"Because of our ongoing funding from the National Science Foundation, we were prepared to interrogate the source of mysterious oil sheens in the Gulf of Mexico," said Valentine. "We've been exploring new ways to do this for several years in the context of natural seeps and this event provided us an opportunity to apply our fundamental advances to a real-world problem. This is a classic case where fundamental science finds a real world application."
This research analyzed 14 sheen samples they skimmed from the sea surface during two trips to the Gulf of Mexico. Using comprehensive two-dimensional gas chromatography (GCxGC), a technique developed in Reddy's lab, the researchers first confirmed the sheens contained oil from the Macondo well. But the sheen samples also contained trace amounts of "olefins"industrial chemicals that are used in drilling operationscompounds that were absent from the sample taken directly from the Macondo well. The presence of "olefins" provided a fingerprint for the sheens that the authors could compare to the library of samples they had analyzed over the past three years.
The "olefins" are not found in crude oil and their uniform distribution in the sheens indicated that the Macondo well was unlikely to be the source. The team surmised that the sheens must be coming from equipment exposed to olefins during drilling operations. Reddy's lab holds a patent on measuring olefins in crude oils.
"The occurrence of these man-made olefins in all of our sheen samples points to a single main source which contains both Macondo oil and lesser amounts of the drilling fluids that harbor the olefins," said Valentine. "This pointed us to the wreckage of the rig, which was known to have both, as the most likely source for the sheens."
It also meant the olefins could be used by the team as a fingerprint in the search for the source of the leak.
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Woods Hole Oceanographic Institution