ABSTRACT
Over thirteen years ago, Iraqi soldiers caused the release of over 10 million barrels of oil into Arabian Gulf waters from various sources. The oil impacted the majority of the western Gulf shoreline, estimated at over four hundred miles. Coastal development is having to deal with oil which was buried, stock-piled, or otherwise left in place. One such development is underway at Al Khiran (southern Kuwait) where oil is within planned construction areas for public beaches,
housing lots, a marina, and channels. Although the oil is weathered and generally considered non-toxic (based on chemical analyses below), expanses of it pose physical and esthetic problems for construction and human use of the areas. Tests were performed using various means of treating this oil, and the results are given herein.
A variety of bioremediation methods was tested, including the use of products from four companies, selected at random from the oil spill chemical industry (U.S. and abroad). All four were bacterial powders, with nutrients included or added separately, applied according to manufacturers' specifications. Test plots were on mildly contaminated soil (33 mg/kg total hydrocarbons) which had oil mixed throughout. Plots were located in the upper intertidal zone, where they were exposed to minimal (<30 cm), diurnal, high tide flooding, and the research site was protected from wave and wind action by a levee. Extreme conditions at the sites included high temperatures, lack of rainfall, and flushing by high salinity seawater (40 parts per thousand salt).
Sites were sampled before treatment, and at various times beginning 44 days after treatment. Composite samples were collected from each test plot and analyzed for total petroleum hydrocarbons (TRPH), and for three hydrocarbon ranges: C8–C10, C10–C28, and C28–C40. Results showed no significant reduction in total hydrocarbons by any product, compared to pre-treatment levels. Aggressive physical tilling of contaminated soils at a second site provided some reduction in total hydrocarbons during this period. Various methods were tried in the next phase of testing, including additional product exposure time, increased tilling, and screening. The results provide guidelines for the use of chemical products and physical treatments, in extreme coastal conditions, for the treatment of weathered hydrocarbons.
Insights into the biodegradation of weathered hydrocarbons in contaminated soils by bioaugmentation and nutrient stimulation
