Bacterial methylmercury degradation in Florida Everglades peat sediment
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Abstract
Methylmercury (MeHg) degradation was investigated along an eutrophication gradient in the Florida Everglades by quantifying 14CH4 and 14CO2 production after incubation of anaerobic sediments with [14C]MeHg. Degradation rate constants (k) were consistently ≤0.1 d-1 and decreased with sediment depth. Higher k values were observed when shorter incubation times and lower MeHg amendment levels were used, and k increased 2-fold as in-situ MeHg concentrations were approached. The average floc layer k was 0.046 ± 0.023 d-1 (n = 17) for 1−2 day incubations. In-situ degradation rates were estimated to be 0.02−0.5 ng of MeHg (g of dry sediment)-1 d-1, increasing from eutrophied to pristine areas. Nitrate-respiring bacteria did not demethylate MeHg, and NO3- addition partially inhibited degradation in some cases. MeHg degradation rates were not affected by PO43- addition. 14CO2 production in all samples indicated that oxidative demethylation (OD) was an important degradation mechanism. OD occurred over 5 orders of magnitude of applied MeHg concentration, with lowest limits [1−18 ng of MeHg (g of dry sediment)-1] in the range of in-situ MeHg levels. Sulfate reducers and methanogens were the primary agents of anaerobic OD, although it is suggested that methanogens dominate degradation at in-situ MeHg concentrations. Specific pathways of OD by these two microbial groups are proposed.
Publication type | Article |
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Publication Subtype | Journal Article |
Title | Bacterial methylmercury degradation in Florida Everglades peat sediment |
Series title | Environmental Science & Technology |
DOI | 10.1021/es971099l |
Volume | 32 |
Issue | 17 |
Year Published | 1998 |
Language | English |
Publisher | ACS |
Contributing office(s) | Toxic Substances Hydrology Program |
Description | 8 p. |
First page | 2556 |
Last page | 2563 |
Country | United State |
State | Florida |
Other Geospatial | Everglades |
Google Analytic Metrics | Metrics page |