Ecotoxicology and Environmental Safety ( IF 6.2 ) Pub Date : 2023-05-21 , DOI: 10.1016/j.ecoenv.2023.115047 Jianling Fan 1 , Cuiying Liu 2 , Jinjin Zheng 3 , Yang Song 4
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.
中文翻译:
连二亚硫酸盐促进六氯苯的微生物脱氯,而针铁矿进一步加速水稻土硫化非生物降解
探索土壤中六氯苯(HCB)加速降解的机理具有重要的科学意义和实际意义。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仍不清楚。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,以揭示其潜在机制。结果表明,单独添加针铁矿不会显着影响 HCB 脱氯,因为所研究的土壤缺乏铁还原菌。相反,添加连二亚硫酸盐可显着降低 HCB 含量 44.0–54.9%,而连二亚硫酸盐和针铁矿的共存进一步降低了 HCB 含量 57.9-69.3%。随机森林分析表明指标类群(类芽孢杆菌属、嗜酸嗜热菌属、Haliagium 属、G12-WMSP1 和Frankia 属)、假单胞菌属、微生物群落的丰富度和香农指数以及固定化铁含量是 HCB 脱氯的主要驱动因素。添加连二亚硫酸盐,无论有无针铁矿,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 厌氧脱氯。当针铁矿和连二亚硫酸盐共存时,针铁矿与连二亚硫酸盐的硫化可以显着增加 FeS 的形成,进而进一步提高 HCB 的脱氯率。总的来说,我们的结果表明,针铁矿和连二亚硫酸盐的联合应用可能是修复 HCB 污染土壤的可行策略。