Complexation of trace metals by natural ligands and nano-particles exerts well-known, profound influences on their biogeochemistry and ecotoxicology. Yet, the identification of the metal-binding moieties and quantification of complex stability constants is analytically challenging due to their low concentrations and heterogeneous nature. Electrochemists have developed sophisticated methods of measuring complexation by environmental ligands for several important trace metals, but not for one of the most important methylmercury. The difficulty of separating methylmercury from ambient organic matter, which is known to contain both thiol moieties and sulfide-containing nanoparticles that likely bind MeHg, is a major reason why. Here, results obtained using a novel approach to methylmercury analysis in natural water samples that suggest the presence of kinetically-inert complexes or nanoparticulate MeHg in aquatic ecosystems are presented. Experiments investigating the nature of these complexes and theoretical explorations of their implications for MeHg biogeochemistry, including its bioavailability and fate, are reported.

Strong complexation of metals in natural waters: The case of methylmercury

246th National Meeting (2013)

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