Long term monitoring of pollutants in eggs of Yellow-legged Herring Gull from Capraia island (Tuscan Archipelago).

Chlorinated hydrocarbons (hexachlorobenzene, lindane, pp'DDE, polychlorinated biphenyls) and trace elements (Hg, Se, Cd, Pb) were determined in eggs of Yellow-legged Herring Gull (Larus cachinnans) collected in an island of the Tyrrhenian Sea during the period 1981-1986. PCBs levels vary on the average between 30.4μg g(-1) d.w. in 1981 to 56.1 μg g(-1) d.w. in 1983. The capillary chromatograms revealed the presence of about 30 somers of PCBs without significant variations in the eggs of the same year; more than 50% of the residues is made up only three isomers: the 22'44'55', the 22'344'5' and the 22'344'55'. Average DDE residues were 7-8 times lower than those of PCBs and declined during the period (from 9.2 μg g(-1) d.w. in 1981 to 4.5 μg g(-1) d.w. in 1986). Cadmium and lead are present in low concentrations. The average levels of mercury and selenium are around 2-2.5 μg g(-1) d.w., and a cumulative correlation, on a molar basis, exists between these two elements.