Bacterial demethylation of methylmercury in the South Florida EcosystemEntry ID: USGS_SOFIA_mmarvin
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 per day, and decreased with sediment depth. Higher k values were observed when shorter incubation times and lower MeHg amendment levels ... were used, and k increased two-fold as in-situ MeHg concentrations were approached. The average floc layer k was 0.046 +/- 0.023/ d (n=17) for 1-2 day incubations. In-situ degradation rates were estimated to be 0.02 to 0.5 ng MeHg/g dry sed/d, 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 PO4-3 addition. 14CO2 production in all samples indicated that oxidative demethylation (OD) was an important degradation mechanism. OD occurred over five orders of magnitude of applied MeHg concentration, with lowest limits (1-18 ng MeHg/g dry sediment) 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.
The objective of this research is to provide ecosystem managers with MeHg degradation rate data from a number of study sites that represent a diversity of hydrologic and nutrient regimes common to the Everglades, and to forge a better understanding of the microbial and geochemical controls regulating MeHg degradation in this system.
Data Set Citation
Dataset Originator/Creator: Mark Marvin-DiPasquale Ronald Oremland
Dataset Title: Bacterial demethylation of methylmercury in the South Florida Ecosystem
Dataset Release Date: 2005
Data Presentation Form: spreadsheetOnline Resource: http://sofia.usgs.gov/projects/bact_demeth/
Access Constraints None
Use Constraints None
Data Set Progress
Distribution Size: 0.041
Distribution Format: MS Excel
Role: TECHNICAL CONTACT
Email: mmarvin at usgs.gov
U.S. Geological Survey Bldg 15, McKelvey Building 345 Middlefield Road, MS 480
City: Menlo Park
Province or State: CA
Postal Code: 94025
Role: DIF AUTHOR
Email: alicia.m.aleman at nasa.gov
Goddard Space Flight Center Code 610.2
Province or State: MD
Postal Code: 20771
Marvin-DiPasquale, Mark C., Oremland, Ronald S., 1998, Bacterial methylmercury degradation in Florida Everglades peat, sediment, Environmental Science and Technology, v. 32, n. 17, Washington, DC, American Chemical Society, All users may view the abstract of this article. If you are a
subscriber, you may view the article. If you are not a subscriber, you may purchase and download the PDF version ... of the article.
Marvin-DiPasquale, Mark C., Agee, Jennifer; McGowan, Chad; Oremland, Ronald S.; Thomas, Martha;
Krabbenhoft, David; Gilmour, Cynthia C. 2000, Methyl-mercury degradation pathways: a comparison among three mercury-impacted ecosystems, Environmental Science and Technology, v. 34 , n. 23,
Washington, DC, American Chemical Society, All users may view the abstract of this article. If you are a
subscriber, you may view the article. If you are not a subscriber, you may purchase and download the PDF version of the article.
Creation and Review Dates
DIF Creation Date: 2007-02-20
Last DIF Revision Date: 2009-02-24