Nucleophilic reactions of methyl halides

Zafiriou (1975) recently reported that methyl iodide is thermodynamically unstable in seawater and its chemical fate is kinetically controlled. The equations showing the fate of methyl iodide are as follows  

Chloride ion was theoretically predicted to be the most kinetically reactive species, with water second, and other anions of lesser importance. This suggested that methyl iodide in seawater would react predominantly via a nucleophilic substitution reaction with chloride ion (eq. 1) to yield methyl chloride. Methyl iodide and the methyl chloride produced by (1) would also 

Rates of Sn2 reactions of methyl halides in water (Zafiriou, 1975) 

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