Methylmercury in Bay and Wetland Sediments of the San Francisco Bay Region Don Yee, SFEI RMP 2008 Hg...
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Transcript of Methylmercury in Bay and Wetland Sediments of the San Francisco Bay Region Don Yee, SFEI RMP 2008 Hg...
Methylmercury in Bay and Methylmercury in Bay and Wetland Sediments of the San Wetland Sediments of the San
Francisco Bay RegionFrancisco Bay Region
Don Yee, SFEIDon Yee, SFEIRMP 2008 Hg Coordination MeetingRMP 2008 Hg Coordination Meeting
San Francisco Estuary Institute
UC Santa Cruz
USGS WRD Menlo Park CA, Middleton WI, BRD Vallejo CA
San Francisco Hg SourcesSan Francisco Hg Sources
Anthropogenic sources dating to Gold Rush
USBM/USGS
Ongoing SF Bay Hg SourcesOngoing SF Bay Hg Sources
Source kg/yrBed Erosion 460Central Valley Watershed 440Urban Stormwater Runoff 160Guadalupe River Watershed (mining legacy) 92Atmospheric Deposition 27Non-Urban Stormwater Runoff 25Wastewater (municipal and industrial) 18Sediment Dredging and Disposal 0
SFBRWQCB TMDL
Bay Sampling LocationsBay Sampling Locations
Regional Monitoring Program – survey Bay1993-– summer (annual)– 49 sediment sites– random stratified
5 bay segments + rivers
Wetland Sampling LocationsWetland Sampling Locations
3 wetlands along Petaluma River– Gambinini Ranch– Mid-Petaluma Marsh– Black John Slough
Gradient of increasing salinity/Bay influence
San Pablo Bay
City of Petaluma
< Gambinini Marsh< Gambinini Marsh
< Mid Petaluma< Mid Petaluma
Black John Slough >Black John Slough >
Wetland Site DistributionWetland Site Distribution
Habitat elementsa) medium channelsb) small channelsc) high marsh edged) high marsh interior
Composites (transects or clusters)
Replicates of habitat elements
ab c
d
Hydro-Biological Hydro-Biological InteractionsInteractions
Overbank events recharge groundwater table
Marsh plain interiors drain slowly Redox swings with O2 supply and
respiration
-1200
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-800
-600
-400
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0
200
6/1
7/0
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1/0
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2/0
6
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3/0
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6/0
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6/2
7/0
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6/2
9/0
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6/3
0/0
6
7/1
/06
7/2
/06
DATEOR
P m
V o
r m
mH
20
vs
Su
rfa
ce
Redox GW_mmH20 chan_mmH20
Bay Hg and MeHg 2002-2006Bay Hg and MeHg 2002-2006
Intersegment DifferencesIntersegment DifferencesSan Pablo Bay (SPB) Hg high but MeHg low
SF Bay MeHg vs Total HgSF Bay MeHg vs Total Hg
Sediment concentrations poorly correlated
0.00
0.50
1.00
1.50
2.00
2.50
0.0 0.2 0.4 0.6 0.8 1.0
Hg mg/kg dw
MeH
g µ
g/kg
dw
2002
2003
2004
2005
2006
y = 1.41x + 0.235
R2 = 0.092
Wetland MeHg vs Total HgWetland MeHg vs Total Hg
Sediment MeHg vs Hg also poorly correlated
0
5
10
15
20
25
100 200 300 400 500STHg (ng/g dry)
SM
Hg
(ng/
g dr
y)
BJMPGM
BJy = -0.0201x + 7.8516R2 = 0.1482
MPy = -0.0144x + 8.4838R2 = 0.076
GMy = -0.0053x + 5.3061R2 = 0.0107
What Drives MeHg?What Drives MeHg?
Plenty of Hg, SO4, bacteria need food!
BJ y = 0.0012x - 0.0039
R2 = 0.278MP y = 0.0014x - 0.0105
R2 = 0.517
GM y = 0.0004x + 0.0061
R2 = 0.102
0%
1%
2%
3%
4%
5%
6%
7%
8%
5 10 15 20 25 30 35 40
% Loss on Ignition
% M
eHg/
TH
g
BJ
MP
GM
Linear (BJ)
Linear (MP)
Linear (GM)
Wetland Plant ProcessesWetland Plant Processes
(Windham will give details)
Compare untreated vs devegetated areas
Wetland Devegetation Wetland Devegetation EffectsEffects
organic = reduced reduction
-100
-75
-50
-25
0
25
50
75
MeH
gPro
du
ction
Rate
Con
sta
nt
(k)
Estim
ate
d
MeH
g
Pro
du
ction
Rate(k
*Hg
II)
Mic
rob
ial S
ulfate
Red
uction
Rate
(k)
Acid
Vola
tile
Su
lfu
r
Tota
l R
ed
uced S
ulfu
r
Ch
rom
ium
Red
ucib
le S
ulfu
r
Ferr
ou
s I
ron
Pore
wate
rDis
solv
ed
Org
an
ic C
arb
on
Pore
wate
rSu
lfid
e
Pore
wate
rSu
lfate
(mm
ol)
Pore
wate
rCh
lorid
e (m
mol)
Red
ox(E
h)
% D
iffe
rence b
etw
een p
air
s o
f veg
eta
ted a
nd
d
eveg
eta
tedplo
ts
Pairwise t-tests p<0.05-100
-75
-50
-25
0
25
50
75
MeH
gPro
du
ction
Rate
Con
sta
nt
(k)
Estim
ate
d
MeH
g
Pro
du
ction
Rate(k
*Hg
II)
Mic
rob
ial S
ulfate
Red
uction
Rate
(k)
Acid
Vola
tile
Su
lfu
r
Tota
l R
ed
uced S
ulfu
r
Ch
rom
ium
Red
ucib
le S
ulfu
r
Ferr
ou
s I
ron
Pore
wate
rDis
solv
ed
Org
an
ic C
arb
on
Pore
wate
rSu
lfid
e
Pore
wate
rSu
lfate
(mm
ol)
Pore
wate
rCh
lorid
e (m
mol)
Red
ox(E
h)
% D
iffe
rence b
etw
een p
air
s o
f veg
eta
ted a
nd
d
eveg
eta
tedplo
ts
Pairwise t-tests p<0.05
SF Bay MeHg vs TOCSF Bay MeHg vs TOC
Not all carbon is good bacterial food
0.00
0.50
1.00
1.50
2.00
2.50
0.0 0.5 1.0 1.5 2.0 2.5
% TOC
MeH
g µ
g/kg
dw
2002
2003
2004
2005
2006y = 0.44x + 0.072
R2 = 0.099
SF Bay MeHg vs Total NSF Bay MeHg vs Total N
N better proxy for labile organic matter?
0.00
0.50
1.00
1.50
2.00
2.50
0.00 0.05 0.10 0.15 0.20 0.25
% Total N
MeH
g µ
g/kg
dw
2002
2003
2004
2005
2006
y = 5.27x - 0.056
R2 = 0.23
SF Bay MeHg vs RedoxSF Bay MeHg vs Redox
OM substrate -> reduction -> methylation
0.00
1.00
2.00
0 100 200 300 400 500 600
Eh mV 1-6cm Average
MeH
g µ
g/kg
dw
2003
2004
2005
2006
y = -0.0017x + 0.89
R2 = 0.20
Linkage to BiotaLinkage to Biota
Biota Hg concentrations mirror ambient MeHg– matrix linked to nearest food web element
– e.g. Slotton water MeHg vs fish in Sacramento Delta
0.00
0.01
0.02
0.03
0.04
0.05
0.06
0.07
GM MP BJ
me
Hg
ug
/g w
w
Target marsh invertebrates
aa
b
HM Average
0
2
4
6
8
10
GM MP BJ
MeH
g 0-
2cm
Dep
th (
ng/g
dry
)
SummarySummary
New(ish): Total Hg not limiting MeHg in SF Bay (both wetlands & subtidal)– MeHg generally < 1% of total Hg– Legacy loads, ongoing inputs >> sufficient for all
MeHg production
Q1 (what “hot” spots) & Q2 (what processes): high Sediment MeHg linked to OM/ redox– Less reduction less methylation, more
demethylation
Management ImplicationsManagement Implications
Q3 (how might we manage) even small Hg inputs could support a major portion of standing MeHg pool– 1 week air input = water MeHg pool– 2 years input = sediment MeHg pool top 5cm
Might some Hg be more manageable?– e.g. METAALICUS new 202Hg 1% of total Hg
overall but 6% of vegetation Hg within 15 weeks
Management ImplicationsManagement Implications
More productivity = more OM more MeHg?– Will wetland restoration exacerbate Hg problem?– Competing goal of more wildlife habitat
Indirect management levers– MeHg control by-product of nutrient TMDL?
Need better understanding of– Relative availability of Hg loads– MeHg transport and uptake into food web
Closing CreditsClosing CreditsFunding: SF Estuary Regional Monitoring Program, CBDA Ecosystem
Restoration Program Sampling, Site Access: USBR Endeavor, CA DFG, R.Phelan & S.BrandProject Partners:
AMS: P.Salop, B.Bemis, C.Dominik, B.HajduczekSFEI: J.Collins, L.Grenier, J.Hunt, S.Pearce, C.Striplen, S.Shonkoff, S.Bezalel, N.David, A.Franz,M.WilliamsUCSC : A.R.Flegal, S. HibdonUSGS WRD-CA: M.Marvin-DiPasquale, J.Agee, L.Kieu, N.Ladizinski, L.WindhamUSGS WRD-WI: D.Krabbenhoft, T.Sabin, J.DeWildUSGS BRD- J.Takekawa, I.Woo, D.Tsao-Melcer,
Photo: D.Gaube, E.Lindgren, B.Hill