Biological Methylation of Mercury in Aquatic Organisms

FRESHWATER fish, especially pike (Esox lucius), from Sweden sometimes contain abnormally large amounts of mercury1. It was initially concluded to be either inorganic mercury or phenyl mercury, which are known to be released as industrial wastes, but later it was shown that the mercury was present almost entirely as methyl mercury (CH3Hg+)2. A possible explanation is that living organisms have the capacity to methylate mercury compounds present in pollution. We now report that both mono and dimethylmercury (CH3Hg+ and CH3HgCH3) can be produced in bottom sediments and in rotten fish, and relate the findings to the hazards of mercury pollution.