A chemical analysis of oil sheens found floating recently at the ocean's surface near the site of the Deepwater Horizon disaster indicates that the source is pockets of oil trapped within the wreckage of the sunken rig. Both the Macondo well and natural oil seeps common to the Gulf of Mexico were confidently ruled out.
Researchers from Woods Hole Oceanographic Institution (WHOI) and the University of California, Santa Barbara (UCSB) used a recently-patented method to fingerprint the chemical makeup of the sheens and to estimate the location of the source based on the extent to which gasoline-like compounds evaporated from the oil sheens. The study was published online this week in Environmental Science & Technology.
The oil sheens were first reported to the United States Coast Guard by BP in mid-September 2012, raising public concern that the Macondo well, which was capped in July 2010, might be leaking.
"It was important to determine where the oil was coming from because of the environmental and legal concerns around these sheens. First, the public needed to be certain the leak was not coming from the Macondo well, but beyond that we needed to know the source of these sheens and how much oil is supplying them so we could define the magnitude of the problem," said WHOI chemist Chris Reddy.
When oil sheens appear on the ocean surface, how do researchers determine where the oil is coming from? Every oil sample contains chemical clues pointing to the reservoir it came from, allowing scientists to compare it to other samples to determine if they share a common source. The lead scientists Chris Reddy (WHOI) and Dave Valentine (UCSB) were aptly prepared to investigate these sheens. They have worked on the Deepwater Horizon for much of the last three years, investigating a wide range of problems from the composition of the oil, detection of subsurface plumes, the biodegradation of the oil, the fate of the dispersants, and the
|Contact: Press Office|
Woods Hole Oceanographic Institution