PARENT SESSION
PM21 - Multimedia Models
Monday, 18 November 2002
8:00 AM to 6:30 PM
Exhibit Hall

(P400) Modelling the Deposition of Chemicals in High Altitude Lakes.

Di Guardo, Antonio^*,1, Mackay, Donald², ¹ Environmental Research Group, DBSF, University of Insubria, Varese, Italy² Canadian Environmental Modelling Centre, Trent University, Peterborough, ON, Canada

ABSTRACT- Monitoring programs have clearly shown that organic contaminants such as PCBs can achieve significant concentrations in high altitude or Alpine lakes and their resident biota. It appears that the lower temperatures which prevail in these ecosystems increase the rate of air to surface deposition and displace the equilibrium in favor of condensation, but other factors such as precipitation as snow rather than rain, more prolonged ice cover, slower degradation rates, reduced pressure and differences in organisms and food webs also play roles. In an attempt to quantify the relative effects of these processes an illustrative mass balance model of a typical lake is compiled, including run off from a local watershed and a simple food chain. The model is run at a series of altitudes with 1000 m increments with corresponding temperature changes for HCH and PCB congeners and the influences of the various factors explored individually and collectively. The results are compared with available monitoring data from high altitude lakes in Europe and Canada.

Key words: Altitudinal Lake, QWASI model, PCBs, deposition