Mechanical Dispersal of Oil Stranded in the Littoral Zone

Abstract

The natural weathering and dispersion of oil stranded in the littoral zone depend on the type and volume of the oil and on the amount of available energy. Energy inputs can be biological, chemical, mechanical, or thermal; however, the single most important input appears to be from mechanical energy (winds, waves, tides, water levels, and ice). The residence time or persistence of stranded oils increases as mechanical energy levels at the shoreline decrease. The primary inputs of mechanical energy at the shoreline are due to wave action, and energy levels vary depending on the wind regime, fetch areas, and local exposure of a section of coast. In cold or polar climates, energy levels at the shoreline are reduced by the presence of ice on the sea or an ice foot on the beach. This review of the concepts associated with littoral processes, in terms of the mechanical dispersal of stranded oil, provides the basis for estimation of the persistence of oil on shorelines. Key words: petroleum (weathering, dispersal), coastal processes, wave energy, sea ice, ice foot, Canada

Oil, oil dispersants and related substances in the marine environment

“…The most important factor which influences the persistence of oil on intertidal beaches is the mechanical energy available (Gundlach & Hayes, 1978;Owens, 1978). While exposed beaches (high energy beaches) can be free of oil within 2 to 3 months even after heavy pollution, oil can persist for decades in salt marshes or tidal flats.…”

Proceedings of the 1979 U.S. Fish and Wildlife Service Pollution Response Workshop, 8-10 May 1979, St. Petersburg, Florida

“…The persistence of oil is determined primarily by physical processes (waves, tides, and when present, ice movements) , Owens 1978.…”

Analyses of hydrocarbons in BLM sediment intercalibration sample from Santa Barbara basin and spiked with API South Louisiana crude oil. A preliminary report

“…The absolutely higher concentration of the heaviest compounds must be explained by a concentrating of the remaining oil in surface sediment from both depth in the peat and horizontally in the study area. Our samples came from a mid-tide region where marsh sedimentation is most rapid, while erosive processes are likely to be most active near high land low water (Owens, 1978) which could lead to just such a concentration.…”