Aluminum Adsorption and Antimonite Oxidation Dominantly Regulate Antimony Solubility in Soils

Soil antimony (Sb) contamination occurs globally due to natural processes and human activities. Total Sb concentration in soils fails to assess its ecological risk, while determined by the concentration of available Sb, which is readily for biological uptake. Available Sb in different soils varied significantly according to soil properties. However, so far it is unknown how soil properties regulate Sb availability, and no model has been established to predict it through soil properties. In this study, 19 soils spiked with antimonite [Sb(III)] were used to identify the major factors controlling Sb availability and establish its predicting models. The results showed that available Sb in different soils varied largely depending on the contents of free aluminum (fAl), free iron (fFe) and electric conductivity (EC), which explained 33%, 27% and 24.9% of the total variation, respectively. During the first 42 days of soil aging, fAl and EC effectively predicted the concentrations of available Sb with R