Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, 219 Ningliu Road, Nanjing 210044, China.
Jiangsu Key Laboratory of Agricultural Meteorology, School of Applied Meteorology, Nanjing University of Information Science and Technology, 219 Ningliu Road, Nanjing 210044, China.
Ecotoxicol Environ Saf. 2023 Jul 1;259:115047. doi: 10.1016/j.ecoenv.2023.115047. Epub 2023 May 21.
It is of great scientific and practical importance to explore the mechanisms of accelerated degradation of Hexachlorobenzene (HCB) in soil. Both iron oxide and dithionite may promote the reductive dechlorination of HCB, but their effects on the microbial community and the biotic and abiotic mechanisms behind it remain unclear. This study investigated the effects of goethite, dithionite, and their interaction on microbial community composition and structure, and their potential contribution to HCB dechlorination in a paddy soil to reveal the underlying mechanism. The results showed that goethite addition alone did not significantly affect HCB dechlorination because the studied soil lacked iron-reducing bacteria. In contrast, dithionite addition significantly decreased the HCB contents by 44.0-54.9%, while the coexistence of dithionite and goethite further decreased the HCB content by 57.9-69.3%. Random Forest analysis suggested that indicator taxa (Paenibacillus, Acidothermus, Haliagium, G12-WMSP1, and Frankia), Pseudomonas, richness and Shannon's index of microbial community, and immobilized Fe content were dominant driving factors for HCB dechlorination. The dithionite addition, either with or without goethite, accelerated HCB anaerobic dechlorination by increasing microbial diversity and richness as well as the relative abundance of the above specific bacterial genera. When goethite and dithionite coexist, sulfidation of goethite with dithionite could remarkably increase FeS formation and then further promote HCB dechlorination rates. Overall, our results suggested that the combined application of goethite and dithionite could be a practicable strategy for the remediation of HCB contaminated soil.
探索六氯苯（HCB）在土壤中加速降解的机制具有重要的科学和实际意义。氧化铁和连二亚硫酸盐都可能促进 HCB 的还原脱氯，但它们对微生物群落的影响及其背后的生物和非生物机制尚不清楚。本研究调查了针铁矿、连二亚硫酸盐及其相互作用对微生物群落组成和结构的影响，以及它们对水稻土中 HCB 脱氯的潜在贡献，以揭示潜在的机制。结果表明，单独添加针铁矿对 HCB 脱氯没有显著影响，因为研究土壤中缺乏铁还原菌。相比之下，添加连二亚硫酸盐可使 HCB 含量显著降低 44.0-54.9%，而连二亚硫酸盐和针铁矿共存时则进一步降低 57.9-69.3%。随机森林分析表明，指示菌（Paenibacillus、Acidothermus、Haliagium、G12-WMSP1 和 Frankia）、假单胞菌、微生物群落的丰富度和 Shannon 指数以及固定化 Fe 含量是 HCB 脱氯的主要驱动因素。添加连二亚硫酸盐，无论是否添加针铁矿，都通过增加微生物多样性和丰富度以及上述特定细菌属的相对丰度来加速 HCB 的厌氧脱氯。当针铁矿和连二亚硫酸盐共存时，连二亚硫酸盐与针铁矿的硫化作用可显著增加 FeS 的形成，从而进一步促进 HCB 的脱氯速率。总体而言，我们的研究结果表明，针铁矿和连二亚硫酸盐的联合应用可能是修复 HCB 污染土壤的一种可行策略。
