Draft data - do not cite or quote Spatial and temporal patterns in food web accumulation of Hg...

Draft data - do not cite or quote

Spatial and temporal patterns in food web accumulation of Hg

Project UpdateRMP Exposure and Effects Work Group

May 12, 2008


Workplan: Specific questions to address

1. Where is mercury entering the Bay food web?

2. What habitats, conditions, or factors help to identify hotspots of food web accumulation in Bay margins?

3. Are there interannual trends in MeHg bioaccumulation resulting from wetland and margin restoration activities?

4. What are the best biomonitoring tools for characterizing hotspots of MeHg bioaccumulation?


General approach

• Spatial analysis– Stratified random design– Identify hotspots based on conceptual

model

• Seasonal trend evaluation • Interannual trend detection• Field sampling for Hg isotopes and for

DGT study


Allocation of effort

• Total of 62 sampling events per year to evaluate spatial, seasonal, and interannual patterns

Type Sites

Events per

Year

Total Events

per Year

Total EventsOver 3 Years

% Sampling Budget

Spatial 36 1 36 108 73%

Interannual 8 1 8 24 17%

Seasonal 2 9 18 54 10%

62 186

Spatial survey design - hypothesis testing

Hydrology:Site Type

Open Shoreline

Enclosed Total Number

High Hg Wetland NA NA 6/yr

Low Hg Wetland NA NA 6/yr

Hg Source Area 6/yr 6/yr 12/yr

Other 6/yr 6/yr 12/yr

Total number sites 36/yr

Draft data – do not cite or quote

Spatial survey sites chosen probabilistically

• Same GRTS method as Status and Trends Program

• What types of conditions Bay-wide higher Hg

• Stratified sampling scheme

• Even if all our hypotheses are wrong, we are still characterizing conditions and identifying hotspots Bay-wide



How separating different site types?

Hydrology:Site Type

Open Shoreline







Map of areas to be sampled

GIS based on morphology, size, depth

-Strata 1:Open Shorelines-Strata 2:Enclosed areas and creeks



Identifying Hg source areas

Hydrology:Site Type

Open Shoreline








Source site selection • Mining sources

– Creeks draining probable source mines

• POTW discharges– Feedback from RB NPDES Permitting Staff

• Creeks draining urban/industrial areas– Feedback from BASMAA

• Industrial areas with high sediment THg• Total of about 50 sites


Hydrology:Site Type

Open Water Embayment Total Number






Wetland site selection

•Oversight by Josh Collins and Letitia Grenier

•Based on GRTS sampling performed for SBMP and CRAM

•Stratified based on:•relative wetland elevation and age•Is wetland hypothesized to be high or low in bioavailable Hg

Wetland site selection



Results of site selection

Non-wetland site selectionYears 1 - 3


Wetland site selectionYears 1-3


Source site selectionYears 1-3


All sitesYear One


Source SitesYear One


Enclosed vs.Open shorelineYear One


All sitesYear Two(does not include wetlands)



Coordination and Collaboration

• University of Michigan – RMP Hg stable isotope study (Joel Blum, Gretchen Gehrke)– Hg isotope sites characterize specific

sources• Urban runoff, mining, waste water, atmospheric

deposition• Sites will be chosen from small fish source sites

after probabilistic site selection is complete• Sediment Hg and isotope analysis


Coordination and Collaboration• Trent University – Diffusive Gradient in

Thinfilm devices (Holger Hintelmann)– Just completing analyses of the pilot study data

(2007)– Year 1 - validation

• 15 small fish sites varying in chemistry and expected bioaccumulation

• Will overlap with mercury isotope sites– Year 2 – process studies

• Source sites of interest including fishless locations• Gradient studies • Likely include SPL sites (e.g., Z4LA)• Report available February 2010

– Addition of water column DOC as correlate


Discussion points• How select sites for DGT and Hg

isotope in year one


END OF TALK

• REST IS ANCILLARY MATERIAL IN EVENT OF DISCUSSION


THg (ng/g)10 100 1000 10000

MeH

g (n

g/g)

0.01

0.1

1

10

Land Within 2 Km Buffer0.0 0.2 0.4 0.6 0.8 1.0

TOC (%)0.1 1 10

Latitude (Degrees N)37.4 37.6 37.8 38.0 38.2

MeH

g (n

g/g)

0.01

0.1

1

10



Sediment MeHg may be correlated with topsmelt Hg

0.5 1.0 1.5 2.0 2.53.03.5

MeHg in sediment (ng/g)

0.02

0.03

0.04

0.05

0.06

0.070.08

Hg

in f

ish

(u

g/g

)

•Topsmelt 2006 data

•RMP and Calfed sediment data within 1.5 km disk of fish

•R2 = 0.61

Trend analysis – a multiple station BACI design

0

0.05

0.1

0.15

0.2

0.25

0.3

1 2 3 4 5 6 7 8 9

Year

Mer

cury

Con

cent

ratio

ns Control 1

Impact 1

Control 2

Impact 2

Control 3

Impact 3

Control 4

Impact 4


Trend Sampling Locations

Alviso Slough

Newark Slough

Bird Island/Steinberger Slough

Eden Landing

China Camp

Benicia Park

Control

Impact (Restoration)Point Isabel

CandlestickPoint

Hamilton

Oakland Middle Harbor


Monthly sampling locations

Martin Luther King Shoreline

Additional North Bay Station Sampled by USFWS


MLK Shoreline Location



Collection of additional parameters

• Aimed at better understanding mechanisms for spatial variation in bioavailable Hg

• GIS spatial parameters

• Sediment parameters


Sediment parameters

• Sediment parameters: redox, TON, grain size, total and methyl Hg

• Samples at subset of 20 Sites


-122.6 -122.3 -122.0 -121.7Longitude

37.4

37.5

37.6

37.7

37.8

37.9

38.0

38.1

38.2La

titud

e

-3-2-1012

LOGMEHG

0.00.51.01.52.02.5

MEHG_HIGH1

Sediment MeHg: < 1 ng/g 1 – 2 ng/g > 2 ng/g

Annual monitoring of trend stations


0.5 1.0 1.5 2.0 2.53.03.5

SEDIMENT

0.02

0.03

0.04

0.05

0.06

0.070.08

FIS

H

SQ

Pt Isabel

Tiburon

Alviso

Newark

Oakland Harb

Treasure Isl

China Camp

Draft data - do not cite or quote Spatial and temporal patterns in food web accumulation of Hg...

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