Bird covered in oil -GOLUBENKOV
Oil spills—the release of crude oil (petroleum hydrocarbon)—are well known for their potential in creating devastating effects on the marine environment. This form of pollution constantly bombards our oceans, pouring approximately 49 million gallons of waste oil into the oceans each year (Embach). Furthermore, oil spills create stress on the intertidal zone, an environment that thousands of species of animals depend on for survival.
One of the best known oil spills was that of the Exxon Valdez. On March 24, 1989, the Oil Tanker Exxon Valdez struck the Bligh Reef in Prince William Sound, Alaska, spilling 10.8 million gallons of crude oil into the sea and contaminating 2,000 kilometers of Alaskan shorelines (Bragg et al. 1994). The Exxon Valdez spill was the largest spill ever in United States territorial waters and is considered to be one of the worst marine environmental disasters (Sugai et al. 1997).
Impacts on the environment
Oil spills such as the Exxon Valdez spill create devastating effects on the environment, especially the shorelines and the intertidal zone (Lee and Page 1997). Nevertheless, petroleum is a poison to most animals, no matter the location. As a result, the poisonous substance immediately killed off thousands of fish, sea mammals, seabirds, and reptiles through exposure and ingestion, the smothering and deterioration of thermal insulation, and damage to reproductive systems (Embach).
However, more important are the long-term effects that oil spills have on the sensitive marine ecosystem. As primary producers and consumers die from the poison, food chains destabilize and secondary, tertiary, and even quaternary consumers no longer have a reliable food supply to feed on. Consequently, their numbers decline as well and whole communities eventually suffer and begin to disappear.
Bioremediation as a possible solution to oil spills
Nature has its own method of cleaning an oil spill; the intertidal zone is already full of hydrocarbon-degrading microorganisms that naturally break down oil. However, their effectiveness is limited by the amount of nitrogen and phosphorus nutrients available. In order to combat these nutrient limitations, nitrogen-based fertilizers are added to the environment in order to stimulate growth of indigenous hydrocarbon-degrading microorganisms (Pritchard and Costa 1991). Using microorganism in the cleanup of oil spills is known as bioremediation. The idea of accelerating the natural degradation of oil is probably the most effective and environmentally safe cleanup treatment of oil spills.
Bioremediation was not widely used prior to 1989. However, that changed with the Exxon Valdez spill, as it was the pioneer in which bioremediation demonstrated its full potential (Bragg et al. 1994), as it resulted in significant steps towards improvements and understanding of bioremediation methods. The Exxon Valdez cleanup became the largest bioremediation project at the time of the incident.
Alaskan shorelines were treated with an oleophilic liquid fertilizer and slow-release granulated fertilizer (Bragg et al. 1994). Furthermore, field studies undertaken by the United State Environmental Protection Agency (EPA) provided striking evidence that bioremediation was an effective method for oil spill cleanup (Pritchard and Costa 1991), increasing the natural biodegradation rate of oil tremendously.
The success of the Exxon Valdez cleanup demonstrated that bioremediation is the most realistic remediation strategy for oil spills and further research is necessary for more effective methods of using microorganisms to further accelerate the degradation of oil. Past studies have shown that adding nitrogen-based fertilizers to microorganisms enhance biodegradation of oil efficiently and more importantly, environmentally safely as well.
References
Bragg, J., Prince, R., Harner, E., and Atlas, R. 1994. Effectiveness of bioremediation for the Exxon Valdez oil spill. Nature. 368, 413-418.
Embach, C. Oil spills: impact on the ocean. Water Encyclopedia.
Lee, R. and Page, D. 1997. Petroleum hydrocarbons and their effects in subtidal regions after major oil spills. Marine Pollution Bulletin, 34, 928-40.
Pritchard, P. and Costa, C. 1991. EPA’s Alaska oil spill bioremediation project. Environmental Science and Technology. 25, 372-79.
Sugai, S., Lindstrom, J., and Braddock, J. 1997. Environmental influences on the microbial degreadtion of Exxon Valdez oil on the shorelines of Prince William Sound, Alaska. Environmental Science and Technology. 31, 1564-72.
