Biogeochemical evidence for microbial community change in a jet fuel hydrocarbons-contaminated aquifer

A glacio-fluvial aquifer located at Wurtsmith Air Force Base, MI, had been contaminated with JP-4 fuel hydrocarbons released after the crash of a tanker aircraft in October of 1988. Microbial biomass and community structure, associated with the aquifer sediments, were characterized based on the analysis of phospholipid ester-linked fatty acids (PLFA). Fatty acids ranged from C12–C20 in carbon chain length, including saturated, monounsaturated, branched, and cyclopropyl fatty acids. Polyunsaturated fatty acids were virtually absent from the aquifer sediments. These findings suggested that bacteria were dominant organisms within the aquifer microbial communities. The total microbial biomass and community composition in aquifer sediments, as determined by PLFA analysis, varied with depth, and between locations at similar depths, indicating considerable microbial heterogeneity in the subsurface. PLFA patterns in the hydrocarbon-contaminated anaerobic zones indicated higher microbial biomass and metabolically more diverse microbial communities than those in aerobic zones.