title: Nearshore dynamics of artificial sand and oil agglomerates.
abstract: Weathered oil can mix with sediment to form heavier-than-water sand and oil agglomerates (SOAs) that can cause beach re-oiling for years after a spill. Few studies have focused on the physical dynamics of SOAs. In this study, artificial SOAs (aSOAs) were created and deployed in the nearshore, and shear stress-based mobility formulations were assessed to predict SOA response. Prediction sensitivity to uncertainty in hydrodynamic conditions and shear stress parameterizations were explored. Critical stress estimates accounting for large particle exposure in a mixed bed gave the best predictions of mobility under shoaling and breaking waves. In the surf zone, the 10-cm aSOA was immobile and began to bury in the seafloor while smaller size classes dispersed alongshore. aSOAs up to 5 cm in diameter were frequently mobilized in the swash zone. The uncertainty in predicting aSOA dynamics reflects a broader uncertainty in applying mobility and transport formulations to cm-sized particles.
authors.affiliation: U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, 600 4(th) Street South, Saint Petersburg, FL 33704, United States. Electronic address: sdalyander@usgs.gov.
authors.forename: P Soupy
authors.initials: PS
authors.lastname: Dalyander
authors.affiliation: U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, 600 4(th) Street South, Saint Petersburg, FL 33704, United States.
authors.forename: Nathaniel G
authors.initials: NG
authors.lastname: Plant
authors.affiliation: U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, 600 4(th) Street South, Saint Petersburg, FL 33704, United States.
authors.forename: Joseph W
authors.initials: JW
authors.lastname: Long
authors.affiliation: U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, 600 4(th) Street South, Saint Petersburg, FL 33704, United States.
authors.forename: Molly
authors.initials: M
authors.lastname: McLaughlin
mesh_terms: D004784:Environmental Monitoring; D057446:Hydrodynamics; D008956:Models, Chemical; D010578:Petroleum / Q000032:analysis*; D059392:Petroleum Pollution / Q000032:analysis*; D012822:Silicon Dioxide / Q000737:chemistry*; D014887:Weather
chemical_list: D010578:Petroleum; D012822:Silicon Dioxide
keywords: Deepwater Horizon; Oil spill; Sand and oil agglomerates; Sediment transport; Surface residual balls; Tarballs