School of Environmental Studies, China University of Geosciences, Wuhan 430074, PR China.
School of Environmental Studies, China University of Geosciences, Wuhan 430074, PR China; State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, PR China.
Sci Total Environ. 2023 Feb 1;858(Pt 2):159884. doi: 10.1016/j.scitotenv.2022.159884. Epub 2022 Nov 2.
Iron (Fe)-manganese (Mn) minerals formed in situ can be used for the natural remediation of the primary poor-quality groundwater with coexistence of arsenite [As(III)], Mn(II), and Fe(II) (PGAMF). However, the underlying mechanisms of immobilization and coupling of As, Mn, and Fe during in-situ formation of Fe-Mn minerals in PGAMF remains unclear. The simultaneous immobilization and coupling of arsenic (As), Mn, and Fe in PGAMF during in-situ formation of biogenic Fe-Mn minerals induced by O perturbations and indigenous bacteria (Comamonas sp. RM6) were investigated at the different molar ratios of Fe(II):Mn(II) (1:1, 2:1, and 3:1). Compared with systems without Fe(II) in the presence of Mn(II), the coexisted Fe(II) significantly enhanced Mn(II) bio-oxidation and mineral precipitation, resulting in As immobilization increased by 5, 7, and 7 times at initial Fe(II) concentration of 0.3, 0.6, and 0.9 mM, respectively. Moreover, the As(III) immobilization efficiencies in Mn(II) and Fe(II) mixed system at initial Fe(II) concentration of 0.3, 0.6, and 0.9 mM were 73%, 91%, and 92%, respectively, that were significantly higher than those of single Fe(II) system (30%, 59%, and 74%) and those of single Mn(II) system (12%), indicating that Fe(II) and Mn(II) oxidation synergically enhanced As(III) immobilization. This was mainly attributed to the formation and As adsorption capacity of biogenic Fe-Mn minerals (BFMM). The formed BFMM significantly facilitated simultaneous immobilization of Fe, Mn, and As in PGAMF by oxidation, adsorption, and precipitation/coprecipitation, a coupling of biological, physical, and chemical processes. Fe component was mainly responsible for As fixation, and Mn component dominated As(III) oxidation. Based on the results from this work, biostimulation and bioaugmentation techniques can be developed for in-situ purification and remediation of PGAMF. This work provides insights into the simultaneous immobilization of pollutants in PGAMF, as well as promising strategies for in-situ purification and remediation of PGAMF.
铁（Fe）-锰（Mn）矿物原位形成可用于共存亚砷酸盐[As（III）]、Mn（II）和 Fe（II）（PGAMF）的原生劣质地下水的自然修复。然而，在 PGAMF 中原位形成 Fe-Mn 矿物时，As、Mn 和 Fe 的固定和偶联的潜在机制仍不清楚。在 O 扰动和土著细菌（Comamonas sp. RM6）诱导的 PGAMF 中生物生成的 Fe-Mn 矿物原位形成过程中，同时固定和偶联砷（As）、Mn 和 Fe，研究了不同的 Fe（II）：Mn（II）摩尔比（1:1、2:1 和 3:1）。与存在 Mn（II）但没有 Fe（II）的系统相比，共存的 Fe（II）显着增强了 Mn（II）的生物氧化和矿物沉淀，导致在初始 Fe（II）浓度分别为 0.3、0.6 和 0.9 mM 时，As 固定率分别增加了 5、7 和 7 倍。此外，在初始 Fe（II）浓度为 0.3、0.6 和 0.9 mM 的 Mn（II）和 Fe（II）混合体系中，As（III）固定效率分别为 73%、91%和 92%，明显高于单一 Fe（II）体系（30%、59%和 74%）和单一 Mn（II）体系（12%），表明 Fe（II）和 Mn（II）氧化协同增强了 As（III）固定。这主要归因于生物生成的 Fe-Mn 矿物（BFMM）的形成和 As 吸附能力。形成的 BFMM 通过氧化、吸附和沉淀/共沉淀显着促进了 PGAMF 中 Fe、Mn 和 As 的同时固定，实现了生物、物理和化学过程的偶联。Fe 组分主要负责 As 固定，而 Mn 组分主导 As（III）氧化。基于这项工作的结果，可以开发生物刺激和生物增强技术，用于原位净化和修复 PGAMF。这项工作为 PGAMF 中污染物的同时固定提供了新的见解，并为 PGAMF 的原位净化和修复提供了有前景的策略。
