An environmental study of Esquimalt Harbour : Part I. Historical inputs, marine sediment contamination, and biological uptake
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The Environmental Sciences Group (ESG) of Royal Roads Military College, in consultation with the Environmental Protection (EP) Pacific and Yukon Branch of Environment Canada, is conducting an environmental study of Esquimalt Harbour, British Columbia. This report documents the results of Part I of this investigation and considers sediment contamination and associated contaminant uptake in mussels, Mytilus trossulus, and Red Rock crabs, Cancer productus. Contaminant concentrations in sediments provide an appreciation of the overall health of the harbour. Spatial distributions of contaminants (i.e. contaminant locations), together with historical data, permit the identification of current and past contaminant sources. Surface sediment samples were collected from 24 stations (locations) in basin areas of the harbour, as well as from 26 stations, close to the shoreline, in proximity to possible contaminant inputs. Inorganic elements (arsenic, cadmium, copper, lead, mercury and zinc), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and tributyltin were found in some sediments at concentrations which exceeded natural or background concentrations by one to three orders of magnitude. Sediment contaminant levels were highest in Constance Cove - particularly near major ship construction, maintenance and repair facilities; elevated concentrations were also found near jetties in the western harbour. Contaminant levels were lower toward the center and northern portions of the harbour, and toward the harbour mouth. The majority of the results were similar to contaminant concentration ranges for sediments from other urbanized/industrialized areas such as Vancouver Harbour and portions of Puget Sound. Maximum concentrations of PCBs, P AHs and mercury in Esquimalt Harbour were high, however, even in comparison with these other major harbours. It would be valuable to compare the Esquimalt results to marine sediment quality criteria or guidelines that could predict the environmental consequences or impact associated with the determined values. Unfortunately, there are currently no such criteria which have found universal acceptance. It should be noted, however, that contaminant concentrations in several of the Esquimalt Harbour sediment samples exceed existing U.S. and proposed Norwegian criteria/standards/guidelines. Tissue levels of several inorganic elements, PCBs and P AHs in mussels and Red Rock crab leg muscle or hepatopancreas indicate that the higher contaminant concentrations in Constance Cove are accompanied by increased biological uptake. Environmental impact associated with the sediment contamination can therefore be expected. Part II of this study, currently in progress, will directly examine contaminant effects on bottom-dwelling organisms in Esquimalt Harbour. Collectively these reports will provide the first comprehensive environmental evaluation of any harbour in the Greater Victoria region.