Bizarre Facts: Sunlight Linked to Breakdown of Crude Oil

GULF OF MEXICO一 In a paper published on the American Association for the Advancement of Science website, two researchers from Woods Hole Oceanographic Institution in Massachusetts, Collin Ward and Danielle Haas Freeman, said sunlight could play a major role in cleaning up oil spills in the ocean.

The study, published on Feb. 16, suggests that sunlight may have helped remove as much as 17 percent of the oil slick from a massive oil spill in the Gulf of Mexico.

On April 20, 2010, the Deepwater Horizon oil spill in the Gulf of Mexico left more than three million barrels of crude oil out in the ocean, making it the largest marine oil spill in history.

The spill was caused by an explosion on the Deepwater Horizon oil rig located almost 41 miles off the coast of Louisiana.

The explosion was linked to a surge of natural gas, which blasted through a concrete core killing 11 workers and injuring 17 before capsizing and sinking on April 22.

During the weeks, months, and years following the oil spill, scientists found the sunlight hitting the spill initiated chemical reactions in the slicks, transforming them into new compounds.

In a 2018 study in Environmental Science and Technology, it was found that sunlight triggered a chemical reaction adding oxygen to the oil molecules creating oxygenated hydrocarbons allowing the oil to stick around years after the spill.

The study also identified a smaller category of oxygenated hydrocarbons, which broke down more readily in water.

In the most recent study released on Feb. 16, Freeman and Ward studied crude oil under LED lights, which simulates wavelengths found in natural sunlight, to determine the factors of photo dissolution.

Photo-dissolution is the process of sunlight transforming insoluble components like crude oil into water-soluble products.

During the study, scientists found important factors for photo-dissolution were the thickness of the oil slick and the wavelengths of light.

For example, longer wavelengths toward the red end of the spectrum dissolved less oil than shorter wavelengths toward the violet end of the spectrum.

Rough estimates show sunlight dissolved 3 to 17 percent of the surface oil from the spill; the impact of sunlight-produced compounds on the marine ecosystem is still unknown.

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