Biocides in eggs of aquatic birds. Completion of a food chain enrichment study for DDT,PCB and HG

Eggs (N=224) of seven aquatic bird species of Lake Päijänne, Finland, were analyzed for their contents of HCB, DDE, PCB, mercury (TOTHG) and methyl mercury (METHG as per cent of TOTHG). METHG was 85.5 % which is the same as in fish. Also the levels of TOTHG were of the same order of magnitude in eggs and in fish of Päijänne, but the levels of chlorinated hydrocarbons were much higher in eggs. Differences between species were highly significant but the annual and regional differences were mostly insignificant. The chlorinated hydrocarbons correlated positively with each other and with fat contents but insignificantly with mercury contents. Calculation of total residue amounts in egg, juvenile and adult bird specimens exposed an enrichment of DDT to three, PCB to five and mercury to all seven species.