Abstract
Methylmercury is a potent human neurotoxin that is biomagnified in aquatic food webs. Several anaerobic microorganisms that carry the recently discovered hgcA gene can potentially mediate the biological formation of methylmercury in natural environments, but their diversity and activity levels in the boreal landscape remain largely unexplored. In my talk, I will summarize a suite of studies where we use mercury isotope tracer incubations and DNA-based approaches to map biological mercury methylation in different landscape elements. We further identify factors controlling the process and provide a comprehensive understanding of the microbial systems underpinning the process. This and other recent findings are changing the way we perceive and understand mercury methylation and call for further studies on the environmental factors regulating mercury methylation.