Comparative analysis of nearshore contaminated sites in lake Ontario: Ranking for environmental hazard

Abstract
A ranking method, based on partially ordered set theory, is applied to degraded inshore waters of Lake Ontario. This ranking method uses test data collected by Dutka et al. [1] in bottom sediments. The result of this ranking analysis is displayed by Hasse diagrams. Hasse diagrams avoid the loss of information that occurs when data are aggregated into a ranking index. Both ranking schemes, that of Dutka et al. [1] and ours, have identified the same sites as the most degraded: Humber River STP outfall, Mimico Creek mouth and the harbour in Port Hope. In addition, we also identify Whitby Harbour and another site in Port Hope Harbour as degraded. These two sites, together with the Industry's Area in Toronto and Lasco Steel in Whitby Harbour, are degraded in a manner different from all other sites (because samples from these sites are highly toxic). We also note that Cherry St. in Toronto (Site 27) should be considered degraded because of the high ranking in fecal coliforms (FC). Finally, the ranking method identifies two tests, namely the Microtox test and the genotoxicity test as important for ordering the sites.