WA9 Semi-Volatile Pollutants in Polar and Alpine Ecosystems
D137-140
8:00 AM - 12:00 PM, Wednesday
() Rapid changes in SVOC concentrations in the arctic snowpack.
Herbert, B.1, Villa, S.2, Halsall, C.1, Jones, K.1, Kallenborn, R.3, 1 Environmental Science Dept, Lancaster University, Lancaster, UK2 Department of Environmental and Landscape Science, University of Milano Bicocca, Milan, Italy3 Norwegian Institute of Air Research, Kjeller, Norway
ABSTRACT- Combined air and snow samples were taken consecutively over an 11-day period at Tromsø in the Norwegian Arctic to investigate the short-term fate of semi-volatile organic compounds (SVOCs) in a fresh snowpack. Daily snow samples were collected from the same fresh-snow layer using novel high volume (50 L) aluminium snow cans. Throughout the sampling period, air concentrations for the OC pesticides displayed a relatively narrow range (i.e. 
-HCH 13 - 40 pg m-3) whereas the 
PCBs ranged from 8 to 74 pg m-3, probably reflecting the influence of the nearby town of Tromsø. However, both OC pesticide and PCB concentrations in the fresh snowpack decreased significantly throughout the sampling period: e.g. PCB 2500 to 300 pg L-1 (meltwater). The most rapid decrease was within the first 96 h, with ∼75% of the PCB lost during this period(PCB t1/2=65 h). The decrease in snowpack PCB and OC pesticide concentrations was mirrored by an increase in snow density, highlighting the effects of changes in snowpack physical properties on the contaminant burden. Interestingly, both PCB and OC pesticide concentrations in the re-sampled snow layer increased significantly after a fresh snowfall event, indicating the propensity for exchange of SVOCs within a snowpack. Rates of loss (k) were calculated for a selection of compounds and were found to be similar for all ICES PCB congeners and 
-, -HCH (ks = 0.01 h-1). No relationship was found between rates of loss (k) and physical/chemical descriptors such as vapour pressure or Henry's Law Constants (r2 <0.02). This suggests that environmental parameters, particularly the rapid increase in snow density, are having a pronounced effect on the snowpack chemical composition over a short time period. Results from this work indicate considerable snowpack dynamics immediately following snowfall, which has important implications when modelling chemical fate and estimating contaminant contributions from the snowpack to Arctic catchments.
Key words: Air, Polar, Snow, Persistent Organic Pollutants