Citation:

Kastury, F., J. Basedin, Aaron R. Betts, R. Asamoah, C. Herde, P. Netherway, J. Tully, Kirk G. Scheckel, AND A. Juhasz. Arsenic, cadmium, lead, antimony bioaccessibility and relative bioavailability in legacy gold mining waste. JOURNAL OF HAZARDOUS MATERIALS. Elsevier Science Ltd, New York, NY, 469:133948, (2024). https://doi.org/10.1016/j.jhazmat.2024.133948

Impact/Purpose:

This study investigated human health exposure to As, Cd, Pb and Sb from 30 legacy gold mining impacted soils (7 calcine sands, 11 grey battery sands and 12 tailings) from Victorian goldfields (Australia). Pseudo-total As concentration in 29 samples was 1.45-148-fold higher than the soil guideline value of 100 mg/kg for residential areas with soil accessible to children. Additionally, pseudo-total Cd and Pb concentrations in calcine sands were up to 2.4-fold and 30.1-fold higher than soil guideline values of 20 mg/kg and 300 mg/kg respectively. Five calcine sands also showed elevated Sb (31.9-5,983 mg/kg), however, Australian soil guideline value is currently unavailable for this element. Arsenic bioaccessibility (n=30) ranged from 6.10-77.6% and RBA (n=8) ranged from 10.3-52.9%. Samples with >50% insoluble arsenopyrite or scorodite showed low bioaccessibility (<20.0%) and RBA (<15.0%). Co-contaminant RBA was assessed in 4 calcine sands. Pb and Cd RBA was higher (73.7-119% and 55.0-67.0% respectively) than Sb (<5%). While high Pb RBA was associated with organic and mineral sorbed Pb, proportionally lower Pb RBA was observed in samples with insoluble plumbojarosite. Antimony was present as Sb(V) in all calcine sands. Cadmium speciation was not undertaken due to the low number of samples exceeding guideline values.

Description:

Bioaccessibility and relative bioavailability of As, Cd, Pb and Sb was investigated in 30 legacy gold mining wastes (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 (31.9–5983 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 As bioaccessibility (<20.0%) and RBA (<15.0%). Co-contaminant RBA was assessed in 4 calcine sands; Pb RBA ranged from 73.7–119% with high Pb RBA associated with organic and mineral sorbed Pb and, lower Pb RBA observed in samples containing plumbojarosite. In contrast, Cd RBA ranged from 55.0–67.0%, while Sb RBA was < 5%. 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.

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