Speciation, in vitro bioaccessibility and health risk of antimony in soils near an old industrial area

Antimony (Sb) contamination in soil has become a major environmental issue due to its adverse effects on ecosystems and human health. In this paper, 1255 soil samples were analyzed to investigate the distribution, speciation, in vitro oral bioaccessibility (8 soil samples) and human health risk of Sb in contaminated soils and its impacts on groundwater. The results showed that 4.38 % of the soil samples within the depth of 0-31 m exceeded the Risk Screening Values (RSV). Sb mainly existed in the residual fraction (38.05 % similar to 94.22 %), Fe/Mn oxides (0.01 % similar to 31.80 %) and the organic fraction (0.32 % similar to 21.55 %) with poor mobility. The bioaccessibility of Sb was approximately < 31 %. The total concentration of Sb (TSb) in soil was the dominant factor influencing the bioaccessible concentration of Sb (Sb-Bio). Soil physiochemical properties such as Fe, Mn, and organic matter content (OM) also affected the magnitude of Sb-Bio. Health risk assessment based on in vitro bioaccessibility suggested that the hazard quotient (HQ) of adults was within the acceptable level (HQ < 1) for industrial scenario, while the HQ of children and adults was greater than the acceptable level (HQ >= 1) for residential scenario, with a higher risk to children than adults. The results of the leaching experiment involving Dilution-Attenuation Factor (DAF) model suggested that the predicted maximum concentration of Sb in groundwater was 2.40 mu g/L that is lower than the acceptable standard value (5 mu g/L), implying that ground-water was not contaminated by Sb in soil. The findings of this study provide some insights into the speciation, in vitro bioaccessibility and health risk of toxic trace metals in contaminated soils and the potential environmental impacts.