Glowing Oil Could Aid Gulf Spill Cleanup
By Chris Combs, The National Geographic.
Late last week coastal geologist Rip Kirby (University of South Florida) was on the seashore as part of an effort to detect oil by shining UV lights, widely used to spot vital fluid at crime scenes, on Gulf beaches. The method, he hopes, will allow scientists and cleanup crews to tackle hard-to-spot oil, such as crude mixed with mud or light stains on sand, that’s washed ashore from the sinking of the BP-leased Deepwater Horizon rig.
Under UV light, clean sand appears purple or black. Some minerals, such as calcium carbonate in seashells, glow blue, as does a shovel handle in the picture above. Tar from the Gulf of Mexico oil spill lights up orange-yellow on the beaches.
Although hydrocarbons have long been known to fluoresce, or glow, under ultraviolet light, this may be the first time the technology has been used outside a lab to spot oil.
“The first time I took the UV flashlight out on the beach to see if it would work, it was beyond my wildest dreams,” Kirby said. “It was easy to see that there was oil on the beach … the contamination was widespread.”
Under UV light, even lightly contaminated sand glows bright orange-yellow.
One challenge of cleaning up the oil is collateral contamination, including the transfer of oil via workers’ boots, Kirby said.
“BP hasn’t put cleaning stations at all the exits [to the beach], as required by federal law,” he said. “People … go back to the parking lot and scrape off the oil. Other people step in the brown gunky stuff,” and the oil contamination spreads.
Footprints in the sand at Florida’s Gulf Islands National Seashore appear clean under a normal flashlight.
The same footprints, seen under ultraviolet light, are shown to be heavily contaminated by oil. Kirby said that the best way to clean up oil of this nature could be so-called bioremediation. Once the oil stops washing ashore in large quantities, such as if the leaking wellhead were to be capped, “you could spray microbes on it that would eat the oil and leave [the sand] in place,” he said.
“The bacteria are naturally occurring. We just harvest them and grow a bunch in a 42-gallon (160-liter) barrel so we can spray it out in a food-rich environment.”
In a trench dug by a University of South Florida Coastal Research Lab team, layers of oil-stained sand light up orange under ultraviolet light. Clean sand appears violet.
According to graduate student Kirby, UV light could help cleanup crews pinpoint hard-to-see oil that might then be treated with oil-eating bacteria.
“You could drive up the beach and dig a trench and see if you get layers of orange sand, and spray bacteria there to eat the oil.”
Some scientists, however, warn that encouraging bacterial growth could upset a beach’s ecological balance.