| Abstract
| - Snow scavenging, a seasonal snowpack, and a dynamicwater balance are incorporated in a non-steady-state genericmultimedia fate model in order to investigate the effectof snow on the magnitude and temporal variability of organiccontaminant concentrations in various environmentalmedia. Efficient scavenging of large nonpolar organic vaporsand particle-bound organic chemicals by snow can leadto reduced wintertime air concentrations and incorporationin the snowpack. The snow cover functions as a temporarystorage reservoir that releases contaminants accumulatingover the winter during a short melt period, resulting intemporarily elevated concentrations in air, water, and soil.The intensity of these peaks increases with the length ofthe snow accumulation period. Organic chemicals of sufficientvolatility (log KOA< 9; e.g., light polychlorinated biphenyls)can volatilize from the snowpack, resulting in springtimeconcentration maxima in the atmosphere. The behavior offairly water-soluble chemicals during snowmelt dependson their relative affinity for the newly formed liquid waterphase and the rapidly diminishing ice surfacequantitativelyexpressed by their interface−water partition coefficient(KIW). Chemicals with a preference for the dissolved phase(low KIW; e.g., pentachlorophenol) can become enrichedin the first meltwater fractions and experience a temporaryconcentration peak in lakes and rivers. Organic chemicalsthat are neither volatile enough to evaporate from thesnowpack nor sufficiently water soluble to dissolve in themeltwater (e.g., polybrominated diphenyl ethers) sorb tothe particles in the snowpack. These particles may besufficiently contaminated to constitute the major input routeto the terrestrial environment upon release duringsnowmelt. Because wintertime deposition to the snowpackmay be higher than to a non-snow covered surface, thiscan result in higher soil concentrations of persistent organiccontaminants in the long term. The potential ecotoxicologicalsignificance of peak exposures demands a betterunderstanding of the role of snow in the fate of organiccontaminants.
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