TAMPA — One of the most controversial decisions made during the Deepwater Horizon disaster two years ago was allowing BP to spray unprecedented amounts of chemical dispersant on the oil spewing into the Gulf of Mexico — both on and below the surface.
Tiny globs of oil mingled with dispersant are still showing up on gulf beaches, scientists say. The dispersant prevented the gulf's normally voracious oil-eating bacteria from consuming the oil, they found.
So a scientist at the University of South Florida has been working on a non-toxic alternative, based on a story she heard from her grandmother.
Norma Alcantar, a chemical engineering professor, showed reporters Thursday how it works. She filled a petri dish with water, put in crude oil provided by BP, then sprinkled on a white powder made from the lowly prickly pear cactus.
The cactus powder immediately began to disperse the oil, forming bubbles that Alcantar said could be much more easily consumed by the gulf's bacteria.
If her dispersant catches on, it will be easily obtained. The cacti are found growing throughout the world, and Alcantar said one pad of one cactus, when processed in her lab and converted into mucilage, can produce 80 gallons of powder solution for dispersant.
Alcantar has been experimenting with the mucilage from cactus for years based on stories she heard from her grandmother when she was just a girl in Mexico. Her grandmother, Balbina Zamora, who died in 2008, once told her how in her old village they would boil cactus and use the juice they extracted to clean any impurities from the river that provided their drinking water supply.
"That story really stuck with me," Alcantar said.
Alcantar's research has already resulted in a patented process for using cactus mucilage for water filtration. Now she has a patent application pending for using the powdered cactus mucilage as a non-toxic dispersant.
She is part of a nationwide group of scientists focused on developing alternatives to synthetic dispersants, using research funding BP put up in the wake of the disaster involving its rig that exploded off the Louisiana coast on April 20, 2010.
During the Deepwater Horizon spill, the Environmental Protection Agency allowed BP to spray 1.4 million gallons of a dispersant called Corexit on the oil at the surface. That was more dispersant than had ever been used before.
What proved even more controversial was the EPA's decision to allow BP to spray 800,000 gallons of Corexit directly at the oil coming out of the wellhead nearly a mile beneath the surface. No one had ever tried that before, either.
Studies subsequently found vast underwater plumes of oil mingled with the dispersant flowing deep beneath the surface, and lasting for months after BP capped the well in July 2010.
Although bacteria consumed much of the oil that spewed into the gulf, some is still washing ashore all across the coast.
Recently another USF scientist, James "Rip" Kirby, reported he was still finding small globs of oil and dispersant mixed in with the shells in the so-called "swash zone," just off the beaches in the Panhandle. When Kirby ran an ultra-violet light over the legs of his graduate assistant, they found that the oil and dispersant was already absorbing into his skin, even though the assistant had washed off after leaving the water.
There are still questions to be answered about Alcantar's cactus-based dispersant, said Ryan Toomey, an associate professor who's been working with Alcantar. They need to determine how the dispersant works in various conditions — choppy seas, for instance. And they need to determine how to keep the bubbles from becoming unstable when they clump together, because that could make them more difficult for the bacteria to consume.
At this point, although some companies have expressed an interest in the potential of Alcantar's product, it's not likely to be a big moneymaker, Toomey said. After all, dispersants aren't used often — just when something goes terribly wrong.
Craig Pittman can be reached at firstname.lastname@example.org.