Sediment-associated organopollutants, metals and nutrients in the Nechako River, British Columbia: a current study with a synthesis of historical data

The flow-diverted Nechako River is the second largest tributary of the Fraser River which drains 25% of mainland British Columbia, Canada. The watershed provides critical reproductive habitats for anadromous chinook salmon (Oncorhynchus tshawytscha) and sockeye salmon (O. nerka) and year-round habitat for the endangered Nechako white sturgeon (Acipenser transmontanus) population. In this study, the chemical quality of sediment in the upper Nechako River and its major tributaries was examined for polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), legacy organochlorine (OC) pesticides, polycyclic aromatic hydrocarbons (PAHs), organophosphorus and phenoxy acid herbicides, polychlorinated dibenzo-p-dioxins (PCDDs) and furans (PCDFs), labile (exchangeable) metals/metalloids, and major nutrients (N and P). ΣPCB and ΣPBDE were detected in channel bottom sediments at all Nechako River and tributary sites; hexachlorobenzene (HCB) and 4,4′-DDE (dichlorodiphenyldichloroethylene) were a...