Distribution of Surficial and Buried Oil Contaminants across Sandy Beaches along NW Florida and Alabama Coasts Following the Deepwater Horizon Oil Spill in 2010

Wang, P. and Roberts, T.M., 2013. Distribution of surficial and buried oil contaminants across sandy beaches along NW Florida and Alabama coasts following the deepwater horizon oil spill in 2010. The failed Deepwater Horizon (DWH) well released approximately 7.0 × 105 m3 of oil into the northern Gulf of Mexico during an 84-day period from 20 April 2010 to 15 July 2010. This study examined the beach oiling that resulted from the DWH spill, specifically the cross-shore distribution of both surface and buried oil, based on a series of field investigations and transport mechanisms following principles of beach morphodynamics. Five types of oil contamination were distinguished, including tar balls, tar patties, tar cakes, oil sheet, and stained sand. All five types were identified both on the beach surface and buried underneath contaminated and clean sand. The cross-shore distribution of surface oil was bound landward by the maximum high-tide wave run-up, which was, in turn, controlled by the incident wave condition. Concentrated surface oil contaminants were often found along the maximum high-tide wave run-up and in the trough landward of the berm crest. The foreshore, with dynamic and constant swash motion, was not conducive for preservation of surface oil deposition. The burial of oil contaminants occurred at similar temporal scales and was driven by the same processes as the initial surface deposition. The buried layers of oil contaminants were documented in varying thicknesses (up to 15 cm) and depths (up to 50 cm) below the surface. The deepest buried oil was found beneath the active (or storm) berm crest and decreased in depth both landward and seaward. Buried oil contaminants can resurface as the beach erodes. Buried oil can be removed through mechanical excavation. Detailed description of cross-shore distribution of oil contaminants relating to beach morphodynamic terminology may help optimizing beach cleanup planning