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How were chemical dispersants used during the Deepwater Horizon cleanup?

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Fireboats battle a blaze on the Deepwater Horizon drilling rig in the Gulf of Mexico, April 2010. — Deepwater Horizon oil spill Fireboat response crews attempt to extinguish the blaze aboard the Deepwater Horizon oil rig in the Gulf of Mexico, April 21, 2010.

During the Deepwater Horizon cleanup, approximately 1.8 million gallons of dispersants were utilized to manage the massive oil slick. These chemical substances function by emulsifying the oil, which breaks it down into smaller droplets to facilitate easier metabolism by bacteria.1

The application of these dispersants occurred in two primary ways:
* Direct Injection: The substances were pumped directly into the leak at the source.1
* Aerial Application: Dispersants were sprayed aerially over the oil slick on the surface of the water.1

While these efforts aimed to accelerate the natural dispersion of the oil, the use of dispersants raised significant environmental concerns. Research indicated that the combination of oil and dispersants made coral reproduction more difficult and proved fatal to rotifers, which are microorganisms essential to the gulf food web. Furthermore, modeling suggested that the presence of dispersants negatively affected the activity of oil-eating microbes by encouraging the growth of other bacteria that preferred to feed on the dispersants themselves.2