Technoloy Research Center for Pollution Control and Remediation of Northwest Soil and Groundwater, College of Earth and Environmental Sciences, Lanzhou University, China.
Technoloy Research Center for Pollution Control and Remediation of Northwest Soil and Groundwater, College of Earth and Environmental Sciences, Lanzhou University, China.
J Hazard Mater. 2024 Jun 5;471:134415. doi: 10.1016/j.jhazmat.2024.134415. Epub 2024 Apr 24.
The migration and transformation mechanisms of arsenic (As) in soil environments necessitate an understanding of its influencing processes. Here, we investigate the subsurface biogeochemical transformation of As and iron (Fe) through amended in the top 20 cm with iron oxidizing bacteria (FeOB) and organic fertilizer (OF). Our comprehensive 400-day field study, conducted in a calcareous soil profile sectioned into 20 cm increments, involved analysis by sequential extraction and assessment of microbial properties. The results reveal that the introduction of additional OF increased the release ratio of As/Fe from the non-specific adsorption fraction (136.47 %) at the subsoil depth (40-60 cm), underscoring the importance of sampling at various depths and time points to accurately elucidate the form, instability, and migration of As within the profile. Examination of bacterial interaction networks indicated a disrupted initial niche in the bottom layer, resulting in a novel cooperative symbiosis. While the addition of FeOB did not lead to the dominance of specific bacterial species, it did enhance the relative abundance of As-tolerant Acidobacteria and Gemmatimonadetes in both surface (39.2 % and 38.76 %) and deeper soils (44.29 % and 23.73 %) compared to the control. Consequently, the amendment of FeOB in conjunction with OF facilitated the formation of poorly amorphous Fe (hydr)oxides in the soil, achieved through abiotic and biotic sequestration processes. Throughout the long-term remediation process, the migration coefficient of bioavailable As within the soil profile decreased, indicating that these practices did not exacerbate As mobilization. This study carries significant implications for enhancing biogeochemical cycling in As-contaminated Sierozem soils and exploring potential bioremediation strategies. ENVIRONMENTAL IMPLICATION: The long-term exposure of sewage irrigation has potential adverse effects on the local ecosystem, causing serious environmental problems. Microorganisms play a vital role in the migration and transformation of arsenic in calcareous soil in arid areas, which highlights the necessity of understanding its dynamics. The vertical distribution, microbial community and fate of arsenic in calcareous farmland soil profile in northwest China were studied through field experiments. The results of this work have certain significance for the remediation of arsenic-contaminated soil in arid areas, and provide new insights for the migration, transformation and remediation of arsenic in this kind of soil.
砷（As）在土壤环境中的迁移和转化机制需要了解其影响过程。在这里，我们通过在顶部 20 cm 中添加铁氧化细菌（FeOB）和有机肥（OF）来研究砷和铁（Fe）的地下生物地球化学转化。我们在钙质土壤剖面中进行了为期 400 天的综合现场研究，该研究将土壤剖面分成 20 cm 增量进行分析，包括连续提取分析和微生物特性评估。结果表明，在亚土层（40-60 cm）深度下，额外添加 OF 会增加非特异性吸附（136.47%）中砷/铁的释放比例，这突出了在不同深度和时间点采样以准确阐明剖面中砷的形态、不稳定性和迁移的重要性。细菌相互作用网络的检查表明，底层初始小生境被破坏，导致新的共生关系。虽然添加 FeOB 不会导致特定细菌物种的优势，但它确实增强了表面（39.2%和 38.76%）和较深土壤（44.29%和 23.73%）中耐砷酸杆菌和芽单胞菌的相对丰度，与对照相比。因此，与 OF 一起添加 FeOB 促进了土壤中贫非晶形铁（水合）氧化物的形成，这是通过非生物和生物固持过程实现的。在整个长期修复过程中，土壤剖面中生物可利用砷的迁移系数降低，表明这些措施并未加剧砷的迁移。这项研究对增强受砷污染的黑钙土中生物地球化学循环和探索潜在生物修复策略具有重要意义。
污水灌溉的长期暴露对当地生态系统有潜在的不利影响，造成严重的环境问题。微生物在干旱地区钙质土壤中砷的迁移和转化中起着至关重要的作用，这突出了了解其动态的必要性。通过田间实验研究了中国西北干旱地区钙质农田土壤剖面中砷的垂直分布、微生物群落和归宿。这项工作的结果对于干旱地区受砷污染土壤的修复具有一定的意义，为这种土壤中砷的迁移、转化和修复提供了新的思路。
