科研之友
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摘要
Water column concentrations of alpha-HCH were measured in the southern Beaufort Sea as part of the Canadian Arctic Shelf Exchange Study (CASES; 2003-04), the Circumpolar Flaw Lead System Study (CFL; 2007-08), and in the Mackenzie River during the 2008 NAHIDIK program. Atmospheric alpha-HCH concentrations were measured during CASES program. Inventories of alpha-HCH in the Polar Mixed Layer (PML) and the Pacific Mode Layer (PL) of the Beaufort Sea were calculated between 1986 and 2007 based on the available data. Between 1986 and 1993, there was a significant loading of alpha-HCH to the Beaufort Sea via the ocean currents. About 12% of the loading to the PML could be explained by the combined effect of the air-water gas exchange and the river runoff. After 1993, alpha-HCH inventories started decreasing, and could be well predicted exclusively by degradation. Ice formation was shown to be a solvent depleting process leading to a significant increase in the alpha-HCH concentration in the water just beneath the ice. Associated low alpha-HCH concentrations in the ice and relatively low ice export from the Beaufort Sea resulted in negligible influence of this output route on the inventories in the PML. The majority of alpha-HCH in the Beaufort Sea could be eliminated due to degradation by 2020, with concentrations in 2040 dropping to %26lt;0.006 and %26lt;0.004 ng L-1 in the PML and PL, respectively. Elimination of alpha-HCH from sea water takes significantly longer than from the atmosphere, with a lag of about two decades.
- 出版日期2013-11
