Presentation
Mixed Rock and Sediment Shorelines: Long-term Persistence of Intertidal Oiling and Remediation Considerations
DescriptionMixed rock- and sediment shorelines are globally prevalent in many regions, particularly in tectonically active and periglacial regions but the behavior and persistence of spilled oil on these mixed shorelines is little investigated, in contrast to pure beach or rock shorelines. We report on the results of a detailed investigation of intertidal asphalt pavements and oiled sediment residues present on Abu Ali and Batinah Islands, located on the Arabian (Persian) Gulf coast of Saudi Arabia, likely deposited during the Nowruz oil field spill that occurred from 1983 to 1985 during the Iran–Iraq War. These pavements extend for more than 30 km along the shoreline and have been present for over 40 years, with little known cleanup. The impacted shoreline consists of sand beaches co-occurring in many locations, both along- and across-shore, with complex and extensive carbonate beach rock platforms and headlands. Because of this, this location provides a provide a natural laboratory to study the effect of such geological controls on the persistence of these pavements and residues.
We used data from an extensive field campaign over nearly 500 shoreline transects, combined with remote sensing, shoreline change assessments, and wave climate modeling, to investigate the specific influence of exposed and subsurface beach rock platforms, ramps, and headlands on ongoing persistence of these oil pavements and residues. Persistent continuously oiled sediments are much more likely to occur on or in the vicinity of beach rock, either buried or exposed at the surface. We infer that 1.) the reduced sediment mobility of geologically constrained beaches and 2.) reduced hydraulic permeability above subsurface beach rock platforms likely lead to longer persistence of shoreline oiling on mixed rock and sediment shorelines than might be expected along beaches or rock shorelines alone. Further, we summarize the reasons why cleanup of shoreline oiling on mixed rock and sediment shorelines poses multiple substantial remediation challenges. These results have broad implications for the design of strategies during active responses, sensitivity ranking of shorelines, and suggest new avenues for applied research in interactions between spilled contaminants and morphodynamics in these widespread but relatively little-studied intertidal habitats.
We used data from an extensive field campaign over nearly 500 shoreline transects, combined with remote sensing, shoreline change assessments, and wave climate modeling, to investigate the specific influence of exposed and subsurface beach rock platforms, ramps, and headlands on ongoing persistence of these oil pavements and residues. Persistent continuously oiled sediments are much more likely to occur on or in the vicinity of beach rock, either buried or exposed at the surface. We infer that 1.) the reduced sediment mobility of geologically constrained beaches and 2.) reduced hydraulic permeability above subsurface beach rock platforms likely lead to longer persistence of shoreline oiling on mixed rock and sediment shorelines than might be expected along beaches or rock shorelines alone. Further, we summarize the reasons why cleanup of shoreline oiling on mixed rock and sediment shorelines poses multiple substantial remediation challenges. These results have broad implications for the design of strategies during active responses, sensitivity ranking of shorelines, and suggest new avenues for applied research in interactions between spilled contaminants and morphodynamics in these widespread but relatively little-studied intertidal habitats.
Event Type
Paper
TimeWednesday, May 15th1:50pm - 2:10pm CDT
Location291-292
Restoration