'Dirty Blizzard' sent 2010 Gulf oil spill pollution to seafloor
Scientists working in the Gulf of Mexico have found that contaminants from the massive 2010 Deepwater Horizon oil spill lingered in the subsurface water for months after oil on the surface had been swept up or dispersed. In a new study, they also detailed how remnants of the oil, black carbon from burning oil slicks and contaminants from drilling mud combined with microscopic algae and other marine debris to descend in a "dirty blizzard" to the seafloor.
The work, published May 30 in the Proceedings of the National Academy of Sciences, confirms that contaminants found in the water column and on the seafloor were indeed from the Deepwater Horizon spill, and not from the many natural oil seeps in the Gulf. The initial dispersal of materials in the water made pollutants hard to detect, but the eventual accumulation of "marine snow" concentrated the toxins on the seabed, where they can enter the food web, possibly affecting fish and corals in deep waters.
The findings suggest that the ecological effects of oil spills could last longer than previously thought. The paper comes on the heels of the most recent spill, detected May 12. About 88,200 gallons of oil were released from an underwater pipeline operated by Shell about 90 miles off the coast of Louisiana, according to news reports. Much of the oil has been recovered, and there are as yet no reported impacts on wildlife. But scientists are just beginning to assess the effects.
"We knew oil pollutants can be carried downward by marine snow, but we didn't expect the pollutants to stay in the water for such a long time," said Beizhan Yan of the Lamont-Doherty Earth Observatory, an environmental chemist who is lead author of the study.
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https://www.sciencedaily.com/releases/2016/05/160530153258.htm
