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[Display omitted] • Herbaceous plants were the primary native vegetation in the landfill cover. • Rumex Acetosa increased non-rhizosphere soil CH 4 oxidation capacity nearly 20-fold. • Root exudates induced microbial migration and specific metabolic pathways. • Limonexic acid enhanced methanotrophic bacteria activity and CH 4 degradation. Vegetation root exudates have the ability to shape soil microbial community structures, thereby enhancing CH 4 bio-oxidation capacity in landfill cover systems. In this study, the CH 4 oxidation capacity of indigenous vegetation rhizosphere microorganisms within operational landfill covers in Chongqing, China, was investigated for the first time, with the objective of identifying suitable plant candidates for CH 4 mitigation initiatives within landfill cover systems. Furthermore, a multi-omics methodology was employed to explore microbial community structures and metabolic variances within the rhizospheric environment of diverse vegetation types. The primary aim was to elucidate the fundamental factors contributing to divergent CH 4 oxidation capacities observed in rhizosphere soils. The findings demonstrated that herbaceous vegetation predominated in landfill covers. Notably, Rumex acetosa exhibited the highest CH 4 oxidation capacity in the rhizosphere soil, approximately 20 times greater than that in non-rhizosphere soil. Root exudates played a crucial role in inducing the colonization of CH 4 -oxidizing functional microorganisms in the rhizosphere, subsequently prompting the development of specific metabolic pathways. This process, in turn, enhanced the functional activity of the microorganisms while concurrently bolstering their tolerance to microbial pollutants. Consequently, the addition of substances like Limonexic acid strengthened the CH 4 bio-oxidation process, thereby underscoring the suitability of Rumex acetosa and similar vegetation species as preferred choices for landfill cover vegetation restoration. [ABSTRACT FROM AUTHOR]

The remediation of volatile chlorinated hydrocarbons in the quasi-vadose zone has become a significant challenge. We applied an integrated approach to assess the biodegradability of trichloroethylene to identify the biotransformation mechanism. The formation of the functional zone biochemical layer was assessed by analyzing the distribution of landfill gas, physical and chemical properties of cover soil, spatial-temporal variations of micro-ecology, biodegradability of landfill cover soil and distributional difference metabolic pathway. Real-time online monitoring showed that trichloroethylene continuously undergoes anaerobic dichlorination and simultaneous aerobic/anaerobic conversion-aerobic co-metabolic degradation on the vertical gradient of the landfill cover system and reduction in trans-1,2-dichloroethylene in the anoxic zone but not 1,1-dichloroethylene. PCR and diversity sequencing revealed the abundance and spatial distribution of known dichlorination-related genes within the landfill cover, with 6.61 ± 0.25 × 104–6.78 ± 0.09 × 106 and 1.17 ± 0.78 × 103–7.82 ± 0.07 × 105 copies per g/soil of pmoA and tceA , respectively. In addition, dominant bacteria and diversity were significantly linked with physicochemical factors, and Mesorhizobium , Pseudoxanthomonas and Gemmatimonas were responsible for biodegradation in the aerobic, anoxic and anaerobic zones. Metagenome sequencing identified 6 degradation pathways of trichloroethylene that may occur in the landfill cover; the main pathway was incomplete dechlorination accompanied by cometabolic degradation. These results indicate that the anoxic zone is important for trichloroethylene degradation. [Display omitted] • The attenuation mechanism of TCE was traced using five dimensions of data along landfill cover. • The microecology and function of anoxic zone are different from those of anoxic and anaerobic zone. • Mesorhizobium , Pseudoxanthomonas and Gemmatimonas are responsible for biodegradation in aerobic, anoxic and anaerobic zone. • TCE tends to be converted to cis-1,2-dichloroethylene in anoxic zone, but not 1,1-dichloroethylene. • Identifiedsix TCE metabolic pathways in anoxic zone, with main pathway of incomplete dechlorination and co-metabolism. [ABSTRACT FROM AUTHOR]