SS3.17 Global Mercury Cycling: From Natural to Anthropogenic Sources
Date: Tuesday, June 11, 2002
Time: 2:30:00 PM
Location: Carson C
 
CELOV, University of Ottawa, Dept. of Chemistry, Ottawa, Canada, vcelo@science.uottawa.ca
Lean, D, R, University of Ottawa, Dept. of Biology, Ottawa, Canada, dlean@science.uottawa.ca
Scott, S, L, University of Ottawa, Dept. of Chemistry, Ottawa, Canada, sscott@uottawa.ca
 
NATURE OF THE REACTION BETWEEN MERCURY AND METHYL IODIDE TO FORM METHYL MERCURY
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Naturally occurring methyl iodide is abundant in the marine environment, as an extra cellular metabolite produced by seaweed. Several studies have shown that methyl iodide is capable of causing methylation of mercury, although the reaction mechanism remains obscure, particularly with respect to the form of mercury that is susceptible to methylation We have studied the mechanism of the reaction between the aqueous mercuric ion and methyl iodide. It proceeds via electrophilic abstraction of iodide, yielding mercury- iodide complexes and methanol as primary reaction products. The half-life of mercuric ion at room temperature is 3.25 min. Methyl mercury iodide is a minor product of the reaction, never exceeding 0.1% yield based on mercury. Although the yield of methyl mercury iodide is low, the reaction of elemental mercury with methyl iodide could be an important component of the mercury cycle.