July 27, 2010
FOR IMMEDIATE RELEASE
Contact: Kate or Ken Gooderham, (239) 489-2616 or exdir@asbpa.org

Oil in your beach, but not on it
The spill's impacts can lurk below the surface of an otherwise clean beach, and research shows storm waves will push more oil onto beaches even if landfall is hundreds of miles away.

It seems counterintuitive, but you can have oil in your beach but not on it. That is just one of the findings from Dr. Ping Wang and his research team who studied the 150-mile-long beachfront from Dauphin Island, Alabama, through Santa Rosa Island, Florida, this summer.

Wang, an associate professor in geology at the University of South Florida (USF), was part of the oil spill rapid response research team funded by the National Science Foundation in response to the Deepwater Horizon catastrophe in the Gulf waters south of Louisiana. Their report was part of the USF Coastal Research Laboratory’s effort to provide baseline beach condition and initial beach oiling from the spill.

The research team first visited the beaches in mid-May, before the slick from the April 20 explosion had spread to the area's beaches. They returned in mid-June to follow up their studies as oil had begun to come onshore regularly.

What they found was not only an oily impact on the white-sand surface of these world-renowned beaches, but a hidden impact beneath. Despite manual cleanup efforts focused on surface oil, tar balls and oil sheen, residue could still be found underneath the sand.

The researchers found that the depth of oil contamination depends on the sand movement along the shoreline and across the beach. If you stand in the surf zone, you can feel the sand movement. The oil can be deposited on the surface and then buried by the moving sand. They found oil buried up to two feet under the beach in some cases. Under most situations, the oil is buried between 0.1 and 1 foot.

Dr. Wang acknowledged the challenges: “The difficulty is that the depths of contamination vary. In some places it might be 2 feetdown, and a few feet away it is less than 1 foot below the surface. If mechanical methods (i.e. digging with machines) are to be used to clean these beaches, it is difficult to decide how deep to dig.”

Tar balls on the surface of the beach in the Gulf sun oxidize quickly and become less sticky and easier to remove. However, oxidation is much slower for buried oil that doesn’t become so easily weathered and, thus, may have longer effect to the beach environment.

How far the waves run up the beach determines the amount of contamination. During mild weather, Dr. Wang found less than 20 feet of beach was contaminated by oil. When they returned to the same stretch of beach after Hurricane Alex, they found the storm-driven waves pushed oil into a 100-foot-wide area despite the fact the hurricane was 500 miles away and there was no storm surge.

According to Wang: “Clean up is much more difficult after big waves, since oil can be washed into bird nesting areas and turtle nests.

“High waves and storm surges are capable of spreading the oil contamination over a much larger area than the narrow beach zone where the tar balls are currently found. It doesn’t need to be a major hurricane to push the oil onto the shore and spread over a large area, including numerous bird nesting areas, it just needs to be a storm.”

(The full NSF progressive report is available online at http://usfweb3.usf.edu/absoluteNM/articlefiles/2456-progressive_report_1_061210.pdf. This report documents the initial beach fall of oil late May and early June. Most of the findings on the buried oil, as discussed above, were obtained from the two investigations after this report.)

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