Scientist: Oil slick likely from natural seafloor seepage

Scientist: Oil slick likely from natural seafloor seepage
In this photo provided by the Santa Barbara County, Calif., Fire Department, Henry Duncan, left, and Bob Seiler, legs covered in oil, foreground, stand in the Goleta Beach parking lot with their oil-covered kayaks, on the truck at rear, in Goleta, Calif., Wednesday, July 29, 2015. The pair encountered a large oil sheen and called the fire department to investigate. The Coast Guard is investigating this new oil slick off the Southern California coast about a dozen miles from where a broken pipeline spilled thousands of gallons of crude into the ocean in May. (Mike Eliason/ Santa Barbara County Fire Department via AP)

Coast Guard officials were still trying to determine the source of a mysterious miles-long oil slick off California's Santa Barbara County shoreline, but a scientist said Thursday that it's likely the result of naturally occurring seepage from the sea floor.

Authorities said the 3-mile sheen was harmless to people and beaches remained open—in contrast to the mass closure that occurred in May when a broken pipeline spilled 100,000 gallons of crude , fouling sands, seabirds and fishing areas in the same general area.

The oil is floating in the Santa Barbara Channel above the Coal Oil Point seep field, a region known for releasing methane and also about 100 barrels of liquid petroleum per day, said Jordan Clark, professor of earth science and environmental studies at University of California, Santa Barbara.

It's not uncommon for even larger amounts of oil to be occasionally "burped" from the , he said, noting that Spanish explorers first documented the natural seepage centuries ago. It's one of the largest seep fields in the world, he said.

"If you fly in to Santa Barbara airport you can often see slicks on the water out there. It's reasonable for a slick this size to be spotted in the seepage area" of Coal Oil Point, Clark said. He called the size of the sheen "relatively insignificant" and agreed with Coast Guard officials who predicted it would likely dissipate in a day or two.

Coast Guard Petty Officer Andrea Anderson said samples were sent to labs after the slick was reported by kayakers Wednesday about 1,000 yards off the city of Goleta. Officials were hoping to find out if the oil was from seepage, crude extraction operations or from another source. There was no word when the results might come back.

Scientist: Oil slick likely from natural seafloor seepage
This photo provided by the Santa Barbara County, Calif., Fire Department shows a sample of oil scraped off the side of a kayak after two kayakers encountered a large oil sheen and called the fire department to investigate, seen at the Goleta Beach parking lot in Goleta, Calif., Wednesday, July 29, 2015. The Coast Guard is investigating this new oil slick off the Southern California coast about a dozen miles from where a broken pipeline spilled thousands of gallons of crude into the ocean in May. The oil sheen was reported late Wednesday morning about 1,000 yards offshore from Goleta. (AP Photo/Mike Eliason, Santa Barbara County Fire Department)

"It's going to be a waiting game," she said. "We hope to rule some things out, as far as the source goes. Is it natural, is it not natural?"

The new slick was drifting east toward waters off the city of Santa Barbara.

Firefighters who went to the Goleta pier Wednesday to check on reports of a smell of gas found two kayakers who had just come ashore with their legs and boats covered in oil. One of them, Bob Seiler, told KABC-TV that he and a friend were fishing when they suddenly found themselves enveloped by the oil.

"We were heading to the end of the kelp bed that's out there and the further we got out there the thicker this film was," he said.

Although the slick was large, it wasn't thick and gooey enough to be scooped up, Coast Guard Petty Officer Sondra-Kay Kneen said. It should simply break up and deplete on its own in the days ahead, she said.

Meanwhile, beaches in picturesque Santa Barbara and Goleta remained open and were expected to be packed as a heat wave gripped California.

The Santa Barbara County Department of Public Health said the slick provided no threat to public health and safety, although officials advised people to avoid contact with the oil.

The sheen was floating not far from the channel's Platform Holly oil facility, but officials with Venoco Inc., which operates the platform, said it could not have come from there.

The platform is shut down and there is no oil in its pipeline, said Zach Shulman, the company's director for corporate finance and investor relations.

Clark said seepage generally increases when the platform is not active.

The sheen was located about 12 miles away from the site where an onshore pipeline operated by Texas-based Plains All American ruptured at Refugio State Beach in May. The break flooded the area with 100,000 gallons of crude, of which 21,000 gallons ended up in the ocean.


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Citation: Scientist: Oil slick likely from natural seafloor seepage (2015, July 30) retrieved 22 November 2019 from https://phys.org/news/2015-07-scientist-oil-slick-natural-seafloor.html
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