Study hints at methane leakage
COAL-seam gas fields around Tara in Queensland's Darling Downs are leaking the tracer gas radon at levels three times higher than areas with no CSG wells, new research from Southern Cross University has found.
Radon exists naturally in soils but when the soil structure is changed more radon can be released to the atmosphere - for example during earthquakes.
"We hypothesise that an analogous process is happening when the soil structure is altered during CSG mining through processes such a drilling, hydraulic fracturing and alteration of the water table," co-author Dr Isaac Santos said.
The researchers from the Centre for Coastal Biogeochemistry Research said the presence of radon may also indicate the release of other gases such as methane.
This would link the paper with research released last year (yet to be peer-reviewed) that methane levels in the air around Tara were three times higher than normal.
Co-author Dr Damien Maher said the findings suggested leakage from not only infrastructure but alternative gas pathways though diffuse soil emissions that had yet to be accounted for.
"Fixing the infrastructure is relatively easy. Fixing up the changes in the soil structure is much more difficult," Dr Maher said.
But more baseline research needed to be done before the radon seeps could be attributed to CSG extraction.
"Natural seeps coincidently occurring near CSG wells in the area could cause similar patterns therefore it is essential to conduct baseline studies before the development of CSG fields," said Dr Maher.
The work by researchers at Southern Cross University and published in the international scientific journal Environmental Science and Technology (http://pubs.acs.org/doi/abs/10.1021/es304538g) is the first peer-reviewed study in Australia reporting a field experiment specifically designed to look into potential influences of CSG on the chemistry of the atmosphere.