Patterns of Contaminant Distribution in the Sediments of Lake Nipissing

Session: Chemical Contaminants (3)

Douglas Chase, Nipissing University, [email protected]
Lesley Lovett-Doust, Nipissing University, [email protected]

Abstract

At an area of 873 km², Lake Nipissing is the 7^th largest lake in the Laurentian Great Lakes basin. Generally, it is a mesotrophic lake with two large eutrophic embayments, Cache Bay and Callander Bay. We mapped the distribution of nutrients and metal ions in the lake sediment. Samples were collected with a Ponar Grab sampler, and sent to Lakehead University Environmental Laboratory for analysis. The results for each of the 67 sampling points were compared with provincial, national and international guidelines; some areas had levels of metals that were above both the US-EPA “threshold level” and OMOECC “probable effect” levels and the Canadian federal (CCME) guidelines for the protection of aquatic life. Using the georeferenced concentration data, isopleths or “contours of contamination” were created by interpolating surfaces in ArcMap using Python. These contours allow us to examine competing hypotheses regarding contaminant sources and relationships to land use in the watershed and “airshed”. This technique offers a potential standardized approach to the assessment of environmental conditions, and a baseline for tracking of ecosystem recovery and restoration in aquatic environments.