Dai Wenjing, Shi Rongguang, Li Xiaodong, Zhao Zhiqi, Xia Zihan, Li Dongli, Li Yan, Cui Gaoyang, Ding Shiyuan
School of Earth System Science, Tianjin University, Tianjin 300072, China.
School of Earth Science and Resource, Chang'an University, Xi'an 710054, China.
Microorganisms. 2024 Nov 21;12(12):2385. doi: 10.3390/microorganisms12122385.
Contained arsenic (As) and unsafe brackish groundwater irrigation can lead to serious As pollution and increase the ecological risk in cultivated soils. However, little is known about how Fe oxides and microbes affect As migration during soil irrigation processes involving arsenic-contaminated brackish groundwater. In this study, the samples (porewater and soil) were collected through the dynamic soil column experiments to explore the As migration process and its effect factors during soil irrigation. The results showed that the As concentration in porewater samples from the topsoil was enriched compared to that in the subsoil, and the main solid As fractions were strongly adsorbed or bound to amorphous and crystalline Fe oxides. The aqueous As concentration and the solid As fractions indicated that reductive dissolution and desorption from amorphous Fe oxides were the primary mechanisms of As release at the topsoil and subsoil, respectively. Meanwhile, _sp., and were the dominant microbes affecting As biotransformation by arsenate reductase gene () expression. Accompanied by the Eh and competitive ions concentration change, amorphous Fe oxide dissolution increased to facilitate the As release, and the changes in the microbial community structure related to As reduction may have enhanced As mobilization in soils irrigated by As-containing brackish groundwater.
含砷的咸水灌溉会导致严重的砷污染，并增加耕地土壤的生态风险。然而，在涉及受砷污染的咸水灌溉的土壤灌溉过程中，铁氧化物和微生物如何影响砷的迁移却鲜为人知。在本研究中，通过动态土柱实验采集了样品（孔隙水和土壤），以探究土壤灌溉过程中的砷迁移过程及其影响因素。结果表明，与下层土壤相比，表层土壤孔隙水样品中的砷浓度有所富集，主要的固体砷组分强烈吸附或结合于无定形和结晶态铁氧化物。孔隙水中的砷浓度和固体砷组分表明，无定形铁氧化物的还原溶解和解吸分别是表层土壤和下层土壤中砷释放的主要机制。同时，_sp.、和_是通过砷酸盐还原酶基因（）表达影响砷生物转化的主要微生物。伴随着氧化还原电位（Eh）和竞争离子浓度的变化，无定形铁氧化物溶解增加，促进了砷的释放，与砷还原相关的微生物群落结构变化可能增强了含砷咸水灌溉土壤中砷的迁移能力。
