Australian native grasses offer a cheap, effective and environmentally sound way to help clean-up old mines and other industrial sites.

The roots of certain native grasses give a boost to microbes in the soil that break down pollution caused by fuel oil and other hydrocarbon contaminants, doctoral researcher Sharyn Gaskin of Flinders University revealed on 25 June 2007 at the 2nd International Contaminated Site Remediation Conference in Adelaide.

The technique, known as rhizoremediation (root remediation), is easy to apply and low cost compared with traditional clean-up methods like digging up soil and treating it, Ms Gaskin says.

"This is new work. Till now there have been no published reports of rhizoremediation using native species being applied as a technology for organic contamination in Australia.

"This study aimed to identify the types of native grasses that are best for achieving a clean-up of old mine and other industrial sites contaminated with fuel oil and other hydrocarbons."

Ms Gaskin tested nine grass species in various kinds of contaminated soil and measured their growth rates. She found three to be particularly promising for use in minesite rehabilitation.

Studies overseas have identified a range of grasses - particularly ryegrass and other perennials - as able to degrade organic pollution, but this is the first time Australian grasses have been put to the test.

Ms Gaskin said the use of native varieties would avoid the environmental issues associated with use of introduced plants to remove contamination. Native species are also better adapted for local conditions.

"This is the first time Australian species of grass have been explored as agents for phytoremediation of petroleum-based hydrocarbons, typically found at mine sites. They are fairly easy to grow and propagate, are hardy and have dense root systems and thick top cover - they are not high maintenance."

"Essentially, the grasses secrete compounds, especially organic acids, that stimulate micro-organisms that already exist in the root zone," Ms Gaskin said. "These micro-organisms then break down the pollutants."