POLYCHLORINATED BIPHENYL LEVELS IN EGGS OF LARUS-RIDIBUNDUS, RIPARIA-RIPARIA, LANIUS-COLLURIO AND CARDUELIS-CHLORIS FROM SELECTED SITES IN SLOVAKIA

The level of polychlorinated biphenyls (PCBs) in the eggs of Larus rid ibundus, Riparia riparia, Lanius collurio and Carduelis chloris from t he Podunajska nizina lowland and the Trnavska pahorkatina highland, co llected in the year 1988, was measured by means of gas chromatography. In this study we have confirmed the dependence of increased levels of PCB residue upon the species' position in the food chain. The herbivo rous species, Carduelis chloris, exhibited the lowest PCB level found whilst the insectivorous species, Riparia riparia, and the partly carn ivorous species, Lanius collurio, had PCB concentrations approximately 10 times higher. The highest PCB levels were detected in the eggs of Larus ridibundus. This was as a consequence of the character of its nu trition and longer lifespan. The eggs of Lanius collurio and Carduelis chloris, from the locality of Dobrohost, exhibited a higher contamina tion by PCB then those from Jur pri Bratislave. The concentrations of PCB in the early clutches of Riparia riparia, Lanius collurio and Card uelis chloris were found to be higher than in the later clutches.