Organic Contaminants in the Suspended Sediments of the Niagara River

Suspended sediment samples were collected approximately every 2 weeks from the Niagara River at Niagara-on-the-Lake between April, 1979 and April, 1980. Three other samples were collected from the Fort Erie end of the river during July, 1979. All samples were analyzed for organochloride pesticide residues.Of the residues tested, PCB was the most prevalent, followed by DDT, mirex, chlordane, methoxychlor, and endosulfan. The Niagara River is apparently the largest single source of PCBs to Lake Ontario. Comparison with other work indicates that the loadings of total PCBs from this source have more than doubled since 1968.Evidence suggests that much of the suspended sediment contaminated with PCB, mirex, and p,p′-DDT emanates from sources which enter the Niagara River between Grand Island and Niagara-on-the-Lake.