Atmospheric PCB concentrations at Terra Nova Bay, Antarctica

Concentrations of gas-phase polychlorobiphenyls (PCBs) were studied over an austral summer at a site in Terra Nova Bay, Antarctica. Gas-phase concentrations of individual PCB congeners in the atmosphere of Terra Nova Bay ranged from below the detection limit to 0.25 pg m-3, with a mean concentration of ∑PCB of 1.06 pg m-3. The PCB profile was dominated by lower-chlorinated PCB congeners; in fact 78% of the total PCB content was due to congeners with 1-4 chlorine atoms and only about 10% with 5-7 chlorines, whereas higher-chlorinated PCB congeners were below detection limits. The mean ∑PCB concentration obtained in this study were lower than those reported in previous Antarctic studies. Temporal concen- tration profiles of ∑PCB do not correspond to seasonal temperature changes. In consideration of the low PCB concentrations observed, the studies with the wind roses, the regression between ln P(PCB) and T-1, and the distribution of congeners, we can hypothesize that PCB local source contributions are not very important, whereas long-distance transport is the prevalent factor bringing PCBs to Terra Nova Bay.