Methane and methylmercury production potentials in North Carolina Piedmont stream sediments

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Peter W. Blum IV (Creator)
The University of North Carolina at Greensboro (UNCG )
Web Site:
Anne Hershey

Abstract: Methylated mercury (MeHg) is produced by sulfate reducing bacteria (SRB), iron reducing bacteria (FeRB), methane producing Archaea (MPA), and other microbes under anaerobic conditions. These microbial groups compete for substrates including hydrogen and acetate. SRB are able to outcompete other anaerobic microbes when sulfate is in excess. However, low concentrations of sulfate in streams are thought to reduce the metabolic importance of SRB in streams. Although SRB are regarded as the primary producers of MeHg in many aquatic environments, it may not be universal. MPA have been implicated as the primary producers of MeHg in periphyton in a Canadian fluvial lake. Suppression of methanogenesis by SRB and the potential contributions from SRB, MPA and other MeHg producing microbes (including FeRB) to the production of MeHg in stream sediments was evaluated. Lower methanogenesis rates occurred if SRB were not inhibited, but methane production significantly increased if SRB were inhibited. These data suggest SRB reduce methane production, and are potentially the primary producers of MeHg. Other MeHg producing microbes (i.e., FeRB) contributed less than SRB to MeHg production. MPA produced MeHg in negligible amounts. This suggests that Hg methylation in sediments examined in this study was mediated primarily by SRB. This additionally suggests that microbes other than SRB may perform the majority of mercury methylation in the absence of SRB. Availability of sulfate and electron acceptors likely determines the relative importance of these microbial groups and thus pathways of Hg methylation in natural stream conditions.

Additional Information

Language: English
Date: 2016
Methanogenesis, Methanogens, Methylmercury, Microbial ecology, Sulfate-reducing bacteria
Methylmercury $x Environmental aspects $z North Carolina
Microbial ecology $z North Carolina
Sulfate-reducing bacteria

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