AEROBIC SOIL MICROCOSMS FOR LONG-TERM BIODEGRADATION OF HYDROCARBON VAPORS

Characterization and understanding of hydrocarbon vapor behavior and persistence in the subsurface is essential for the complete evaluation of a petroleum hydrocarbon spill site. The aims of the research project included the development of laboratory protocols for the preparation of aerobic soil microcosms using aseptic field soil samples, and for the gas chromatographic analysis of hydrocarbon vapor biodegradation based on vapor samples obtained from these microcosms. The results were applied to a mathematical model from which rigorously controlled estimates of Michaelis-Menten type maximum rate parameters were produced. The latter were compared to independently derived estimates of the same kinetics parameter, and were used to establish whether any depth-dependence on this parameter exists. The maximum rate parameter value for the mid-depth soil range was found to be a successful test of previously acquired field data.