Microbial Mercury Transformation in Anoxic Freshwater Sediments under Iron-Reducing and Other Electron-Accepting Conditions

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• 作者：Kimberly A. Warner ; Eric E. Roden ; and Jean-Claude Bonzongo
• 刊名：Environmental Science & Technology
• 出版年：2003
• 出版时间：May 15, 2003
• 年：2003
• 卷：37
• 期：10
• 页码：2159 - 2165
• 全文大小：128K
• 年卷期：v.37,no.10(May 15, 2003)
• ISSN：1520-5851

文摘

Potential rates of microbial methylation of inorganicmercury (added as HgCl₂) and degradation of methyl mercury(MeHg) (added as CH₃HgCl) were investigated in anoxicsediments from the Mobile Alabama River Basin (MARB)dominated by different terminal electron-accepting processes(TEAPs). Potential rates of methylation were comparableunder methanogenic and sulfate-reducing conditionsbut suppressed under iron-reducing conditions, in slurriesof freshwater wetland sediment. In contrast, MeHgdegradation rates were similar under all three TEAPs.Microbial Hg methylation and MeHg degradation were alsoinvestigated in surface sediment from three riverinesites, two of which had iron reduction and one sulfatereduction, as the dominant TEAP (as determined by ¹⁴C-acetate metabolism and other biogeochemical measurements). Methylation was active in sulfate-reducingsediments of a tributary creek and suppressed in iron-reducing, sandy sediments from the open river, whereasMeHg degradation was active at all three sites. Although iron-reducing conditions often suppressed methylation, somemethylation activity was observed in two out of three replicatesfrom iron-reducing sediments collected near a dam.Given that MeHg degradation was consistently observedunder all TEAPs, our results suggest that the net flux of MeHgfrom iron-reducing surface sediments may be suppressed(due to inhibition of gross MeHg production) comparedto sediments supporting other TEAPs.