Oil spill bioremediation: experiences,lessons and results from the Exxon Valdez oil spill in Alaska

The use of bioremediation as a supplemental cleanup technology in the Exxon Valdez oil spill, in Prince William Sound, Alaska, has proven to be a good example of the problems and successes associated with the practical application of this technology. Field studies conducted by scientists from the U.S. Environmental Protection Agency have demonstrated that oil degradation by indigenous microflora on the beaches of Prince William Sound was accelerated by adding fertilizer directly to the surfaces of oil-contaminated beaches. Although several types of fertilizers were used in the studies, only the results from the application of an oleophilic fertilizer are presented. The fertilizer enhanced biodegradation of the oil, as measured by changes in hydrocarbon composition and bulk oil weight per unit of beach material, by approximately two-fold relative to untreated controls. Laboratory studies verified the usefulness of the oleophilic fertilizer as a nutrient source, but the contribution of its oleophilic components towards enhancing biodegradation is still unclear.These studies supported bioremediation as a useful cleanup strategy that was subsequently used by Exxon on a large scale. The Exxon Valdez experience has also provided a number of informative lessons that have significant relevance to future oil bioremediation efforts. This paper discusses these lessons and the difficulties in assessing the effectiveness of bioremediation in the field.