9523932 Lovely Hydrological, Geochemical and Microbiological Controls on Anaerobic Aromatic Hydrocarbon Degradation in a Petroleum-Contaminated Aquifer Contamination of ground water with petroleum products as the result of terrestrial oil spills and leaking underground storage tanks is a serious environmental problem. Toxic aromatic hydrocarbons such as benzene and toluene which are important components of many fuels are water soluble and thus migrate with the ground water. Although aerobic microorganisms can readily degrade aromatic hydrocarbons when oxygen is present, most heavily contaminated ground waters lack oxygen. Recent studies have demonstrated that there are microorganisms which can degrade aromatic hydrocarbon contaminants in ground water in the absence of oxygen. These anaerobic microorganisms use ferric iron or sulfate as an electron acceptor for the degradation of aromatic hydrocarbons rather than oxygen. In some instances this anaerobic microbial metabolism can remove significant quantities of aromatic hydrocarbons from contaminated ground waters and may alleviate the need for expensive remediation procedures. The purpose of this research is to determine what microorganisms are responsible for the degradation of aromatic hydrocarbons in petroleum-contaminated aquifers and to elucidate the environmental conditions which might stimulate or inhibit this microbial activity. Microbial populations in the aquifer will be studied with several novel techniques including a newly developed molecular method which permits rapid screening of the microbial populations in the sediments without the need to culture the microorganisms. The effect of changes in hydrological and geochemical conditions on the size and activity of the anaerobic microbial populations responsible for aromatic hydrocarbon degradation will be evaluated with field observations and in aquifer material that is experimentally manipulated in laboratory incubations. It is expected that these studies will identify key p arameters which can be used to simply and reliably predict the rate and extent of anaerobic romatic hydrocarbon degradation in petroleum-contaminated environments. ??
