Studies reveal that sunlight can help dissolve oil in seawater

An oil slick that turned into sunlight in the Gulf of Mexico after the 2010 Deepwater Horizon disaster. A team of researchers at the Woods Hole Oceanographic Institution found that nearly 10% of the oil in the bay after a spill was dissolved in water by sunlight. This is a process called photolysis. Credits: Cabell Davis III / Woods Hole Oceanographic Institution

The Deepwater Horizon oil spill in 2010 was the largest offshore oil spill in US history. The disaster was caused by the explosion of a Deepwater Horizon oil rig, killing 11 people and releasing nearly 210 million gallons of crude oil into the Gulf of Mexico. Twelve years later, after spending hundreds of millions of dollars, scientists are still working to understand where this oil has arrived. This is a concept known as environmental fate.

The most commonly discussed fate of oil spilled into the sea is biodegradation (microorganisms consume and decompose oil), evaporation (liquid oil turns into gas), and oil stranded on the coastline.

However, a team of researchers at the Woods Hole Oceanographic Institution (WHOI) discovered that nearly 10% of the oil in the bay after the Deep Water Horizon disaster was dissolved in seawater by sunlight. This is a process called “photolysis”. The findings were published today in a paper entitled “Solar melting is the main fate of oil at sea.” Science Advances.

“The amount of oil converted to compounds dissolved in seawater by sunlight during the 2010 Deep Water Horizon spill is comparable to the amount of commonly accepted oil fate, such as biodegradation and coastline stranded. “Colinward, a deputy scientist at WHOI’s Marine Research Institute, said. Chemistry and Geochemistry Department.

Daniel Haas Freeman, lead author of the Massachusetts Institute of Technology / WHOI Joint Program, said: student. “If this significant amount of oil is converted by sunlight and dissolved in seawater, less oil may reach other places, such as sensitive coastal ecosystems, but the effect of the compound on marine life. You need to consider it. Before deciding whether the final result is positive or negative. “

To reach this important discovery, Freeman and Ward used a bespoke light-emitting diode (LED) reactor to determine how the fate of this oil fate with different types of light, including ultraviolet and visible light. I measured whether it changed.

“The process of photomelting petroleum has actually been known for over 50 years,” Ward said. “But what’s new here is that we understand how this process changes with the wavelength of the light. This was determined using an LED reactor. This is this at the time of the outflow. This is important information for estimating the importance of the process. “

New measurements using LEDs also provided an opportunity to determine which conditions were most important in controlling this process. The team created fictitious spill scenarios by varying the thickness of the oil slick, the time of year, the location around the world, and the type of light. What they noticed was that some of these changing conditions were more important than others.

“If you’re looking at thin and thick oil slicks, the importance of this process changes dramatically,” says Freeman. “We also found that, contrary to common belief, this process is related to the Arctic Ocean, which is especially important given the increased traffic of cargo ships and the increased risk of spills in the region. This kind of modeling is important in predicting spills. Consider the impact on the marine ecosystem. “

The idea that offshore oil may have a new fate is a monument to shaping the future of oil spill research and spill response tactics. The fate and potential toxicity of these solar-producing compounds is currently unknown and poses challenges in assessing the impact of this petroleum fate. Freeman and Ward encourage the field to be drawn to these gaps in knowledge.

“Our findings suggest that a significant portion of the surface oil can dissolve in the sea after being exposed to sunlight, but the logical next step is its persistence and aquatic animals. It’s about assessing the potential harm to you, “Ward said.

What did scientists learn from Deepwater Horizon?

For more information:
Danielle Haas Freeman et al, sunlight dissolution is the main fate of oil at sea, Science Advances (2022). DOI: 10.1126 / sciadv.abl7605

Quote: According to research, sunlight may help dissolve oil in seawater (February 16, 2022).

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Studies reveal that sunlight can help dissolve oil in seawater

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