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LSU Researcher Investigates Oil Aggregates from BP Spill

In the aftermath of the explosion at BP's Macondo Well on April 20, 2010, approximately 5 million barrels of oil leaked into the Gulf of Mexico. While some of the problems and damages associated with the BP oil spill were typical of other spills, others consequences were unique to the deep underwater leak that resulted from the Deepwater Horizon disaster.

Photo Rock-like oil aggregates are still washing up on Fourchon three years after the Deepwater Horizon oil spill.
John Pardue/Louisiana Water Resources Research Institute

John Pardue, Louisiana Water Resources Research Institute Director and Elizabeth Howell Stewart Professor of Civil & Environmental Engineering, has extensively studied the oil aggregates that formed as oil from the BP spill came ashore in the form of an emulsion of water and oil. In the aftermath of the April 20, 2010, oil spill in the Gulf of Mexico, Pardue received support funds from BP's Gulf Research Initiative to study the recovery and remediation of emulsified oil in contaminated marshes, and funds from the Wisner Donation to study the fate of oil on coastal headland beaches.

"Emulsified oil spills have happened before, but perhaps not at this scale," Pardue said. "What was different about the oil spill this time was that it came ashore as an emulsion, which is a mixture of water and oil. The emulsified oil happened because the leak occurred off at sea, with wave action and weathering of the oil components contributing to the emulsified form that made its way to shore. The mixture was stable in this form, and it sat on the beach for some time after the oil spill. In the meantime, sand blowing over the beach covered and mixed with the water and oil, forming small aggregates," Pardue said, pulling what looked like small rocks out of a sandy glass jar.

"You would look at this, and you would think, well that is just a rock," Pardue said, breaking one of the clumps in half to reveal its dark oily interior. "But on the inside of these aggregates, you can see and smell oil."

According to Pardue, these small oil aggregates still cover many Louisiana beaches, including Fourchon Beach, an area closed for recreational use due to continued oil spill cleanup. The aggregates along the beach are intermittently covered by sand and uncovered by waves and storm surge.

photo By using special photographic techniques and image processing methods, Pardue's group has been able to more accurately quantify remaining oil aggregates in clean-up areas.
John Pardue/Louisiana Water Resources Research Institute

"The clean-up of these aggregates along our beaches involves either manually picking them up, or leaving them to break down on their own," Pardue said. "What we have been studying is first, how to find these aggregates more effectively by studying how they are distributed along the beach, and second, how fast the chemicals in the oil of these aggregates breaks down over time."

Pardue's research group has spent years since the BP spill conducting detailed sampling of small oil aggregates along Fourchon Beach and surrounding areas. The group has devised new techniques for finding and quantifying aggregates.

"Clean-up crews typically clean the beaches until they reach 1 percent coverage, using colored charts to estimate by eye the amount of oil remaining in any given area," Pardue said. "We developed a new photographic technique to better understand how these aggregates are distributed along the beach surface and the chemistry of their breakdown."

By using special photographic techniques and image processing methods, Pardue's group has been able to more accurately quantify remaining oil aggregates in clean-up areas. These detection and sampling techniques are helping clean-up crews to better find remaining oil aggregates along beaches and to gauge how quickly the aggregates will break down on their own if left behind.

"It's crazy, but three years later, this is still going on," Pardue said, referring to BP oil spill clean-up efforts. During any given week in the field, Pardue's team is joined by as many as 100 other people in charge of clean-up efforts along Fourchon Beach.

"That is how hard it is to find all of these oil aggregates and to get them off the beach," Pardue said. "The oil that is left in the form of small aggregates is not as easy to remove as large oil deposits. Much of this oil will be left behind, so we will need to study how quickly these forms will degrade over time."

Photo Fourchon Beach is currently closed to the public, because even though it may appear clean of aggregates, wind and water quickly wash away top layers of sand, revealing oil that remains behind.
John Pardue/Louisiana Water Resources Research Institute

However, leftover oil aggregates on the beach pose potential health threats to the public once the areas are re-opened for recreational use. While the beaches may appear clean of aggregates at one point in time, hurricane and other storm weather often washes away tops layers of sand, revealing oil that remains behind.

"What we are worried about is that, while this area is closed to the public now, it is scheduled to be open again at some point in the future," Pardue said. "You can imagine that if these aggregates are still present on the beach at that point, the first thing kids are going to want to do is go around collecting them – they look cool and rather mysterious. They will get exposed to the oil simply by handling these aggregates."

Efforts to restore beach quality include digging up large oil mats discovered through beach sample cores and bringing in clean sand to cover small remaining deposits. However, Pardue warns, with oil deposits remaining offshore and small oil aggregates remaining buried by surface layers of sand, new sand may quickly become contaminated.

"Fourchon Beach is the location of one of the priority coastal restoration projects in the state – a multi-hundred million dollar project on the state's master plan," Pardue said. "The problem is, do you take the precious sand that we have and mix it into a beach that is still contaminated?"'

According to Pardue, restoration projects at the beach have been delayed by oil clean-up efforts. Fourchon Beach sits directly in the path of hurricanes that approach New Orleans, serving as a barrier and first line of defense against storm surge. The beach also serves to protect Port Fourchon, the number one port in Louisiana for serving offshore oil and gas. However, the beach is also one of the fastest eroding landscapes in the world, eroding at a rate of 100 feet per year.

Photo Fourchon Beach, which offers New Orleans’ first line of defense again storm surge, is one of the fasted eroding landscapes in the world, losing an average of 100 feet a year. Restoration projects at the beach have been delayed by oil clean-up efforts.
John Pardue/Louisiana Water Resources Research Institute

"The erosion is clearly visible," Pardue said. "Having been out there for three years now, I've seen the beach thin out and sand dunes disappear. The beach is in a critical state. But until we can get the rest of the oil off, we face a difficult situation in moving forward with restoration efforts."

Pardue's research team is also currently helping federal clean-up crews locate and sample offshore oil.

"BP and federal clean-up crews are just now starting to evaluate remaining offshore oil," Pardue said. "The beach won't be clean until they address that."

With Fourchon Beach and the adjacent Elmer's Island beach accounting for nearly 13 of the only 20 miles of sandy beach that exist in Louisiana, the landscape is a rare and valuable natural resource. Pardue and his team will continue to provide advice for federal clean-up efforts and well as restoration projects aimed at the beach.

For more information about Fourchon Beach, visit http://www.portfourchon.com/explore.cfm/beaches/.

For more information on John Pardue's research, visit http://www.cee.lsu.edu/people/Bios/John_Pardue.aspx.