Air-Water Gas Exchange of Hexachlorocycloheane Enamtiomers in the South Atlantic Ocean and Antarctica

The spatial distribution of α-HCH and the net direction of air/water gas exchange were determined between November 1997 and February 1998. Air and water samples were collected between South Atlantic Ocean (South Africa) and Antarctica SANAE Base (70°S, 3°E). The α-HCH concentrations in air and surface water were much lower than in Arctic regions, consistent with the historically lower usage of technical HCH in the Southern Hemisphere. The water/air fugacity ratios of α-HCH were lower than or equal to 1.0, indicating steady state or net deposition conditions. One analysis of the enantiomeric fractionation was also made The results showed that the α-HCH in water was enantioselectively metabolized and that the two isomers [(-)α-HCH and (+)α-HCH] in the air boundary layer reflected those in surface water, showing the bidirectional nature of gas exchange.