Methanogenic Biodégradation of Creosote Contaminants in Natural and Simulated Ground‐Water Ecosystems

Abstract

Wastes from a wood preserving plant in Pensacola, Florida have contaminated the near‐surface sand‐and‐gravel aquifer with creosote‐derived compounds and pentachlorophenol. Contamination resulted from the discharge of plant waste waters to and subsequent seepage from unlined surface impoundments that were in direct hydraulic contact with the ground water. Two distinct phases resulted when the creosote and water mixed: a denser than water hydrocarbon phase that moved vertically downward, and an organic‐rich aqueous phase that moved laterally with the ground‐water flow. The aqueous phase is enriched in organic acids, phenolic compounds, single‐ and double‐ring nitrogen, sulfur, and oxygen containing compounds, and single‐ and double‐ring aromatic hydrocarbons. The ground water is devoid of dissolved O2, is 60–70% saturated with CH4 and contains H2S. Field analyses document a greater decrease in concentration of organic fatty acids, benzoic acid, phenol, 2‐, 3‐, 4‐methylphenol, quinoline, isoquinoline, l(2H)‐quinolinone, and 2(lH)‐isoquinolinone during downgradient movement in the aquifer than could be explained by dilution and/or dispersion. Laboratory microcosm studies have shown that within the study region, this effect can be attributed to rnicrobial degradation to CH4 and CO2. A small but active methanogenic population was found on sediment materials taken from highly contaminated parts of the aquifer.

Distribution patterns of attached and suspended bacteria in pristine and contaminated shallow aquifers studied with an in situ sediment exposure microcosm

“…6). Similar observations from contaminated aquifers have been documented by Harvey et al (1984), Harvey & George (1987) and Godsy et al (1992). Ratios of attached to suspended cells are therefore suggested to be indicative of actual nutritional conditions in aquatic sedimentary environments (Griebler et al 2001).…”

“…Consequently, biofilm communities are supposed to control the flux of matter in the subsurface. Nevertheless, studies focusing on the distribution of microorganisms in the saturated subsurface are scarce (Marxsen 1982, Harvey et al 1984, Kölbel-Boelke et al 1988, Hazen et al 1991, Amy et al 1992, Godsy et al 1992, Albrechtsen 1994, Alfreider et al 1997, Bekins et al 1999, Lehman et al 2001b, which is mostly due to difficult access to subsurface samples. In general, sampling of sediment requires expensive mining and drilling activities (Wilson et al 1983, Griffin et al 1997, Russell 1997.…”

Composition and Diversity of Microbial Communities Recovered from Surrogate Minerals Incubated in an Acidic Uranium-Contaminated Aquifer

“…New studies are needed to determine the significance of coupon incubation time on community diversity and structure associated with surrogate minerals. Several studies from subsurface (21,29,30,43), freshwater (8,47), and marine (8, 9, 52) environments have indicated differences in microbial activity and diversity between attached and planktonic communities, and some investigators have concluded that the majority of biomass and activity are dominated by attached microorganisms (2,15,18,20,43,51). The sediment and groundwater T-RFLPs at the FRC were highly distinct from one another, sharing fewer than 16% of their T-RFs in common.…”

“…Due to these limitations, studies requiring numerous samples (e.g., temporal studies) are unrealistic with current methods. It has been suggested that those microorganisms most likely to be involved in contaminant transformation are often associated with the surfaces of the geological matrix through which the groundwater percolates (15,18,20,21,28). While water-sampling techniques allow for temporal and large-scale spatial sampling of transient or planktonic communities, they may not capture key populations partitioned on the solid phases.…”

Risk-Based Characterization of Site ST-08 (Building 41105), Pope Air Force Base, North Carolina

“…Aronson and Howard (1997) report that, in general, high molecular weight, multi-ring polynuclear aromatic hydrocarbons (PAHs) are thought to be resistant to anaerobic biodegradation in groundwater. These authors cite the results of a field study (Godsey et al, 1992) where an anaerobic decay rate of 0.004 day" 1 was determined for acenaphthene in methanogenic groundwater. A biodegradation rate for acenaphthene of 0 (no degradation) to 0.004 day" 1 was derived by Aronson and Howard (1997).…”