Chloroacetates in snow, firn and glacier ice

A study of chloroacetates in snow, firn and glacier ice was undertaken to determine how widespread such compounds are in precipitation and to elucidate the possible involvement of anthropogenic and natural sources. Samples of snow were collected in remote areas, including Antarctica, the Russian tundra and northern Scandinavia, and at a few more populated sites. Glacier ice was sampled at two sites in northern Sweden, and fun from Antarctica was obtained from an archived ice core. Chemical analysis of the collected samples showed that mono-, di- and trichloroacetate were prevalent in all investigated regions, and concentrations of the respective compounds at remote sites normally ranged from 10 to 100 ng/L. The levels found were too high to be explained by direct anthropogenic emissions of chloroacetic acids or any of their salts. Furthermore, it was difficult to trace the nearly ubiquitous occurrence of all three chloroacetates to suggested anthropogenic precursors, such as 1,1,1-trichloroethane, trichloroethene and tetrachloroerhene. The presence of mono-, di- and trichloroacetate in glacier ice from northern Sweden and in firn representing the past 100 years of snow accumulation in Antarctica strongly indicates that chloroacetates may occur naturally in precipitation (C) 1999 Elsevier Science Ltd. All rights reserved.