Partitioning of inorganic and organic mercury in cockles Cardium edule (L.) and C. glaucum (Bruguiére) from a chronically polluted area: influence of size and age.

Partitioning of inorganic and organic mercury was studied in the cockles Cardium edule and C. glaucum sampled in a chronically polluted area in the Western Limfjord, Denmark. The proportion of organic mercury in the cockles was linearly correlated to age (and weight) but not to total mercury concentration in the cockles. In 2-, 3- and 4-year-old cockles organic mercury constituted c. 30%, 60%, and 90% of total mercury, respectively. The age correlated proportion of organic mercury is discussed in a food chain context.