Manganese (II) sulfate affects the formation of iron-manganese oxides in soil and the uptake of cadmium and arsenic by rice
Yan Qin, Zhiming Li, Jing Sun, Meihua Xu, Minghua Gu, Yanyan Wei, Jing Lei
Abstract
Rice (Oryza sativa L.) consumption represents a major route of human exposure to cadmium (Cd) and arsenic (As), especially in Asia. This study investigated the effects of adding MnSO4 (0, 200, 400, and 800 mg kg‐1−1) on the formation of soil Fe/Mn oxides and Cd and As uptake in rice. The application of MnSO4 reduced soil pH, increased Eh, increased the contents of Fe/Mn oxides in the soil, and decreased the total Fe and Mn2+ contents in the porewater. It also led to lower contents of available Cd and As, higher levels of Cd and As bound to Fe/Mn oxides, and higher abundances of Thiobacillus and Syntrophobacter. Furthermore, Mn application increased the Fe and Mn contents in the root Fe/Mn plaque and decreased the grain Cd and As contents. Therefore, Mn application may modify the microbial community and porewater composition in soil, resulting in higher levels of Fe/Mn oxides in soil and Fe/Mn plaque at the root surface and in a lower accumulation of Cd and As in rice grains. Thus, Mn application can be a promising strategy for Cd and As stabilization in soils.