2008 Annual Report
Gulf of Maine Research Institute
Spotlight on Science

GMRI studies movement of natural oil slicks to help spill mitigation

Nick Record Research questions are often inspired by a new idea, a way to improve, fix, or prevent something. Sometimes, a major disaster or new technology jumpstarts investigations. For Dr. Andrew Pershing, Research Scientist at the Gulf of Maine Research Institute (GMRI) and Assistant Professor at the University of Maine's School of Marine Sciences, and his research associate Nick Record (pictured right), experimenting with photography has lead to a novel approach minimizing impacts from possible future oil spills.

In 1996, the tanker ship Julie N tore a hole in her hull as she collided with the Portland Harbor Bridge, more popularly known as the "Million Dollar Bridge." Over 179,000 gallons of petroleum fuel was released into Portland Harbor and the Fore River. The quick reaction of cleanup crews contributed to the removal of almost 78% of the fuel. Despite their best efforts, some of the wetlands remained contaminated for a short time. Portland's lobster fleet had to remove all gear within a 16-mile radius of the spill - a hard hit to the industry and local economy.

"When oil is spilled in a body of water, it moves mostly at the mercy of the tides, currents, and winds," said Record. The oil slicks are visible at the surface and can be tracked as they move.

Pershing and Record are working on a tool that could predict where future oil spills are most likely travel given certain environmental conditions. Since it wouldn't be a good idea to dump a barrel of oil overboard and track its movement, they came up with a strategy to build their model based on the visible sheen that comes from harmless natural slicks produced by algae. These are the lighter streaks of color that you see in most near-shore areas.

Record set up a digital camera on the Casco Bay Bridge - the replacement bridge for the Million Dollar - in the control tower of the drawbridge. It aimed northeast, toward the mouth of the Fore River, and snapped a photo of the seascape every minute for a year - over a half million photos. Record performed monthly checks on the camera to ensure everything was working properly. Nighttime, sea smoke, sea ice, poor weather, and large ships moving through all presented problems when observing the photos, rendering some of them useless for the analysis. Record had to go through the photos and perform a technique called georectification.

Georectification is a method of taking a photo of a landscape, or in this case seascape, and turning it into a top-down view. This is done through "stretching" the pixels of the photo based on distance from an anchor point. The two photos below show what happens in the process of georectification. The left is the raw photo from the control tower on the bridge. Visible natural oil slicks appear as lighter, snake-like features at the surface. On the right, the photo has been georectified, and the oil slicks can be seen more clearly.

The slicks close to the camera are quite visible. A series of images over the course of a day would form an animation as the tide, wind, and current flows move the slick. If a model can be created to show the relationship between those environmental conditions and the way the slicks converge, it could be incorporated into oil spill mitigation, says Record.

"If there were a spill, you could contain it better if you know where the oil usually converges," said Record. The model would be available in real-time, so in the event of another spill in Portland Harbor, you plug in the parameters of the equation - where the spill originated, wind, current and tide direction - and it would identify locations to deploy booms in the area. "We wouldn't have to waste oil booms where they aren't needed," he explained. For now, the team is still analyzing the photos and building the model. With over a half million photos, a lot of work is yet to be done. "With so much data, pulling patterns is a major challenge," said Record. If successful, the team hopes to replicate the project in other areas.

To read more about this project and others please visit the lab’s blog.

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