The degree of methylation and organ distribution of mercury in some birds of prey in Norway.

The concentrations of total mercury and methyl mercury were determined in organs from several species of birds of prey. The organ distributions were calculated for each species. For total and non-methyl mercury, significant differences were found between the species. For methyl mercury no such differences were found. The liver: kidney ratios in White-tailed Eagle were 1 : 2.4 and 1 : 0.9 for total and methyl mercury, respectively. The corresponding figures for the Eagle Owl were 1 : 0.7 and 1 : 0.8. The distribution pattern and the degree of methylation were mainly dependent on the mercury levels, and there seemed to be an inverse relationship between the total mercury levels and the percentages of methyl mercury in the organs, especially in the kidney. There were good correlations between the methyl mercury concentrations in the liver, kidney, and muscle. The demethylation of methyl mercury seems to be a significant detoxication route for methyl mercury in birds of prey.