An Approach for Characterizing Arsenic Sources and Risk at Contaminated Sites: Application to Gold Mining Sites in Yellowknife, NWT, Canada

摘要

Yellowknife, Canada has an extensive soil arsenic contaminant problem as a result of 60 years of gold mining activity. Multivariate statistics (PCA) were used to determine that the natural concentration of arsenic in the area is also elevated (up to 150 ppm). As total arsenic concentrations may overestimate the actual risk posed to ecological and human health, sequential selective extraction (SSE) and a simulated gastric fluid extraction (GFE) were used to assess environmentally available and bioavailable fractions in soils. Subjecting various soil types to these techniques confirmed this hypothesis. The high arsenic content in crushed mine rock was neither environmentally available (<10% for SSE) or bioaccessible (<12% for GFE). Conversely, the low arsenic content in organic soils is more environmentally available (10-50% for SSE) and bioaccessible (>30% for GFE). Collectively, these techniques can be used to identify actual risks and develop effective remediation strategies.