Deepwater Horizon Oil Spill II

With more than 200 million gallons of oil spilled into the sea thus commenced several cleanup strategies which encompass both physical and chemical means.

Physical

To prevent oil from spreading to other sites of biological importance, floating booms were set up as physical barriers to contain the affected zones. After which, three methods were used to either recover or remove oil from the Gulf of Mexico. The first is known as skimming, which recovers the top layer of oil from the water surface. This was carried out using skimmers, which are boats or other devices, that can recover floating oil from liquids. In the Deepwater Horizon oil spill, approximately 2-4% of the oil was recovered through skimming (The Ocean Portal Team, 2018). To clean up the oil that was not recovered by skimmers, sorbents were also employed. These sorbents work by either absorbing or adsorbing oil, which aids in recovering oil spilled in the sea. The last method is in-situ burning, which removes the oil spilled in the sea. Since oil is flammable, controlled in-situ burning can remove the oil molecules; approximately 5-6% of oil spilled in the Deepwater Horizon incident were removed through in-situ burning (The Ocean Portal Team, 2018). 

Chemical

In the Deepwater Horizon oil spill, approximately 1.84 million gallons of dispersants were employed (Center for Biological Diversity, n.d.). 2 types of dispersants were used, Corexit 9500A and Corexit 9527A; most of which were sprayed over the open sea aerially, and a relatively less amount was injected directly into the Macondo well, which is the source of the oil spillage. Dispersants are chemicals that aid in breaking down the oil molecules into smaller particles. This allows for easier mixing with water, which dilutes the oil in the sea, as well as increases exposure to evaporation, sunlight, and bacteria, which speeds up the degradation process of the oil molecules. However, dispersants do not reduce the amount of oil entering the marine environment. The mixing of oil below the water surface reduces the potential to skim or absorb oil molecules from the water surface. It also results in greater exposure to dispersed oil and dispersants to marine animals, which can be hazardous, especially considering that the dispersants selected by BP are significantly more toxic and less effective than other EPA-approved dispersants. Only a month after the oil spill, the EPA ordered BP to adopt dispersants that are less toxic and more effective. 

References

Center for Biological Diversity. (n.d.). Dispersants. Center for Biological Diversity. Retrieved February 14, 2022, from https://www.biologicaldiversity.org/programs/public_lands/energy/dirty_energy_development/oil_and_gas/gulf_oil_spill/dispersants.html

The Ocean Portal Team. (2018, April). Gulf Oil Spill. Smithsonian. http://ocean.si.edu/conservation/pollution/gulf-oil-spill