Pedosphere 36(5): 1023--1035, 2026
ISSN 1002-0160/CN 32-1315/P
©2026 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Roles of different-valence manganese oxides and hydroxyl radicals in controlling cadmium and arsenic mobilization in paddy soils |
Xuewei WANG1, Qingling FU1, Jun ZHU1, Linchuan FANG2, Hongqing HU1 |
1 State Environmental Protection Key Laboratory of Soil Health and Green Remediation, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070 (China);
2 Hubei Key Laboratory of Mineral Resources Processing and Environment, Wuhan University of Technology, Wuhan 430070 (China) |
| ABSTRACT |
| The redox states of manganese (Mn) oxides profoundly affect the mobility of cadmium (Cd) and arsenic (As) in soil. Hydroxyl radicals (·OH) have been identified as being generated in paddy soils. However, the effects of different-valence Mn oxides on the mobilization of Cd and As in soil still remain unclear, and the role of ·OH is not fully understood. This study investigated how Mn oxides of different valences affected the activities of Cd and As in paddy soils and elucidated the role of ·OH. The results demonstrated that birnessite (a high-valence Mn oxide) displayed a stronger inhibitory effect on Cd and As mobility, with 35.6%–60.9% extractable Cd and 24.2%–53.2% soluble As being suppressed, compared to MnO (a low-valence Mn oxide), which suppressed extractable Cd and soluble As by only 24.3%–38.0% and 9.5%–37.5%, respectively. Birnessite facilitated the oxidation of As(III) and Fe(II), which increased Fe-Mn oxide-bound Cd content and promoted the retention of As in Fe(III) phases. However, MnO limited the oxidation of As and Fe, weakening the immobilization of Cd and As by Fe-Mn oxides. Additionally, more Mn(III) generated by birnessite induced more H2O2 to degrade into ·OH under drainage than that by MnO. Importantly, ·OH promoted the conversion of low-valence Mn phases to high-valence counterparts, facilitated As oxidation, and inhibited As release, while enhancing Cd availability. This study provides novel insights into how Mn redox mediates the migration and transformation of Cd and As in paddy soils. }, |
| Key Words: As oxidation,birnessite,Fenton-like pathway,Mn redox,reactive oxygen species,soil Cd availability |
| Citation: Wang X W, Fu Q L, Zhu J, Fang L C, Hu H Q. 2026. Roles of different-valence manganese oxides and hydroxyl radicals in controlling cadmium and arsenic mobilization in paddy soils. Pedosphere. 36(5): 1023-1035. |
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