Guangdong Engineering Technology Research Center of Heavy Metal Pollution Control and Restoration in Farmland Soil, South China Institute of Environmental Sciences, MEE, Guangzhou 510535, China; State Environmental Protection Key Laboratory of Water Environment Simulation and Pollution Control, Guangzhou 510535, China.
Guangdong Engineering Technology Research Center of Heavy Metal Pollution Control and Restoration in Farmland Soil, South China Institute of Environmental Sciences, MEE, Guangzhou 510535, China.
J Hazard Mater. 2023 Feb 5;443(Pt B):130100. doi: 10.1016/j.jhazmat.2022.130100. Epub 2022 Sep 30.
Soil particle size fractions (PSFs) are important for arsenic (As) partitioning, migration, and speciation transformation. However, information is lacking about the environmental fate of As and its distribution on different PSFs. In the present study, two types of soils from mining areas were divided into four PSFs, including coarse sand (2-0.25 mm), fine sand (0.25-0.05 mm), silt (0.05-0.002 mm), and clay (< 0.002 mm) fractions. The results showed that As was enriched in the coarse sand, which was primarily affected by the content of organic carbon (OC), followed by iron (Fe), aluminum (Al), and manganese (Mn) (hydr)oxides. The elevated total As (TAs), As(III), organic As, Fe(II), and dissolved organic carbon (DOC) concentrations were mainly originated from the clay fraction. The intensified humification degree of DOM and promoted bacterial metabolism related to As/iron bioreduction were also exhibited in the clay fractions. The dynamics of As fractions in soils indicated the potential formation of secondary minerals and re-adsorption of As in the PSFs. The highest abundances of arrA, arsC, arsM, and Geo genes were found in the clay fraction, implying that the clay fraction potentially released more As, including As(III) and organic As. Results from the correlation analysis showed that elevated DOC concentrations promoted the catabolic responses of iron-reducing microorganisms and triggered microbial As detoxification. Overall, this study provides valuable information and guidance for the remediation of As-contaminated soils.
土壤颗粒大小分级（PSFs）对砷（As）的分配、迁移和形态转化具有重要意义。然而，有关砷的环境归宿及其在不同 PSFs 上的分布的信息仍然缺乏。在本研究中，我们将来自矿区的两种土壤分为四个 PSFs，包括粗砂（2-0.25 毫米）、细砂（0.25-0.05 毫米）、粉砂（0.05-0.002 毫米）和粘土（<0.002 毫米）。结果表明，As 主要富集在粗砂中，主要受有机碳（OC）、铁（Fe）、铝（Al）和锰（Mn）（氢）氧化物的含量影响。总 As（TAs）、As(III)、有机 As、Fe(II)和溶解有机碳（DOC）浓度的升高主要源于粘土。DOM 的腐殖化程度增强，以及与 As/铁生物还原相关的细菌代谢也在粘土中得到促进。土壤中 As 分级的动态表明，次生矿物的形成和 PSFs 中 As 的再吸附具有潜在可能性。arrA、arsC、arsM 和 Geo 基因的丰度在粘土中最高，表明粘土可能释放更多的 As，包括 As(III)和有机 As。相关性分析结果表明，DOC 浓度的升高促进了铁还原微生物的代谢反应，并触发了微生物的 As 解毒。总的来说，本研究为受 As 污染土壤的修复提供了有价值的信息和指导。
