The Influence of Nitrogen & Reduced Sulfur on Microbial Mercury Methylation

The scope of the talk covers how organic matter and sulfide act as controls on the process of microbial mercury methylation and presents the results of time-series characterizations of porewater chemical profiles. The talk also provides a comparison of the effects of nitrogen amendments on potential methylation rate constants determined from sediment microcosms representing two sites at Younger Lagoon Reserve, sandy Beach Zone, and organic-rich East Fork. The observation that the sulfate-reduction specific inhibitor, molybdate, suppressed Hg methylation led to the conclusion that Hg methylation at Younger Lagoon is dominated by sulfate-reducing bacteria (SRB). A brief discussion comparing the results of 16S rRNA sequencing at Younger Lagoon to the results at other locations is presented.