How Investigators Track Oil Culpritsby Eric Nalder & Phuong Cat Le
Chemists employ 'fingerprinting' -- but sometimes more is needed
To the untrained eye, an oil spill is just a brackish mess speckled with rainbows, but to a forensic chemist it's a collection of clues pointing to its origin.
Chemists have been fingerprinting oil spills for 30 years, since the 1970s when improved laboratory equipment made the technique more accurate. The science of oil fingerprinting has been around even longer than that, having been used originally to help drillers trace the source of oil fields underground.
A test that takes one or two hours can match two samples of oil -- say, one from the spill and another from a suspect ship -- with 100 or more distinct features. The lab test can detect characteristics imprinted into the oil eons ago when it was formed in the ground, and Indonesian crude is very different from Alaskan crude.
But even when investigators have a good suspect ship or boat to examine -- one that was perhaps in the area at the exact time the spill occurred -- they still have to eliminate other suspects. That's a big problem. Samples must be taken from all ships in the area.
While the technique is often effective, the chemists sometimes come up empty. If the spill is bunker fuel, for example, many other ships in the area might be using the same fuel from the same source. In such cases, more conventional investigative techniques must be used to finger the culprit, such as logbook entries, engine logs, vessel traffic system spotting charts, measurement of fuel tanks, and any other evidence that might place the ship at the scene. Sometimes none of this works, and spillers get away free.
There have been cases where a ship's crew, knowing it will be asked for a sample, has mixed fuels from two tanks filled at different locations to permanently contaminate evidence, said Jim Bruya, a chemist in Seattle who does fingerprinting.
Massachusetts forensic chemist Scott Stout used a successful California case to illustrate the difficulty of the work. A 10-mile-long slick was spotted in 1998 just outside San Francisco Bay. Thirty possible sources, ships traveling in the area, were identified. Many lab tests were necessary, on every source, to help the Justice Department narrow the search. Finally, the tests led investigators to a tanker that was spotted by the Coast Guard trailing oil near Panama. He said the case was eventually settled.
"The fingerprinting was only able to do so much. More than one of those 30 or so candidates had received the same kind of fuel," he said. "Building the case was a combination of modeling and circumstantial evidence."
In the case of yesterday's spill, shipping records indicate fewer than a dozen, perhaps even fewer than half a dozen, ships were in the area at the time of the spill.
The Coast Guard sends samples of mystery oil spills to its own version of a CSI crime lab, the Marine Safety Laboratory in Groton, Conn.
The lab handles about 200 cases a year, mostly involving mystery oil spills, said Dr Wayne Gronlund, who manages the 10-person lab.
"Most mystery spills are bilge spills" which are often relatively easy to identify, he added. Bilge tanks hold waste materials.
"If the spill sample is fairly fresh, unweathered, our chances are very high of being able to match it to the source," Gronlund said.
Paul Philp of the University of Oklahoma, a prominent forensic geochemist, said it helps when samples are collected quickly, avoiding the effects of evaporation, time and weathering. But scientists have successfully identified oil that's been in the water as long as 48 hours, experts said.
A scientist using mass spectrometry will uncover characteristics of the oil, "like peeling back the layers of an onion," and the more fingerprints that can be found ("five fingers rather than one") the better, said Philp.
About once a month, a large ship runs into trouble somewhere along the West Coast, according to the Pacific States/British Columbia Oil Spill Task Force. In Washington and Oregon, recent history is full of oil spills and incidents that could have resulted in a spill, according to state records. A partial listing:
March 19: 200,000 gallons of crude oil spilled by tanker SS Mobil Oil into Columbia River near Longview.
Dec. 21: 239,000 gallons of crude oil spill when tanker Arco Anchorage runs aground near Port Angeles.
Dec. 23: Barge Nestucca breaks loose from a tug and collides with it, spilling 231,000 gallons of bunker oil off Grays Harbor. More than 3,500 seabirds are killed, most caught in an oily mousse washed up on Vancouver Island.
April: Oil tanker Exxon Philadelphia loses power, goes adrift off the mouth of the Strait of Juan de Fuca, loaded with 23 million gallons of Alaska crude. Five hours later, a tug meets the ship for towing to Port Angeles.
January: 600,000 gallons of oil spills at U.S. Oil and Refining in Tacoma. Most didn't reach Commencement Bay.
July: Chinese freighter Tuo Hai hits and sinks the Tenyo Maru, a Japanese- owned fish processor, spilling 100,000 gallons of diesel and heavy oil off the Strait of Juan de Fuca. Tens of thousands of seabirds were killed.
July: Chinese bulk freighter Tian Tan Hai collides with tank barge Cascades, laden with 2.4 million gallons of oil, about 30 miles west of the Columbia River entrance. No oil spilled.
July 11: Oil tanker Kenai, en route to Valdez, Alaska, loses power off Port Angeles after a stop there. A tug brings it back to Port Angeles.
Nov. 25: Bulk carrier Aristotelis, having engine trouble, drifts from Cape Flattery to Vancouver Island, anchors to keep from going aground.
Feb. 4: Freighter New Carissa runs aground off Oregon coast, carrying more than 400,000 gallons of diesel and bunker fuel. 70,000 gallons of fuel oil leaks.
Feb. 5: APL Japan, a 900-foot container ship, loses power while approaching Port Angeles and comes within a few yards of running aground before being rescued by two tugs.
July 15 and 29: Two fully loaded oil tankers arrive in Fidalgo Bay, near Anacortes, without proper nautical charts.
April 29: Tugboat towing another tug and a barge with 2 million gallons of gasoline in the Strait of Juan de Fuca suffers partial engine failure. Neah Bay rescue tug dispatched to rescue.
Dec. 27: Tug Pacific Avenger, towing 430-foot-long tank barge hauling 50,000 barrels of diesel fuel, loses hydraulic steering about 15 miles west of Cape Alava; crew steers with backup hand-crank system.
May 19: Panamanian-flagged tanker Gaz Diamond spills 500-800 gallons while refueling in Port Angeles harbor. Oil fouls areas of the harbor and the beach near Ediz Hook.
Dec. 30: Mistake during a fuel oil transfer at Point Wells near Edmonds spills about 4,800 gallons into Puget Sound. The spill spread 6-7 miles, harming shellfish beds and marine life on the eastern Kitsap Peninsula.
May 17: State Ecology Department cites the Army Corps of Engineers for more than 33 oil spills at nine dams on the Columbia and Snake rivers over the past five years.
Aug. 26: Front-end loader pierces oil pipe at a Weyerhaeuser Co. pulp mill in Longview, spilling thousands of gallons. An earthen berm contains the spill; oil doesn't reach the nearby Columbia River.
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