Formation of oil-SPM aggregates using natural sediment from Jiaozhou Bay, China

When oil spills occur in the coastal environment, the spilled oil may interact with the suspended particulate matter (SPM) in the water column to form oil-SPM aggregates (OSAs). This process has been recognized for decades to enhance the natural cleansing of oiled shorelines. Studies have been conducted to understand the formation and characteristics of OSAs. However, more studies are needed to address the OSA formation with different SPM properties. Most of our previous work on OSA formation was conducted using the standard reference material, which has special properties suitable for OSA formation. This laboratory study was conducted using different natural sediment samples collected from Jiaozhou Bay, China. The main objective of this work was to study the variance of OSA formation with different sediment properties. The experiments were conducted using sediments with different particle size distribution and mineral composition, one crude oil sample, filtered natural seawater, and a reciprocating shaker. The sediment-to-oil ratio was kept constant to 1 in all the experiments. The oil trapped in negatively buoyant OSAs was measured using an Infrared Oil Content Analyzer. Results showed that OSA formation increased with the decrease of the sediment size, more floating OSAs formed when the sediment size was below 6 μm. Kaolinite forms more OSAs compared to bentonite, and multiple mineral composition samples. The highest of the oil trapping efficiency in settled OSAs was 59%, and the highest of the oil-to-sediment ratio was 0.69 mg oil/ mg sediment.