Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8884481 | Deep Sea Research Part II: Topical Studies in Oceanography | 2018 | 7 Pages |
Abstract
Remaining lingering subsurface oil residues from the Exxon Valdez oil spill (EVOS) are, at present, patchily distributed across the geologically complex and spatially extensive shorelines of Prince William Sound and the Gulf of Alaska. We review and synthesize previous literature describing the causal geomorphic and physical mechanisms for persistence of oil in the intertidal subsurface sediments of these areas. We also summarize previous sampling and modeling efforts, and refine previously presented models with additional data to characterize the present-day linear and areal spatial extent, and quantity of lingering subsurface oil. In the weeks after the spill in March of 1989, approximately 17,750Â t of oil were stranded along impacted shorelines, and by October of 1992, only ~2% of the mass of spilled oil was estimated to remain in intertidal areas. We estimate that lingering subsurface residues, generally between 5 and 20Â cm thick and sequestered below 10-20Â cm of clean sediment, are present over 30Â ha of intertidal area, along 11.4Â km of shoreline, and represent approximately 227Â t or 0.6% of the total mass of spilled oil. These residues are typically located in finer-grained sand and gravel sediments, often under an armor of cobble- or boulder-sized clasts, in areas with limited groundwater flow and porosity. Persistence of these residues is correlated with heavy initial oil loading together with localized sheltering from physical disturbance such as wave energy within the beach face. While no longer generally bioavailable and increasingly chemically weathered, present removal rates for these remaining subsurface oil residues have slowed to nearly zero. The only remaining plausible removal mechanisms will operate over time scales of decades.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Geology
Authors
Zachary Nixon, Jacqueline Michel,