title: Multi-trophic level response to extreme metal contamination from gold mining in a subarctic lake.
abstract: Giant Mine, located in the city of Yellowknife (Northwest Territories, Canada), is a dramatic example of subarctic legacy contamination from mining activities, with remediation costs projected to exceed $1 billion. Operational between 1948 and 2004, gold extraction at Giant Mine released large quantities of arsenic and metals from the roasting of arsenopyrite ore. We examined the long-term ecological effects of roaster emissions on Pocket Lake, a small lake at the edge of the Giant Mine lease boundary, using a spectrum of palaeoenvironmental approaches. A dated sedimentary profile tracked striking increases (approx. 1700%) in arsenic concentrations coeval with the initiation of Giant Mine operations. Large increases in mercury, antimony and lead also occurred. Synchronous changes in biological indicator assemblages from multiple aquatic trophic levels, in both benthic and pelagic habitats, indicate dramatic ecological responses to extreme metal(loid) contamination. At the peak of contamination, all Cladocera, a keystone group of primary consumers, as well as all planktonic diatoms, were functionally lost from the sediment record. No biological recovery has been inferred, despite the fact that the bulk of metal(loid) emissions occurred more than 50 years ago, and the cessation of all ore-roasting activities in Yellowknife in 1999.
authors.affiliation: Department of Biology, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5 joshua.thienpont@gmail.com.
authors.forename: Joshua R
authors.identifier: 0000-0003-1856-8756
authors.initials: JR
authors.lastname: Thienpont
authors.affiliation: Department of Biology, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5.
authors.forename: Jennifer B
authors.initials: JB
authors.lastname: Korosi
authors.affiliation: Paleoecological Environmental Assessment and Research Laboratory, Department of Biology, Queen's University, Kingston, Ontario, Canada K7L 3N6.
authors.forename: Kathryn E
authors.initials: KE
authors.lastname: Hargan
authors.affiliation: Department of Biology, Carleton University, Ottawa, Ontario, Canada K1S 5B6.
authors.forename: Trisha
authors.initials: T
authors.lastname: Williams
authors.affiliation: Department of Biology, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5.
authors.forename: David C
authors.initials: DC
authors.lastname: Eickmeyer
authors.affiliation: Department of Biology, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5.
authors.forename: Linda E
authors.initials: LE
authors.lastname: Kimpe
authors.affiliation: NWT Cumulative Impact Monitoring Program, Environment and Natural Resources, Government of the Northwest Territories, Yellowknife, Northwest Territories, Canada X1A 3S8.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Palmer
authors.affiliation: Paleoecological Environmental Assessment and Research Laboratory, Department of Biology, Queen's University, Kingston, Ontario, Canada K7L 3N6.
authors.forename: John P
authors.initials: JP
authors.lastname: Smol
authors.affiliation: Department of Biology, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5.
authors.forename: Jules M
authors.initials: JM
authors.lastname: Blais
mesh_terms: D000818:Animals; D002170:Canada; D033361:Cladocera; D017377:Diatoms; D004784:Environmental Monitoring; D006046:Gold; D060106:Lakes / Q000737:chemistry*; D008906:Mining; D014874:Water Pollutants, Chemical
chemical_list: D014874:Water Pollutants, Chemical; D006046:Gold
keywords: aquatic ecosystems; metals; mining; palaeolimnology; polycyclic aromatic hydrocarbons; roaster emissions