The effect of straw-returning on antimony and arsenic volatilization from paddy soil and accumulation in rice grains

Pollution by antimony (Sb) and arsenic (As) in soil can pose a great threat to human health. Straw-returning is widely applied to paddy fields for improving and remediating soil. A pot experiment was conducted to investigate the effect of straw-returning on Sb and As transformation and translocation in a soil–rice system. In this study, Sb and As co-contaminated soil was thoroughly mixed with different proportions (0, 0.5, 1, and 2%) of straw and used for growing rice plants through the entire growing stage in a pot experiment and 4 weeks in a microcosm experiment. The straw application significantly increased Sb and As mobility. The concentrations of total Sb and As in soil-pore water increased after the application of straw in most growing stages. The Sb volatilization in the pot and microcosm experiments was also stimulated by straw application. With the high dose of straw application (2%), the concentration of Sb in brown grain was reduced by 72% compared with the control, but As concentrations increased by around 77%. These findings provide a new perspective in that straw-returning could affect the behavior of both Sb and As in soil and reduce the Sb accumulation in brown grain and some guidance in the use of straw-returning in Sb-contaminated paddy soil. [Display omitted] •Straw-returning promoted the release of Sb and As from soil to pore water.•Straw-returning stimulated the volatilization of Sb and As from paddy soil.•Straw-returning decreased Sb translocation from straw to grain.•2% straw application reduced Sb concentration in rice grain compared with control. Straw-returning promoted the release and volatilizations of Sb and As from soil, as well as reducing the Sb content, but increasing the As content in rice brown grain.