Contaminant dispersal in the strait of Georgia and Salish Sea

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The Greater Vancouver Sewerage and Drainage District (GVS&DD), which handles liquid waste for 7% of Canada's population, discharges wastewater from 5 treatment plants directly or indirectly into the Strait of Georgia, a semi-enclosed oceanic waterway at the inshore end of the Salish Sea. This wastewater contains organic substances including polybrominated diphenyl ethers (PBDEs), whose concentrations have been growing in recent years, polychlorinated biphenyls (PCBs), which are still present decades after being banned, metals like silver and cadmium which can be toxic in high concentrations, and organic material which depletes dissolved oxygen. The basic questions for GVS&DD are: should they be worried about the effect of these substances in the Strait of Georgia, now or in the foreseeable future, and if so, what might be done about mitigating these effects? Answering these questions means addressing basic science issues about biological, chemical and physical transport processes for these substances in a coastal ocean area, and about processes leading to the bioaccumulation of these substances in marine food webs.Here we propose a project to quantify water column concentrations of four potential contaminants discharged into the Strait, understand how and why regional ocean circulation and particle dynamics can cause environmental levels to change over space and time, determine the bioaccumulation as these substances move into higher trophic levels in the Strait, and study whether or at what point the ambient concentrations may become of environmental concern.