Vertical Dispersion in Oil Spill Fate and Transport Models

The evolution of oil spilled in marine environments is affected by its spread, evaporation, emulsion, dissolution and dispersion in the water column. Although it has an environmental impact on marine ecosystems and affects determination of the spilled oil lifetime, vertical dispersion is of great importance; however, less attention has been paid to this complex phenomenon in comparison with other processes. This article is a critical review of the existing analytical relationships for oil dispersion calculation. The implementation of these formulae in numerical models is not straightforward. A comprehensive review of numerical oil dispersion models is presented with the advantages and disadvantages of each approach. In addition, experimental oil spill studies are reviewed and their obstacles are discussed. Analysis of experimental data cited in the literature has been carried out and variations in the oil concentration distribution in water bodies has been investigated. The current knowledge gaps and areas that require further investigation are identified and future research directions are proposed for in-depth assessment of vertical oil dispersion in the marine environment. Major areas of future study should focus on gradients of oil concentration by depth in the water column instead of overall penetrated oil mass in a water body. It is also suggested that advanced models use explicit physically-based formulations rather than empirical oil concentration relationships. It should be noted that selection of appropriate space and time intervals for sampling in experimental studies is required to form a proper understanding of the temporal and spatial oil concentration distribution in a water body.