Unraveling the biogeochemical behaviour of arsenic and antimony in soils and bioavailability to agricultural plants

The enrichment of soil arsenic (As) and antimony (Sb) is putting increasing pressure on the environment and human health. The biogeochemical behaviour of Sb and its uptake mechanisms by plants are poorly understood and generally assumed to be similar to that of As. Accurate assessment of the bioavailability of these toxic elements to agricultural crops grown in contaminated soils under different scenarios is important for the management of contaminated soils and minimising the risk of human exposure. In this study, the diffusive gradients in thin films (DGT) technique and sequential extraction procedure (SEP) were applied to assess the partitioning and lability of As and Sb under agricultural conditions in historically contaminated soils with various physicochemical properties. The performance of DGT in predicting As and Sb uptake by two cultivars of radish (Raphanus sativus), water spinach (Ipomoea aquatica) grown in these soils were investigated, compared to soil solution analysis and sequential extraction. The competitive interactions of As and Sb in single (As-only and Sb-only) and multi-contaminant (As+Sb) soils and the interactive effects of As and Sb on accumulation by I. aquatica were also examined. Furthermore, the effect of changing redox conditions on the behaviour and speciation of As and Sb in soils using multiple in situ DGT samplers and their accumulation and speciation in I. aquatica cultivated in such changing environments were investigated