in the Fraser River

intertidal region, levels of all metals including cadmium, copper, nickel, lead, zinc and

mercury have decreased or remained stable over the past years (Table X). Most of the

-7

-3y-

. T.

Tab

le X

. R

ange

s of t

otal

trac

e m

etal

con

cent

ratio

ns in

var

ious

estu

arin

e sur

face

sedi

men

ts (p

glg

dry

wei

ght)

.

Aut

hor

Est

uary

C

d C

u N

i P

b Z

n H

g

With

in th

e F

rase

r Riv

er E

stua

ry

Thom

as,

1997

Sw

ain

& W

alto

n, 1

990

Fee

ney,

199

5 M

cGre

er, 1

979

Bin

dra

& H

all,

1977

F

letc

her,

197

6 O

ther

Est

uari

es

Thom

as,

1997

S

urija

& B

rani

ca, 1

995

Das

sena

kis

el a

l., 1

995

Vas

conc

elos

et a

l., 1

995

Pru

dent

e et

al.,

199

4 H

uili

et a

l., 1

993

Mor

se e

t al.,

199

3 Lu

oma

el a

l., 1

990

Lang

ston

, 198

2 B

ryan

& U

ysal

, 197

8 Lo

ring,

197

8 - m

etal

not

mea

sure

d

Stu

rgeo

n B

ank

Rob

erts

Ban

k B

ound

ary

Bay

B

ound

ary

Bay

S

turg

eon

Ban

k S

turg

eon

Ban

k S

turg

eon

Ban

k S

turg

eon

& R

ober

ts B

ank

Fra

ser R

iver

, Can

ada

Krk

a, C

roat

ia

Ach

eloo

s, G

reec

e B

ay o

f P

en B

e, F

ranc

e M

anill

a B

ay, P

hilip

pine

s Z

hujia

ng, C

hina

G

alve

ston

Bay

, U.S

.A.

Sui

sun

Bay

IDel

ta, U

.S.A

. se

vera

l U.K

. est

uarie

s Ta

mar

, U.K

. S

t. La

wre

nce,

Can

ada

80

research in this area has focused on Sturgeon Bank, where there has been a dramatic

decrease in metal levels as a result of the cessation of sewage discharge onto the bank in

1988. Tevendale & Eng (1984) measured constituents of the Iona STP effluent and found

that copper, iron, lead, mercury, nickel and zinc were the main metals present. In the past

20 years, monitoring efforts on Roberts Bank have been sparse. Prior to this time, a

comprehensive survey done by Fletcher (1976) looked at trace metals iron, manganese,

copper, lead and zinc at both Roberts and Sturgeon Bank. Since this survey, levels of all of

the above metals appear to have remained stable. More recently, a study by Feeney (1995)

looked at total metal concentrations across the Sturgeon Bank area only. Ranges of metal

concentrations in her study are very close to those observed in the present study. Levels of

all metals at Boundary Bay have remained relatively constant over the last five years, except

for cadmium which appears to have increased.

2.3.2 Relative to other estuaries

Table X gives an overview of the condition of the Fraser River estuary relative to other

studies. Except for copper, metal concentrations in the Fraser River intertidal area are

generally equal to or lower than those measured in other estuarine systems. Copper levels

in the Fraser River Estuary sit about mid-range in comparison to the other estuaries.

2.4 Linking Sediment Geochemistry to Tissue and Shell Levels

Previous studies in estuarine environments have demonstrated that metal concentrations in

invertebrates can, in part be explained by a combination of metal concentrations within the

sediment (Luoma & Bryan, 1982; Rule et al., 1996). As one would expect, correlations

with tissue metal concentrations are much better for the more easily extractable metals (ER

Mn, RED Fe and ORG) than for tightly bound metals (RES or total).

Metal ions can become incorporated into the crystalline structure of the shell by

replacement of calcium in the carbonate complex or by association with the organic

component of the shell. The ionic radii of some metals i.e., cadmium and lead, resemble

8 1

that of calcium and therefore, more likely to be taken up into the shell matrix in place of

calcium (Sturesson, 1978). Incorporation of metals into a bivalve shell can occur via two

processes: i) physiological uptake i.e. during shell deposition from mantle tissue; or ii)

passive adsorption onto shell surfaces exposed to seawater. In general, the nature of the

absorption processes, the complexing capacity of shell proteins, ionic radii of the metals,

genetic variations of the organisms involved etc., all govern the uptake of metals into shells.

Many studies have looked at metals in the shells of bivalves, but only a few have tried to

relate levels to those in the environment. For example, Bryan and Uysal(1978) found that

most of the manganese incorporated into the shell matrix came from that ingested from the

sediments, while copper, iron and zinc were probably incorporated directly from the

overlying seawater.

2.4.1 General Trends in Bivalve Metal Concentrations

For over half of the correlations, uptake of the various metals into the tissue and the shell by

M. balthica was significantly correlated with the concentration of metal recovered in the ER

phase (i.e., metals associated with manganese oxides) as well as with ER Mn itself (i.e.,

manganese oxides). As expected, correlations were better for the relatively easily

extractable metals than for total trace metal concentrations. The only exception was

mercury and nickel, which both showed a weak correlation with total levels in the sediment.

The importance of the ER Mn phase and the metals associated with it has been

demonstrated. Luoma et al., (1995) found that the concentration of silver associated with

the iron and manganese oxides was a reasonable predictor of silver bioavailability to M.

balthica in estuarine sediments. Also, Bendell-Young et al., (1994) showed that zinc and

copper concentrations in chironomids correlated with zinc and copper concentrations

associated with the Mn-oxide portion and were modified by amounts of organic matter.

2.4.2 Specific Metals

Cadmium, Lead, Nickel and Mercury

Cadmium in bivalve tissues was negatively correlated with RED Fe and positively with ER

cadmium, that is cadmium associated with manganese oxides (d .59) . Hence, the model

82

predicted higher tissue concentrations of cadmium at sites where concentrations of RED Fe

are low and ER cadmium is high. The negative correlation between cadmium tissue

concentrations and RED Fe suggests that this component is modifying what cadmium is

available for uptake, possibly through a 'protective' or 'competitive' effect. An

explanation for this inverse dependence could be: i) RED Fe (presumably as iron oxides)

that enters the gut competes with uptake sites on the intestinal tract for solubilized metals;

ii) RED Fe becomes solubilized in the gut and as a result the iron itself competes with trace

metals for uptake sites; and iii) RED Fe adsorbs dissolved trace metals in the external

phase, such as on the gill or mantle tissue (Tessier et al., 1984). Rule et al. (1996) found

that the largest portion of the variance in tissue concentrations of cadmium in three

estuarine organisms (grass shrimp, blue mussel and hard clam) was also related to the ER

cadmium fraction.

The strongest correlation was found between lead tissue and lead in the ER phase (M.78).

Luoma and Bryan (1978) found that the biological availability of lead to Scrobicularia

plana (a deposit feeding estuarine bivalve) was controlled mainly by the concentration of

lead in the sediment extracted with a weak acid digestion similar to that used for the RED

Fe fraction, as modified by the effects of iron. Note however, the extraction scheme in the

above study did not include an ER phase.

Nickel concentrations in the tissues did not correlate significantly with any of the sediment

parameters; however, concentrations in the shell correlated positively with %LO1 and

negatively with total nickel concentrations (M.52). This suggests that higher

concentrations of nickel in the shell are found at locations with higher organic matter and

low total concentrations of nickel.

In the present study, a weak correlation was found between shell mercury concentrations

and total mercury in the sediment (M.34). A regression was not attempted for mercury in

the tissues as there was insufficient sample numbers. Few studies have addressed the

relationship between mercury in shells and sediment bound mercury; albeit, previous

83

studies have shown a strong relationship between total mercury in the sediment normalised

for organic matter and tissue concentrations for M. balthica in British estuaries ( d . 8 0 ,

~ 0 . 7 4 ) . (Langston, 1982; 1985). Organic matter is believed to be the most influential

variable on mercury tissue concentrations (Langston, 1985; Rae & Aston, 1982). Organic

matter acts as a modifier of mercury uptake (not unlike iron); hence, higher tissue

concentrations of mercury are found at sites concurrently low in organic matter (Breteler et

al., 1981; Langston, 1982). Nickel and mercury were the only metals for which a

correlation with total metal was found.

Copper and Zinc

Copper concentrations in the tissue and the shell were correlated positively with both RED

and ER copper, that is copper associated with iron and manganese oxides ( d . 6 5 , d . 7 1 ) .

Hence, high concentrations in the tissue and the shell are more likely to occur at sites high

in both RED and ER copper. Other studies have found RED Fe and ER Mn (Bendell-

Young et al., 1994) and copper in the organic-sulfide fraction (Rule et al., 1996) to account

for the majority of the variation in tissue copper concentrations. Tissue and shell zinc

concentrations correlated positively with concentrations of ER Mn recovered from the

sediment ( ~ 0 . 6 2 , d . 3 9 ) . Therefore, high zinc concentrations in M. balthica occurred at

locations high in ER Mn.

2.5 Implications of Metals in Macoma balthica

2.5.1 Tissue versus Shell

In some cases, metals will preferentially accumulate in the shell versus the tissue of

bivalves. For example, Babukutty and Chacko (1992) observed higher lead, manganese and

cobalt concentrations in the shells of the estuarine bivalve Villotoria cyprinoides var.

cochinensis. However, all metals were found at higher concentrations in the tissues rather

than shell in the present study. Some benefits of using bivalve shells rather than tissues as

indicators of metal contamination that have been quoted in previous literature include less

variability (factors contributing to a higher variability in tissue-bound metal concentrations

84

are season, age, size, etc.) (Bowgoin, 1990), negligible depuration rate (i.e. shells will retain

a history of past events) (Babukutty & Chacko, 1992) and they are easier to handle and store

(Koide et al., 1982). In the present study, variability in shell metal concentrations was high,

with coefficients of variation in the same range as tissues (Table VT). This was probably a

result of the relatively low concentrations measured in the shell. Considering that shells had

significantly lower concentrations of metals with high variability, tissue-bound metal

concentrations are the more useful indicator of metal contamination in the sediment of the

Fraser River intertidal region.

Based on the present findings, the use of M. balthica as a bio-monitor of metal

contamination has both advantages and disadvantages. An advantage is that M. balthica is

an ideal bio-monitor of metal contamination in the sediment given that it feeds directly on

the deposit sediments, integrating the bioavailable fraction of metals from the sediment over

time. However, the respective tissue concentrations are influenced by biological processes

which can create variability (i.e. age, size, season, etc.). This variability was kept to a

minimum by ensuring samples were collected at the same time of year; organisms were

placed into similar size groups and standardized methods were used to remove ingested

sediments or surface contamination. However, a direct dose-response relationship between

metals in the sediment and tissues does not usually exist, given that environmental and

biological conditions such as sediment geochemistry, salinity, age, life history stage, etc.,

vary.

2.5.2 Relative to other studies within the estuary

Considering its role as a primary prey item for several fish and shorebirds in the intertidal

area (Nichols & Thompson, 1982), it was surprising to find that metal concentrations in M.

balthica have only been measured on one occasion (McGreer, 1979). McGreer (1979)

found concentrations in the tissues of M. balthica at Sturgeon Bank to be (in pglg dry

weight) 49.1-3 14 for copper, 0.74-6.76 for mercury and 392.2-743.2 for zinc (cadmium and

lead were also measured but were below the detection limit). Samples of M. balthica for

85

his study were taken in the vicinity of the Iona Island (STP) discharge, hence, explaining the

relatively high concentrations of zinc and mercury.

2.5.3 Relative to other estuaries

Table XI summarizes tissue concentrations in M. balthica in the Fraser River intertidal

region (the present study) with other estuaries. Compared to other estuaries, metal

concentrations in M. balthica from the Fraser River intertidal area are average for cadmium,

average to high for copper, high for nickel, low for lead and zinc and about average for

mercury.

Tab

le X

I. R

ange

s of

tra

ce m

etal

con

cent

ratio

ns in

the

tissu

es (

who

le b

ody

excl

udin

g sh

ell)

of

Mac

oma

balth

ica

in v

ario

us e

stua

ries

.

ug/g

dry

wei

ght

Aut

hor

Est

uary

C

d C

u N

i P

b Z

n H

g

Tho

mas

, 1997

Fra

ser R

iver

, Can

ada

0.1 5-1.5

9.5-308.4 4.2-26.9 0.50-1 3.5

86-527

0.1 5-0.27

(ave

rage

) (0.65)

(84.8)

(12.9)

(2.8)

(287)

(0.21)

Bor

din

et a

l., 1992

Wes

ters

chel

de, N

ethe

rland

s 0.19-1.13 16.8-32.1

377-692

Bry

an &

Hum

mer

ston

e, 1977

Looe

Est

uary

, U.K

. 0.21 -0.85 96-61 5

6.9-7.9

15-61

51 0-1 160

Luom

a et

al.,

1985

San

Fra

ncis

co, U

.S.A

. 50-500

200-600

Tho

mps

on e

t al.,

1984

San

Fra

ncis

co, U

.S.A

. 30->I000

150-500

Ter

vo, 1987t

Bal

tic o

pen

sea

0.06-0.1 2

2.3-1 1 .O

30-1 00

Bry

an e

t al.,

1985"

seve

ral U

.K. e

stua

ries

Tee

s 0.2

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CHAPTER 5: SUMMARY AND IMPLICATIONS

The present study examined the geochemical processes that influence the distribution,

partitioning and hence bioavailability of metals across an entire intertidal region. Due in

part to the difficulty in accessing sites as well as the enormous analytical demands required

with this type of study, sample sites within the estuarine intertidal area are often limited.

However, as result of the discordant nature of the estuary, physical, chemical and biological

conditions can vary on the scale of centimeters to kilometers (Shine et al., 1995; Sewall,

1996). Extrapolating results from a few sites to an entire estuary is not viable, necessitating

a comprehensive sampling design to incorporate temporal and spatial patchiness. The

sampling design of this study allowed for the consideration of spatial variability (i.e., meters

to kilometers) with respect to sediment geochemistry and metal bioavailability in the Fraser

River intertidal region. This can be particularly important from a biological stand point,

where physical and chemical changes on the smallest scale can have serious implications to

the biota.

The Fraser River Estuary provides a vital habitat for a wide range of wildlife as well as

serving as an important agricultural, industrial and urban area. The input of metals at any

point along the length of the river is reason for concern as they can eventually be transported

downriver and deposited in the estuarine sediments. Higher levels of metals are already

evident at Roberts Bank where riverine input is the greatest, suggesting that the Fraser River

is a source of metals to this area. In addition to the Fraser River, point (Iona Island STP at

Sturgeon Bank) and non-point (agricultural and municipal run-off at Boundary Bay) sources

of metal were also identified as contributing to the levels of metals in the intertidal area.

Porewater profiles were useful in determining the relative contribution of diagenesis to the

geochemical matrix at the sediment-water interface. Diagenesis was a major contributor of

iron oxides at the sediment-water interface; however, concentrations of manganese oxides

appear to be influenced by diagenetic processes and proximity to the Fraser River. As a

result, the spatial heterogeneity of iron and manganese oxides in the intertidal region may be

88

explained by a combination of these two factors, with the relative importance of both being

element specific. Considering the relative importance of oxides of iron and manganese in

the binding, cycling and availability of metals, this heterogeneity also influenced the

partitioning and uptake of metals.

The importance of sediment geochemistry as a predictor of trace metals levels in M.

balthica, was also demonstrated. Tissue concentrations of cadmium, copper, lead and zinc

and shell concentrations of copper, nickel, zinc and mercury were found to be related to

sediment geochemistry. The relative contribution of the different matrix components and

associated trace metals were highly element specific. Only in two cases was total metal in

the sediment found to be a good predictor of bivalve metal concentrations (nickel and

mercury in the shell). Based on the findings of this study, ER metals (metals associated

with the ER phase) and the ER Mn phase itself, appear to be the most important factor

enhancing the bioaccumulation of metals in M. balthica.

Based on the present findings, the use of M. balthica as a bio-monitor of metal

contamination has both advantages and disadvantages. An advantage is that M. balthica

feeds directly on the deposit sediments, integrating the bioavailable fraction of metals from

the sediment over time. However, tissue concentrations do not provide information

regarding the origin of an organism's metal concentration. For example, higher tissue

concentrations of cadmium at Roberts Bank were attributed in part to the concentration of

cadmium associated with manganese oxides, primarily supplied from the Fraser River. If

the geochemistry had not been measured, the actual source of bioavailable cadmium would

be missed. The approach used in the present study shows that measuring both tissue

concentrations and sediment geochemistry compliment each other and allow for a better

understanding of metal availability.

The Fraser River was found to be an important source of manganese oxides (ER Mn) and

trace metals to estuarine sediments. This has implications given that metals associated with

manganese oxides (ER Mn) have an enhanced bioavailability. Hence, the Fraser River

89

could be contributing significantly to the bioavailable fraction of metals in the intertidal

region. In contrast, iron, primarily supplied from the porewaters, reduces metal

bioavailability. Iron can act as a modifier of metal uptake, either through a protective or

competitive effect, with the potential of reducing metal uptake in an organism. This was

demonstrated for cadmium, where RED Fe was inversely related to the concentration of

cadmium in the tissues and ER cadmium (i.e., cadmium associated with manganese oxides)

was positively related to cadmium tissue concentrations. In addition, all other metals except

for nickel and mercury, showed a positive relationship between tissue metal concentrations

and the concentration of metal associated with manganese oxides ( ER metal) or the

manganese oxide phase itself (ER Mn).

The prediction and assessment of the extent to which metals may become available and

potentially lead to adverse effects in organisms is subject to a variety of environmental and

biological processes. A holistic approach, such as the one used in the present study,

considers factors contributing to and influencing metal bioavailability, such as porewaters

and sediment geochemistry, and will ultimately aid in the management and conservation of

ecosystems.

Based on the present findings, future research in the Fraser River estuary intertidal region

should focus on:

1) Determining other factors influencing tissue concentrations of metals in M. balthica i-e.,

sediment geochemistry could account for 3 1% of cadmium concentrations in the tissues of

M. balthica. What other environmental and biological factors account for the rest? For

example, environmental variables that would be important to consider for cadmium would

be salinity and the concentration in the dissolved phase. Biological variables that merit

consideration would be actual age of bivalve (measured from growth rings on shells) and

feeding strategy (i.e., how much time does M. balthica spend deposit feeding vs filter

feeding).

90

2) Linking the ecology of higher trophic levels to areas of higher metal bioavailability i.e.,

determine whether 'hot spots' in metal availability correspond to foraging areas used by

higher trophic levels.

Recommendations

1) Historically total levels of metals in the sediment have been used as an indicator of trace

metal contamination in sediment and biota. Given that only a certain fraction of metals in

the sediment are available for uptake by an organism, a more biologically relevant measure

of trace metals in the sediment should be used. In the present study, metals associated with

the ER phase (i.e., manganese oxides) were found to be the most bioavailable. Therefore,

future surveys or studies concerned with trace metal bioavailability should focus on the ER

fraction of the sediment, as it was found to be the most biologically relevant fraction.

2) Tighter regulations regarding metal discharges into the Fraser River are required as

higher levels of most metals were found at Roberts Bank, which receives the largest input

from the Fraser River. In addition, point and non-point discharges directly to the intertidal

area also contribute to higher levels of certain metals. For example, higher levels of

cadmium in sediment and biota (M. balthica) at Boundary Bay were linked to the use of

cadmium as a fungicide for agricultural and municipal purposes in surrounding areas. In

addition, the effects of the Iona Island STP are still evident, with highest overall lead

concentrations in sediment and biota taken from Sturgeon Bank (sites A0 and W6).

3) The present study was able to show that spatial heterogeneity in regards to sediment

geochemistry and metal partitioning precluded the overall generalization of metal

bioavailability in the intertidal area. Future studies in the intertidal area should include this

variability in their sampling design and refrain from presenting conditions within the estuary

as overall averages.

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Tevendale, T. J. and P. Eng, 1984. Rationale for selection of a deep sea outfall to serve the Iona Island Sewage Treatment Plant. Presented in: The workshop on municipal marine discharge - 1984. (Environmental Protection Service - Pacific Region).

Thomas, C.A., 1997. Linking sediment geochemistry in the Fraser River estuary to metal bioaccumulation in Macoma balthica. M.Sc. thesis - Department of Biology, Simon Fraser University, Burnaby, B.C., 104 pp.

Thompson, E.A., S.N. Luorna, C.E. Johansson and D.J. Cain, 1984. Comparison of sediments and organisms in identifying sources of biologically available trace metal contamination. Water Research, 18:755-765.

US EPA, 1991. Methods for the determination of trace elements in waters and wastes by inductively coupled plasma - mass spectrophotometry. Office of Research and Development, Washington D.C. 20460. EPN60014-9 11010

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Williamson, M. A. and R. A. Parnell, 1994. Partitioning of copper and zinc in the sediments and porewaters of a high-elevation alkaline lake, east-central Arizona, U.S.A.. Applied Geochemistry, 9:597-608.

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APPENDIX I: INSTRUMENT THEORY

Graphite Furnace Atomic Absorption Spectrophotometry (GFAAS)

Graphite furnace atomic absorption spectrophotometry employs a graphite furnace to heat

the sample up in three or more stages. First, a low current heats the tube to dry the

sample. The second, or charring stage, destroys organic matter and volatilizes other

matrix components at an intermediate temperature. Finally, a high current heats the tube

to incandescence and in an inert atmosphere, atomizes the element being determined. An

external radiation source (such as a hollow cathode lamp) passes through the vapour

containing the ground-state atoms from the sample. Some of the spectral lines emitted by

the source are partially absorbed by the outer electrons in the ground-state atoms of the

test element. The extent of absorption corresponds to the amount of the test element in

the sample. The concentration of the test element in the sample is determined by

comparing the absorbance of the resonance line in the sample to the absorbance of the

resonance. line in standards containing known concentrations of the test element.

Samples were analysed for cadmium, lead and nickel using GFAAS as this method

permits determination of most metals with detection limits 20-1000 times better than

those of flame techniques without extraction or sample concentration (APHA, 1992).

Cold-Vapour Atomic Absorption Spectrophotometry (CVAAS)

This technique involves the generation of mercury vapor followed by subsequent

quantification by AAS. This process is initiated by mixing an aqueous sample with an

acid and sodium borohydride solution and allowing the mixture to react. The mixture

then passes through a gasAiquid separator where the gaseous mercury vapor is separated

from the liquid stream and passed into a quartz tube. Heating of the quartz tube is not

necessary as mercury vapor is generated at room temperature. An external radiation

source passes through the quartz tube containing the mercury vapour. Some of the

spectral lines emitted by the source are partially absorbed by the outer electrons in the

ground-state atoms of mercury. The extent of absorption corresponds to the amount of

the test element in the sample. The concentration of the test element in the sample is

determined by comparing the absorbance of the resonance line in the sample to the

101

absorbance of the resonance line in standards containing known amounts concentrations

of the test element.

Inductively Coupled Plasma Atomic Emission Spectrophotometry (ICP-AES)

An ICP source typically consists of a flowing stream of argon gas ionized by an applied

radio frequency. Samples are aspirated into the nebulizer where an aerosol is created and

then desolvated in a chamber before introduction to the source. In the source, the sample

and its constituent atoms are subjected to temperatures of about 6000-8000•‹K. The high

temperature of the plasma vaporizes, atomizes and excites the atoms, efficiently

producing ionic emission spectra. Emission occurs as a result of excited atoms losing

energy by giving off photons of characteristic energy. Atomic emission can be used to

identify and quantify a particular element because the wavelengths of photons emitted are

different for each element and under the proper conditions the emission intensity is

proportional to the concentration of that element in the sample.

Inductively Coupled Plasma-Mass Spectrophotometry (ICP-MS)

This method of elemental analysis employs a mass spectrometer interfaced to the

inductively coupled plasma described above. The inductively coupled plasma acts as the

ion source by breaking all but the most stable molecules into monatomic, singly and

doubly charged ions. This mixture of ions and atoms are extracted from the plasma

through a differentially pumped vacuum interface and separated on the basis of their

mass-to-charge ratio by a quadropole mass spectrometer. The ions transmitted through

the quadropole are registered by a detector and the ion information processed by a data

handling system. The advantages of using ICP-MS are; low detection limits, extensive

linearity for many orders of magnitude and many elements can be measured at once

(USEPA, 1991).

APPENDIX 11: DETECTION LIMITS AND DILUTION FACTORS

Table 1. Detection limits (DL) (mg/L) and dilution factors of iron and manganese in porewater.

Site I Fe I Mn ( DL I Dilution 1 DL I Dilution

A sites 1 0.15 1 31 1 0.031 1 31 Sturgeon Bank

W sites 1 0.25 ( 5 1 I 0.051 I 5 1

( m g m

BPt sites 1 0.51 1 101 I 0.101 I 101

( m g m

Roberts Bank A1 4 sites WI sites

Table 2. Detection limits (DL) (pg/g dry weight) and dilution factors (DF) for metals in each sediment extract.

0.1 1 0.11

Boundary Bay BB sites

G = analysed by GFAAS I = analysed by ICP-AES C = analysed by CVAAS - = no dilution na = not analysed

2 1 2 1

0.5 1

0.02 1 0.02 1

101

2 1 2 1

0.101 101

Table 3. Detection limits (pg/g dry weight) for the analysis of metals in biota samples by ICP-AES and ICP-MS.

* - Mercury analysed by CVAAS

APPENDIX 111: QUALITY ASSURANCE 1 QUALITY CONTROL

Table 1. Mean and SE of metal concentrations in each fraction from NRCC MESS-2 estuarine reference sediment. The number of reference samples analysed for all metals was 12. Mercury was only measured in the aqua regia extract (n=6). Only certified values for total metal using a strong acid digestion are available from NRCC.

] Mean f SE

Metal

11 k0.2

na = not analysed

Easily Reducible

Mean _+ SE Mean 2 SE Mean -+ SE

O&g) (P&) ( M k )

Reducible NRCC Certrjied Total (Strong acid

digestion)

Mean 2 95% CI

(Mid

Organic

bd = below detection - = no comparison possible

Aqua Regia

Table 2. Mean and SE of metal concentrations in MST oyster tissue (1566a) and NRCC lobster hepatopancreas (TORT-1) reference material analysed by ICP-AES. The number of reference samples analysed for oyster tissue (1566a) was n=4 and for lobster hepatopancreas (TORT- 1) was n=6.

Metal I Lobster Hepatopancreas TORT- 1 (pg/g)

bd = below detection

Measured Certified Mean + SE I Mean + 95% CI

* = analysed by CVAAS


Table 3. Mean and SE of metal concentrations in NIST oyster tissue (1566a) and NRCC lobster hepatopancreas (TORT- 1) reference material analysed by ICP-MS. The number of reference samples analysed for oyster tissue (1566a) was n=9 and for lobster hepatopancreas (TORT- 1) was n=7.

bdi below detection

Lobster Hepatopancreas TORT- 1 (pg/g)

Metal


Oyster Tissue 1.566~ (~g/g)

Measured Certified Mean +. SE I Mean + 95% C1

APPENDIX IV: SEDIMENT MATRIX ATTRIBUTES OF DEPOSIT SEDIMENTS

Table 1. Concentrations of ER Mn and RED Fe and % LO1 (organic matter) measured at each site in the spring and summer. Values are means of three measures f 1 SD.

A0 A1 0 A12 W6 w 7 W8 w 9 WlO

A14 A14a A14b W.I.-1 w. I. -2 W. I. -3 BPt-1 BPt-2 BPt-3

BB-1 BB-2 BB-3 BB-4 BB-5 BB-6 BB- 7 BB-8 BB-9

Spring 79.9 + 9.9 116.7 + 3.8 227.4 + 6.8 102.0 + 4.8 88.4 f 0.8 96.8 f 9.5 38.2 + 3.8 47.5 + 7.7

140.6 f 22.2 96.1 + 2.8 46.0 + 3.6 143.3 + 8.2 114.5 + 13.0 137.4f 17.0 52.0 2 17.8 46.1 f 9.5 27.7 + 6.2

15.2 + 5.0 5.2f 1.5 12.9 + 1.9 4.6 f 1.2 5.1 + 1.4 4.7 + 2.0 20.9 + 9.0 16.7 f 2.8 21.2 + 6.6

Summer Spring 3244 + 1067 4775 f 432 4207 + 170 6075 f 221 4085 + 270 3881 + 210 3226 + 304 4315 + 831

6993 + 857 6589 f 573 4804 f 423 6009 + 163 4273 + 304 2732 + 145 10938 + 345 9730 + 496 10395 f 518

2100 + 179 1890 + 220 1867 f 157 2484 + 213 1705 f 51 2104 + 50 3407 + 273 1962 f 21

3459 f 331

Summer

% LOI

Spring 5.03 f 0.24 1.88 + 0.28 1.70 + 0.15 3.45 f 0.26 1.53 + 0.22 1.41 + 0.10 1.29 f 0.26 1.82 + 0.16

4.13 + 0.61 2.23 + 0.01 1.82 + 0.34 4.84 + 0.14 2.32 + 0.20 1.23 f 0.19 5.78 + 0.49 5.25 + 0.36 6.36 + 1.38

1.84 + 0.42 1.43 f 0.20 1.19 f 0.01 2.84 + 0.52 1.64 + 0.29 1.28 + 0.04 3.54 f 0.24 1.61 + 0.14 2.66 f 0.64

Summer 3.85 + 0.05 1.65 + 0.03 1-77 + 0.17 2.77 st 0.25 1.82 f 0.22 1.63 + 0.04 1.48 + 0.21 1.67 f 0.28

3.20 5 0.12 1.80 + 0.16 2.57 + 0.06 4.65 + 0.89 2.29 f 0.1 1 1.40 f 0.34 6.39 f 0.21 5.90 + 0.85 5.20 f 0.91

1.90 + 0.21 1.65 + 0.09 1.47 + 0.23 2.65 + 0.55 1.39 + 0.17 1.64 + 0.03 3.17 f 0.65 1.96 + 0.22 3.07 + 0.04

APPENDIX V: GRAIN SIZE CHARACTERISTICS

Table 1. Grain size characteristics (% wt) for each location averaged over the two seasons.

A0 A10 A12 W6

w 7 W8 w 9 WIO

A14 A1 4a A14b w. I. -1 w. I. -2

W. I. -3 BPt-I BPt-2 BPt-3

BB-I BB-2 BB-3 BB-4 BB-5 BB-6 BB- 7

BB-8 BB-9

% Clay (< 2.0 P)

21.0 2.9 2.6 12.9

1.2 2.3 2.9 3.7

14.3 7 .O 9.3 16.5 5.1

2.6 19.2 18.7 20.3

2.0 1.2 1.2 4.2 2.1 1.2 8.2

5.1 8.5

% Silt (2.0-50 m)

69.4 2.3 0.8 3 1.6

1.6 1.3 0.2 2.5

50.6 17.5 30.8 73.5 25.2

1 .o 77.5 70.6 67.2

6.9 2.0 0.4 7.2 2.3 1.1 16.9

5 .O 19.4

% Sand (50 pn-2.0 mm)

9.7 94.8 96.5 55.5

97.2 97.0 97.0 93.9

35.1 75.5 59.9 10.0 69.7

97.0 3.3 10.7 12.5

91.1 96.8 98.7 88.6 95.6 97.7 74.9

89.9 72.1

% Clay & Silt (< 50 w)

90.3 5.2 3.5

44.5

2.8 3.0 3.1 6.2

64.9 24.5 40.1 90.0 30.3

3.1 96.7 89.3 87.5

8.9 3.2 1.3

11.4 4.4 2.3 25.1

10.1 27.9

Texture Class

Fine - silt loam Very coarse - sand Very coarse - sand Coarse - sandy loam Very coarse - sand Very coarse - sand Very coarse - sand Very coarse - sand

Fine - silt loam Very coarse - sand Fine - silt loam Fine - silt loam Coarse - sandy loam Very coarse - sand Fine - silt loam Fine - silt loam Fine - silt loam

Very coarse - sand Very coarse - sand Very coarse - sand Very coarse - sand Very coarse - sand Very coarse - sand Coarse - sandy loam Very coarse - sand Coarse - sandy loam

APPENDIX VI: TRACE METALS IN DEPOSIT SEDIMENTS

ietal site locatior

ipring :d Sturgeon Bank A0

Roberts Bank A14 A 1 4 A14b W.1.-1 W.1.-2 W.1.-3 BPl-1 BPl-2 BPt-3

avg+SE

Boundary Bay BB-1 88-2 BE3 BB-4 BE5 BE6 88-7 BE8 BE9

avg&E

ummer :d Sturgeon Bank A0

A10 A12 W6 W7 W8 W 9

WlO avg+SE

Roberts Bank A14 A14a A14b W.1.-1 W.1.-2 W.1.-3 BPt-1 BR-2 BR-3

a-SE

Boundary Bay BB-1 BE2 BE3 88-4 BB-5 BE6 BE7 88-8 BE-9

--

a w S E otals for each traction otal Cd 0.140t.120

RED (KW mean 1 SD

ORG (PS/S) mean 2 1SD

RES (~943) mean t 1SD

0.000 0.000 0.000 0.000 0.026 0.000 0.008 0.000 0.000 0.000 0.009 0.000 0.000 0.000 0.000 0.000 0.005 0.000

0.050 0.037 0.014 0.007 0.009 0,010 0.063 0.006 0.030 0.002 0.023 0.006 0.020 0.000 0.007 0.002 0.010 0.008 0.025 0.009

0.000 0.000 0.000 0.000 0.014 0.000 0.028 0.023 0.023 0.006 0.020 0.042 0.023 0.009 0.014 0.003 0.088 0.1 13 0.023 0.022

netal site locatior

Spring :u Sturgeon Bank A0

A1 0 A1 2 W 6 W7 W8 W9 W10

avgtSE

Roberts Bank A14 A1 4a A14b W.1.-1 W.1.-2 W.1.-3 BPt-1 BPt-2 BPt-3

avgtSE

Boundary Bay BB-1 88-2 88-3 88-4 88-5 BB-6 68-7 BB-8 BB-9

avgtSE

;ummer :u Sturgeon Bank A0

A10 A12 W6 W7 W8 W9

W10 avgaSE

Roberts Bank A14 A1 4a A1 4b W.1.-1 W.1.-2 W.1.-3 BPt-1 BPt-2 BPt-3

avgtSE

Boundary Bay BB-1 88-2 88-3 88-4 BB-5 BB-6 88-7 88-8 BB-9

avgtSE otals for each fraction avg*SE

RED (1~9'g) mean t 1 SD

otal Cu 21.91 t 13.28

netal s~te locatior

Spring 'b Sturgeon Bank A0

A10 A1 2 W6 W7 W8 W9 W10

avgiSE

Roberts Bank A1 4 A1 4a A14b W.1.-1 W.1.-2 W.I.4 BPt-1 BPt-2 BPI-3

avgtSE

Boundary Bay BB-1 BB-2 88-3 88-4 BB-5 BB-6 88-7 BB-8 BB-9

avgtSE

iummer b Sturgeon Bank A0

A1 0 A1 2 W6 W7 W8 W9

W10 avgtSE

Roberts Bank A1 4 A1 4a A14b W.1.-1 W.1.-2 W.I.4 BPt-1 BPt-2 BPt-3

avgtSE

Boundary Bay BB-1 88-2 88-3 88-4 88-5 BB-6 88-7 BB-8 BB-9

avg&E otals for each fraction avgtSE

RED (1~9'9) mean + 1 SD

ietal site locatior

ipring li Sturgeon Bank A0

A1 0 A1 2 W6 W7 W8 W 9

W10 avg*SE

Roberts Bank A1 4 A1 4a A14b W.1.-1 W.1.-2 W.1.-3 BPt-1 BPt-2 BPt-3

avgtSE

Boundary Bay BB-1 BB-2 BB-3 88-4

, BB-5 BB-6 BB-7 BB-8 BB-9

avg*SE

ummer i Sturgeon Bank A0

A1 0 A12 W6 W7 W8 W9

W10 avg*SE


avgiSE

Boundary Bay BB-1 BB-2 88-3 88-4 BB-5 BB-6 88-7 88-8 BB-9

avg*SE otals for each fraction avg*SE

RED (lJg/g) mean * I SD

otal Ni 29.91 * 13.26

netal site locatior

Spring !n Sturgeon Bank A0

A1 0 A1 2 W 6 W7 W 8 W9 W10

avgiSE

Roberts Bank A1 4 A1 4a A14b W.1.-1 W.l.-2 W.1.-3 BPt-1 BPt-2 BPt-3

avg*SE

Boundary Bay BB-1 88-2 88-3 08-4 88-5 08-6 BB-7 00-8 88-9

avgiSE

;ummer :n Sturgeon Bank A0

A1 0 A1 2 W6 W7 W8 W9 W10

avgiSE

Roberts Bank A1 4 A1 4a A14b W.1.-1 W.1.-2 W.1.-3 BPt-1 BPt-2 BPt-3

avgiSE

Boundary Bay 00-1 00-2 88-3 88-4 00-5 00-6 88-7 BB-8 BB-9

avgiSE btals for each fraction avg*SE

ER (Ir9'g) mean i 1SD

RED W g ) mean * 1SD

ORG W g ) mean i ISD

RES ( ~ 4 ) mean i 1SD

'otal Zn 54.86 i 21.99

netal site locatior

Summer %I Sturgeon Bank A0

A1 0 A1 2 W6 W7 W8 W9

W10 avg*SE


avg*SE

Boundary Bay BB-1 86-2 BB-3 B E 4 B E 5 BB-6 B E 7 BB-8 B E 9

APPENDIX VII: TRACE METALS IN MACOMA BALTHICA (pglg)

Site

A0 A1 0 A12 W6 W7 W8 W9 W10

A14 A14a A1 4b W.1.-1 W.1.-2 W.1.-3 BPt-1 BPt-2 BPt-3

BE5 BB-6 BE9

Totals:

Site

A0 A1 0 A1 2 W6 W7 WE W9 W10

A1 4 A1 4a A14b W.1.-1 W.1.-2 W.1.-3 BPt-1 BPt-2 BPt-3

BB-5 BE6 ,BE9

Totals:

Cd in tlssues mean i 1 SD

0.488 0.137 0.373 0.058 0.332 0.051 0.452 0.135 0.686 0.167 1.132 0.000 0.468 0.1 18 0.223 0.061

1.300 0.200 0.813 0.093 0.477 0.035 1.043 0.289 1.172 0.199 0.727 - 0202 0.059 0.442 0.321 0.497 0.074

0.949 - 0.992 0.285

W . W

0.653 * 0.363

Cu in shells mean * 1 SD 19.0

Pb in tissues mean * 1 SD 11.91 1.66 2.07 0.99 1.72 0.44 7.08 1.49 1.92 0.38 1.79 2.19 0.54 2.20 0.48

1.00 0.00 0.97 0.06 2.37 0.15 3.67 1.34 3.75 0.85 2.82 0.08 - 1.29 2.00 1.05 0.24

0.67 0.63 0.1 4 W W

283 * 2.91

Zn in tissues mean * 1 SD

376.0 71.4 278.7 53.6 177.1 15.6 251.6 86.1 272.9 93.5 734.0 - 3124 145.6 140.4 24.0

482.0 40.9 374.7 16.1 338.0 14.8 451.7 88.3 394.7 33.4 182.7 - 146.5 27.3 197.6 43.1 161.5 37.4

100.0 - 96.6 10.3 W W

287.1 142.6

Pb in shells mean* 1 SD 1.03 0.15

Ni in tissues mean * 1 SD 14.9

Ni in shells mean i 1 SD 0.9 0.2

Zn insheils I Hg in tissues I Hg in shells

tissues - whole body excluding the shell bd below detection na sample not measured

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