Microbes recruited in Valdez cleanup.
Just after midnight on March 24, the Exxon Valdez supertanker ran aground in Alaska's Prince William Sound, spilling 10.1 million gallons of crude oil and fouling 368 miles of shoreline in that sound alone. Roughly 2,500 people have already enlisted in the manual cleanup of area branches and wildlife. But the newest recruits in the cleanup are local communities of bacteria that specialize in detoxification.
Last week, Environmental Protection agency scientists began seeding six oil-stained beach plots with nitrogen and phosphorus fertilizer in a 2-acre experiment at Alaska's Snug Harbor. Previous studies had detected air-breathing bacteria in Prince William Sound and nearby beach waters with the ability to break down slowly volatilizing alkanes (straight-chained compounds) and simple aromatic (ring-shaped) hydrocarbons. Together, these compounds represent about half the oil left on the beaches. Moreover, says EPA's Hap Pritchard in Valdez, Alaska, they account for most of that oil's toxicity.
The 90-day test will compare two nutrient formulations aimed at spurring the yet-unidentified bacteria's growth and alkane/aromatic degradation. One formulation incorporates oleic acid, best known as the primary fatty acid in olive oil. Researchers conducting the test think this "fat" will glue the mixed-in bacterial nutrients to any crude oil on which they're sprayed. The other formulation is an off-the-shelf fertilizer "brickette." The researchers are packing several brickettes into biodegradable plastic sacks and tying the sacks to pipes anchored in the beach. Over the course of a month, they expect wave and tidal action to flush the slowly dissolving fertilizer back and forth across the shoreline's rocks and sand.
The team will use its preliminary data, available by early July, to determine whether either information offers enough promise for widespread treatment of Alaska's beaches. Neither regimen, however, can restore affected beaches to their former, nearly pristine state. Because these bacteria ignore asphalt-like oil constituents, a tarry residue will remain.
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|Title Annotation:||Science & Society; Exxon Valdez supertanker|
|Date:||Jun 17, 1989|
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