Caged mussels and passive samplers used to identify Niagara River organic contaminant sources and shoreline water quality impacts (2012–2018)

Since 1983 the Ontario Ministry of Environment (MECP) monitored and identified Niagara River contaminant sources using caged mussels, and recently (2012–2018), passive samplers. Source identification was consistent among monitoring tools. The advantage of passive samplers was the capability to estimate dissolved water contaminants concentrations enabling comparisons with Water Quality Criteria (WQC) and ambient river concentrations. Dieldrin, p, p’-DDE, p, p’-DDD, hexachlorobenzene, and total PCBs exceeded WQC throughout the river. The highest concentrations of mirex (1.4 ng/L), octachlorostyrene (2.8 ng/L), and hexachlorobutadiene (16 ng/L) were at Occidental Chemical Co. Buffalo Ave. sewer 003, and the highest concentrations of α-HCH were at Cayuga Creek (36 ng/L) and Gill Creek (68 ng/L): all were >WQC. The Pettit Flume cove, Little Niagara River downstream of the 102nd St. Waste Site, Bloody Run Creek (associated with the Hyde Park Hazardous Waste site) and Occidental sewer 003 had the highest concentrations of chlorinated benzenes. Sources of dioxins to the Niagara River included; Pettit Flume cove: (water: 3.9–10 pg TEQ/L; sediment: up to 989,400 pg/g), and Bloody Run Creek: (water: 1.2 pg TEQ/L; sediment: 35,098 pg/g–101,113 pg/g). Total PCBs remain high at known and newly identified sources along the Tonawanda Channel (USA): concentrations ranged up to 387 ng/L with most sites between 5 and 19 ng/L compared with the Chippawa Channel (Canada) (