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Images: After the Oil Spill, Finding a Drop in the Ocean

When oil and gas mixtures are ejected from a deep wellhead, liquid oil droplets of many different sizes form and rise toward the ocean surface. Smaller droplets become as dense as the surrounding water deep below the surface and are swept away laterally by prevailing ocean currents (left panel). When a dispersant is added at the depth of the wellhead, a component called a surfactant breaks up the oil into small droplets (middle panel). If the dispersant works perfectly, virtually all the liquid oil is in these “neutrally buoyant” droplets and is carried away before ever reaching the surface, and the droplets become small enough to be consumed, or “biodegraded,” by bacteria. In the Deepwater Horizon spill (right panel), scientists found evidence that the dispersant mixed with the small droplets in the deep-water hydrocarbon plume at a depth of 1,100 meters, but they also discovered the oil/dispersant mix had not yet biodegraded several months after the spill. (The study could not distinguish between oil droplets coated with surfactant and surfactant floating freely on its own, so scientists cannot distinguish whether the dispersant worked as planned or did not attach to the oil, as intended.) (Illustration by Jack Cook, Woods Hole Oceanographic Institution)

WHOI marine chemist Elizabeth Kujawinski (left) and research associate Melissa Kido Soule monitor a mass spectrometer that can detect and identify molecules in low concentrations within a mixture of compounds. With colleague Krista Longnecker, they developed methods using this instrument to detect the chemical dispersant Corexit in samples of water from the Gulf of Mexico after the Deepwater Horizon oil spill. (Photo by Tom Kleindinst, Woods Hole Oceanographic Institution)

WHOI chemist Liz Kujawinski (back left) watches as service engineer Rob Harper installs a Fourier-transform ion cyclotron resonance mass spectrometer in the Fye Laboratory. The room-sized mass spectrometer can measure the molecular mass of many compounds simultaneously with very high precision and accuracy. It is used to identify and characterize organic compounds produced and used by marine microbes, and to detect petroleum products or pharmaceuticals in the environment. Kujawinski and Chris Reddy led a group that won a grant from the National Science Foundation for the new equipment. A complementary piece of equipment in this laboratory was provided by the Gordon and Betty Moore Foundation. (Photo by Tom Kleindinst, Woods Hole Oceanographic Institution)