Image above: Experimental PVC-pipe microcosm study.
Photo Credit: Anna Iverson.
Offshore oil production along Alaska’s arctic coast is expected to increase in the coming years. While this is expected to create large economic benefits for the state, crude oil spills may occur. An oil spill may reach the shoreline, where it could create adverse short and long- term ecological effects. Mass transfer processes play an important role in determining the fate of crude oil along shorelines. These processes—diffusion, dispersion, and viscosity—are strongly temperature dependent. Nutrients, commonly added to stimulate bioremediation, may be washed out with waves and tides. It is therefore necessary to study how factors such as the beach matrix and temperature affect hydrocarbon and nutrient distribution.
Laboratory experiments were implemented to help understand how the soil composition and tidal action will affect the oil’s movement through the shoreline sediments. Experiments were conducted at two different grain sizes (sand-gravel/pebble) using material obtained from Barrow and two different temperatures (20° and 3° Celsius). A microcosm study using a PVC pipe setup was used to simulate a more in depth look at the transport of oil through the soil profile based on a tidal flushing. Data shows that higher amounts of crude oil were found in the middle layer for sandy gravel sediments, whereas pebble sediments had higher concentrations in the top and bottom layers. Future experiments will use a wave tank as a scale model of an actual shore environment to investigate the effect of wave action on contaminant movement.