Kari Huus writes:The use of chemical dispersants in the wake of the massive BP oil spill ended on July 15, when the broken Deepwater Horizon well was capped, with only one exception four days later, according to federal agencies. But photos and chemical lab results obtained by msnbc.com suggest that the controversial chemicals have been sprayed much more recently than that.

The photos and tests lend credence to persistent but unsubstantiated reports by Gulf Coast residents that the spraying of dispersants has continued well beyond the cutoff date acknowledged by the Deepwater Horizon response team.

The image above — time stamped and embedded with geographical coordinates — was captured by New Orleans photographer Jerry Moran off the coast of Mississippi when he was out with scientists on Aug. 9

“We were on our way back to Ocean Springs from Horn Island, about a mile or two off the coast … (and) we ran into these hundreds of yards long swaths of that cauliflower stuff,” said Moran.

Moran said the foamy substance on the water’s surface looked just like what he encountered while covering the oil spill response when dispersant — a product with the brand name Corexit — was being applied daily to oil slicks. The smell was unmistakable, he said.

“I almost passed out from the fumes,” he said. “It smelled like a gas station.”

An environmental technician who was present took water samples, which were then sent to a certified lab -- ALS Laboratory Group in Fort Collins.

The results, according to environmental investigator and engineer Marco Kaltofen, president of Boston Chemical Data Corp.: “Definitively Corexit and BP petroleum.”

Kaltofen is among the scientists retained by New Orleans attorney Stuart Smith to conduct independent environmental testing data from the Gulf on behalf of clients who are seeking damages from BP. (Click here to read about their effort.)

An independent marine chemist who reviewed the data said that their conclusion stands up.

“The analytical techniques are correct and well accepted,” said Ted Van Vleet, a professor at the College of Marine Science at the University of South Florida. “Based on their data, it does appear that dispersant is present.”

Why responders would continue to use chemical dispersants after the government announced a halt is a mystery. If the oil was gone or already dispersed, as the federal government and BP have said, what would be the point? And, because dispersants don’t work very well on oil that has been “weathered” by the elements over long periods of times, there would be little point in spraying it that situation.

Doug Myers, science director for People with Puget Sound, a nonprofit marine restoration group in Olympia, Wash., has a theory: Oil emerging from the wellhead — about a mile beneath the surface — may have been prevented from rising to the surface by the high pressure and low temperatures of the waters at that depth.

“The depth stratification of the ocean is possibly the reason that pockets of oil could be hovering off the bottom but far below the surface for a fairly long time,” he said. “If it’s been at depth and … at those temperatures, it’s likely it stayed in liquid form.”

But if an upwelling current or other changes in conditions forced that oil to the surface, cleanup crews still working for BP would encounter fresh oil on the surface, he said.

If dispersant has in fact been sprayed in substantial quantities since July 15, an explanation will probably not be forthcoming from the federal government.

According to the official Deepwater Horizon response website, the EPA approved BP’s use of 1.84 million gallons, about two-thirds of the total for subsea use up to July 15, when the broken well was capped.

“Use of dispersant stopped when the well was capped” on July 15, said Coast Guard Petty Officer Susan Blake, a spokeswoman at Unified Command Center for the ongoing spill response. “The only exception was on July 19^th, when they used 200 gallons.”

EPA communications officer Alisha Johnson requested and received copies of the photographs and chemical analysis of the water samples for review, but the agency did not respond to msnbc.com’s request for comment.

The use of chemical dispersants in unprecedented volume and in an unprecedented manner at the bottom of the sea has stirred controversy.

The dispersants — though nowhere near as toxic to humans as crude oil — are still toxic. And some scientists remain concerned about how dispersants might change the “fate” of oil. By breaking up the crude into tiny particles that sink into the water, they fear the contaminants could be more easily ingested by marine life and thus enter the food chain.

On May 14, the EPA told BP to find a less-toxic type of dispersant than Corexit, but BP continued using the dispersant, arguing that it was the best option available. On May 26, 2010, EPA and the Coast Guard issued a directive to BP requiring them to decrease overall volume of dispersant by 75 percent and to cease use of dispersant on the surface of the water altogether unless provided prior written authorization from the Coast Guard.

Response to the Deepwater Horizon disaster, which began with an explosion on the BP drilling rig on April 20, continues into the New Year. About 6,000 personnel, nearly 400 vessels, along with heavy equipment, skimmers and other machinery are still employed in daily cleanup operations.

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