193 / 2025-04-14 16:55:15

Modified nano zero-valent iron coupling microorganisms to degrade BDE-209: Degradation pathways and microbial responses

Modification; Debromination; Intermediate products; Dehalogenated genes; Coupling systems; CSIA

Theme 2: Geobiology of Modern Habitable Earth > Session 2c: Geomicrobiology of Hazardous Elements Generated by Anthropogenic Activities

Polybrominated diphenyl ethers (PBDEs) in soil and groundwater have garnered considerable attention owing to the significant bioaccumulation potential and toxicity. Currently, the coupling treatment method of nano zerovalent iron (nZVI) with dehalogenation microorganisms is a research hotspot in the field of PBDE degradation. In this study, various systems were established within anaerobic environments, including the nZVI-only system, microorganism-only system, and the nZVI + microorganisms system. The aim was to investigate the degradation pathway of BDE-209 and elucidate the degradation mechanism within the coupled system. The results indicated that the degradation efficiency of the coupled system was better than that of the nZVI-only or microorganismonly system. Two modified nZVI (carboxymethyl cellulose and polyacrylamide) were prepared to improve the coupling degradation efficiency. CMC-nZVI showed the highest stability, and the coupled system consisting of microorganisms and CMC-nZVI showed the best degradation effect among all of the systems in this study, reaching 89.53% within 30 days. Furthermore, 22 intermediate products were detected in the coupling systems. Notably, changing the inoculation time did not significantly improve the degradation effect. The expression changes of the two reductive dehalogenase genes, e.g. TceA and Vcr, reflected the stress response and self-recovery ability of the dehalogenating bacteria, indicating such genes can be used as biomarker for evaluating the degradation performance of the coupling system. These findings provide a better understanding about the mechanism of coupling debromination process and the direction for the optimization and on-site repair of coupled systems.

Compound Specific Isotope Analysis (CSIA) refers to the technique of extracting and analyzing stable isotope ratios such as carbon, hydrogen, oxygen, chlorine, bromine, and nitrogen in each organic compound monomer at the molecular level. The technology based on stable isotopes is a powerful tool for exploring the degradation mechanism of organic pollutants and evaluating pollution remediation. The follow-up research plan is to use carbon and chlorine isotope analysis technology to analyze the migration, transformation pathways, and degradation mechanisms of POPs in polluted environments.