http://www.whoi.edu/page.do?pid=7545&tid=282&cid=106090&ct=162News Release : WHOI Scientists Analyze, Explain the Chemical Makeup of Gulf Plume
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July 18, 2011
Source: Media Relations
Taking another major step in sleuthing the 2010 Deepwater Horizon oil spill, a research team led by the Woods Hole Oceanographic Institution (WHOI) has determined what chemicals were contained in a deep, hydrocarbon-containing plume at least 22 miles long that WHOI scientists mapped and sampled last summer in the Gulf of Mexico, a residue of the Deepwater Horizon oil spill. Moreover, they have taken a big step in explaining why some chemicals, but not others, made their way into the plume.
The findings, published this week in the online edition of the Proceedings of the National Academy of Sciences, “help explain and shed light on the plume formation and verify much of what we thought about the plume’s composition,” said WHOI chemist Christopher Reddy, lead author of the study. The data “provide compelling evidence” that the oil component of the plume sampled in June 2010 essentially comprised benzene, toluene, ethybenzene, and total xylenes—together, called BTEX—at concentrations of about 70 micrograms per liter, the researchers reported.
The 70 micrograms per liter in the plume, were “significantly higher than background,” Reddy said. “We do not know with certainty the adverse effects it might cause on undersea life.”
WHOI Senior Scientist Judith McDowell said that acute toxicity levels of BTEX are in the range of 5 to 50 milligrams per liter (mg/L) for aquatic organisms—100 to 1,000 times greater than that observed in the plume. Sublethal effects, including neurological impairment, are observed at lower levels, she said. “In most instances the BTEX compounds are volatilized very quickly such that exposure duration is very short,” McDowell said. “The persistence of BTEX at depth poses an interesting question as to the potential effects of these compounds on mid-water organisms.”
…http://dx.doi.org/10.1073/pnas.1101242108