Toxicity and bioavailability of antimony in edible amaranth (Amaranthus tricolor Linn.) cultivated in two agricultural soil types

Abstract

Although elevated levels of antimony (Sb) in agricultural soil and plant systems can have harmful effects on human health and ecosystems, little is known about the toxicity of Sb to plants and its mechanism. The assessment of Sb bioavailability is essential for understanding its potential risks and toxicity. In this study, we used pot experiments with two agricultural soil types spiked with Sb to investigate the dose-effect relationship between exposure to Sb and toxic effects (growth and bioaccumulation) on edible amaranth (Amaranthus tricolor Linn.). Soil solution (pore water) and seven single extractants were used to assess the bioavailability of Sb. Different toxic effects of Sb to amaranth cultivated in two types of soils (alkaline and acid soil) were observed. In alkaline soil (chestnut soil, pH 8.39), antimony is more easily absorbed by root and transported to shoot by plants, leading to more adverse effects, than in acid soil (pH 4.91) under the same exposure level. Our findings also highlight the need for more attention on asymptomatic accumulation of Sb in plants, especially for agricultural products cultivated in contaminated areas. The extraction efficiency of Sb was various in different extractants and soil types, Mehlich 3, NaHCO3 and Na2HPO4 for Sb were more efficient than other extractants in both tested alkaline and acid soil. Based on the extractability and correlation coefficients of toxic effects on amaranth and extractable Sb, we found that 0.1 M Na2HPO4 is the best extractant to predict the bioavailability of Sb in soil, and M3 is a suitable alternative. Antimony concentration in soil solution can also be used as an alternative indicator of the bioavailability of Sb.