Marine Scientists Spot 23-Mile Long Oil Plume Off Florida’s Gulf Coast -Will It Be Pulled into Loop Current Towards the Dry Tortugas?

Oil_depot_11_12_05_1150 Researchers from the University of Miami's Cooperative Institute for Marine and Atmospheric Studies (CIMAS) and the National Oceanic and Atmospheric Administration's Atlantic Oceanographic and Meteorological Laboratory (NOAA/AOML) were determined to check on whether oil was, as predicted, being pulled into the Loop Current and carried toward the Dry Tortugas.

The University of Miami's 96-foot catamaran the RV/F.G. Walton Smith had just completed a two-week National Science Foundation (NSF) sponsored cruise sampling the deep submerged plumes near the Deepwater Horizon well site.

The team decided that the most likely pathway for oil to reach the Florida Keys was for it to be pulled into a counterclockwise rotating frontal eddy in the northeast corner of the Loop Current, and then south along the eastern frontal zone of the Loop Current to the Dry Tortugas.

Charting a course to the south, they found an area of strong flow convergence within a southward flowing jet that resulted from flow being pulled into the eddy. Knowing that this was just the type of oceanographic feature that would concentrate any floating material, including oil, they followed it. At about the same time a U.S. Coast Guard flight that had been sent to visually survey the area spotted what they thought could be an oil slick in the area and contacted the scientists aboard the Walton Smith to have the ship get a closer look at the slick.

"As we approached, we found an extensive oil slick that stretched about 20 nm (20 miles) along the southward flowing jet which merged with the northern front of the Loop Current. The slick was made up of tar balls shaped like pancakes that went from the size of a dime to about 6 inches in diameter," said Tom Lee, UM Research Professor Emeritus and CIMAS scientist. "The combination of models and satellite images, along with our shipboard observations and ROFFS daily analysis had helped us to identify and study this previously unidentified oil plume located off Florida's southwest coast and heading toward the Tortugas."

Scientists set up net tows and lowered a CTD (Conductivity, Temperature and Depth) instrument equipped with oil sampling devices into the water, collecting samples of both the oil and saltwater in the area. As they headed further south they kept looking for other tendrils oil, but increased winds made spotting tell-tale sheens more difficult. As a result they could not confirm the exact length of this southern arm of the oil slick, which they had previously inferred from their data. Samples have been provided to federally sanctioned laboratories to confirm the source of materials gathered.

"The good news is that the various approaches we are using to project its pathway seem to be yielding similar answers and guiding us properly. We need to maintain our vigilance and expand our efforts to determine the degree of risk to unique downstream resources like the Dry Tortugas and Florida Keys National Marine Sanctuary, which are vital natural environments that we need to protect," said Peter Ortner, UM Marine Biology and Fisheries professor and director of CIMAS. 

Casey Kazan via University of Miami Rosenstiel School of Marine & Atmospheric Science.

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