Specific accumulation of mercury and selenium in seabirds.

Total mercury (T-Hg), methyl mercury (MeHg) and selenium (Se) concentrations were determined to elucidate the relationship between Hg and Se levels in the liver of 10 seabird species. Highest concentrations of T-Hg (mean 267 microg/g dry wt), MeHg (mean 25.5 microg/g dry wt) and Se (mean 113 microg/g dry wt) were in the liver of black-footed albatross (Diomedea nigripes). An equivalent molar ratio of 1:1 between T-Hg and Se was found in the liver of individuals which contain over 100 microg Hg/g. However, such a relationship was unclear in other individuals which had relatively low Hg levels. This suggests that Se plays a role in Hg detoxification for those individuals with high Hg. In seabird tissues, Hg and Se levels should be a most important factor determining the relationship between Hg and Se, and fluctuation of Hg burden through molting and the species-specific demethylation capacity would also influence their relationships.