title: Historical decline and altered congener patterns of polychlorinated dibenzo-p-dioxins and dibenzofurans in fish and sediment in response to process changes at a pulp mill discharging into Jackfish Bay, Lake Superior.
abstract: Improved regulations for pulp and paper mill effluents and an industry shift away from elemental chlorine bleaching in the 1990s greatly reduced the release of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) into the environment. However, the high potential of these contaminants to persist in sediment and bioaccumulate in biota means that they have remained a concern. To document current contamination from bleached kraft pulp mill effluent, PCDD/Fs were measured in white sucker (Catostomus commersoni) collected from Jackfish Bay, Lake Superior. These values were contrasted to historically reported fish data as well as PCDD/F patterns from dated sediment cores. Patterns of PCDD/Fs in sediment cores from Jackfish Bay and reference sites demonstrated a relationship between contamination and mill process changes. During the peak PCDD/F contamination period (1991), when the mill was still using elemental chlorine, the contamination patterns in fish and sediment were distinct and dominated by 2,3,7,8-tetrachlorodibenzo-p-dioxin and 2,3,7,8-tetrachlorodibenzofuran. Following the reduction in the use of elemental chlorine during the early 1990s, a rapid decline was observed in PCDD/F contamination of fish tissue, and levels are now approaching background conditions with congener patterns more reflective of atmospheric sources. Although surface sediments from Jackfish Bay continue to have elevated PCDD/Fs, with some locations exceeding sediment quality guidelines, they do not appear to be highly bioavailable to benthic fish.
authors.affiliation: Department of Biology, University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: Shari C
authors.initials: SC
authors.lastname: Dahmer
authors.affiliation: Emerging Methods Branch, Aquatic Contaminants Research Division, Water Science and Technology Directorate, Environment Canada, Burlington, Ontario, Canada.
authors.forename: Gerald R
authors.initials: GR
authors.lastname: Tetreault
authors.affiliation: Department of Biology, University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: Roland I
authors.initials: RI
authors.lastname: Hall
authors.affiliation: Department of Biology, University of New Brunswick, Saint John, New Brunswick, Canada.
authors.forename: Kelly R
authors.initials: KR
authors.lastname: Munkittrick
authors.affiliation: Emerging Methods Branch, Aquatic Contaminants Research Division, Water Science and Technology Directorate, Environment Canada, Burlington, Ontario, Canada.
authors.forename: Mark E
authors.initials: ME
authors.lastname: McMaster
authors.affiliation: Department of Biology, University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: Mark R
authors.initials: MR
authors.lastname: Servos
mesh_terms: D000818:Animals; D061006:Bays; D001572:Benzofurans / Q000032:analysis* / Q000737:chemistry; D002247:Carbon Isotopes / Q000737:chemistry; D000072338:Dibenzofurans, Polychlorinated; D004784:Environmental Monitoring; D005399:Fishes / Q000378:metabolism*; D019015:Geologic Sediments / Q000737:chemistry*; D060106:Lakes / Q000737:chemistry*; D007856:Lead Radioisotopes / Q000737:chemistry; D008297:Male; D013058:Mass Spectrometry; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000032:analysis / Q000737:chemistry; D025341:Principal Component Analysis; D013051:Spectrometry, Gamma; D013997:Time Factors; D014865:Waste Disposal, Fluid
chemical_list: D001572:Benzofurans; D002247:Carbon Isotopes; D000072338:Dibenzofurans, Polychlorinated; D007856:Lead Radioisotopes; D000072317:Polychlorinated Dibenzodioxins
keywords: Bleached kraft pulp mill effluent; Dibenzofurans; Ecosystem recovery; Polychlorinated dibenzo-p-dioxins; Process changes