PCB and PCT contamination in Winter Quarters Bay, Antarctica

Winter Quarters Bay at McMurdo Station in Antarctica provides docking facilities to visiting ships and is adjacent to a former dump site. Sediments are heavily contaminated with a tarry material and contain a moderately high level of chlorinated biphenyls, in the range of 100–1400 ng g −1 dry wt. Composition in most samples is identical to that of Aroclor 1260, with no evidence of partial degradation, indicating a dominant point source of contamination. Chlorinated terphenyls, also with a 60% chlorine composition, are present at levels in the order of 30–1200 ng g −1. Outside Winter Quarters Bay, PCB levels decrease sharply, by two orders of magnitude over 1 km, and four orders of magnitude at stations 9 and 15 km distant. A substantial modification of the congener composition is evident at the distant stations, but the McMurdo PCB ‘signature’ nevertheless dominates over the ‘global’ signature characteristic of PCBs in the global atmospheric circulation.