This illustration shows the route traveled by oil leaving the subseafloor reservoir as it travels through the water column to the surface and ultimately sinks and falls out in a plume shape onto the seafloor where it remains in the sediment. (Illustration by Jack Cook, Woods Hole Oceanographic Institution)
Oil and methane bubble to the ocean's surface from natural seeps off Coal Oil Point, near Santa Barbara, California. (Photo courtesy of Dave Valentine, UCSB)
Two-dimensional gas chromatograms show how many compounds were in the oil at the ocean surface (top) and how few compounds remain in the sediments (bottom) after parts of the oil dissolved into the water, evaporated into the air, or were degraded by microbes. (Chromatogram by Bob Nelson, Woods Hole Oceanographic Institution)
UCSB's Dave Valentine, left, and WHOI's Chris Reddy. (Photo by Julia Vraspir)
Researchers found that the total petroleum hydrogen (TPH) content in sampling locations (dots) was highest in sediments closest to the seeps and gradually diminished over distance as it was dispersed by currents—much the way smoke trails away in the wind.