Distribution of polychlorinated biphenyls (PCBs) and organochlorine pesticides in soils from the East Antarctic coast

Abstract

Concentrations of hexachlorobenzene (HCB), α-, β- and γ-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 dry weight) and pesticides (0.86–4.69 ng g⁻¹ and 0.11–1.22 ng g⁻¹ dry weight for HCHs and DDTs, respectively), atmospheric long-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 1.98–6.94 ng g⁻¹ dry weight) and variable concentrations of pesticides (γ-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 that on a local scale, biotic focussing of pollutants, due to bird activities (nesting and excrement) can cause high contamination levels and become more significant than contaminant input via abiotic pathways.