Petroleum hydrocarbons from oil spills threaten marine life worldwide. Animals become coated in the oil and ingest the contaminants while trying to clean themselves. The toxic effects of petroleum often result in death for much of the surrounding life. Although contaminants could be removed by physical means, this does not dispose of the dangerous petroleum hydrocarbons. Bioremediation offers an efficient solution for cleaning up oil spills. The pollutants are biologically degraded by complete mineralization of the organic contaminants, turning the toxic waste into harmless products such as carbon dioxide, water, inorganic compounds, and cell protein (Das and Chandran 2010). Bioremediation can clean up our oceans without producing harmful byproducts in a relatively inexpensive way using minimal technology.
HISTORY OF OIL SPILLS
Although bioremediation can be used for many sources of contamination such as pesticides, gas sites, landfills and more, oil spills are a large source of pollution for our oceans. Pollution by petroleum hydrocarbons is common and mostly due to tanker accidents, offshore drilling, pipeline leaks, and from vehicles when their spilled oil is washed into storm drains from run-off (Margesin et al. 2007). In 1979, there was an offshore drilling spill in the Mexican coast releasing 400 thousand tons of oil. In 1989, the Exxon Valdez oil spill leaked over 14 thousand tons of oil into Alaskan waters (Swannell et al. 1996). In 1991, Iraq intentionally “spilled” over 14 million tons of crude oil into the Persian Gulf. In 2000, there was an oil spill from pipelines in Guanabara Bay releasing more than one thousand tons of oil. In November 2002, the vessel Prestige sank to the bottom of the ocean after breaking into two, releasing around 60 thousand tons of fuel oil 209 kilometers from the shores of Northwest Spain (Fernandez-Alvarez et al. 2006). In 2010, there was an oil spill in the Great Barrier Reef when a Chinese bulk coal carrier released 40 tons of oil after striking the reef. There have been numerous spills in oceans worldwide that release such a large amount of oil and every resource possible must be used for damage control. Enhanced natural biodegradation is a natural alternative that removes the physical pollution but also the biological contaminants at this time.
NECESSARY CONDITIONS FOR BIOREMEDIATION
Most crude oils are naturally biodegradable and are broken down into biomass, water, and natural gases (Swannell et al. 1996). Bioremediation is most efficient with the maximum availability of microorganisms at the waste site. This is dependent upon several factors, including (but not limited to) the concentration of nutrients, oxygen levels, climate conditions, and the characteristics of sediments (Swannell et al. 1996). It is vital that extra nutrients such as nitrogen and phosphorous be added, or bioremediation will be slow and insignificant (Cappello et al. 2006). Cappello et al. tested...