CENSUS – Bacterial Groups Table
Redox conditions and microbial populations are intrinsically coupled in that availability of electron acceptors influences the microbial community composition and microbial processes in turn impact site geochemistry. The link between site microbiology and geochemistry then plays a governing role in the microbial metabolism and therefore the processes responsible for contaminant biodegradation. In the most general terms, microbial metabolism is an oxidation/reduction reaction where oxidation of one compound (electron donor) is coupled to reduction of another compound (electron acceptor). Depending on the contaminant of concern and the biodegradation process involved, site contaminants can serve as either an electron donor or electron acceptor. Compounds that are already in a reduced state like BTEX and PAHs are more readily oxidized and typically serve as electron donors. Oxidation of BTEX, however, must be coupled to reduction of a terminal electron acceptor such as oxygen (DO) or biodegradation will be limited. Conversely, highly oxidized compounds like PCE and TCE can serve as electron acceptors provided a suitable electron donor is present. However, reductive dechlorination of PCE and TCE can be limited by the presence of competing electron acceptors (DO, nitrate, etc.) that may also be present in the subsurface. While quantification of electron acceptor concentrations provides valuable information, analysis of site geochemistry can at times be convoluted. CENSUS analysis provides direct quantification of the bacterial groups responsible for dominant terminal electron accepting processes that compliments geochemical analysis and CENSUS quantification of contaminant degrading bacteria.
CENSUS – Bacterial Group Targets include: