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CH3041
METHYL MERCURY II
• Microorganisms
use a derivative of vitamin B12 called methylcobalamin
to transfer a methyl
group to Hg2+ eg. HgCl2® MeHgCl
• Methylmercury
does not exist as a
discrete ionic species in solution. It is invariably found as MeHgX (X = Cl, OH in water or X = amino acid in tissue, Me-Hg2+Cl-).
discrete ionic species in solution. It is invariably found as MeHgX (X = Cl, OH in water or X = amino acid in tissue, Me-Hg2+Cl-).
• In the atmosphere
49% of Hg is present
as
the metal, 25% as HgX2, 21% as as MeHgX.
the metal, 25% as HgX2, 21% as as MeHgX.
• As all these species are volatile they are
deposited around the globe, 5d < t½ < 90d
deposited around the globe, 5d < t½ < 90d
• After deposition on the surface waters Hg is
then transformed into MeHgX.
