Yielding hydroxyl radicals in the Fenton-like reaction induced by manganese (II) oxidation determines Cd mobilization upon soil aeration in paddy soil systems

文献类型： 外文期刊

第一作者： Wang, Meng

作者： Wang, Meng;Chen, Shibao;Liu, Yongbing;Shi, Huading;Li, Shanshan

作者机构：

关键词： Soil cadmium availability; Paddy soil; Manganese redox; Fenton-like pathway; Hydroxyl radical

期刊名称：ENVIRONMENTAL POLLUTION （ 影响因子：9.988； 五年影响因子：10.366 ）

ISSN： 0269-7491

年卷期： 2022 年 292 卷

页码：

收录情况： SCI

摘要： As a redox-sensitive element, manganese (Mn) plays a critical role in Cd mobilization, especially in paddy soil. In an anoxic environment, the precipitation of Mn(II)-hydroxides specifically favors Cd retention, while draining the paddy fields results in substantial remobilization of Cd. However, how the change in Mn redox states during the periodical transit of anoxic to oxic systems affects Cd mobility remains unclear. In this study, we demonstrate that the radical effect generated during the oxidation of Mn(II)-hydroxides exerts a significant effect on the oxidative dissolution of Cd during the aeration of paddy soils. The extractable Cd concentration decreased rapidly during the reduction phases but increased upon oxidation, while Cd availability produced the opposite effect with soil pe + pH and the extractable Mn concentration. Inhibiting the oxidation of Mn(II)-containing phases by microbes suppressed the production of hydroxyl free radicals (center dot OH) and Cd mobilization in the drainage phase. Analysis of X-ray absorption spectroscopy and sequential extraction demonstrated that the transformation from the Mn phase of Mn(II) to Mn(III/IV) determines Cd solubility. Altogether, the oxidization of Mn(II)-hydroxides was associated with the generation of significant amounts of center dot OH. The dissolution of Mn(II)-incorporating phases lead to a net release of Cd into soils during soil aeration.

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