Evaluation of antimony availability in a mining context: Impact for the environment, and for mineral exploration and exploitation.

This work aims to establish Sb mobility, its transfer to biota and its effect on soil health in a semi-arid climate. The results show the presence of stibnite (Sb2S3) as the main primary Sb compound, bindhemite (Pb2Sb2O6(O, OH)), and minor proportions of stibiconite (Sb3+(Sb5+)2O6(OH)) as oxidised Sb species. This research also observes very high total Sb contents in mining materials (max: 20,000 mg kg- 1) and soils (400-3000 mg kg- 1), with physical dispersion around mining materials restricted to 450 m. The soil-to-plant transfer is very low, (bioaccumulation factor: 0.0002-0.1520). Most Sb remains in a residual fraction (99.9%), a very low fraction is bound to Fe and Mn oxy-hydroxides or organic matter, and a negligible proportion of Sb is leachable. The higher Sb mobility rates has been found under oxidising conditions with a long contact time between solids and water. The main factors that explain the poor Sb mobility and dispersion in the mining area are the low annual rainfall rates that slow down the Sb mobilisation process and the scarce formation of oxidised Sb compounds. All these data suggest poor Sb (III) formation and a low toxicological risk in the area associated with past mining activities.

Automated summary

This study focuses on Sb mobility, its transfer to biota, and its impact on soil health in a semi-arid climate. The research identifies stibnite (Sb2S3) as the primary Sb compound and observes high Sb contents in mining materials and soils. The soil-to-plant transfer of Sb is very low, and most of it remains in a residual fraction, with a negligible amount being leachable. The study suggests that the low annual rainfall rates and the scarcity of oxidized Sb compounds explain the limited Sb mobility and dispersion in the mining area, indicating a low toxicological risk associated with past mining activities.