SORPTION OF NONPOLAR ORGANIC VAPORS BY ICE AND SNOW

Two complementary methods of measuring the sorption of nonpolar organi c vapors to snow and ice surfaces are described. Sorption measurements are presented for n-hexane, n-heptane, n-octane, benzene, chlorobenze ne, 1,4-dichlorobenzene, dichloromethane, trichloromethane, tetrachlor omethane, 1,1,1-trichloroethane, trichloroethene, and tetrachloroethen e over the temperature range from -10 to 0 degrees C. A gas chromatogr aphic retention time method using a column containing ice-coated Chrom osorb P has the advantage of giving precise determinations of the air- ice surface partition coefficient for volatile chemicals. A snow pack method involves measuring the sorption of chemical from a gas stream i nto a bed of snow, the quantity sorbed being determined by the change in gas concentration and by directly measuring the snow concentration. This method more closely simulates environmental conditions, but the snow surface area is uncertain. It is concluded that to a first approx imation partitioning at the air-ice interface can be estimated by extr apolating adsorption constants for the air-water interface. Implicatio ns concerning the fate of organic contaminants in environmental snow s amples are discussed.