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1G - Long-range transport of pollutants (chemicals) (WE13/3) Assessing the Potential of Persistent Organic Chemicals for Long-Range Transport and Accumulation in Polar Regions. Wania, Frank1, 1 University of Toronto at Scarborough, Toronto, Ontario, Canada ABSTRACT- A zonally averaged global distribution model is used to identify chemical partitioning properties and emission scenarios that favor enrichment in Arctic ecosystems. An immediate and a long-term Arctic Contamination Potential (ACP) are defined as the fraction of the total amount in the global environment that is in Arctic surface media after 1 and 10 years of steady emissions with a generic zonal distribution. Simulations for a two-dimensional space of hypothetical chemical property combinations indicate that the ACP of a perfectly persistent organic chemical is determined by a complex set of processes, but tends to be higher for two combinations of partitioning properties: volatile substances (log KOA < 9) that are relatively water soluble (-4 < log KAW < -0.5) and substances which are semi-volatile (log KOA 6.5 to 10) and relatively hydrophobic (log KAW > -3). Very volatile chemicals with log KOA < 6.5 and log KAW > -0.5 remain in the atmosphere even under Arctic temperature conditions, whereas very involatile chemical with a log KOA > 10 are efficiently and irreversibly deposited with atmospheric particles before reaching the Arctic. The two sets of partitioning characteristics with elevated ACP overlap in the range 6.5 < log KOA < 10 and -3 < log KAW < -0.5, which also corresponds to a log KOW range of 5 to 8, i.e. comprises substances with a potential for bioaccumulation. Organic contaminants known to accumulate in the Arctic, such as hexachlorobenzene and the PCBs indeed have such partitioning properties. Marine currents contribute significantly to the long range transport of chemicals with log KAW < -2. Emissions to surface media greatly reduce the ACP, except for chemicals with log KOW < 5. Key words: long range transport potential, persistent organic pollutants, Arctic contamination, global fate modelling |
