Title: Ecosystem level controls on mercury methylation: the Carbon-Sulfur-Mercury Triad

Speaker: Dr. Andrew Heyes (Associate Research Professor, UMCES-CBL)

Abstract: For more than a century burning of fossil fuel and industrial activity has contaminated global ecosystems with mercury. While efforts to reduce mercury loading through emission reductions are ongoing fisheries around the world remain contaminated with methylmercury. The transformation of mercury into this organic form is done within ecosystems, therefore it is essential to understand how mercury is cycled and transformed within the environment if we are to develop effective mitigation strategies. The methylation of mercury is biotic and mainly performed by anaerobic bacteria. Therefore factors that control the activity of mercury methylating bacteria and the bioavailability of mercury to bacteria determines the extent of methylmercury production in a given ecosystem. The degree to which the food web is connected to zones of methylation is the last step in the transfer.  The mercury methylation process is mainly centered about the interaction and cycling of three elements: mercury, carbon and sulfur.  Carbon and sulfur control the bioavailability of mercury and the activity of mercury methylating bacteria. Through studies that span the beaker to the ecosystem, I will describe how the understanding of these extremely complex interactions among this triad has progressed and the path forward.