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Despite claims by BP and government agencies, dispersants have not evaporated
Marine biologist Heather Reed describes the arrival of oil on our local coastlines.
(Photo: Tony Giberson/tgiberson@pnj.com )
A common ingredient in human laxatives and in the controversial dispersants that was used to break down oil from the BP Deepwater Horizon oil spill is still being found in tar balls four years later along Gulf Coast beaches including Perdido Key.
This finding in a new study contradicts the message that the chemical dispersant quickly evaporated from the environment, which BP and EPA officials were telling a public who grew outraged over the widespread use of the chemicals in the Gulf of Mexico in the weeks following the April 20, 2010, oil spill disaster.
More than 1.8 million gallons of chemical dispersant was used on oil slicks and injected subsurface to prevent oil from fouling beaches and marshes.
Scientists at Haverford College and Woods Hole Oceanographic Institution, whose research paper was published in Environment Science & Technology Letters, say it’s important for other scientists studying the impacts of the Deepwater Horizon oil spill disaster to know dispersant is still present.
The study, according to a news release from Woods Hole, examined samples from deep sea corals and surrounding sediments collected in December 2010 along with oil-soaked sand patties found along Gulf Coast beaches from July 2010 to the present.
See also: Tar mat cleanup continues
Photo gallery: Fort Pickens tar mat larger than first thought
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The dispersant chemical DOSS persisted in variable quantities in deep-coral communities six months after the spill and 26 to 45 months on beaches, Helen White, an assistant professor of chemistry with Haverford College in Pennsylvania, pointed out.
“These results indicated that the dispersant, which was thought to undergo rapid degradation in the water column, remains associated with oil in the environment and can persist for around four years,” she said.
The scientists expected to find dispersants degrading more slowly in the cold, dark depths of the deep sea.
“The interesting thing is that the sand patties we’re finding on beaches four years after the spill have DOSS in them. That was somewhat unexpected,” co-author Elizabeth Kujawinski of Woods Hole in Massachusetts said.
The tar patties and tar balls are often referred to as weathered because they’ve been exposed to the weather, wave action, temperature changes and air, which were believed to provide more opportunities for the dispersant to dissipate.
“The amounts we detected are quite small, but we’re finding this compound in locations where we expected the dispersants to disappear, either by dissolving in the water or by being degraded by bacteria,” Kujawinski said.
One question the study did not answer is what kind of danger the presence of the chemical in question – DOSS or dioctyl sodium sulfosuccinate – has on marine and human life that frequent the areas in which it’s found.
“It’s hard to say because we don’t know how toxic it may be,” White said.
She hopes in the future to collaborate with other scientists to find out.
For now, researchers hope their revelation will be helpful to other scientists studying the Deepwater Horizon oil spill disaster and prove valuable in the decision-making process to use dispersants in the future.
“The purpose of the paper was really to let researchers and policy makers know these components are still in the sand patties but they are at levels where we don’t know the health affects,” Kujawinski said. “We don’t know if sand laced with this molecule is harmful.”
Trace levels
Prior to the study, which was funded by the Gulf of Mexico Research Initiative, dispersant had only been analyzed in aqueous samples, the researchers said.
White and her team at Haverford developed a method to isolate the DOSS from the solid sand patties.
They sent the isolated compounds to Kujawinski’s Woods Hole lab. Researchers there used sophisticated instruments to quantify the DOSS samples collected from environments known to contain oil persisting from the oil spill.
The concentration of DOSS still present is very low compared to the original concentration of 2 percent to 10 percent dispersant to oil, White said.
“In sand patties, we’re seeing 0.001 percent dispersant to oil ratio,” she said. “It’s very low but it’s present, and we don’t know what that means and if it’s harmful.”
BP rebuffs report
Jason Ryan, BP America Inc. spokesman in Houston, maintains the concentrations of the dispersant compounds are so low – so small they are not detectable with standard laboratory equipment – they do not pose a risk to human health or aquatic life.
“In 2010, government agencies tested thousands of water and sediment samples for dispersant compounds in order to examine the potential persistence of dispersants in the environment,” he said. “None of the samples tested exceeded the Environmental Protection Agency’s dispersant benchmarks.”
Moreover, he said, the study has no data suggesting the traces identified came from the dispersants used in responding to the Deepwater Horizon oil spill.
Ryan says the compound measured by the researchers is common in the Gulf’s environment and can be found in many consumer products.
“Prior studies have noted that it is difficult to directly link DOSS traces in the environment to dispersants, given that these compounds can come from several sources,” he said
White said researchers did make certain they were detecting the dispersant chemical and not one from another product by comparing it to other samples in the same environment, which were found to not contain DOSS.
No cause for alarm
Richard Snyder, director of the University of West Florida Center for Environmental Diagnostics and Bioremediation, said he is not surprised by the scientists’ finding, but he cautioned beachgoers not to become alarmed and to continue to avoid tar mats and tar balls.
“Yes, it has impacts, but it’s not super toxic,” he said of DOSS. “The fear of the chemical is greater than reality. It’s a valuable chemical in treating oil spills.”
But he’s concerned about the impacts the dispersant mixed oil dispersed through the Gulf water column had on the ecosystem.
“The dispersant has toxicity (think about putting dish soap in a fish tank),” he said. “Oil has toxicity. Use of dispersant on oil slicks increases toxicity because it increases exposure – disperses the oil as microscopic droplets throughout the water. This effect was devastating to the plankton in the offshore area where dispersant was applied to the oil slicks. That material is very different than the tar mats still buried in the sand.”
Troubling sign
Sava Varazo, director of Emerald Coastkeepers, is not ruling out the fact that the lingering dispersant could be inflicting harm on human and marine life.
“I compare this to what happened in the (1989 Exxon) Valdez spill in Alaska’s Prince William Sound,” he said. “Four years later, the herring population was decimated because of these same issues. We have four years behind us. We have a lots of studies saying lots of things. We’re starting to see the long-range impacts.”
He pointed to one recent study that indicated the oil spill has caused heart problems in Gulf tuna populations, which is causing them to swim more slowly and making them more vulnerable to predators.
He wonders whether dispersant is playing a role in this, too.
“The chemical has the ability to affect muscles and digestive and reproductive systems,” he said. “In samples on the tuna, their reproduction systems were affected,” he said.
He also wonders how much of the dispersant is being passed along the food chain and onto our plates. These are all questions he hopes further studies will reveal now that it’s known dispersants are still hanging around.
“BP scientists and government officials put a lot of faith in dispersants, and the residual effects are here to stay,” he said.
Adding to our chemical world
Keith Wilkins, Escambia’s director of community and environment, said researchers’ findings should serve as a cautionary tale about widespread use of all chemicals, even though he believes dispersants should play a limited role in oil spill response.
“People think things go away and they don’t,” he said. “All the chemicals we use every day and all of the pharmaceuticals we use don’t disappear. They dilute but don’t go away. We start adapting to those things, and pharmaceuticals go through our treatment plants and end up in our surface water.”
If there is anything we can learn from this study it is to be more conservative in the use of chemicals, he said.
If there is an upside to the oil spill, it has sparked an avalanche of money – much of it from BP fine dollars – to conduct unprecedented research of the Gulf of Mexico’s ecosystem.
Wilkins said he’s hopeful the dispersant study will lead to more research to reveal how toxic these trace levels of dispersant are to humans, marine life and the ecosystem.
“Using our environment as a giant experiment, we’re going to be learning so much, and some of what we learn might be good,” he said. “And some might be bad.”
203.8 million pounds of oily material collected in four states.
(For the first year, the total includes not only the mixture of residual oil and materials such as sand and shells, but also other solid material such as protective clothing and debris. Since May 2011, only the mixture of residual oil and sand, shells and water and other material was included.)
Mississippi:
29 million pounds
Alabama:
55.3 million pounds
Florida:
28.3 million pounds
Louisiana:
91.2 million pounds
Sources: BP; U.S. Coast Guard and other sources.
BP oil spill disaster by the numbers
April 20, 2010: And explosion ripped through the Deepwater Horizon drilling rig as the rig’s crew completed drilling the exploratory Macondo well deep under the waters of the Gulf of Mexico, killing 11 crew members, injuring others and destroying the rig.
87 days: Oil gushed from the well, spewing 4.9 million barrels of crude into the Gulf until it was capped on Sept. 19.
April 22: With approval from the U.S. Coast Guard, responders first sprayed dispersants on the surface oil slick in the Gulf.
1.8 million gallons: Amount of dispesants, primarily Corexit 9500, BP applied to both the water’s surface and injected directly on the wellhead.
3 miles: BP claims no dispersants were used within 3 nautical miles of the shoreline.
98 percent: Pecentage of all use of aerial dispersant application that occurred more than 10 nautical miles offshore.
July 19, 2010: No dispersants were used for the response after this date, with the exception of 5 gallons applied on Sept. 4, 2010, within the moon-pool of a recovery vessel that brought the capping stack to the surface of the Gulf of Mexico.
4,739: Total miles of shoreline in Louisiana, Mississippi, Alabama and Florida surveyed for oil.
203.8 million pounds: Amount of oily material collected in the four states. (For the first year, the total includes not only the mixture of residual oil and materials such as sand and shells, but also other solid material such as protective clothing and debris. Since May 2011, only the mixture of residual oil and sand, shells and water and other material was included.) Totals by state: Mississippi: Total-29 million pounds; Alabama: Total- 55.3 million pounds;-Florida: Total-28.3 million pounds; Louisiana: Total-91.2 million pounds.
1,783: Amount of weathered BP oil being removed by hand from the surf zone at the Gulkf Islands National Seashore’s Fort Pickens area.
Sources: BP; U.S. Coast Guard and other sources.
ONLINE
Hear what marine biologist Heather Reed of Pensacola has to say about the dispersant study online at www.pnj.com.
Special thanks to Richard Charter
