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Extramural Research

Grantee Research Project Results

Grantee Research Project Results

The Effect of Sulfate and Sulfide on Mercury Methylation in Florida Everglades

EPA Grant Number: U915152
Title: The Effect of Sulfate and Sulfide on Mercury Methylation in Florida Everglades
Investigators: Benoit, Janina M.
Institution: University of Maryland
EPA Project Officer: Broadway, Virginia
Project Period: January 1, 1997 through January 1, 2000
Project Amount: $102,000
RFA: STAR Graduate Fellowships (1997)
Research Category: Fellowship - Oceanography , Academic Fellowships , Aquatic Ecosystems

Description:

Objective:

The overall objective of this research project is to investigate how pore water sulfate and sulfide control methylmercury (MeHg) production and accumulation in sediments. The specific objective of this research project is to determine how the addition of sulfate and sulfide affect Hg methylation rates in Florida Everglades sediments.

Approach:

Experimental additions of sulfate and sulfide to ambient sediments, along with measurements of pore water chemistry, were used to study the effect of these two constituents on Hg methylation in the Florida Everglades. Cores were collected from three sites along a nutrient and sulfate gradient caused by runoff from the agricultural region at the northern edge of this wetland. The sites exhibited a range in ambient pore water sulfate from <1 µM (TS7), to 2 µM (LOX), to 17 µM (3A15). Results indicate that addition of sulfate stimulated Hg methylation at the two low ambient sulfate sites (TS7 and LOX). At TS7, sulfate addition did not result in an increase in pore water sulfide, and at LOX a fivefold increase was observed, but sulfide levels did not become high enough to inhibit methylation. At 3A15, modest increases in sulfide lowered rates of Hg methylation; added sulfate reduced MeHg production rates. Results indicate that processes that lead to the sequestration or reoxidation of sulfide may have an important effects on MeHg formation in aquatic sediments.

Supplemental Keywords:

fellowship, sulfate, sulfide, mercury methylation, Florida Everglades, methylmercury production, sediments., Scientific Discipline, Geographic Area, Waste, Water, Ecosystem Protection/Environmental Exposure & Risk, POLLUTANTS/TOXICS, Hydrology, Contaminated Sediments, Environmental Chemistry, State, Fate & Transport, Ecology and Ecosystems, Soil Contaminants, Mercury, fate and transport, Florida Everglades, contaminated marine sediment, sulfate reducing bacteria, bioavailability, contaminated sediment, agriculture runoff, soils, sulfur, biogeochemical cycling, marine sediments, methylmercury, watershed influences, terrestrial and aquatic fate, sulfide, aquatic sediment, mercury methylation, microbiological aspects

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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