Yang Jing-Min, Wang Xin, Guan Dong-Xing, Huang Rui, Ji Xiong-Hui, Xie Yun-He, Peng Bo, Qin Qin-Bo
School of Geographical Sciences, Hunan Normal University, Changsha 410081, China; Institute of Interdisciplinary Studies, Hunan Normal University, Changsha 410081, China.
School of Geographical Sciences, Hunan Normal University, Changsha 410081, China; Institute of Interdisciplinary Studies, Hunan Normal University, Changsha 410081, China.
J Hazard Mater. 2025 Aug 15;494:138718. doi: 10.1016/j.jhazmat.2025.138718. Epub 2025 May 25.
This study investigated how reactive oxygen species (ROS) mediated by radial oxygen loss (ROL) function in arsenic (As) remediation through soil-rice iron barriers. Using high- and low-ROL rice varieties combined with zero-valent iron (ZVI) and steel slag amendments, As transformation pathways at soil-root interfaces were examined. ZVI increased soil amorphous Fe content by 22.8 %-49.3 % and iron plaque Fe by 59.9 %, while steel slag increased iron plaque weakly crystalline Fe by 62.4 %. Despite higher ROL, minimal As(III) oxidation occurred in rhizosphere compared to bulk soil due to counteracting effects of Fe(III)-reducing bacterial activity. However, substantial oxidation occurred on root surfaces, with As(V)/total As proportion reaching 59.3 %-74.3 %, attributed to hydroxyl radical accumulation driven by iron plaque thickening and amorphous Fe enrichment. In situ visualization using ROS-capturing membranes confirmed strong ROS accumulation specifically at root surfaces with negligible signals in surrounding soil. Path analysis established a positive relationship between hydroxyl radical production and As(V) proportion at iron plaque interfaces (path coefficient = 0.74, p < 0.01), which indirectly reduced grain inorganic As. These findings elucidate the critical role of localized ROS processes in As immobilization and provide a mechanistic foundation for developing effective rhizosphere-targeted remediation strategies in contaminated paddy systems.
本研究调查了通过土壤-水稻铁屏障进行砷（As）修复过程中，径向氧损失（ROL）介导的活性氧（ROS）如何发挥作用。利用高ROL和低ROL水稻品种，结合零价铁（ZVI）和钢渣改良剂，研究了土壤-根际界面处的砷转化途径。ZVI使土壤中无定形铁含量增加了22.8% - 49.3%，铁膜中铁含量增加了59.9%，而钢渣使铁膜中弱结晶铁含量增加了62.4%。尽管ROL较高，但由于铁还原细菌活性的抵消作用，根际中As(III)的氧化量与原状土相比最少。然而，在根表面发生了大量氧化，As(V)/总砷比例达到59.3% - 74.3%，这归因于铁膜增厚和无定形铁富集驱动的羟基自由基积累。使用ROS捕获膜的原位可视化证实，ROS在根表面特异性强烈积累，周围土壤中的信号可忽略不计。路径分析表明，在铁膜界面处羟基自由基产生与As(V)比例之间存在正相关关系（路径系数 = 0.74，p < 0.01），这间接降低了籽粒中的无机砷。这些发现阐明了局部ROS过程在砷固定中的关键作用，并为在受污染稻田系统中开发有效的根际靶向修复策略提供了机理基础。
