Oil Spill Science: Five years later, what have we learned?

The Deepwater Horizon (DWH) oil spill occurred about 50 miles offshore of Louisiana in April 2010. Approximately 172 million gallons of oil entered the Gulf of Mexico. Five years after the incident, locals and tourists still have questions. This article addresses the five most common questions.

QUESTION #1: Is Gulf seafood safe to eat?

Ongoing monitoring has shown that Gulf seafood harvested from waters that are open to fishing is safe to eat. Over 22,000 seafood samples have been tested and not a single sample came back with levels above the level of concern. Testing continues today.

QUESTION #2: What are the impacts to wildlife?

This question is difficult to answer as the Gulf of Mexico is a complex ecosystem with many different species — from bacteria, fish, oysters, to whales, turtles, and birds. While oil affected individuals of some fish in the lab, scientists have not found that the spill impacted whole fish populations or communities in the wild. Some fish species populations declined, but eventually rebounded. The oil spill did affect at least one non-fish population, resulting in a mass die-off of bottlenose dolphins. Scientists continue to study fish populations to determine the long term impact of the spill.

Question #3: What cleanup techniques were used, and how were they implemented?

Several different methods were used to remove the oil. Offshore, oil was removed using skimmers, devices used for removing oil from the sea’s surface before it reaches the coastline. Controlled burns were also used, where surface oil was removed by surrounding it with fireproof booms and burning it. Chemical dispersants were used to break up the oil at the surface and below the surface. Shoreline cleanup on beaches involved sifting sand and removing tarballs and mats by hand.

QUESTION #4: Where did the oil go and where is it now?

The oil spill covered 29,000 square miles, approximately 4.7% of the Gulf of Mexico’s surface. During and after the spill, oil mixed with Gulf of Mexico waters and made its way into some coastal and deep-sea sediments. Oil moved with the ocean currents along the coast of Texas, Louisiana, Mississippi, Alabama, and Florida. Recent studies show that about 3-5% of the unaccounted oil has made its way onto the seafloor.

QUESTION #5: Do dispersants make it unsafe to swim in the water?

The dispersant used on the spill was a product called Corexit, with doctyl sodium sulfosuccinate (DOSS) as a primary ingredient. Corexit is a concern as exposure to high levels can cause respiratory problems and skin irritation. To evaluate the risk, scientists collected water from more than 26 sites. The highest level of DOSS detected was 425 times lower than the levels of DOSS known to cause harm to humans.

For additional information and publications related to the oil spill please visit: https://gulfseagrant.wordpress.com/oilspilloutreach/

Adapted From:

Maung-Douglass, E., Wilson, M., Graham, L., Hale, C., Sempier, S., and Swann, L. (2015). Oil Spill Science: Top 5 Frequently Asked Questions about the Deepwater Horizon oil spill. GOMSG-G-15-002.

 

 

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