Simulating the Influence of Snow on the Fate of Organic Compounds

Abstract

Snow scavenging, a seasonal snowpack, and a dynamic water balance are incorporated in a non-steady-state generic multimedia fate model in order to investigate the effect of snow on the magnitude and temporal variability of organic contaminant concentrations in various environmental media. Efficient scavenging of large nonpolar organic vapors and particle-bound organic chemicals by snow can lead to reduced wintertime air concentrations and incorporation in the snowpack. The snow cover functions as a temporary storage reservoir that releases contaminants accumulating over the winter during a short melt period, resulting in temporarily elevated concentrations in air, water, and soil. The intensity of these peaks increases with the length of the snow accumulation period. Organic chemicals of sufficient volatility (log KOA < 9; e.g., light polychlorinated biphenyls) can volatilize from the snowpack, resulting in springtime concentration maxima in the atmosphere. The behavior of fairly water-soluble chemicals during snowmelt depends on their relative affinity for the newly formed liquid water phase and the rapidly diminishing ice surface-quantitatively expressed by their interface-water partition coefficient (KIW). Chemicals with a preference for the dissolved phase (low KIW; e.g., pentachlorophenol) can become enriched in the first meltwater fractions and experience a temporary concentration peak in lakes and rivers. Organic chemicals that are neither volatile enough to evaporate from the snowpack nor sufficiently water soluble to dissolve in the meltwater (e.g., polybrominated diphenyl ethers) sorb to the particles in the snowpack. These particles may be sufficiently contaminated to constitute the major input route to the terrestrial environment upon release during snowmelt. Because wintertime deposition to the snowpack may be higher than to a non-snow covered surface, this can result in higher soil concentrations of persistent organic contaminants in the long term. The potential ecotoxicological significance of peak exposures demands a better understanding of the role of snow in the fate of organic contaminants.

Evolution of the Snow Area Index of the Subarctic Snowpack in Central Alaska over a Whole Season. Consequences for the Air to Snow Transfer of Pollutants

“…During spring, the warming and melting of the snowpack leads to the emission of a fraction of adsorbed compounds to the atmosphere, the rest being transferred to ecosystems by runoff (10). Because of its increased reservoir capacity and its lower ability for exchange, we speculate that the Arctic snowpack will be much more efficient in the transfer of adsorbed species from the atmosphere to ecosystems.…”

Evaluating officially reported polycyclic aromatic hydrocarbon emissions in the Athabasca oil sands region with a multimedia fate model

“…The nonsteady-state multimedia fate model CoZMo-POP (Coastal Zone Model for Persistent Organic Pollutants) (31,32) was used in all model simulations. First, the model was parameterized to better represent the AOSR environment and the contaminants being modeled: phenanthrene (PHE), pyrene (PYR), benzo (a)pyrene (BaP), DBT, C1-, C2-, and C3-naphthalenes (C1-NAP, C2-NAP, and C3-NAP), C1-fluorenes (C1-FLU), and C1-phenanthrenes/anthracenes (C1-P/A).…”

Temporal variations of perfluoroalkyl substances and polybrominated diphenyl ethers in alpine snow

“…However, concentrations of persistent organic pollutants are influenced by several postdepositional effects such as volatilization and degradation of compounds, dissolution of substances in meltwater or wind scour of deposited snow (Daly and Wania, 2004;Wania, 1997). Colle Gnifetti air temperatures during the investigated period were almost always below 0 C and the borehole temperatures ranged from À12.5 C to À13.5 C, minimizing the risk of snow melt and meltwater percolation.…”