Long-term dynamic changes in attached and microbial communities in a phenol-contaminated aquifer

As plumes of organic contaminants migrate through groundwater aquifers, concentrations fall as a consequence of combined physiochemical and biological processes. Under permissive conditions, much of the contaminant removal is biologically mediated and fastest at the plume fringes, where microbial numbers and activities are highest. As the plume migrates, the contaminants and planktonic microbial community encounter uncontaminated substrata on which an attached community then develops. Attached communities are known to be important in many systems but the time needed for their establishment and relationship with the planktonic community is not well understood. These processes are important for parameterising hydrological models, contaminant-plume management and understanding the biology of disturbed environments. Here, we compare the dynamics of development of attached microbial communities on sterile substrata in the field and laboratory microcosms, sampled simultaneously at intervals over two years. Measurements were made of geochemistry and microbial communities using epifluorescence microscopy and 16S rRNA gene sequencing.