By George Foulsham

	Christopher Farwell, left, and David Valentine

Twenty years ago, the oil tanker Exxon Valdez struck a reef as it exited Alaska’s Prince William Sound in the middle of the night. What happened next is considered one of the nation’s worst environmental disasters: 10.8 million gallons of crude oil spilled into the pristine Alaskan waters, eventually covering 11,000 square miles of ocean.

Now, imagine 8 to 80 times the amount of oil spilled in the Exxon Valdez accident.

According to new research by scientists from UCSB and the Woods Hole Oceanographic Institution (WHOI), that’s how much oil has made its way into sediments offshore from petroleum seeps near Coal Oil Point in the Santa Barbara Channel. Their research, reported in an article published last month in Environmental Science & Technology, documents how the oil is released by the seeps, carried to the surface along a meandering plume, and then deposited on the ocean floor in sediments that stretch for miles northwest of Coal Oil Point.

In addition, the research reveals that the oil is so degraded by the time it gets buried in the sea bed that it’s a mere shell of the petroleum that initially bubbles up from the seeps. “These were spectacular findings,” said Christopher Reddy, a marine chemist at WHOI and one of the co-authors of the new paper.

Other co-authors include David Valentine, associate professor of earth science; and Libe Washburn, professor of geography; and Emily Peacock and Robert K. Nelson, both of WHOI.

The lead author is Christopher Farwell, who at the time of the research was an undergraduate studying chemistry at UCSB. Inspired by this project, Farwell has changed his career path and is now a graduate student at UCSB studying marine science and earth science.

In an earlier paper published in 2008, Valentine and Reddy documented how microbes devour many of the compounds in the oil emanating from the seeps. The new study examines the final step in the life cycle of the oil.

“It’s dramatic how much the oil loses in this life cycle,” Reddy said. ”

It’s the amount of residual oil that made it to the ocean floor that surprised all of the researchers. “Based on what we found in the sample cores at our sites, we calculated the amount of hydrocarbon in the whole area,” Valentine said. “We have to make assumptions about how deep the sediment is, so we assume a range of between 50 centimeters and 5 meters. We come out with 8 to 80 Exxon Valdezes worth of oil, just in this area.”