PARENT SESSION
PW7 - Biotransformation / Metabolisms / Degradation
Wednesday, 20 November 2002
8:00 AM to 6:30 PM
Exhibit Hall
(P795) GEOCHEMICAL EVIDENCE OF JET FUEL BIODEGRADATION IN A CONTAMINATED KARST AQUIFER.
Byl, Thomas1,2, Darlington, Ramona*,1, 1 Tennessee State University, Nashville, Tennessee, USA2 United States Geologi Society, Nashville, Tennessee, USA
ABSTRACT- Bacteria in water can break down the components of jet fuel, BTEX, benzene, toluene, ethyl benzene and xylene. The jet fuel is the electron donor (food), which the bacteria ingest then give off electrons. There must be electron-acceptors present to receive the electrons or the process cannot occur. The primary electron acceptors in a groundwater system include oxygen, iron, manganese, sulphate and carbon dioxide. As the more efficient terminal electron acceptors are used in the biodegradation process, the bacteria begin to use less efficient terminal electron acceptors. This sets up an oxidation reduction gradient or geochemical zones along the contaminant plume. The zones are as a result of bacteria using different terminal electron acceptor processes (TEAPS). TEAP zones have been well documented in fuel contaminated sandy groundwater aquifers, but not in karst. Karst refers to geologic formations primarily composed of calcium carbonate bedrock that have dissolution openings in it. The objective of this project was to characterize the TEAP conditions in a fuel contaminated karst aquifer in southern Kentucky through geo-chemical analysis and electronic monitoring devices. Groundwater TEAP characterization is traditionally done using geochemical tests and YSI datasonde units. These data were used to observe trends in aquifer geochemistry and depth over time. It was seen that there is a correlation between the concentration on TEAPs and the redox conditions. Bacteria tests were also conducted on water samples to ascertain what type of bacteria was present in the karst aquifer. The bacteria sampling was biased toward free-living bacteria therefore water samples were collected. Trends and correlations were evident between the bacteria population and changes in the water quality, which include pH, geochemistry and even weather conditions. At first glance the data and trends appeared simplistic but various factors had to be taken into account for better trend analysis. Taking all the factors into consideration the geochemical conditions associated with a karst aquifer are determined and the biodegradation pathways identified.
Key words: Geochemical, Biodegradation