Effects of concurrent PFASs and CAHs on microbial communities in soil and groundwater: an insight for their ecological niches and implications for bioremediation

Abstract

The combined impacts of per- and polyfluoroalkyl substances (PFASs) and chlorinated aliphatic hydrocarbons (CAHs) on native microbial communities in subsurface remain poorly understood. In this study, we employed high-throughput sequencing to investigate the impacts of concurrent PFASs and CAHs on the indigenous microbial communities in soil and groundwater. Additionally, we assessed the relative contributions of deterministic and stochastic processes in shaping microbial community assembly across these two subsurface compartments. The results revealed that perfluorooctanoic acid was the dominant PFAS compound in subsurface, and short-chain perfluorocarboxylic acids (C < 8) were prevalent in groundwater, while perfluorosulfonic acids were more likely retained in soil. CAHs were detected at concentrations up to 650.15 mg/L in groundwater, suggesting the presence of dense non-aqueous-phase liquids in subsurface. The comparative analysis on the microbial diversity and compositions showed that microbial diversity in groundwater was more influenced by the distribution of contaminants compared to that in soil. Additionally, the βNTI analysis results indicated that microbial community assembly in soil was mainly shaped by homogeneous selection, whereas stochastic processes dominated the evolution of microbial community in groundwater. Furthermore, anaerobic fermentative taxa species such as Bacillus and Sva0485 dominated in soil, while aerobic pollutant-degrading taxa like Oxalobacteraceae and Dehalogenimonas were enriched in groundwater. These findings highlight the need to consider microbial communities and ecological processes when designing effective in-situ bioremediation strategies.