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article imageWhere did all that BP oil go? Scientists find out

By Karen Graham     Oct 28, 2014 in Environment
The 2010 Deepwater Horizon oil spill lasted 83 days before the well-head was sealed off, and in that time, 172 million gallons of oil spewed into the Gulf of Mexico. But one question has plagued officials for years. Where did all the oil go?
Based on new research by the University of California (UC) Santa Barbara's David Valentine and colleagues from Woods Hole Oceanographic Institute (WHOI) and UC Irvine, the BP oil spill left its mark on the ocean floor. It's being described as a "bathtub ring" on the floor of the Gulf of Mexico about the size of the state of Rhode Island.
The team's findings were published on Monday in the Proceedings of the National Academy of Sciences. The scientists used publicly available data from the Natural Resource Damage Assessment study conducted by the National Oceanic and Atmospheric Administration (NOAA). The data came from the 3,000 samples of sea floor sediment collected at 534 locations over a two-year period from 2010 to 2011.
Valentine is a geochemistry professor at UC Santa Barbara. He said that while no chemical signature tests were done because the oil had degraded, "it was obvious the oil was from the Macondo well. There's this sort of ring where you see around the Macondo well where the concentrations are elevated," (The Proceedings of the National Academy of Sciences, calls it a "bathtub ring").
The oil levels inside the 1,200 square-mile ring were 10,000 times higher than the levels outside the ring, Valentine said. A chemical element of the oil called hopane, a nonreactive hydrocarbon, was analysed. Hopane was found on the sea floor anywhere from two-thirds of a mile to a mile below the ocean surface. The chemical was found within 25 miles of the capped well.
Jason Ryan, a spokesman for BP sent an email, saying the petroleum company questions the accuracy of the studies. The email pointed out "the authors failed to identify the source of the oil, leading them to grossly overstate the amount of residual Macondo oil on the sea floor and the geographic area in which it is found."
Valentine and study co-author Christopher Reddy, a marine chemist at Woods Hole Oceanographic Institute, say it's impossible to do a chemical analysis on the residual oil found on the sea floor, but there is evidence, including the depth of the oil, the way the spread is laid out, and the distance from the well. Equally important is the validation this study has given to the destruction of deep-water coral by the oil spill.
More about Deepwater horizon oil spill, bathtub ring, macondo well, gulf of mexico sea floor, deep water coral damage
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