The effects of snow and ice on the environmental behaviour of hydrophobic organic chemicals

A review is presented of the roles of snow and ice as they influence the environmental fate of hydrophobic organic chemicals (HOCs). Measurements of HOC concentrations in snow are reviewed and present information on the partitioning and depositional and post-depositional behaviour of HOCs in snow is described and implications for environmental monitoring and assessment of fate are discussed. It is concluded that snow is an efficient scavenger of HOCs from the atmosphere both by adsorption of gaseous HOCs to the ice interface, and by particle scavenging. The post-depositional fate of HOCs in ageing snow packs is poorly understood. Suggested structures of quantitative models describing HOC interactions with ice and snow are presented. Key parameters in these models include the interfacial area of snow and the extent of HOC sorption to the ice surface. Recent laboratory determinations of these parameters are reviewed. Finally, research needs and gaps are identified with a view to compiling more accurate estimates of net atmospheric wet deposition of HOCs, establishing their fate in snow packs, developing reliable sampling protocols and assessing the usefulness of the glacial record as an indicator of past atmospheric compositions.