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Abstract:

Smelting activities in the Trail, British Columbia region since the late 1890’s has emitted metal(loid) contamination in the region (Pb, Zn, Cu, As, and Cd). The objective of this study was to determine the potential availability, mobility and operationally defined speciation of Sb and Pb in contaminated soils. Total Sb and Pb are strongly enriched in surface horizons in the profile (maximum of 737 and 26 376 mg kg-1), with concentrations decreasing with depth. Sequential extractions on soils indicate an enrichment of Sb in the operationally-defined residual > reducible > oxidizable > easily extractable fractions (< below detection limits), whereas Pb shows residual > oxidizable > reducible > easily extractable fractions. Electron optical and microchemical analysis of selected magnetic grains from LFH horizons indicate the anthropogenically derived Sb- and Pb particles to be present as discrete oxide- and sulfide/sulfate particles. The mineralogical and morphological nature of Sb- and Pb- particulate matter is diverse, ranging from angular massive Sn- bearing Sb- Pb oxides, euhedral and subrounded Sboxides, and Pb-sulfides and sulfates. These results indicate that, although soils are highly enriched in Sb and Pb relative to soil quality guidelines, minimal biological uptake and mobility should exist for both elements.