RECENT EMISSIONS DETECTED IN THE NATURAL SNOWPACK AROUND A SMELTER AT ROUYN-NORANDA, QUEBEC

Deborah Kliza*(Geological Survey of Canada, 601 Booth St., Ottawa, Ontario K1A 0E8), Kevin Telmer (University of Victoria, University of Victoria, Victoria, BC, Canada, V8W 3P6), Graeme Bonham-Carter, Gwendy Hall, Robert Garrett (Geological Survey of Canada, 601 Booth St., Ottawa, Ontario K1A 0E8)

As part of the the Metals in the Environment (GSC-MITE) Initiative, snow was used as a sample medium to characterize the atmospheric deposition of metal emissions around the Horne smelter in Rouyn-Noranda, Quebec. To date, a regional helicopter-supported survey has been completed with a total of approx 160 sample sites from a radial distance out to 250 km.

Geochemical analyses have shown that the mass of metals per unit area (such as Pb and Cu) contained in snow shows a strong negative correlation with distance from smelter. Mapping the data shows distinct bull's eye effect, most prominent in direction of prevailing winds. A nonlinear model with 3 parameters (background level, level at the source, and decay half-distance) fitted to the sum of the two size fractions versus distance from smelter provides a measure of transport distance and allows the amount of metal emissions deposited to be calculated. Results show that background metal levels are reached < 50 km from smelter, and the bulk of the total deposition occurs within 10-15 km of the stack. Estimated total metal loading (tonnes/ yr, assuming that the snow represents deposition for 1/4 yr) of Pb, Cu, Zn, Cd, and As account for about 20%, 74%, 26%, 17%, and 10% of the total measured emissions for that year, respectively.

Total geochemistry includes both a filtered meltwater component (<0.45 um) and the resulting filtered residue component (>0.45 um). Comparison of the mass of metals in each component (ng) shows that on average for the entire suite of metal particulate, the ratio is 1:1. However, the bulk of the larger smelter-derived particles such as C u, Pb, As, and Zn tend to deposit within 10-15 km from the smelter.