A team of University of South Florida researchers studying the impact of the Deepwater Horizon oil spill on northern Gulf beaches say areas just offshore from some of Florida's most heavily oiled beaches appear to be free of visible oil contamination in the sediments.
The update from the USF Coastal Research Laboratory, led by Geologist Ping Wang, are significant because they allay one of the chief concerns among coastal researchers: that oil which might have sunk just out of sight offshore could be easily stirred up by a storm and be washed onto beaches.
Wang, working with the chair of USF's Department of Integrative Biology Susan Bell and a team of researchers, surveyed areas Sept. 23-27 just off the coast from Santa Rosa Island in Florida west to Gulf Shores, Ala. The five-day expedition is part of ongoing research projects funded by the National Science Foundation in the aftermath of the Deepwater Horizon spill, the nation's largest environmental disaster.
The team found no visually identifiable oil contamination, including no tar balls, tar patties or oil sheets, they said in a new report. Sediment cores gathered by divers also were free of visual evidence of oil. Further laboratory tests are being conducted to look for further hydrocarbon contamination, which often can be invisible and is detected only through sophisticated laboratory tests.
"Since no visually identifiable oil was found on or below the surface in the nearshore zone at any of the sampling sites, we believe that it is unlikely that significant amounts of 'new oil from the nearshore' will be washed onto the beach during storms," Wang said. "However, it should be noted that based on our earlier study of buried oil along the beaches, erosion of buried beach oil and subsequent redistribution is expected during storms."
Bell said researchers will make more detailed observations of diver-collected cores in the lab, including microscopic examination of sand grains, to assess whether there is any indication of oil contamination. The group also plans to survey additional sites.
The work by Wang and the Coastal Geology Lab team garnered worldwide attention this summer when they examined beaches in northwest Florida and Alabama to document the extent of BP oil contamination. The researchers later returned to beaches that had been cleaned by BP crews only to find a thick layer of oil buried inches below the sand and that cleaning machines had chopped oil sheets into tiny tar balls, spreading the contamination on a wider area.
In the most recent exploration, however, their findings reached a more hopeful initial conclusion. The team collected 60 sediment cores and 60 surface sediment samples just off of those heavily contaminated beaches in waters from nine to 45 feet deep. Samples also were also collected in areas such as Pensacola Bay and Perdido Bay, which suffered some of the brunt of the oil contamination in Florida this summer.
The latest update comes as some of the nation's top scientists studying the spill gathered in St. Petersburg Beach Tuesday and Wednesday to compare findings and initial observations on the complex picture left by the Deepwater Horizon blowout. More than 145 researchers gathered in workshops organized by the National Oceanic and Atmospheric Administration, the NSF and the National Science and Technology Joint Sub-Committee on Ocean Science and Technology.
Given the unprecedented nature of the spill, scientists say they are facing a complex series of questions and factors to consider as they begin to chart the long-term impact of the spill on the Gulf environment.
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