Environmental Distribution of Mercury Related to Land Use and Physicochemical Setting in Watersheds of the Apalachicola-Chattahoochee-Flint River Basin
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Author(s)
Couch, Carol A.
Advisor(s)
Editor(s)
Hatcher, Kathryn J.
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Abstract
During 1992 and 1993, a survey was conducted to
determine the distribution of mercury (Hg) in bed sediments
and aquatic biota in surface-water bodies of the
Apalachicola-Chattahoochee-Flint River basin. The objective
of the survey was to relate broad-scale patterns in mercury
distribution to watershed land use and physicochemical
setting. Concentrations of Hg in fine sediments (less than 63
micrometers particle size) were determined at 41
surface-water sites, and in whole tissue of aquatic biota
(Asiatic clams or mosquitofish) at 34 of these sites. Typical
background Hg levels in fine sediments ranged from 0.04 to
0.08 micrograms per gam (gg/g). Among all sites sampled in
this study, mean Hg concentration in fine sediment was 0.13,
and concentrations ranged from 0.04 to 0.56 μg/g. Mercury
was detected in tissue at all but two sites. Mercury
concentration in tissue ranged from less than detection to 2.6
tg/g of dry weight. Mean Hg concentration in clam tissue was
0.44 'ug/g, dry weight, and mean concentration in
mosquitofish tissue was 0.15 μg/g, dry weight.
Although the highest concentrations of Hg in sediment
were measured in urban watersheds , in the Piedmont Province,
the highest concentrations of Hg in clam tissue were measured
at sites in Coastal Plain watersheds draining mostly forest or
agricultural land, and where sediment Hg concentrations were
relatively low. Coastal Plain sites are characterized by
physicochemical settings that enhance the formation of
methylmercury—the form of Hg that most rapidly
bioaccumulates. Comparison of Hg concentrations in
sediment and tissue suggests that Hg as methylmercury may
be more available to aquatic biota in the Coastal Plain than in
the Piedmont. Greater bioavailability of Hg in the Coastal
Plain is supported by consumption advisories for fish caught
in widely distributed water bodies in the Coastal Plain.
Sponsor
Sponsored and Organized by: U.S. Geological Survey, Georgia Department of Natural Resources, The University of Georgia, Georgia State University, Georgia Institute of Technology
Date
1997-03
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Text
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Proceedings