Atmospheric Hexachlorocyclohexanes in the North Pacific Ocean and the Adjacent Arctic Region:  Spatial Patterns, Chiral Signatures, and Sea−Air Exchanges

• Published in: Environmental science & technology 2007-08, Vol.41 (15), p.5204-5209
• Main Authors: Ding, Xiang, Wang, Xin-ming, Xie, Zhou-qing, Xiang, Cai-hong, Mai, Bi-xian, Sun, Li-guang, Zheng, Mei, Sheng, Guo-ying, Fu, Jia-mo
• Format: Article
• Language: English
• Subjects: Air Movements; Air pollution; Applied sciences; Arctic Regions; Atmosphere - chemistry; Atmospheric aerosols; Atmospheric pollution; Biodegradation; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; Expeditions; Hexachlorocyclohexane - analysis; Hexachlorocyclohexane - chemistry; Marine; Natural water pollution; Ocean-atmosphere interaction; Oceans; Pacific Ocean; Pollutants physicochemistry study: properties, effects, reactions, transport and distribution; Pollution; Pollution studies; Pollution, environment geology; Seawaters, estuaries; Stereoisomerism; Water Movements; Water treatment and pollution
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es070237w

During the 2003 Chinese Arctic Research Expedition (CHINARE2003) from the Bohai Sea to the high Arctic (37° N to 80° N) aboard the icebreaker Xuelong (Snow Dragon), air samples were collected for the analysis of hexachlorocyclohexanes (HCHs) in the North Pacific Ocean and adjacent Arctic region. The ΣHCHs (α-HCH + γ-HCH) ranged from 2.3 to 95.1 pg/m3 with the highest levels observed in Far East Asia (32.5 pg/m3), followed by the North Pacific Ocean (17.0 pg/m3) and the Arctic (7.3 pg/m3). Compared to previous studies in the same areas in 1990s, our measurements were approximately 1 order of magnitude lower. Because of disproportionate chemical reduction and physical fractioning during long-range transport, the ratios of α-HCH to γ-HCH (α/γ-HCH) showed a significant increasing trend from low to high latitudes, suggesting that the α/γ-HCH range of 4−7 could not be used to identify sources of technical HCHs especially in remote areas. The ratios of (+)-α-HCH to the sum of (+)-α-HCH and (−)-α-HCH were on average much more biased from 0.5 compared to previous observations in mid-1990s, indicating the exchange of atmospheric α-HCH with those in the oceans, where (+)-α-HCH was selectively depleted in biological degradation processes. Estimated fugacity ratios based on available data for both α-HCH and γ-HCH further implied their net volatilization from seawater to air in the Arctic Ocean.