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Hexachlorocyclohexanes (HCHs) In the Canadian Archipelago. 2. Air−Water Gas Exchange of α- and γ-HCH

2007; American Chemical Society; Volume: 42; Issue: 2 Linguagem: Inglês

10.1021/es071646v

1520-5851

Liisa M. Jantunen, Paul A. Helm, Henrik Kylin, Terry F. Bidleman,

Toxic Organic Pollutants Impact

Air and water were sampled in the Canadian Archipelago during summer on the Tundra Northwest 1999 (TNW-99) expedition and air was sampled at Resolute Bay (RB), Nunavut, to determine the gas exchange of α- and γ-hexachlorocyclohexanes (HCHs) and the enantiomers of α-HCH. Air concentrations of ΣHCH during TNW-99 and at RB were similar, averaging 55 and 53 pg m−3, respectively. The net gas exchange direction was volatilization for α-HCH and near equilibrium or deposition for γ-HCH, whereas actual fluxes depended on the fraction of open water. Enantiomer fractions, EF = (+)/[(+) + (−)] of α-HCH in air sampled from shipboard were significantly correlated to those in surface water for events with >90% open water, but were closer to racemic and not correlated to EFs in water for events with 0–50% open water. Levels of α-HCH in air at RB averaged 37 ± 9 pg m−3 from June to early July, and EFs were close to racemic (0.496 ± 0.004). In mid-July the ice pack broke up around RB. From this point through August, air concentrations increased significantly to 53 ± 5 pg m−3, and the mean EF decreased significantly to 0.483 ± 0.009. Air concentrations of γ-HCH at RB did not differ significantly before (8.0 ± 3.7 pg m−3) and after (6.6 ± 0.76 pg m−3) ice breakup. Results show that α-HCH enantiomers are sensitive tracers for following the impact of ice cover loss on gas exchange in the Arctic.