Key Factors Controlling Microbial Distribution on a DNAPL Source Area

Abstract The chlorinated solvents are among the common groundwater contaminants that show high complexity in their distribution in the subsoil. Microorganisms play a vital role in the natural attenuation of chlorinated solvents. Up to now, how the in situ soil microbial community responds to chlorinated solvents contamination remains unclear. In this study, the microbial community distribution within two boreholes located in the source area of perchloroethene (PCE) were investigated via terminal restriction fragment length polymorphism (T-RFLP) and clone library analysis. Microbial data were related to the lithological and geochemical data and the concentration and isotopic composition of chloroethenes to stablish the key factors controlling the distribution of the microbial communities. The results indicated that Proteobacteria, Actinobacteria and Firmicutes were the most abundant phylums in the sediment. The statistical correlation with the environmental data proved that fine granulometry, oxygen tolerance, terminal electron acceptor processes and toxicity control microbial structure. This study improves our understanding of how the microbial community in the subsoil responds to high concentration of chlorinated solvents.