PNNL

Abstract

Weekly high volume air samples were concurrently collected between 2000 and 2003 at six arctic sites, namely Alert, Little Fox Lake, Kinngait in Canada; Point Barrow in Alaska, USA; Zeppelin in Norway; and Valkarkai in Russia. Hexachlorocyclohexanes (HCHs) and hexachlorobenzene (HCB) were quantified in all samples. Data comparison showed that a-HCH and HCB were relatively homogeneously distributed in the circumpolar atmosphere and fairly uniform throughout the seasons. However, significantly high atmospheric a-HCH and HCB concentrations and strong seasonality of a-HCH and ?-HCH were found at the low arctic site of Little Fox Lake. Stronger temperature dependence of a-HCH and ?-HCH at this location suggests that secondary emissions (or re-evaporation from surface environmental media) were more important at this site than others. Tendency of the secondary emissions also appeared increased compared to a decade ago in this region. It is thus hypothesized that higher precipitation rate at this topographically elevated station facilitated the transfer of a-HCH from the atmosphere to surface media when technical HCH was still being used worldwide. On the other hand, relatively higher temperature at this southerly station enhanced re-evaporation to the atmosphere after the global ban of technical HCH. In contrast, larger spatial and seasonal discrepancies were apparent for “current-use” ?-HCH than ?-HCH and HCB in the arctic atmosphere. It likely reflected different influences of primary contaminant sources on various arctic locations. Calculations of fugacity ratio suggest slight net deposition potential of HCB from air to seawater in the circumpolar environment, whereas air/seawater exchange direction of ?-HCH varied from location to location in this region.