Mechanisms and Implications of α‑HCH Enrichment in Melt Pond Water on Arctic Sea Ice

• Published in: Environmental science & technology Vol. 46; no. 21; pp. 11862 - 11869
• Main Authors: Pućko, M, Stern, G. A, Barber, D. G, Macdonald, R. W, Warner, K.-A, Fuchs, C
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 06.11.2012
• Subjects: Applied sciences; Arctic Regions; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Environmental Monitoring; Exact sciences and technology; Ice Cover - chemistry; Lindane - analysis; Natural water pollution; Pollution; Pollution, environment geology; Rainwaters, run off water and others; Seawater - analysis; Water Pollutants, Chemical - analysis; Water treatment and pollution; Arctic Ocean; Arctic Region; Arctic Regions; Agricultural chemical product; Insecticide; Atmospheric fallout; Pollutant behavior; Pesticides; Summer; HCH; Organic chlorine compounds; Floating ice; Persistent organic pollutant; Concentration measurement; Chemical pollution; Enrichment factor; Organochlorine compounds; Enantiomer; Water pollution; Polar region; Organic compounds; Sea ice
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es303039f

During the summer of 2009, we sampled 14 partially refrozen melt ponds and the top 1 m of old ice in the pond vicinity for α-hexachlorocyclohexane (α-HCH) concentrations and enantiomer fractions (EFs) in the Beaufort Sea. α-HCH concentrations were 3 - 9 times higher in melt ponds than in the old ice. We identify two routes of α-HCH enrichment in the ice over the summer. First, atmospheric gas deposition results in an increase of α-HCH concentration from 0.07 ± 0.02 ng/L (old ice) to 0.34 ± 0.08 ng/L, or ∼20% less than the atmosphere-water equilibrium partitioning concentration (0.43 ng/L). Second, late-season ice permeability and/or complete ice thawing at the bottom of ponds permit α-HCH rich seawater (∼0.88 ng/L) to replenish pond water, bringing concentrations up to 0.75 ± 0.06 ng/L. α-HCH pond enrichment may lead to substantial concentration patchiness in old ice floes, and changed exposures to biota as the surface meltwater eventually reaches the ocean through various drainage mechanisms. Melt pond concentrations of α-HCH were relatively high prior to the late 1980-s, with a Melt pond Enrichment Factor >1 (MEF; a ratio of concentration in surface meltwater to surface seawater), providing for the potential of increased biological exposures.