Sorption of diverse organic vapors to snow

Sorption from air to one snow sample has been measured for a broad set of organic vapors covering a wide range of physicochemical properties. Those results that could be compared to literature values mostly lay in the same order of magnitude. As expected, a fit with the vapor pressure did not reveal a good correlation (R2 = 0.11). Therefore, the data set was interpreted with a linear free energy relationship, based on intermolecular interactions (van der Waals interactions and hydrogen bond interactions). Although we cannot assign the observed sorption to a specific process (adsorption to the snow crystal surface, incorporation in the solid ice crystal, absorption into a quasi-liquid layer, or grain boundary effects), the model provides a useful tool for the prediction of snow sorption for other compounds: log K(i snow suface/air) = 0.639 (+/- 0.037) log K(i hexadecane/air) + 3.38 (+/- 0.17) sigmabetai + 3.53 (+/- 0.25) sigmaalphai - 6.85. The sorption coefficients measured could be described well with the compound parameters used (subscript i), with an R2 = 0.90.