Experimental and Modeling Studies on Fate and Transport of Petroleum Contaminants in Soils with Plants

Abstract

The US Air Force uses JP-8, a kerosene-based jet fuel, to run turbine engines. Billions of gallons are used each year and even small percent losses of JP-8 leaking from aboveground and underground storage tanks to soil and groundwater aquifers pose a potential threat to drinking water. The biotic fate processes of JP-8 in soils will help determine the bioremediation potential of JP-8 from accidental spills and leakages. Many US Army training reservations contain vehicle wash facilities where combat and other types of equipment are washed after field maneuvers. During this process, sediments containing petroleum hydrocarbons accumulate in sedimentation basins. A vegetative treatment system could be an inexpensive approach to treat these washwater sediments. Experiments were conducted to differentiate between abiotic and biotic removal of JP-8 in soils with plants. Also, the effect of plant-induced water movement on the fate and transport of JP-8 in the subsurface was determined. Almost 86% of JP-8 disappeared in five months in the simulated surface spill experiments. The losses were not just due to volatilization but also due to biodegradation. The reduction in JP-8 concentration in planted soil systems where subsurface leakages were simulated was only 50% after twelve months. This shows that JP-8 leakages that occur near the groundwater table could persist for longer duration than those that occur near the soil surface. Downward movement of JP-8 was higher in unplanted soil columns compared to columns with plants. A one-dimensional mathematical model was developed to simulate advective transport, retardation, and first-order decay of soluble fractions of JP-8 in soil columns. An inexpensive vegetation treatment system was established to treat sediments from Central Vehicle Wash Facility (CVWF) at Fort Riley, KS. The overall reduction in total petroleum hydrocarbon concentration was about 75%; however, significant differences among treatments were not found until 36 months. Sufficient reduction of petroleum hydrocarbons was obtained in fertilized soil with or without vegetation.