Xu Peng, Sun Linghong, Chen Yun, Guo Zhengzheng, Ding Lei, Wu Zhenbin
Jiangsu Key Laboratory of Ocean-Land Environmental Change and Ecological Construction, China; School of Marine Science and Engineering, Nanjing Normal University, Nanjing 210023, China.
School of Marine Science and Engineering, Nanjing Normal University, Nanjing 210023, China.
Water Res. 2025 Sep 15;284:123975. doi: 10.1016/j.watres.2025.123975. Epub 2025 Jun 7.
This study investigated the potential of bioelectrochemical systems (BESs) in enhancing arsenic (As) sequestration in sulfur-rich sediments through submerged aquatic plant Vallisneria natans (V. natans). A mechanism entailing bioelectrogenesis-driven sulfur oxidation, which facilitated root iron plaque (IP) formation and As oxidation, was proposed. A 125-day microcosm study was conducted using coupled plant-BES configurations, comprising: a microbial fuel cell (MFC), microbial electrolysis cells (MECs) with voltage gradients, and V. natans. Results showed that As accumulation and enrichment efficiency in IPs increased proportionally with applied voltage. Electrogenesis enhanced IP development, with MECs outperforming the MFC. Rhizospheric phosphorus deficiency in MFC stimulated radial oxygen loss (ROL) and microbial Fe oxidation for IP formation. In MECs, enhanced endogenous Fe availability and reduction in ΣHS concentrations collectively facilitated IP development. As oxidation in MFC was significantly amplified within the rhizosphere by As-oxidizing microorganisms. Sulfite (SO), a metabolite of sulfur oxidation, was electrochemically activated in MECs to generate sulfite radicals (SO), demonstrating superior As oxidation efficacy compared to MFC. Metagenomic analysis revealed extracellular electron transfer (EET) efficiency dictated the sulfur oxidation pathway. MFC exhibited FeS-dominated oxidation with terminal S and intermediate SO formation, suppressing ΣHS elimination. MECs displayed insufficient EET, driving ΣHS oxidation, FeS consumption, and SO accumulation. Intracellular sulfur oxidation pathways differed between systems: the rDsr pathway dominated in MFC, while Hdr process prevailed in MECs. Anode-associated keystone genera responsible for sulfur oxidation were Thiobacillus and Pseudomonas in MFC and MECs, respectively. Iron-oxidizing Collimonas and As oxidizing Halomonas/Acinetobacter were crucial for mediating IP formation and As oxidization, respectively in MFC. These findings demonstrate that BESs are effective tools for augmenting As sequestration by submerged aquatic plants. This investigation establishes foundational insights for practical implementation of integrated plant-BESs in As-contaminated sediment remediation strategies.
本研究探讨了生物电化学系统（BESs）通过沉水植物苦草（Vallisneria natans）增强富硫沉积物中砷（As）固定的潜力。提出了一种由生物电产生驱动的硫氧化机制，该机制促进了根际铁膜（IP）的形成和As的氧化。使用耦合植物 - BES配置进行了为期125天的微观研究，包括：微生物燃料电池（MFC）、具有电压梯度的微生物电解池（MECs）和苦草。结果表明，IPs中As的积累和富集效率与施加电压成正比增加。生物电产生增强了IP的发育，MECs的表现优于MFC。MFC中根际磷缺乏刺激了径向氧损失（ROL）和微生物铁氧化以形成IP。在MECs中，内源性铁可用性的增强和ΣHS浓度的降低共同促进了IP的发育。MFC中根际内As氧化微生物显著放大了As的氧化。亚硫酸盐（SO）是硫氧化的代谢产物，在MECs中被电化学激活以产生亚硫酸根自由基（SO），与MFC相比，显示出优异的As氧化效果。宏基因组分析表明，细胞外电子转移（EET）效率决定了硫氧化途径。MFC表现出以FeS为主的氧化，形成末端S和中间SO，抑制了ΣHS的消除。MECs显示出不足的EET，驱动ΣHS氧化、FeS消耗和SO积累。系统之间细胞内硫氧化途径不同：MFC中以rDsr途径为主，而MECs中以Hdr过程为主。MFC和MECs中负责硫氧化的阳极相关关键属分别是硫杆菌属和假单胞菌属。铁氧化菌Collimonas和As氧化菌嗜盐单胞菌/不动杆菌分别对MFC中介导IP形成和As氧化至关重要。这些发现表明，BESs是增强沉水植物对As固定的有效工具。本研究为在受As污染沉积物修复策略中实际应用集成植物 - BESs建立了基础见解。
