NOAA says sediment not visibly oiled

Federal scientists said Thursday they had found no visible oil on the sea floor around the damaged Gulf well that spewed some 206 million gallons of oil. Other scientists say they found a layer of oil on the sea floor.

“At this point, we haven’t seen any oiled sediments,” said Janet Baran, a scientist with the National Oceanic and Atmospheric Administration coordinating efforts to find what oil is left in the Gulf of Mexico. “All the sediments we have taken have no visible oil on them.”

Baran said crews have taken about 114 sediment samples in waters more than 3 miles offshore, including areas around the site of the BP PLC well.

NOAA’s findings are in contrast to those of University of Georgia researcher Samantha Joye, who reported earlier this month that she found oil at least two inches thick about a mile beneath the surface. Joye said that under the oiled sediment she found a layer of dead shrimp and other small animals.

Joye could not be reached for comment Thursday.

Paul Montagna, a marine scientist Texas A&M University-Corpus Christi working with NOAA to study sediment samples, said the different findings “can be explained by sampling at different places and times.” He said that all the sampling would ultimately “be complementary rather than contradictory.”

For oil to sink, it must attach itself to materials that are heavier than water, such as detritus, flecks of mud, sand and other particles. Such materials are abundant in the Gulf in places where rivers, especially the Mississippi, flush mud and sand into the open sea. Oil also can sink as it ages and becomes more tar-like in a process known as weathering.

Scientists also say the oil could sink because it was broken up into tiny droplets by chemical dispersants, making the oil so small that it wasn’t buoyant enough to rise.

The BP well was capped on July 15 after some 200 million gallons flowed into the Gulf.