Natural cleaning of oiled coarse sediment shorelines in Arctic and Atlantic Canada

Two long-term data sets are described that document the natural cleaning of oiled shorelines on an Arctic and a North Atlantic coast in Canada. In both cases there has been a well documented reduction in the distribution and amount of remaining oil that can be explained readily where the shores are exposed to wave action. Added insight into the processes by which shorelines can clean themselves in low wave-energy environments and in the absence of coastal erosion has been offered only recently. This insight involves a process by which mineral fine particulates interact with the oil in the presence of seawater to form positively buoyant, micron-sized aggregates. Laboratory observations of samples collected from these shorelines demonstrate that this process does occur and, therefore, can be invoked to partially account for the natural cleaning of oiled shorelines in the two cases considered here.