MERCURY CONTAMINATION IN S-NEW ENGLAND AND LONG ISLAND SOUND, USA

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MERCURY CONTAMINATION IN S-NEW ENGLAND AND LONG
ISLAND SOUND, USA

• JOHAN C. VAREKAMP
• EARTH ENVIRONMENTAL SCIENCES
• WESLEYAN UNIVERSITY
• MIDDLETOWN CT USA

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Mercury droplets on cinnabar (HgS)
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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

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ENVIRONMENTAL CONCERN
HUMAN HEALTH CONCERN HG IS A NEUROTOXIN
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Victim of the Minamata Bay (Japan) tragedy,
the first documented disaster of Hg pollution
(1954)
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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)

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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

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EPA limit
Wesleyan University study 35gt EPA limit
(nationwide random sample shows 20 above EPA
limit)
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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

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Some important forms of Mercury in the
environment
CH3-Hg organic, charged, lipophilic
Hg2 oxidized
Hg0 reduced, elemental,volatile
CH3-Hg-CH3 organic, volatile, lipophilic
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aerobic
volatilization
Hg0
bioaccumulation
reduction
CH3-Hg
Hg2
demethylation
(CH3)2-Hg
methylation
(Sulfate reducing bacteria)
anaerobic
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Hg Transport

• Dissolved metals (e.g., in complexes with
  dissolved organic matter)
• Attached to fine particles
• Inorganic
• Organic

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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)

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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

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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

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GRAIN SIZE EFFECT ON HG INVENTORIES
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SR
FI
PI
DB
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Mercury profile core Chapman Pond, CT River, CT
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Mercury profile from core BFB3A, Farm River
marsh, Branford, CT
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THE STILL RIVER, WESTERN CONNECTICUT
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1955
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Fowler Island core, Housatonic River
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Pope Island core, Housatonic River
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Floods of 1955
Wooster Square, Danbury
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The floods of 1955 in Waterbury, CT after
two hurricanes hit in a few weeks time
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Norwalk River Core
1955
1900
1820
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Housatonic River, Still River, Norwalk River
strong evidence for Hg from hat-making
sourcesSource signals modified by floods
The return of the mad hatter
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EVERYONE wore hats. Men, women,
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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.
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Men working in Mallorys carroting room
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Benedicts factory initially produced 3 hats
per day
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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?
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R/V UCONN
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Sampling mud
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HG IN LIS SEDIMENT GREATEST ENRICHMENTS ON THE
WEST SIDE NEAR NEW YORK
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1975
1820
Core near Execution Rock near NYC - 1975 peak is
Hg-rich debris of unknown origin
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1955
1900
1820
Core in the delta of the Housatonic River
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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
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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??

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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
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Growth Experiment
Brassica rapa P. (Mustard Spinach)
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1. Good correlation between Hg in leaves and Hg
in spiked soils2. No correlation between Hg
leaves and Hg from field contaminated soils3.
Decrease in Hg in leaves over time
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Hg in Maple TreesSoils with 0.1 -- 75 ppm
HgHg in leaves increased over timePositive
correlation Hg(leaves) with Hg(soil)
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Mean Hg loss from soilsHg in normal leaves
minus Hg in MER A leavesAbout 300 microgram
Hg / m2 per growing seasonTen cm thick soil
with 50 ppm Hg-about 103-104 yrs to clean up
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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
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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
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