Oxidative Weathering Decreases Bioaccessibility of Toxic Metal(loid)s in PM10 Emissions From Sulfide Mine Tailings

摘要: Environmental contamination from legacy mine-waste deposits is a persistent problem due to the long history of hard-rock mining. Sulfide ore can contain elevated levels toxic metal(loid)s that, when mobilized by weathering upon O2 and H2O infusion, result in groundwater contamination. Dry-climate lack vegetative cover near-surface pedogenic processes that produce fine-particulate secondary minerals be translocated as geo-dusts leading ingestion or inhalation exposure nearby communities. In this study, vitro bioassays were combined with synchrotron-based x-ray spectroscopy diffraction determine potential risk for element release dust (PM10) samples into biofluid simulants. PM10 isolated across oxidative reaction front top meter tailings subjected 50 years under semi-arid climate, introduced synthetic gastric- alveolar-fluids. Aqueous concentrations measured function time kinetics. X-ray absorption analyses performed assess associated changes mineralogy elemental speciation. bioaccessibility arsenic lead was highest less-weathered (80-110 cm) lowest sub-oxic transition zone (40-52 cm). Conversely, zinc biofluids greatest highly-weathered tailings. Results indicate As Pb controlled (i) solubility Fe2+-bearing solids, (ii) prevalence soluble SO4 2-, (iii) presence poorly-crystalline Fe(III) oxide sorbents, whereas Zn pH-dependent stable solid phase.