Spatial and temporal patterns in food web accumulation of Hg Project Update RMP Technical Review...
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Transcript of Spatial and temporal patterns in food web accumulation of Hg Project Update RMP Technical Review...
Spatial and temporal patterns in food web accumulation of Hg
Project UpdateRMP Technical Review Committee March 18, 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 70 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 40 1 40 120 73%
Interannual 8 1 8 24 17%
Seasonal 2 9 18 54 10%
66 198
Spatial survey
• Test hypotheses of MeHg entry points and food web accumulation hotspots
A. Hg source sites
B. Wetlands and wetland type
C. Enclosed subembayments and estuarine creeks
D. Sediment parameters
Spatial survey design - hypothesis testing
Hydrology:Site Type
Open Shoreline
Sub-Embayment
Total Number
High Hg Wetland NA NA 6/yr
Low Hg Wetland NA NA 6/yr
Hg Source Area 7/yr 7/yr 14/yr
Other 7/yr 7/yr 14/yr
Total number sites 40/yr
Spatial survey sites chosen probabilistically
• Same GRTS method as Status and Trends Program
• More powerful inference than with sites of convenience
• What types of conditions Bay-wide higher Hg
• Identify spatial gradients (e.g., South/North?)
• Even if all our hypotheses are wrong, we are still characterizing conditions and identifying hotspots Bay-wide
So What Are the Areas Sampled?
• Entire shoreline of Bay• Lower South Bay to Suisun Bay• Estuarine tributaries• All subtidal wetlands• Not sampling
– Offshore locations– Salt ponds (weak connection to Bay)– Marine lakes (e.g., Aquatic Park, Anza Lagoon)– Islands within Bay (e.g., Angel Island, Red Rock)
How separating different site types?
Hydrology:Site Type
Open Shoreline
Sub-Embayment
Total Number
High Hg Wetland NA NA 6/yr
Low Hg Wetland NA NA 6/yr
Hg Source Area 7/yr 7/yr 14/yr
Other 7/yr 7/yr 14/yr
Total number sites 40/yr
Preliminary map of areas to be sampled
GIS based on morphology, size, depth
-Strata 1:Open Shorelines-Strata 2:Submbayments
Identifying Hg source areas
Hydrology:Site Type
Open Shoreline
Sub-Embayment
Total Number
High Hg Wetland NA NA 6/yr
Low Hg Wetland NA NA 6/yr
Hg Source Area 7/yr 7/yr 14/yr
Other 7/yr 7/yr 14/yr
Total number sites 40/yr
Source site selection • Mining sources
– Creeks draining La Joya, Bella Oaks, Borges, and New Almaden Mines
• POTW discharges– 11 shallow-water wastewater treatment plants
recommended by RB NPDES Permitting Staff• Creeks draining urban/industrial areas
– Identified for part of Bay by Prop 13 Stormwater BMP project– Based on historic industrial area and railway lines, auto
recycling facilities, and Hg hotspots• Industrial areas with high sediment THg
– BPTCP sites having sediment THg > 0.7 ppm• Total of about 50 sites
Hydrology:Site Type
Open Water Embayment Total Number
High Hg Wetland NA NA 6/yr
Low Hg Wetland NA NA 6/yr
Hg Source Area 7/yr 7/yr 14/yr
Other 7/yr 7/yr 14/yr
Total number sites 40/yr
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
Wetland site selection
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
• Augment with small number additional sites (e.g., Guadalupe Reservoir to represent mine signal)
• 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
• Likely overlap with mercury isotope sites– Year 2 – process studies
• Source sites of interest including fishless locations• Likely include SPL sites (e.g., Z4LA)• Report available February 2010
– Addition of water column DOC as correlate
Discussion points• Other suggested source sites?• Agree with area and types of sites covered?
– Entire shoreline of Bay– Lower South Bay to Suisun Bay– Estuarine tributaries– All subtidal wetlands– Not salt ponds, marine lakes, offshore, or small
islands – Phased plan for DGT study
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
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