Arsenic, Cadmium, Lead and Antimony Exposure from Legacy Mining Impacted Soils

Abstract

Human health exposure to As, Cd, Pb and Sb was investigated from 30 legacy gold mining impacted soils (calcine sands, grey battery sands, tailings) from Victorian goldfields (Australia). Pseudo-total As concentration in 29 samples was 1.45-148-fold higher than the residential soil guidance value (100 mg/kg) while Cd and Pb concentrations in calcine sands were up to 2.4-fold and 30.1-fold higher than the corresponding guidance value (Cd: 20 mg/kg and Pb: 300 mg/kg). Five calcine sands exhibited elevated Sb (31.9-5,983 mg/kg), although an Australian soil guidance value is currently unavailable. Arsenic bioaccessibility (n=30) and relative bioavailability (RBA; n=8) ranged from 6.10-77.6% and 10.3-52.9% respectively. Samples containing >50% arsenopyrite/scorodite showed low bioaccessibility (<20.0%) and RBA (<15.0%). Co-contaminant RBA was assessed in 4 calcine sands with Pb and Cd RBA of 73.7-119% and 55.0-67.0% respectively, while Sb RBA was <5%. While high Pb RBA was associated with organic and mineral sorbed Pb, lower Pb RBA was observed in samples containing plumbojarosite. Although Cd speciation was not undertaken, Sb was present as Sb(V) in all calcine sands. This study highlights the importance of using multiple lines of evidence during exposure assessment and provides valuable baseline data for co-contaminants associated with legacy gold mining activities.

Keywords: Bioaccessibility, bioavailability, Relative bioavailability, Speciation, Gold mining