Bell, J. T. Academy of Natural Sciences, Estuarine Research Center, bell@say.acnatsci.org
Gilmour, C. T. Academy of Natural Sciences, Estuarine Research Center, Gilmour@acnatsci.org
Heyes, A. Academy of Natural Sciences, Estuarine Research Center, Heyes@acnatsci.org
Benoit, J. M. Academy of Natural Sciences, Estuarine Research Center, benoit@acnatsci.org
Riedel, G. S. Academy of Natural Sciences, Estuarine Research Center, griedel@acnatsci.org

 
THE INFLUENCE OF SULFUR INPUTS ON METHYLMERCURY PRODUCTION IN THE FLORIDA EVERGLADES
 
Our research has examined the importance of Hg methylation to elevated MeHg levels in the Everglades, and to understand the factors that control the methylation process in this wetland. Here we present experimental and distributional data on the impact of S loading on microbial S cycling and MeHg production. The nutrient load, including sulfate, that the Everglades receive from agricultural areas to the north has created a large concentration gradient across the ecosystem, and greatly impacted the distribution of MeHg. Methylmercury concentrations generally increase southward away from eutrophic northern areas, peaking in the south central Everglades. The methylation of Hg occurs in surficial sediment and decaying periphyton. Inhibitor studies indicate that sulfate reducing bacteria are the primary methylators of Hg. Methylation rates in sediments from low sulfate, oligotrophic areas decreased with addition of sulfide and were stimulated by the addition of sulfate or Hg. However, methylation in sulfidic sediments from impacted areas was low and insensitive to changes in sulfate, sulfide or Hg concentration. Sulfide, produced during the eutrophication of the northern water conservation areas, strongly inhibits Hg methylation. We speculate both sulfur and Hg loading to the Everglades has elevated MeHg concentrations in the central Everglades above historical concentrations.
 
Day: Wednesday, Feb. 3
Time: Poster
Location: Sweeney Center
 
Code: SS28WE0559S