Assessing the potential for oil-mineral aggregation in the coastal ocean

The clean-up of oil spilled into the marine environment is a costly and perennial challenge around the globe. Recently, attention has been devoted to the effects that oil-mineral aggregation can have on the natural cleansing of oiled shores. Oil-mineral aggregation is the process by which small oil droplets and sediment particles collide and adhere in turbulent suspensions. The coating of oil droplets with sediment prevents the droplets from re-coalescing or sticking to the shore. The small droplets disperse and are degraded rapidly by naturally occurring microbial communities. A variety of studies have implicated this natural process in the rapid natural cleansing of oiled shores, yet the spill response community still lacks the tools to predict where and when it will be effective. In particular, the effects of sediment size and concentration on extent of oil-mineral aggregation until recently have not been well understood. Over the past three years in my laboratory, we have established relationships that link sediment size and concentration to the amount of oil incorporated into oil-mineral aggregates (OMA). The goal of the proposed research is to extend these laboratory relationships in the field. I propose to assess the potential for OMA formation along the northern shore of the Bay of Fundy. In the field we will make measurements of sediment size and concentration by deploying particle sizing equipment and by gathering and analyzing water samples. Sites will be occupied in the spring, fall and summer over several years to evaluate possible seasonal and interannual effects. With measurements of particle size and concentration, predictions of the extent of OMA formation will be made based on our laboratory relationships. These predictions will be tested by agitating suspensions to which oil has been added. The actual extent of OMA formation will then be measured with a confocal laser scanning microscope. This research will continue to place Canada at the forefront of research into a natural process that assists in the recovery of shorelines affected by oil spills.