Spatial and Seasonal Variations of Hexachlorocyclohexanes (HCHs) and Hexachlorobenzene (HCB) in the Arctic Atmosphere

• Published in: Environmental science & technology 2006-11, Vol.40 (21), p.6601-6607
• Main Authors: Su, Yushan, Hung, Hayley, Blanchard, Pierrette, Patton, Gregory W, Kallenborn, Roland, Konoplev, Alexei, Fellin, Phil, Li, Henrik, Geen, Charles, Stern, Gary, Rosenberg, Bruno, Barrie, Leonard A
• Format: Article
• Language: English
• Subjects: Air Pollutants; Arctic Regions; Atmosphere; Environment; Environmental Monitoring - methods; Evaporation; Hexachlorobenzene - analysis; Hexachlorocyclohexane - analysis; Hydrocarbons, Chlorinated - analysis; Hypotheses; PCB; Pesticides - analysis; Pollutants; Polychlorinated biphenyls; Precipitation; Quality Control; Seasons; Seawater; Surface Properties; Temperature
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es061065q

Weekly high-volume air samples were collected between 2000 and 2003 at six Arctic sites, i.e., Alert, Kinngait, and Little Fox Lake (LFL) in Canada, Point Barrow in Alaska, Valkarkai in Russia, and Zeppelin in Norway. Hexachlorocyclohexanes (HCHs) and hexachlorobenzene (HCB) were quantified in all samples. Comparison showed that α-HCH and HCB were homogeneously distributed in the circumpolar atmosphere and uniform throughout the seasons. However, significantly higher atmospheric concentrations of α-HCH and HCB and stronger temperature dependence of α-HCH and γ-HCH were found at LFL in Yukon (YK), which is unique among the sites by virtue of its high altitude and low latitude, resulting in higher precipitation rates and summer temperatures. Strong temperature dependence of α- and γ-HCH at this location suggests that secondary emissions, i.e., re-evaporation from surfaces, were more important at this site than others. It is hypothesized that a higher precipitation rate at LFL facilitated the transfer of α-HCH from the atmosphere to surface media when technical HCH was still in use worldwide. On the other hand, higher temperature at LFL enhanced re-evaporation to the atmosphere after the global ban of technical HCH. In contrast to α-HCH and HCB, larger spatial and seasonal differences were seen for γ-HCH (a currently used pesticide), which likely reflect the influence of different primary contaminant sources on different Arctic locations. Fugacity ratios suggest a net deposition potential of HCB from air to seawater, whereas seawater/air exchange direction of α-HCH varies in the circumpolar environment.