title: Assessing the cause of impacts on benthic organisms near Rouyn-Noranda, Quebec.
abstract: Sediments from lakes near Rouyn-Noranda, Quebec, contain elevated concentrations of several metals, including Cd, Cu, Pb and Zn. Amphipods, fingernail clams, mayflies and tanytarsid midges were absent, and sediment toxicity was observed in chronic tests with Hyalella in sediments from Lac Dufault, the lake closest to Rouyn-Noranda. Bioaccumulation by Hyalella demonstrated elevated bioavailability of Cd, Co, Cr, Pb and Tl, but only Cd was accumulated to levels close to the toxic threshold. Copper, which is regulated by Hyalella, was not elevated in these amphipods, but it was elevated in overlying water in the toxicity tests. Toxic effects in Lac Dufault sediments are probably caused primarily by Cd, at least in amphipods, with a possible minor contribution from Cu. An integrated assessment, including sediment chemistry, benthic community composition, sediment toxicity, metal bioaccumulation in benthos, and comparison of bioaccumulation and/or overlying water concentrations with threshold effect concentrations, provides the best indication of effects and their cause.
authors.affiliation: National Water Research Institute, Environment Canada, 867 Lakeshore Road, PO Box 5050, Burlington, Ontario, Canada L7R 4A6. uwe.borgmann@ec.gc.ca
authors.forename: U
authors.initials: U
authors.lastname: Borgmann
authors.forename: M
authors.initials: M
authors.lastname: Nowierski
authors.forename: L C
authors.initials: LC
authors.lastname: Grapentine
authors.forename: D G
authors.initials: DG
authors.lastname: Dixon
mesh_terms: D033304:Amphipoda / Q000254:growth & development / Q000378:metabolism*; D000818:Animals; D044822:Biodiversity; D001682:Biological Availability; D002104:Cadmium / Q000493:pharmacokinetics / Q000633:toxicity; D002857:Chromium / Q000493:pharmacokinetics / Q000633:toxicity; D003035:Cobalt / Q000493:pharmacokinetics / Q000633:toxicity; D003300:Copper / Q000493:pharmacokinetics / Q000633:toxicity; D017753:Ecosystem; D004781:Environmental Exposure; D019015:Geologic Sediments / Q000032:analysis / Q000737:chemistry*; D007854:Lead / Q000493:pharmacokinetics / Q000633:toxicity; D019216:Metals, Heavy / Q000493:pharmacokinetics* / Q000633:toxicity; D011792:Quebec; D013793:Thallium / Q000493:pharmacokinetics / Q000633:toxicity; D014877:Water Pollution, Chemical / Q000009:adverse effects
chemical_list: D019216:Metals, Heavy; D002104:Cadmium; D002857:Chromium; D007854:Lead; D003035:Cobalt; D003300:Copper; D013793:Thallium