Comparison of diffusive gradients in thin-films (DGT) and chemical extraction methods for predicting bioavailability of antimony and arsenic to maize

Abstract

Antimony (Sb) and arsenic (As) are hazardous metalloids that cause much attention. Assessing the bioavailability is essential for understanding the potential risk and toxicity of Sb and As in soils. In this study, a set of methods were tested to assess the bioavailability of Sb and As to field/potted maize. Twelve soils, 7 maize (Zea mays L.) samples and corresponding root soils were collected from the world's largest active Sb mining area (Xikuangshan, China). The soils contained average 1074 mg/kg Sb and 65 mg/kg As with the pH varied from 4.78–7.70. Eight soil samples with a gradient of Sb and As concentration were selected for pot experiments of maize. Diffusive gradients in thin-films (DGT) and traditional chemical extraction methods, including six single-step extractions (H2O, 0.01 M CaCl2, 1 M NH4NO3, 0.1 M Na2HPO4, 0.05 M EDTA and 0.005 M DTPA) and modified-BCR sequential extraction were used to predict the bioaccumulation of Sb and As by maize. Sb and As measured by DGT, DTPA and modified-BCR correlated better with Sb and As in the shoots and roots of field/potted maize compared to H2O, CaCl2, NH4NO3, Na2HPO4 and EDTA. The correlation coefficients of DGT, DTPA and modified-BCR were at least 0.869 (p < 0.01), 0.866 (p < 0.01) and 0.831 (p < 0.05), respectively. These three techniques are well applicable for simultaneous prediction of Sb and As bioavailability to both field and potted maize in soils.