Oil-Mineral Flocculation and Settling Dynamics

Abstract

In recent decades, oil spill contamination has tended to occur more commonly in deltaic and estuarial systems. The management of oil spillages has been a major challenge in the surrounding deltas due to the highly sensitivity nature of deltaic ecosystems. Many deltas have an abundance of clay minerals that can flocculate, and these play an important role in determining the transport of spilled oil contamination and its eventual fate, particularly given that suspended sediment and microbial activities are often prevalent and diverse in natural environments. The primary work presented here focuses on laboratory experimental studies that help develop improved parameterizations of flocculation processes for oil-sediment-biogeochemical modeling. Oil-mineral flocs (OMA) have been successfully created from a series of laboratory flocculation experiments. A floc video instrument LabSFLOC-2 has been adopted for the first time to study the settling dynamics of OMAs. Experimental results reveal OMAs can easily form in any oil, cohesive sediment, and seawater mixtures. However, Kaolin and Bentonite forms dramatically different OMA structures, which leads to their variable characteristics. In the Bentonite clay cases, the oil flocs tend to be much larger and with higher densities than those in Kaolin clay cases, resulting in significant variability of flocs settling velocities.