| Abstract
| - The short-term fate of polychlorinated biphenyl (PCB) andorganochlorine (OC) pesticides in the surface snowpackwas investigated by taking consecutive air and snow samplesover a 12 day period at Tromsø in the Norwegian Arctic.A wide range in PCB and OC pesticide concentrations wasobserved in snow and was attributed to the systematicdecrease in concentrations that occurred over the studyperiod. For example, ΣPCB concentrations ranged from 2500to 300 pg L-1 (meltwater) with a rapid decrease observedduring the first 96 h. Rates of decline (ks) conformed to first-order kinetics, with similar rates observed for all compoundsmeasured in this study (ks = 0.01 ± 0.001 h-1). Becausethe particle bound fraction accounted for <10% of theindividual PCB and OC burden in the snow, then the fractionlost may be accounted for by desorption, followingnotable increases in snow density (and presumably,decreases in snow surface area). The fraction of chemicalpresent in the fresh snow (φs) was found to be exponentiallyrelated to changes in snow density (Δρ). Relativelysmall increases in ρ following snowfall result in a largeloss of sorbed chemical, presumably due to decreases insnow surface area. Later sampling of the same snowlayer, but buried under fresh snowfall, revealed a notableincrease in both PCB and OC concentrations. Thiswould indicate a possible downward migration of thesechemicals from the fresh snow into deeper snow layers,suggesting that re-emission of desorbed chemical from theinterstitial pore spaces to the overlying atmosphere maybe complicated by this process.
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