The Use of Aromatic Acids and Phospholipid-Ester-Linked Fatty Acids for Delineation of Processes Affecting an Aquifer Contaminated with JP-4 Fuel

Abstract

A glacio-fluvial aquifer located at Wurtsmith Air Force Base, Michigan, has been contaminated with JP-4 fuel hydrocarbons released by the crash of a tanker aircraft in October of 1988. A comprehensive analysis of the inorganic and organic geochemical constituents and geomicrobiological markers has documented the occurrence of in situ biodegradation of hydrocarbons in the aquifer.Concentration profiles of aromatic hydrocarbons, aromatic acids, and phospholipid ester-linked fatty acids (PLFA) in aquifer solids suggest microbially mediated degradation of hydrocarbons and production of aromatic acid metabolites. Microbial community structure as indicated by the PLFA patterns shows an absence of polyunsaturated fatty acids characteristic of microeukaryotes and high proportions of C 12 -C 20 fatty acids typical of bacteria. Contamination increased microbial biomass by one order of magnitude and shifted the community to a more anaerobic bacterial consortium.Jet fuel-4 (JP-4) spillage has been a source of contamination for soils and ground water. Monoaromatic and aliphatic hydrocarbons are major constituents of this fuel. Because the aromatic fraction of the fuel mixture is relatively water soluble, these compounds tend to migrate from contaminated soils into aquifers (7). A dissolved plume typically develops downgradient from the point of free product release. Physical (dispersion, volatilization), chemical (sorption, dissolution), and biological processes (microbial degradation) control the subsequent fate and transport of the dissolved contaminants in the subsurface. Aromatic hydrocarbons are subject to degradation by a variety of microbial transformation processes in the subsurface (2-3). Degradation of monoaromatic hydrocarbons such as benzene, toluene, ethylbenzene, and xylenes (BTEX) has been demonstrated in numerous laboratory studies. Biodegradation has been documented under aerobic (4), denitrifying (5-72), dissimilatory iron-reducing (75), sulfate-reducing (14-17), and methanogenic conditions (18)(19)(20)(21).Direct measurement of in situ biodegradation of contaminants is often difficult (22). The field evidence for potential microbial remediation of organic contaminants involves demonstration of compound mass removal, production of metabolites, functional microbial activities, and indirect measures of redox changes and isotopic composition of dissolved

Microbial characterization of a JP‐4 fuel‐contaminated site using a combined lipid biomarker/polymerase chain reaction–denaturing gradient gel electrophoresis (PCR–DGGE)‐based approach

“…The VOCs were below detection limits in all vadose and capillary fringe zones and at all levels downgradient of the site. These findings were contrary to those of Fang et al . (1997), who detected trace amounts of VOCs down‐gradient rather than up‐gradient of the crash site.…”

“…The previous study (Fang et al ., 1997), which characterized the organic contamination and the geochemical features at this site extensively, used PLFA analysis to a limited extent by analysing samples from one borehole (within the crash site) but to a greater depth than was done here. The results presented in the study by Fang et al . (1997) suggested a significant anaerobic response in the community adaptation to the presence of hydrocarbons.…”

“…Samples were analysed for VOCs on a HP‐5890 series II gas chromatograph (GC) with an HP 5972 mass selective (MS) detector as described by Fang et al . (1997).…”

“…Accidental spillage of JP‐4 jet fuel has been a significant source of hydrocarbon contamination in soils and groundwaters (Fang et al ., 1997). Microorganisms have been shown to use many of the components of such fuels, including the ‘BTEX’ compounds (benzene, toluene, ethylbenzene and xylenes), as electron donors, thereby facilitating contaminant remediation (Weidemeier et al ., 1995).…”

“…The aim of this study was to provide a detailed microbial community structure characterization using lipid/PCR–DGGE‐based analysis of a hydrocarbon‐contaminated site. We describe a multifaceted microbiological analysis using SLB and PCR–DGGE of total eubacterial 16S rDNA to measure microbial biomass, community diversity and nutritional/physiological status (community stress indicators) at a highly contaminated and at uncontaminated locations in a JP‐4 spill site for which the organic contaminants have been comprehensively documented previously (Fang et al ., 1997).…”