Source Identification of Florida Bay's Methylmercury Problem: Mainland Runoff Versus Atmospheric Deposition and In situ Production

摘要: The first advisory to limit consumption of Florida Bay fish due mercury was issued in 1995. Studies done by others the late 1990s found elevated water column concentrations both total Hg (THg) and methylmercury (MeHg) creeks discharging from Everglades, which had its own recognized problem. To investigate significance allochthonous MeHg upstream freshwater we collected surface sediment along two transects 2000 2002. Concentrations THg MeHg, ranging 0.36 ng THg/L 5.98 <0.02 MeHg/L 1.79 MeHg/L, were mangrove transition zone when compared canals open waters Bay. Sediment ranged 5.8 THg/g 145.6 0.05 MeHg/g 5.4 MeHg/g, with as a percentage occasionally bay. Methylation assays indicated that sediments have potential methylate Hg. Assessment mass loading suggests delivering stormwater northern Everglades are not large source direct atmospheric deposition situ methylation, especially within zone.