Modelling the effect of sediment size on OMA formation

A new theory for natural attenuation of oil spills on shores has emerged which links the formation of oil-mineral aggregates (OMA) to improved rates of removal and biodegradation of stranded oil. This study upgraded a previous Monte Carlo model to simulate OMA formation and includes floc break and aggregation by differential settling. It also examined the real size distribution of sediment grains and oil droplets. The proposed model calculates the formation time and the concentration of OMA in a typical turbulent estuarine environment and determines the effect of sediment size and concentration on OMA concentration. Sedimentation is considered to be the main factor responsible for the formation of stable OMAs. Ideal conditions are when the size ratio varies between 0.1 and 0.4. OMA formation was simulated considering different sediment sizes reacting with Flotta, Scotian Light and Prudhoe Bay oils. Both simulation and laboratory studies indicate a negative effect of sediment size on OMA formation. 38 refs., 2 tabs., 5 figs