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TitleMineralogical controls on the bioaccessiblity of arsenic in weathered gold mine tailings
AuthorCoriveau, M C; Parsons, M B; Jamieson, H E; Koch, I; Reimer, K J; Hall, G E M
Source7th International Symposium on Environmental Geochemistry: abstracts; Chinese Journal of Geochemistry (Ti chiu hua hsüeh ) vol. 25 (suppl.), 2006 p. 33
Alt SeriesEarth Sciences Sector, Contribution Series 20060097
Meeting7th International Symposium on Environmental Geochemistry; Beijing; CN; September 24-27, 2006
Mediapaper; on-line; digital
File formathtml; pdf
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; hydrogeology; metallic minerals; Health and Safety; mining; mines; tailings; tailings analyses; tailings geochemistry; antimony; arsenic; heavy metals contamination; soils; vegetation; groundwater pollution; pollution; human health
ProgramMetals in the Environment (MITE)
AbstractHigh concentrations of As in windblown and vehicle-raised dust from historical gold mine tailings in Nova Scotia, Canada pose a
potential health risk for residents who use these areas for recreational activities. Routes of exposure may include inhalation of dust, as
well as oral ingestion of particles. It is important to understand the particle size, chemical composition, and speciation of As in the
tailings-derived dust t6 evaluate the human health risk, and the need for management actions. In this study, electron microprobe,
conventional and synchrotron-based X-ray diffraction, X-ray absorption near edge structure, and sequential extraction methods were
applied to near-surface tailings samples from three sites. Primary minerals in the railings consist mainly of quartz, muscovite,
clinochlore, and albite. Arsenic concentrations vary from 400x10 "6 to 28600x10 6 in the bulk samples, and from 3000x10 "6 to
105000x10 "6 in the <38 ktm fraction. These concentrations significantly exceed 12x10 6 As, the Canadian Soil Quality Guideline.
Arsenic in the railings was originally in the form of arsenopyrite, but weathering reactions have oxidized most of the sulfide in
near-surface samples. Scorodite (FeAsO4 ~ 2H20) was found to be the dominant secondary phase in some samples. On a microscopic
scale, scorodite cements silicate grains; in the field, it forms hardpans which have been pulverized by vehicle activity at some sites.
Arsenic is also hosted in amorphous Fe arsenates, Ca-Fe arsenates, and Fe oxyhydroxides containing up to 30 wt% As2Os. To
evaluate how much of this As is potentially bioaccessible, the samples were subjected to an in-vitro two-part extraction method
designed to mimic the human digestive system. The results indicate that the percent of bioaccessible As is significantly higher in
samples where As is hosted by Fe oxyhydroxides and Ca-Fe arsenates, as compared to the scorodite-rich samples. However, because
total As in the scorodite-rich samples is much higher, the actual concentration of As that is bioaccessible is also higher, Recognition
of the potential human health impacts from abandoned railings sites led to the formation of a Provincial-Federal Historic Gold Mines
Advisory Committee in 2005. Residents in several areas have been advised to avoid contact with gold mine railings, and signs have
been posted at two sites warning of potential health risks.