33
Assessment of Hg in Sediment, Water, and Biota of VT and NH
Lakes
A Collaborative REMAP Project
Neil Kamman, VTDECNew Hampshire Dep’t Environmental Services
Syracuse UniversityUSEPA Region 1 and USEPA - ORD
VT / NH REMAP-Hg ProjectCollaborators
• NHDES• VTDEC• Syracuse University• Dartmouth College• Sci. Museum of Minnesota• US Fish and Wildlife Service• VT Dep’t of Fish and Wildlife• BioDiversity Research Institute
Project inception
• In 1997, we knew very little about Hg levels in lakes of northern New England, outside of Maine.
• Application of sampling and analytical methods for trace metal work were just becoming available outside of academic realm.
• EPA Region 1 developed a strong interest in having a complete picture of Hg contamination across the entire region.
Core program goals for the period 1998 to 2000
• Use USEPA “EMAP” approach to:
• Identify the physico-chemical identity(ies) and hypothesized trophic Hg transfer pathway of lakes which pose a risk of Hg contamination to people and wildlife;
• Model Hg signal in lakes outside the study set, which can identify target waters for further fish/avian assessments;
• Model air deposition using MDN / UMAQL network
• Understand the historical accretion patterns of Hg into lakes as a tool to understand potential gains given reduced Hg deposition.
VT / NH REMAP-Hg ProjectStudy design:
• 90+ lake geographically randomized sample• Hg and meHg collections in water, sediment, plankton,
fish, avian piscivores, sediment cores• Hg-clean methods used for all Hg collections
– Water by CVAFS– Mud and Biota by CVAA
• Dataset describing current Hg conditions, • Design permits geographic analyses, and • Dataset ripe for opportunistic analyses (e.g. mining).
VT / NH REMAP-Hg ProjectParameter list
• Water: Hg, meHg, nutrients, DOC and acid-base chemistry, physicochemical measures
• Sediment: Hg, meHg , solids and organic content• Macrozooplankton – Hg, bulk >200u fraction• Yellow Perch in two size classes, Hg and meHg• Upper trophic level piscivore tissue Hg (e.g.,
loons, kingfisher): blood, feather, egg
Study lake locations
19981998
19991999
VT / NH REMAP-Hg ProjectIn the field
Pontoon-craft
VT / NH REMAP-Hg ProjectIn the field
Considerations for clean water collections
VT / NH REMAP-Hg ProjectIn the field
Clean, undisturbed overlyingwater
Perfect sediment-H2O interface
Core laminae
VT / NH REMAP-Hg ProjectIn the field
VT / NH REMAP-Hg ProjectFindings:
• Cumulative frequency distributions• Hg and lake trophic status• Hg and land-use• Water chemistry and methylation• Predicting tissue Hg• Piscivore Hg risk assessment• Air deposition models• Historic and current Hg accumulations
VT / NH REMAP-Hg ProjectFindings: Water Hg
020406080
100
0 0.5 1 1.5 2
Epilimnetic meHg (ng l-1)
Cum
ulat
ive
%
0
2040
60
80100
0 2 4 6 8
Epilimnetic HgT (ng l-1)
Cum
ulat
ive
%
New Hampshire
Vermont
020406080
100
0 1 2 3 4 5
Hypolimnetic meHg (ng l-1)
Cum
ulat
ive
%
020406080
100
0 10 20 30 40
Hypolimnetic HgT (ng/L)
Cum
ulat
ive
%
VT / NH REMAP-Hg ProjectFindings: Sediment Hg
020406080
100
0 0.2 0.4 0.6 0.8
Sediment HgT (ug g-1)
Cum
ulat
ive
%
New Hampshire
Vermont
Maine
Sediment Sediment methylHgmethylHg ranges from <0.0006 ug granges from <0.0006 ug g--11 to 0.021 ng gto 0.021 ng g--11
VT / NH REMAP-Hg ProjectFindings: Tissue Hg
020406080
100
0 0.2 0.4 0.6 0.8 1
Yellow Perch Avg. HgT (ug g-1)correted to age 4.6 yr fish
Cum
ulat
ive
%
020406080
100
0 0.1 0.2 0.3 0.4
Prey Yellow Perch Avg. HgT (ug g-1)composites of <15cm whole fish
Cum
ulat
ive
%
020406080
100
0 0.5 1 1.5 2
Zooplankton HgT (ug g-1.)
Cum
ulat
ive
%
VT / NH REMAP-Hg ProjectFindings Hg in Yellow Perch
Fish in acidic lakes have elevated Hg in their tissue:
To
tal H
g in
fis
h (
ug
g-1
d.w
.)
0.0
0.2
0.4
0.6
0.8
ANC < 300 ueq l-1 ANC > 300 ueq l-1
VT / NH REMAP-Hg ProjectHg and Lake Trophic Status
• Bloom Dilution– Pickhardt et al. PNAS 2002.
• More algae means less Hg per unit algae• So lakes of elevated trophic status should
show less Hg in the plankton, and therefore less bioaccumulation.
VT / NH REMAP-Hg ProjectLake trophic status
Epi
limne
tic m
eHg
(ng
l-1)
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
D E M O
Trophic State
D E M O
Mea
n ag
e 4.
6yr
Yel
low
per
ch fi
llet (
ug g
-1 w
.w.)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
VT / NH REMAP-Hg ProjectHg and Land Use
• Do forested and wetland rich watersheds deliver more Hg? Literature says they should.
• What about developed watersheds?
VT / NH REMAP-Hg ProjectLand use correlations (Spearman)
-0.41
ns
ns
ns
% Dev.
-0.53ns-0.33nsSed. HgT
-0.239ns-0.2160.38Perch fillet HgT
-0.198nsns0.228meHg
-0.32nsnsnsHgT
E911% Wetland & water
% Ag.% Forested
VT / NH REMAP-Hg Project Water chemistry influences
PC1PC1àà: +Cond, +ANC, +pH, +SO4, +CL: +Cond, +ANC, +pH, +SO4, +CL--
PC1
-4 -2 0 2 4 6 8T
issu
e H
gT u
g g-1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8There is too much There is too much heterogeneity of lake heterogeneity of lake types and factors to yield types and factors to yield satisfactory ‘univariate’ satisfactory ‘univariate’ relationships. relationships.
Joint ‘multivariate’ Joint ‘multivariate’ distributions provide distributions provide insight into how the insight into how the interaction of factors interaction of factors controls Hg.controls Hg.
Modeling compliance with tissue criterionYellow perch fillets <0.3 ug g-1 HgT, Meets EPA Criterion: -1,580 – 82.92(lnANC) + 45.35(lnDOC) + 1,658(ln_pH) - 18.99(lnCond) – 35.09(invrtFlush) Eq. 1. Yellow perch fillets >0.3 ug g-1 HgT, Violates EPA Criterion: -1,494 – 81.94(lnANC) + 48.49(lnDOC) + 1,610(ln_pH) – 18.65(lnCond) – 33.02(invrtFlush) Eq. 2. Where: lnANC = ln (1+acid neutralizing capacity, in mg l-1, measured from the epilimnion) lnDOC = ln (1+dissolved organic carbon, in mg l-1, measured from the epilimnion) ln_pH = ln (1+pH, in standard units, average of total water column) lnCond = ln (1+conductivity, in us cm3, average of total water column) invrtFlush = (Flushing rate, in # yr-1)-2
Modeling compliance with tissue criterion
0
10
20
30
40
50
60
70
80
%
VT NH
MeetsFails
0
10
20
30
40
50
60
%MeetsFails
VT / NH REMAP-Hg ProjectCumulative Risk Index based on Hg in Loon Blood
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
ME
NH
VT
low
moderate
high
xhigh
History of Hg Accumulation:Atmospheric Hg Deposition
• Can wet Hg deposition be modeled given existing MDN/UMAQL network?
• What about dry Hg deposition?
VT / NH REMAP-Hg Project Atmospheric deposition
VT / NH REMAP-Hg Project
• Is the Hg flux rate to VT and NH lake sediments presently increasing or decreasing?
• Can we then infer changes in the atmospheric deposition rate?
VT / NH REMAP-Hg ProjectFindings HgT Fluxes (ug . m-2 . yr-1)
Note the synchrony of flux increase and decrease
Spring Lake Lake Carmi High Pond Branch Pond Willard Pond
Sessions Pond Wallingford Pond Gilman Pond Intervale Pond McConnell Pond
Beaver Lake
0 50 100 150 200
210 P
b Y
ear
1800
1850
1900
1950
2000Wheeler Pond Dudley Pond
0 20 40 60 80100120
Increasing Basin Area / Lake Area
VT / NH REMAP-Hg Project Synopsis:
• Hg concentrations in VT and NH lakes range widely. [ ]’s are greater in NH, and in lake hypolimnia.
• Yellow perch fillets vary w/ age and size, and age-correction most accurately captures variation in Hg accumulation rates across lakes.
• Hg, meHg, and tissue Hg all vary with trophic status. Eutrophic and dystrophic lakes have higher meHg, but only dystrophic lakes show higher tissue Hg.
• MethylHg varies significantly w/ numerous water chemistry parameters. The way these parameters inter-relate is important to understanding in which lakes meHg is more readily produced.
• For VT-NH lakes, the likelihood that yellow perch tissues will violate current criteria can reasonably be modeled using simple parameters.
VT / NH REMAP-Hg Project Synopsis:
VT / NH REMAP-Hg ProjectPubs:
• Paleolimnology– Atmos. Environ. 2003.
• Water and Tissue Chemistry and Statistics: – Env. Tox. Chem. 2004.
• Modeling, air deposition:– Ecotoxicology in prep.
• Modeling: Air+watersheds+in-lake interactions– Ongoing w/ EPA-ORD
How does this all get used??
• TMDL’s– Air dep maps and by-lake estimates provide one estimate of
critical loads – these dep maps are in preparation for all of NE presently
– Additional modeling can and will follow w/ these data• Env. Indicators:
– CDF’s provide reproducible, statistically valid estimates of region-wide contamination signals
– Paleo profiles provide reproducible, statistically quantified and landscape-integrated estimates of deposition, both presently and historically
• NERC Hg project for NE US and SE Canada.• EPA Regional Modeling Project
