Microbial Community Composition of a Trichloroethene (TCE)- Contaminated Aquifer Undergoing Phytoremediation

摘要

TCE is used as an industrial solvent and has contaminated vast volumes of groundwater worldwide. The microbial community composition of a long-term TCE-contaminated aquifer undergoing phytoremediation was investigated. A combination of genetic, functional, and physiological analyses was used. Chemical analyses of soils and groundwaters from the site revealed that transformation of TCE had occurred with the main daughter product being cis 1,2-dichloroethene (cis 12-DCE). The concentrations varied across the site with the highest concentrations of TCE and its metabolites at the source area. The phytoremediation strategy involved the planting of poplar trees across the site. Water samples were taken from the root zone of the poplars as well as from boreholes between the poplar trees. In general, bacterial numbers, as well as the genetic and functional diversity of the bacterial community structure, were all higher in the root zone of the trees. The concentration of volatile organic carbon compounds (VOCs) was shown to impact negatively on the overall numbers of bacteria. Differential effects of the VOCs on specific sub groups of bacteria were observed. High concentrations of VOCs impacted on the genetic and functional composition of the microbial community. The presence of genes encoding aromatic oxygenases, known to be capable of aerobically transforming TCE, was confirmed across the site.