Factors driving antimony accumulation in soil-pakchoi and wheat agroecosystems: Insights and predictive models

The accumulation of antimony (Sb) in plants and its potential effects on human health are of increasing concern. Nevertheless, only a few countries or regions have established soil Sb thresholds for agricultural purposes, and soil properties have not been taken into account. This study investigated the accumulation of Sb in the edible parts of pakchoi and wheat grain by adding exogenous Sb to 21 soils with varying properties. The results revealed a positive correlation between bioavailable Sb (Sb_ava, extracted by 0.1 M K₂HPO₄) in soil and Sb in the edible parts of pakchoi (R² = 0.77, p < 0.05) and wheat grain (R² = 0.54, p < 0.05). Both machine learning and traditional multiple regression analysis indicated Sb_ava was the most critical feature and the main soil properties that contributed to Sb uptake by pakchoi and wheat were CaCO₃ and clay, respectively. The advisory food limits for Sb in pakchoi and wheat were estimated based on health risk assessment, and used to derive soil thresholds for safe pakchoi and wheat production based on Sb_tot and Sb_ava, respectively. These findings hold potential for predicting Sb uptake by crops with different soil properties and informing safe production management strategies.