7.1 Atmospheric deposition of contaminants to the Athabasca Oil Sands Region
Jeff Brook and Jane Kirk, Environment Canada
presentation
abstract
Monitoring for toxic compounds such as polycyclic aromatic compounds (PACs), trace metals and mercury has been established in the Athabasca Oil Sands Region (AOSR) to determine their atmospheric fate, including transport, transformation, and deposition. We present results from measurements at sites within and outside the major mining development areas including: (1) air and precipitation measurements at 3 locations; (2) integrated passive sampling at 17 locations; (3) snowpack sampling at ~130 sites; and (4) analysis of 19 lake sediment cores to examine long-term (~100 years) trends in contaminant deposition. In addition, an approach to estimating dry deposition from observed air concentrations will be described. Air measurements show that concentrations of PACs and metals decrease with distance from the main surface mining and upgrading activities, that alkylated-PACs are more abundant than the unsubstituted PACs, and that crustal elements, such as iron, silicon, aluminum, and calcium, are some of the most elevated of the metals. Snowpack loadings of PACs and metals decrease with distance from the major developments, with the highest deposition occurring within 50 km of the main development area. Dated lake sediment cores suggest that PACs deposition is 1-19 times higher in recent decades (post-1990s) than before development began (pre-1960s) in lakes located within 50 km from major developments. Next steps include integration of air, snow, precipitation and sediment measurements with water and wildlife data to help improve understanding of the cumulative impact of contaminants on ecosystems within the AOSR. Models will be used to integrate these measurements along with emissions information.
biography