Analysis of contaminated sediments in southwestern portion of Lake Saint-Pierre (Québec, Canada)
Field campaigns were conducted during autumn 2006 in the southwest portion of Lake Saint-Pierre in order to determine the concentration of contaminants in subsurface (0-50 cm) and deep sediments (>50 cm) of the cores collected. These coring campaigns were conducted under the leadership of a team of experts from the Department of National Defence (DND). The study area is part of the former firing range (encompassed by the no fly CYR 606 zone) from the Munitions Experimental Test Centre of the Canadian Armed Forces. It presents environmental risks because Unexploded Explosive Ordnance (UXO) are found in sediments. This zone was also identified as an area affected by various contaminants, including metallic elements and organic pollutants. The analysis in the southwest portion of Lake Saint-Pierre indicates that the concentrations of metallic elements (ME) and other contaminants (PCBs, PAHs) are relatively low at all sampling sites. Arsenic and chromium show the highest concentrations, exceeding the occasional effect level (OEL) and the threshold effect level (TEL), as defined by Federal and Provincial sediment quality guidelines. For sediment classification, loamy sand or sandy loam are the dominant mineral matrices. In comparison with previous work in this portion of Lake Saint-Pierre, sediment contamination has been reduced, which indicates an improvement in the quality of water and sediment. In light of these results, this part of the basin is not seen as a problematic area in terms of sediment contamination by metallic elements (ME), polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs).