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Predicting the consequence of natural and chemical dispersion for oil slick size over time
Author(s) -
ZeinstraHelfrich Marieke,
Koops Wierd,
Murk Albertinka J.
Publication year - 2017
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1002/2017jc012789
Subject(s) - dispersant , dispersion (optics) , environmental science , oil droplet , petroleum engineering , entrainment (biomusicology) , mixing (physics) , oil spill , atmospheric dispersion modeling , environmental engineering , geology , engineering , chemistry , optics , physics , chemical engineering , air pollution , organic chemistry , quantum mechanics , rhythm , acoustics , emulsion
Application of dispersants aims to enhance the natural dispersion process in order to reduce the size of the slick and the amount of oil at the surface. This study presents an approach for modeling the development of the surface oil slick as a function of the wind speed, oil viscosity, and dispersant application. We modeled the oil slick mass distribution across a transect through the slick over time taking into account the continuous entrainment of oil, resurfacing process of the different oil droplet size classes and horizontal transport. Outcomes show distinctively different oil slick features, depending on how favorable conditions are for dispersion. A large comet‐shaped slick is formed in the case of suboptimal dispersion. Optimal dispersion yields a small surface oil slick, with a large mass of oil suspended. The benefit of dispersants is limited to in conditions with suboptimal natural dispersion, with the exception of extremely unfavorable conditions in which the slick size would be increased. The oil slick length, fraction of oil still floating, lifetime of the slick, and wind drift are highly influenced by wind speed and related mixing conditions, and to a lesser extent by oil properties. In the newly defined “Dispersibility Factor” (DF) the oil slick properties and environmental conditions can be combined into one value that correlates with the simulation outcomes and therefore can be used as an indicator of favorability of natural dispersion and likelihood of added value of chemical dispersion.