Sedimentary Evolution of Deepwater Horizon/Macondo Oil on Sand Beaches of the Northern Gulf of Mexico, USA

: Observations of sedimentary evolution of oil along northern Gulf of Mexico sand beaches, made in conjunction with Shoreline Cleanup Assessment Technique (SCAT) surveys for the Deepwater Horizon/Macondo (DWH/M) spill, can assist oil spill managers and responders, and provide further insight into sedimentary processes in this and similar environments. Helicopter over-flights during active oiling gave a broad perspective of distributional patterns from Mississippi to western Florida while ground surveys provided details of the oils sedimentary behavior within the coastal system over a 20-month period. During active oiling, June/July 2010, floating emulsified oil (mousse patties) stranded onshore in appreciable quantities. High wave and tide conditions resulted in overwash and backshore flooding, deposition of oil well into the supratidal zone and burial to depths of as much as one meter. Once stranded, adherence of sand to mousse patties increased their density, promoted burial and began their transformation into oil/sand aggregates. Beachface wave action generally reduced the size of oil/sand aggregates. Under heavy accumulations, oil coalesced into subtidal oil/sediment mats in surf zone depressions. Oil stranded in supratidal pools was remobilized by the suns heat, floated to the surface, and was re-deposited in concentric rings around the pools as water levels decreased. Post-active oiling processes influencing stranded oil had definite seasonal components including eolian, wave energy/overwash, cleanup-related activities and weathering. Higher summer water levels and wave energy/overwash associated with storms reworked stranded oil. Strong northerly fall/winter winds resulted in lower water levels and exposed previously buried supratidal oil as concentrated surface lag deposits. In situ weathering/breakdown occurred under surface, subsurface and subtidal conditions. Continued wave energy/overwash and weathering processes will likely prove effective in removal and the long-term breakdown of remaining oil.

[1]  Edgar Mendoza,et al.  An artificial reef improves coastal protection and provides a base for coral recovery , 2016 .

[2]  F. Calafat,et al.  Rapid changes in the seasonal sea level cycle along the US Gulf coast from the late 20th century , 2014 .

[3]  Elliott Taylor,et al.  Extent and Degree of Shoreline Oiling: Deepwater Horizon Oil Spill, Gulf of Mexico, USA , 2013, PloS one.

[4]  Ping Wang,et al.  Distribution of Surficial and Buried Oil Contaminants across Sandy Beaches along NW Florida and Alabama Coasts Following the Deepwater Horizon Oil Spill in 2010 , 2013 .

[5]  Robert H. Weisberg,et al.  Seasonal Variability on the West Florida Shelf , 2012 .

[6]  F. Vilas,et al.  Simulating the influence of physicochemical parameters on subsurface oil on beaches: preliminary results. , 2010, Marine pollution bulletin.

[7]  X. Nóvoa,et al.  Influence of Beach Morphodynamics in the Deep Burial of Fuel in Beaches , 2009 .

[8]  Ping Wang,et al.  Morphological and Sedimentological Impacts of Hurricane Ivan and Immediate Poststorm Beach Recovery along the Northwestern Florida Barrier-Island Coasts , 2006 .

[9]  F. Vilas,et al.  Beach morphodynamics forcements in oiled shorelines: Coupled physical and chemical processes during and after fuel burial. , 2006, Marine pollution bulletin.

[10]  C. Cheong.  RESEARCH PAPERS : PENETRATION OF DISPERSED AND WEATHERED OIL AND ITS ECOLOGICAL IMPLICATION IN MODEL SANDY BEACH , 2004 .

[11]  G. Stone,et al.  Net Longshore Sediment Transport and Textural Changes in Beach Sediments along the Southwest Alabama and Mississippi Barrier Islands, U.S.A. , 2001 .

[12]  D. Little,et al.  THE PERSISTENCE OF OIL STRANDED ON SEDIMENT SHORELINES , 1987 .

[13]  E. Owens.  FACTORS AFFECTING THE PERSISTENCE OF STRANDED OIL ON LOW ENERGY COASTS , 1985 .

[14]  J. Sadd,et al.  IMPACT AND PERSISTENCE OF IXTOC I OIL ON THE SOUTH TEXAS COAST , 1981 .

[15]  M. Hayes,et al.  VULNERABILITY OF COASTAL ENVIRONMENTS TO OIL SPILL IMPACTS , 1978 .

[16]  M. Hayes,et al.  TheUrquiola oil spill, La Coruña, Spain: Impact and reaction on beaches and rocky coasts , 1978 .

[17]  E. Owens.  Mechanical Dispersal of Oil Stranded in the Littoral Zone , 1978 .

[18]  D. Gorsline.  Dynamic characteristics of west Florida Gulf Coast beaches , 1966 .

[19]  K. O. Emery,et al.  A SIMPLE METHOD OF MEASURING BEACH PROFILES , 1961 .

[20]  G. Stone,et al.  Geomorphologic Evolution of Barrier Islands along the Northern U.S. Gulf of Mexico and Implications for Engineering Design in Barrier Restoration , 2009 .

[21]  Jacqueline Michel,et al.  Distribution and weathering of shoreline oil one year after the Gulf War oil spill , 1993 .

[22]  B. Rouge.  Tide Gauge Records, Water Level Rise, and Subsidence in the Northern Gulf of Mexico , 1991 .