Beyond the natural mercury emission to the atmosphere,
the anthropogenic contribution mainly as Hg(II) has
increased; consequently, the mercury content in natural
waters increased as well. The main part of Hg(II) rapidly
attaches to particles in suspension found in water
bodies, and then is deposited in sediments where covalent
molecules are formed, such as HCl
latter forms dimethylmercury a molecular volatile liquid. The formation of Hg(CH)2in natural waters is
normally favored under anaerobic conditions, where
microorganisms convert Hg(II) to Hg(CH3)2
. This fact occurs mainly in the first layers of sediments in rivers and
lakes. Dimethylmercury is transformed under acidic or
neutral conditions into the monomethylmercury and other
forms, such as CH3HgCl and CH3HgOH. Therefore, the
production of methylmercury in natural waters predominates over the formation of dimethylmercury. Methylmercury diffuses easier than Hg(II) salts into animal fatty
tissues and this characteristic facilitates its bioaccumulation. Once in the body, methylmercury may bind to sulfur-containing amino acids forming soluble compounds
in animal tissues. Due to these reasons, methylmercury is
the most hazardous mercury form (Baird, 1995)
Beyond the natural mercury emission to the atmosphere,
the anthropogenic contribution mainly as Hg(II) has
increased; consequently, the mercury content in natural
waters increased as well. The main part of Hg(II) rapidly
attaches to particles in suspension found in water
bodies, and then is deposited in sediments where covalent
molecules are formed, such as HCl
latter forms dimethylmercury a molecular volatile liquid. The formation of Hg(CH)2in natural waters is
normally favored under anaerobic conditions, where
microorganisms convert Hg(II) to Hg(CH3)2
. This fact occurs mainly in the first layers of sediments in rivers and
lakes. Dimethylmercury is transformed under acidic or
neutral conditions into the monomethylmercury and other
forms, such as CH3HgCl and CH3HgOH. Therefore, the
production of methylmercury in natural waters predominates over the formation of dimethylmercury. Methylmercury diffuses easier than Hg(II) salts into animal fatty
tissues and this characteristic facilitates its bioaccumulation. Once in the body, methylmercury may bind to sulfur-containing amino acids forming soluble compounds
in animal tissues. Due to these reasons, methylmercury is
the most hazardous mercury form (Baird, 1995)
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