US Geological Survey (USGS) scientists have been developing a computer model that could potentially assist scientists in tracking and predicting where oil will go following a spill, sometimes years afterwards.
The tool could also assist in oil spill clean-up, and provide assistance to response efforts following future incidents.
The 2010 Deepwater Horizon oil spill (pictured) leaked an estimated 4.9MMbbl/d into the Gulf of Mexico within three months. Oil spills can be attributed to incidents such as this, or more frequent incidents, such as oil tanks spills, leaks, or seepage into the ocean.
Surface residual balls (SRBs)—heavier-than-water sand and oil agglomerates, often several centimeters thick—that formed along the surf zone after the Deepwater Horizon spill were discovered within the past year, still causing beach re-oiling.
The scientists applied the model to movement of SRBs along the coast of Alabama and western Florida, under normal conditions, where wave heights are less than 1.5m-2m, centimeter-sized SRBs will not move alongshore.
P. Soupy Dalyander, a research oceanographer and lead author of the study explained that the mobility and transport of the SRBs was found to be likely during storms, while calmer weather patterns typically didn’t cause any movement from the SRBs.
"SRBs are dense enough to rest on the seafloor, rather than floating,” Dalyander said. “Because sand grains are smaller and more mobile than the larger SRBs, under non-storm conditions when the SRBs themselves are not moving, they can be buried and exhumed by mobilized sand."
According to the model, inlets trap SRBs, allowing them to accumulate, and larger SRBs that are found onshore may have formed when the oil floated ashore rather than while the oil traveled from its original location.
"The techniques developed here can be applied to evaluate the potential alongshore movement of SRBs in other locations or from any future spill where large quantities of oil and sand mix in the surf zone,” Dalyander said.
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