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TitleAssessing and reducing risks from historical gold mine tailings in Nova Scotia, Canada
AuthorParsons, M B; Smith, P K; Goodwin, T A; Hall, G E M; Percival, J B; Mroz, R; Doe, K G; Tay, K -L; Palace, V P
Source7th International Symposium on Environmental Geochemistry: abstracts; Chinese Journal of Geochemistry (Ti chiu hua hsüeh ) vol. 25 (suppl), no. 1, 2006 p. 32-33,
Alt SeriesEarth Sciences Sector, Contribution Series 20060098
PublisherSpringer Nature
Meeting7th International Symposium on Environmental Geochemistry; Beijing; CN; September 24-27, 2006
Mediapaper; on-line; digital
File formatpdf
ProvinceNova Scotia
NTS11C; 11D; 11E; 11F; 11K; 11L; 11M; 11N; 20O; 20P; 21A; 21B
Lat/Long WENS -68.0000 -60.0000 48.0000 43.0000
Subjectsenvironmental geology; geochemistry; metallic minerals; gold; mines; mining; tailings; tailings disposal; tailings analyses; mercury; arsenic; mineral deposits; heavy metals contamination; arsenopyrite; health hazards
ProgramMetals in the Environment (MITE)
AbstractFrom 1861 to the mid-1940s, stamp milling at lode gold mines in Nova Scotia, Canada, generated more than 3 million tonnes of
tailings. Most of the gold was recovered using Hg amalgamation, and an estimated 10-25% of the Hg used was lost to the tailings and to the atmosphere. Arsenic and other metal (loid)s also occur naturally in the ore, and are present at high concentrations in the mine wastes. Tailings from these operations were generally slurried into local rivers, swamps, lakes, and the ocean. Recent land use changes (e.g. residential development, recreational activities, shellfish harvesting) in some historical mining districts are increasing the likelihood of human exposure to these tailings. This study is a multi-disciplinary investigation of the dispersion, speciation, and fate of metal (loid)s in terrestrial and marine environments surrounding abandoned gold mines. A wide variety of methods are being employed including synchrotron analyses, sequential extractions, and biological sampling. From 2003 to 2005, samples of tailings, soil, humus, till, rock, sediment, water, and biota were collected at 15 former gold mines. Field studies reveal that most sites contain large volumes of'unconfined tailings, and in several districts these have been transported significant distances (>2 kin) offsite by streams and rivers. Chemical analyses of,~33 railings and downstream sediment samples show high concentrations of Hg (<5x 10 .9 to 350 mean 7x10 "6) and As (9x10 "6 to 31 wt%; mean 1 wt%). Mercury is present in elemental form [Hg(0)], amalgam (AuxHg• and in secondary phases (e.g. metacinnabar); however, dissolved Hg concentrations in surface waters are relatively low (mean 13x10-12). Arsenic is hosted in arsenopyrite and a variety of secondary phases such as scorodite (FeAsO4 ~ 2H20). Dissolved As concentrations are very high at some locations (0.2x10-9 to 6600x10-9; mean 390x10-9), as compared to background values of generally <25x 10-9. Both As and Hg have bioaccumulated to various degrees in terrestrial and marine biota, including eels, clams, and mussels. Results from this study have led to the formation of a Provincial-Federal Historic Gold Mines Advisory Committee. This committee is evaluating the potential ecological and human health risks associated with gold mines throughout Nova Scotia, and developing recommendations for future management of these tailings sites.