Antarctic microbes clean up petroleum pollutants

Synthetic oil is mixed into marine sediment.
Synthetic oil is mixed into marine sediment to test its effect on microbial communities and other sediment-dwelling organisms. (Photo: Shane Powell)

13 July 2006

Under the right conditions micro-organisms in Antarctic soils and marine sediments could help environmental managers clean up fuel and oil spills.

In two experiments, Australian Antarctic Division (AAD) scientist Dr Shane Powell, and her colleagues from the AAD and the University of Saskatchewan (Canada), found that fertiliser increased the natural microbial bioremediation or clean up of soils contaminated by diesel; while in marine sediments, biodegradable oil and Special Antarctic Blend diesel were more readily degraded by the resident microbes than synthetic oils.

In the first experiment fertiliser was added to soil contaminated by a spill of Special Antarctic Blend diesel, which occurred at the Old Casey research station in East Antarctica more than 20 years ago. Over five years the fertiliser stimulated an increased removal of diesel hydrocarbons within the soil by denitrifying bacteria. These bacteria use nitrate from fertiliser to help metabolise hydrocarbons in the absence of oxygen.

The finding provides environmental managers in Antarctica with a more efficient and effective means of cleaning up fuel spills than current methods, which include excavating the soil and shipping it to warmer, temperate regions; relying on the slower, natural bioremediation process; or heating the soil to speed up this natural process.

"We need to factor in the role of these bacteria in breaking down hydrocarbons in the future management of fuel spills," Dr Powell said.

In the second experiment Dr Powell looked at the effects of Special Antarctic Blend diesel and three lubricating oils – biodegradable oil, synthetic oil and the same synthetic oil after use in a vehicle – on microbial numbers and community structure in the pristine O'Brien Bay near Casey station.

The team collected clean sediment from the bay and added the different contaminants, before returning the sediment to the bottom of the bay in trays. Five weeks later they measured the number of microbes and assessed the types of microbes present in clean and contaminated samples.

They found a significant increase in the total number of microbes in the sediments contaminated with diesel and biodegradable oil compared with uncontaminated sediment.

"This suggests that the bacteria in the sediment can use chemicals in the diesel and biodegradable oil to grow," Dr Powell said.

The team also found that the types of microbes present in the diesel and synthetic oil treatments were significantly different from those in the untreated control. However, there were no significant differences in community structure between the control and the biodegradable oil treatment.

"This provides the first evidence that using biodegradable oils might be of genuine environmental benefit in the Antarctic," Dr Powell said.

Longer-term studies are now underway to assess the effect of these pollutants on microbial and other sediment-dwelling communities over a five year period.

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