Bioavailability of Contaminant Metals in a Mining Impacted Region of Ontario, Canada.
Graeme A. Spiers and Joinal Abedin. MIRARCO, Laurentian Univ, 933 Ramsey Lake Road, Sudbury, ON P3E 6B5, Canada
The metal mining and smelting industry in Sudbury, Ontario, Canada that is actively working more than a century and emitting hundreds of tons of metal particulates annually in the hot gas plume has contributed to a denuded landscape with a severe contamination in aquatic and terrestrial environments. The emitted particulates are primarily composed of minerals such as magnetite, maghemite and trevorite containing various quantities metallic contaminants including Ni, Cu, Fe Mn, Zn, Pb, Cr, Cd and As. Previous studies on Sudbury soils have focused on the estimation of the level and extent of metal contamination in the surface layers of the regional soils. Even though there are large scale survey projects providing data on total and acid extractable metals, there is no detailed information addressing the potential bioavailability of these metals to the food-webs of the ecosystems of Sudbury region. Information on total concentration of metals/metalloids in soils and sediments alone is not enough to assess the environmental impact of both historical and current emissions of metals as the bioavailability and toxicity is greatly dependent on their specific chemical and mineralogical forms and the ways of binding. The portion of metals present in soil and sediment that are bioavailable and most mobile are generally investigated by single extraction procedures. Although chemical extractants do not extract metals in the same manner as a living plant, correlations between soil extractants and plant uptake can allow predictions of phytoavailable metals in soils and sediments. In this presentation we are comparing several extractants (neutral salts and chelates) generally used for measuring phytoavailability of metals. The results of this study will greatly enhance knowledge and understanding of the availability and toxicity of metals in soils and sediments to vegetation, animals and humans in a regional context.