Oil spills pose a serious direct threat to ocean marine ecosystems, requiring swift intervention to mitigate the risk. Chemical dispersants are one tool used in oil spill response efforts; these chemicals break oil down into small droplets that are diluted rapidly and persist in the water column for less time. However, scientists still don’t have a full picture of how effective these dispersants really are. Researchers led by Bigelow Laboratory for Ocean Sciences have now conducted tests validating the efficiency of oil dispersants under real-word conditions, allowing better preparation to respond to similar environmental disasters in the future.
In order to simulate the real-world conditions of an oil spill in an ocean environment, the researchers conducted their experiments in large outdoor test chambers containing seawater, allowing the oil to be exposed to natural sunlight. Sunlight can cause oil to oxidize, increasing its viscosity and negatively impacting the effectiveness of dispersants. The researchers quantified oil properties over 11 days of irradiation by sunlight and also tested the effectiveness of dispersants using the Baffled Flask Test.
The researchers concluded from their tests that the dispersants were effective under normal oil spill conditions, but that effectiveness fell from 80% to less than 50% after more than three days of irradiation. These results showed the importance of applying dispersants within the two to four day period recommended by current oil spill response guidelines. Their test results were compared with field data from the 2010 Deepwater Horizon oil spill, in which almost one million gallons of dispersants were used over 90 days of continuous operations. This data confirmed the researchers’ findings, and also showed that over 75% of field measurements showed effective dispersion, suggesting that previous laboratory tests had underestimated dispersants’ effectiveness. This research was published in Environmental Science & Technology.
“Oil spills are still going to be happening for a while. Ships are going to be powered by fossil fuel for a long time and goods still need to be transported. Decarbonizing the economy will take time,” said lead author Christoph Aeppli. “Until then, we need to make sure we know how to best respond to any oil spill that can happen.”
This study was part of Aeppli’s efforts to investigate the impact of toxins on the environment. He hopes the work will help society mitigate the damage of oil spills as it works to transition to renewable energy.
Photo: Bigelow Laboratory Senior Research Scientist Christoph Aeppli conducts an experiment to test the effectiveness of chemicals that disperse oil after a spill. A new study validated their efficacy under real-world conditions in order to better prepare for the next disaster. Credit: Courtesy of Christoph Aeppli, Bigelow Laboratory