Distribution of polychlorinated bighenyls (PCBs) and organochlorine Pesticides in soils from the East Antarctis coats

摘要

Concentrations of hexachlorobenzene(HCB),alpha-,beta-and gamma-hexachlorocyclohexane(HCH)isomers,6 o,p - and p,p-isomers of DDT and 28 PCB congeners have been measured in eleven soil samples and one lichen collected on the Eastern coast of Antarctica from 5 Russian stations.For samples with low concentrations of PCBs(range 0.20-0.41 ng g~-1 and 0.11-1.22 ng g~-1 dry weight for HCHs and DDTs,respectively),atmosphericlong-range transport from Africa,South America or Australia was suggested as the sole source of contamination.The profile of PCB congeners was dominated by the more volatile tri-,tetra- and penta-PCBs congeners,thus supporting long-range transport hypothesis.Four samples contained moderate levels of PCBs(range 1.98-6.94ng g~-1 dry weight) and variable concentrations of pesticides(gamma-HCH,P,P-DDT and o,p-DDT being the main contaminants).For samples with high concentrations of PCBs (range 90.26-157.45 ng g~-1) and high concentrations of pesticides,the presence of high molecular weight PCB congeners such as: 153,180,187,170 etc,strongly suggest a local source (biotic)of PCBs rather than atmospheric transport.It is likely than on a local scale,biotic focussing of pollutantd,due to bird activities(nesting and excrement) can cause high contamination levels and become more significant than contaminant input via abiotic pathways.