Modelling the fate of non-polar organic chemicals during the melting of an Arctic snowpack
✍ Scribed by Frank Wania; Ray Semkin; John T. Hoff; Donald Mackay
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 335 KB
- Volume
- 13
- Category
- Article
- ISSN
- 0885-6087
No coin nor oath required. For personal study only.
✦ Synopsis
Recent advances in the understanding of the interactions between non-polar organic chemicals and frozen water have revealed the immense importance of the ice-air interface and the possibility of quantitatively treating the adsorption process on the ice surface in terms of chemical-speci®c interfacial partition coecients and the snow speci®c surface area. A simple fugacity-based chemical fate model is used to describe quantitatively the behaviour of selected non-polar organic contaminants during snowpack melting, namely atmosphere-snow exchange, redistribution within the snowpack and draining with meltwater. The simulations are evaluated using ®eld data on snowpack and meltwater concentrations of these chemicals measured in a small watershed in the Canadian Arctic during the melting period of 1993. The model reproduced the observed preferential elution of hexachlorocyclohexanes in the ®rst meltwater fractions, and the relative retention of polychlorinated biphenyls within the snowpack. The model calculations indicate that the speci®c surface area of the ice crystals and the air-ice and air-water partition coecients of the chemical are key parameters controlling the extent and timing of chemical loss with the meltwater. For particle-sorptive substances, the fate of particles during snowmelt must also be considered. Uncertainty in describing interfacial partitioning and the behaviour of particles during melting presently limits the capabilities of models to simulate and ultimately predict meltwater concentrations of non-polar organic contaminants.