Dimethylmercury Formation Mediated by Inorganic and Organic Reduced Sulfur Surfaces

作者：Jonsson Sofi^*; Mazrui Nashaat M; Mason Robert P

来源：Scientific Reports, 2016, 6(1): 27958.

DOI：10.1038/srep27958

Underlying formation pathways of dimethylmercury ((CH3)(2)Hg) in the ocean are unknown. Early work proposed reactions of inorganic Hg (Hg-II) with methyl cobalamin or of dissolved monomethylmercury (CH3Hg) with hydrogen sulfide as possible bacterial mediated or abiotic pathways. A significant fraction (up to 90%) of CH3Hg in natural waters is however adsorbed to reduced sulfur groups on mineral or organic surfaces. We show that binding of CH3Hg to such reactive sites facilitates the formation of (CH3)(2)Hg by degradation of the adsorbed CH3Hg. We demonstrate that the reaction can be mediated by different sulfide minerals, as well as by dithiols suggesting that e.g. reduced sulfur groups on mineral particles or on protein surfaces could mediate the reaction. The observed fraction of CH3Hg methylated on sulfide mineral surfaces exceeded previously observed methylation rates of CH3Hg to (CH3)(2)Hg in seawaters and we suggest the pathway demonstrated here could account for much of the (CH3)(2)Hg found in the ocean.

• 出版日期2016-6-15