Time Scale for Oil Droplet Stabilization by Mineral Particles in Turbulent Suspensions

Abstract

An equation is presented that defines the time required to coat and stabilize oil droplets with mineral particles suspended in a turbulent medium. The physical model underlying the proposed expression successfully explains variability in the formation rates of oil–mineral aggregates (OMA) observed previously in laboratory studies. Constraint is placed on the coalescence efficiency between oil droplets and mineral particles by reconciling the magnitudes of theoretical and observed coalescence rates. Example stabilization times are calculated for a range of conditions typical of the coastal marine environment. In general, stabilization times are less than one day, supporting the hypothesis that OMA formation is an important process in the cleansing of oiled shorelines. For the range of oil concentrations used in the model (0.01–0.1 kg m −3) OMA stabilization does not occur when sediment concentration is of order 0.01 kg m −3. The finding that OMA form rapidly given adequate sediment concentration indicates that intervention to increase sediment concentration is an effective response on oiled shorelines. The proposed equation will assist the oil-spill countermeasures community by providing a quantitative tool for establishing the importance of OMA formation relative to other oil dispersion processes in the coastal zone.