Simple approach to ‘wipe out’ oil remaining from Exxon Valdez spill

WASHINGTON - Scientists have reported that traces of crude oil from the Exxon Valdez oil spill remain highly biodegradable, despite almost 20 years of weathering and decomposition.

Their findings suggest a simple approach for further cleaning up remaining traces of the Exxon Valdez spill.

Albert D. Venosa and colleagues found that bacteria, evaporation and sunlight work together to break down the oil and make it disappear. It is also known that adding nitrogen and phosphorus fertilizer to oil-contaminated soil can speed the growth of bacteria that decompose, or biodegrade, oil.

The scientists collected oil-contaminated soil from different beaches in Prince William Sound and treated the samples with phosphorus and nitrogen fertilizer in the presence of excess oxygen from the air.

Oil in the fertilized samples biodegraded up to twice as fast as oil in the unfertilized control samples, but significant biodegradation occurred even in the unfertilized controls.

Results showed that oxygen supply was the major bottleneck. They postulated a simple treatment scheme that would involve applying simple nitrate salts to possibly break down the natural organic matter in the sediment.

That would cause an increase in sediment porosity that would allow dissolved oxygen in seawater to penetrate to the oiled zone and create oxygen-rich conditions that might stimulate more rapid biodegradation.

Their findings appear in ACS’ semi-monthly journal Environmental Science and Technology. (ANI)