MERCURY CONTAMINATION IN
S-NEW ENGLAND AND LONG
ISLAND SOUND, USA
JOHAN C. VAREKAMP
EARTH & ENVIRONMENTAL SCIENCES
WESLEYAN UNIVERSITY
MIDDLETOWN CT USA
Mercury droplets on cinnabar (HgS)
MERCURY AND HUMAN HEALTH
Mercury has no known biological function
and binds tightly to sulfhydryl groups,
inhibiting molecular functions
-SH
•reduces membrane permeability
•reacts with and disrupts phosphate bonds in
ATP/ADP
•replaces cations in important molecules
ENVIRONMENTAL
CONCERN
HUMAN HEALTH CONCERN:
HG IS A NEUROTOXIN
Victim of the “Minamata Bay” (Japan) tragedy,
the first documented disaster of Hg pollution (1954)
Exposure to mercury?
 Eating fish or shellfish
 Breathing vapors (home, work)
 Dental work and medical treatments
 Religious rituals that include Hg
inhalation (Santaria in Haiti)
Fish Consumption
Primary form of human exposure to
methylmercury is through fish
consumption.
Population at greatest risk: small children
and pregnant women that consume fish
EPA - RfD is 0.1 ug MeHg/day
Maximum Hg-in-hair level is 1 ppm Hg
EPA limit
Wesleyan University study: 35%> EPA limit
(nationwide random sample shows 20% above EPA limit)
Hg Sources – USA
1998
Oil-Gas Fired power plants
Coal-fired power plants
Municipal waste incinerators
Medical waste incinerators
Commercial/Industrial boilers
Ore metal smelting
Other combustion sources
Total combustion related
Chlor-alkali production
Other sources
TOTAL
Annual Hg
emissions,
106 grams/yr.
0.2
46.9
26.9
14.6
25.8
0.16
10.8
125.4
6.5
12.1
144
Delivery pathways of Hg
to the coastal environment
• Atmospheric deposition in the
watersheds and fluvial transport to the
coast
• Point source contamination on land
with fluvial transport to the coast
• Direct discharge through outfall pipes
of waste water treatment plants
• Dredge and sludge dumping
QuickTime™ and a
None decompressor
are needed to see this picture.
Some important forms of
Mercury in the environment:
2+
Hg
CH3-Hg
oxidized
organic, charged,
lipophilic
Hg0
reduced,
elemental,volatile
CH3-Hg-CH3
organic, volatile,
lipophilic
aerobic
volatilization
Hg0
bioaccumulation
reduction
CH3-Hg+
Hg2+
demethylation
(CH3)2-Hg
methylation
(Sulfate reducing bacteria)
anaerobic
Hg Transport
• Dissolved metals (e.g., in complexes
with dissolved organic matter)
• Attached to fine particles:
• Inorganic
• Organic
Repositories of metals
• Coastal subtidal sediments (delivery
mainly by particulate deposition)
• Coastal salt marshes and estuarine
marshes (delivery mainly by particulate
deposition and to some degree through
in situ atmospheric deposition)
Sediment Cores
• Environmental archives that contain
contamination records of metals
• Record can be blurred by
–Chemical mobility in the
sediment column
–Discontinuous sediment
deposition (flood deposits)
–Bioturbation
Depth, cm
0
10
20
137Cs, dpm/gr
6
5
4
3
1963
2
1
0
30
40
50
Mercury Levels
• Normal modern soil background levels for
mercury in the northeast USA are around
200 to 300 parts per billion
– Mostly due to atmospheric deposition
• Sediment samples with higher Hg suggest
point sources of Hg in watershed
• Hg inventories: total amount of Hg
deposited on 1 cm2 over the full pollution
period
GRAIN SIZE EFFECT ON HG INVENTORIES
RG
RM
SR
DB PI
FI
Mercury profile core Chapman Pond, CT River, CT
Mercury profile from core BFB3A,
Farm River marsh, Branford, CT
500
GI-1
PTB100
Hg ppb
400
300
200
100
0
1550
1600
1650
1700
1750
1800
Age AD
1850
1900
1950
2000
1750
Knell's Island
Core KI 1
Flood
Deposits
1500
Hg, ppb
1250
Onset of severe
Hg contamination
1000
750
500
250
0
1700
"normal" peak level
of Hg contamination
in CT
onset of 'hatting'
industry in Danbury
Natural background Hg level
1750
1800
1850
1900
Age, years AD
1950
2000
Core
SSaalltt
m
maarrsshheess
BI2
BI3
BI5
PTB/J100
GI
E
GA
GK
BFB3a
BFA3
BFL8c
KI1
F
FW
W
M
Maarrsshheess
CP3
DM
M
Mttnn bbooggss
TM
LL
Average
Backgr. Onset Peak
Peak Modern
ppb Hg AD
ppb Hg AD ppb Hg
38
58
93
54
35
36
53
55
44
37
54
68
1850
1850
1850
1890
1860
1900
1870
1860
1800
1810
1790
1800
329
243
474
159
398
293
415
420
525
469
333
1544
1970
1939
1974
1956
1960
1959
1972
1967
1940
1944
1997
1964
218
145
206
107
146
97
326
296
236
249
333
177
103
-
1820
-
414
453
1964 358
118
42
44
54
1842
267
356
441
214
276
1962 219
Modern Hg*
dep. rate, ng
Hg/cm-2 yr-1
13.8
10.8
16.7
% drop
Guilford
GK
GA
Peak Hg* d ep. rate,
ng Hg cm-2 yr-1 (peak
year)
22.8
17.6 (1970)
28.0 (1970)
Barn Island
BI-2
BI-3
10
8.6 (1965)
12 (1940-1950)
6
6.4
5
40 %
25 %
58 %
35 (1950 -1960)
13 (1930 -1940)
Fitzgerald et al.
15
10
57 %
24 %
1-2
Av. :
Marsh
Core
Branford
BFA3
BFB3
Modern
atmospheric Hg
Deposition rate
40 %
40 %
40 %
40 %
15
Mercury Deposition Rates
Measured Modern Atmospheric vs.
Calculated from Inventories
0
5
10
ng/cm^2 yr
Barn Island Pataguanset
Guilford
Branford
Atmosphere
THE STILL RIVER, WESTERN
CONNECTICUT
~1955
Fowler Island core, Housatonic River
Hg ppb
Pope Island core, Housatonic River
5000
4500
4000
3500
3000
2500
2000
1500
1000
500
0
0
~1900
~ 1800
~1950
20 40 60 80 100 120 140
Depth cm
Floods of 1955
Wooster Square, Danbury
The floods of 1955 in Waterbury, CT after two
hurricanes hit in a few weeks time
Norwalk River Core
Hg Concentration vs. Depth of Norwalk Core
6000
Average Hg Concentration (ppb)
1955
5000
4000
3000
1900
2000
1820
1000
0
0
10
20
30
40
50
60
70
80
90
Housatonic River, Still River,
Norwalk River: strong
evidence for Hg from hatmaking sources
Source signals
modified by floods
The return of
the mad hatter
Lee Hat Factory
Mallory Hat Factory
EVERYONE wore hats. Men, women,
Danbury, CT
"The Hatmaking Capital of the World"
 Hatmaking started in Danbury ~ 1780
 The "carrotage" solution (Hg in nitric
acid) is used to make felt from fur
 The felt-making is done in a steam
saturated environment, and the steamcondensate with Hg-nitrate drips from
the walls and runs off into the
environment
 Danbury Hat production:
1808 - 100,000 hats / year
1850 - >1 million hats / year were made;
65 hat factories active in Danbury
1920 - >5 million hats / year
1943 - 'carrotage' process outlawed
The Carroting Solution
…had nothing to do with
vegetables.
This bright yellow-orange
solution of mercury and
nitric acid was used to treat
animal fur from pelts. It
made the fur fibers mat into
felt more easily.
Men working in Mallory’s carroting room
Benedict’s factory initially produced 3 hats per day
Background Hg contamination in
central and eastern Connecticut,
much higher levels of Hg contamination
in western Connecticut (Still River and
Housatonic River wetlands)
How about sediments from
Long Island Sound?
R/V UCONN
Sampling mud
HG IN LIS SEDIMENT: GREATEST ENRICHMENTS
ON THE WEST SIDE NEAR NEW YORK
700
96017
96024
WLIS
600
Connecticut River
Housatonic River
Hg ppb
500
400
300
200
100
0
-73.80
-73.55
-73.30
-73.05
-72.80
Longitude
-72.55
-72.30
200
Hg
10000
C. perfringens
150
1000
100
100
50
10
0
0
10
20
30
Depth (cm)
40
50
C. perfringens
Hg (ppb)
core G1C1
1
60
(c)
Hg Concentration vs. Depth of WLIS 75GGC1 Core
Average Hg Concentration (ppb)
3500
1975
3000
2500
2000
1500
1000
1820
500
0
0
20
40
60
80
100
Average Depth (cm)
120
140
160
180
Core near Execution Rock near NYC - 1975 peak
is Hg-rich debris of unknown origin
Hg Concentration vs. Depth of B1GGC1 Core
1400
1955
Hg Concentration (ppb)
1200
1000
800
1900
600
400
1820
200
0
0
10
20
30
40
50
60
70
80
90
100 110 120 130 140 150 160 170 180 190
Core in the delta of the Housatonic River
Average Depth (cm)
500
A4C1
~1900 floods?
Cu
Housatonic River
sediment pulse?
Pb
400
Zn
Metals, ppm/ppb
Hg
% Clay
300
200
100
0
1800
1850
1900
Age years AD
1950
2000
NYB
600
Hg (ppb)
R^2=0.78
Westernmost Sound
Central-Western Sound
Eastern Sound
R^2=0.98
400
200
0
0
1000
2000
3000
4000
5000
6000
C. perfringens (spores/g dry sediment)
7000
First estimate of Hg sources for LIS
~30-35 % from Waste Water Treatment Plants
~20-25% from Housatonic River/Danbury (WLIS)
Rest from Connecticut River
HG POINT
SOURCES
AD
Housatonic
River
watershed
AD
Connecticut
River watershed
WWTP
FINE SEDIMENT TRANSPORT
LONG ISLAND SOUND
EAST
WEST
IN SITU AD
Natural Background Concentrations
Peak Contamination, Atmospheric Deposition
Modern Surface Sediments
Danbury: Old hatmaking sites/Still River
Ponds and wetlands in town
Still River Surface samples
Core samples near golf course
Housatonic River
Pope Island
Fowlers Island
Long Island HR
Carting Island
Pink House Cove
Knells Island / Wheeler marsh
Long Island Sound
Cores
Surface sediment
Hg ppb
50 – 100
400 – 700
200 – 300
1000 – 60,000
100 – 1000
1500 – 5500; 70,000
500 – 100,000
1000 – 5000
500 – 2500
100 – 2500
100 – 2200
100 – 1100
100 – 2000
50 – 1200
50 – 700
We have documented extensive
Hg contamination in soils and
sediments from a known point
source: hat-making!
How do we get
rid of the Hg??
Phytoremediation
REMOVAL OF POLLUTANTS THROUGH PLANT
UPTAKE:
STORAGE IN PLANT FOLLOWED BY PLANT
REMOVAL
OR FOR HG
UPTAKE IN PLANT, REDUCTION TO Hgo AND
THEN EMISSION OF VAPOR FROM LEAVES
Growth Experiment
Brassica rapa P. (Mustard Spinach)
1. Good correlation between Hg
in leaves and Hg in spiked soils
2. No correlation between Hg
leaves and Hg from ‘field
contaminated soils’
3. Decrease in Hg in leaves over
time
Hg in Maple Trees
Soils with 0.1 -- 75 ppm Hg
Hg in leaves increased over time
Positive correlation Hg(leaves)
with Hg(soil)
Mean Hg loss from soils
Hg in ‘normal leaves’ minus Hg in
‘MER A leaves’
About 300 microgram Hg / m2 per
growing season
Ten cm thick soil with 50 ppm
Hg-about 103-104 yrs to clean up
Conclusions
 Wetland sediments in CT have
peak Hg contamination levels of
400-500 ppb Hg, with values 5090,000 ppb Hg in the Housatonic
& Still River Basins
 Most LIS sediments have 100-650
ppb Hg vs natural concentrations
of ~ 50-100 ppb Hg
 Hg contamination started
~AD 1820-1850, coinciding
with the Industrial Revolution
(and hatting industry) and raised
C.perfringens concentrations
anthropogenic signals!
 Hg contamination has
decreased by about 50 %
since the 1960-1970's
 The Danbury hat-making
industry has been an
important source of Hg for
western CT and western
LIS, starting ~ 1800 AD
 The EW increase in Hg
concentrations in LIS
surface sediments:
1. More “fines” to the West
2. Sediment inputs from the
Housatonic River, with
ppm levels Hg
3. Hg inputs from WWTP
PLANT EXPERIMENTS
HG UPTAKE DEPEND ON PLANT SPECIES AND HG
SPECIATION IN SOIL
HG IN LEAVES FROM MAPLE TREES INCREASES
WITH TIME AND REFLECTS SOIL HG
PHYTOREMEDIATION WORKS IN PRINCIPLE (MER A
PLANTS DO NOT RETAIN MUCH HG IN LEAVES)
BUT MAGNITUDE IS SMALL
ROLE OF PLANTS IN SOIL HG EMISSION IS NOT
YET CLEAR
Thanks to CT Sea Grant College Program,
CTDEP, USGS and the Mellon Foundation
for funding.
Much of the field and analytical work was done by
Wesleyan University students Beth Goldoff,
Kate Lauriat, Bart Kreulen, Billo Jallow and
Patrick Welsh.
THANKS TO YOU FOR LISTENING