New study finds correlation between CSG wells and radon concentrations in the atmosphere
New research has found a significant link between concentrations of radon gas in coal seam gas (CSG) fields and the number of CSG wells nearby.
The work by researchers at Southern Cross University and published recently in the international scientific journal Environmental Science and Technology 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.
“The study measured radon concentrations at monitoring stations both inside and outside the Kenya/Talinga gas fields north of Tara in southern Queensland,” said lead author Douglas Tait, a PhD student with the University’s Centre for Coastal Biogeochemistry Research in the School of Environment, Science and Engineering.
The study found a significant correlation between the number of CSG wells and the concentration of atmospheric radon measured over a 24 hour period in the surrounding area.
“Radon is an excellent tracer of other gases because it is unreactive and its short half-life prevents any significant build-up in the atmosphere over long time scales. Therefore, the presence of radon in the atmosphere requires a nearby source,” said Mr Tait.
Radon exists naturally in soils but when the soil structure is changed more radon can be released to the atmosphere.
“Any air in contact with the soil has a higher concentration of radon, making it an excellent tracer for gases released from processes that alter soil structure associated with CSG mining,” said co-author Associate Professor Isaac Santos.
The research team found radon concentrations approximately three times higher in areas with high densities of CSG wells than those areas with low densities.
“It has been known for years that radon anomalies can be observed during earthquakes. As the soil structure expands or contracts and cracks before and during an earthquake, it creates conduits for the release of soil radon into groundwater and the atmosphere,” Professor Santos said.
“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.”
Dr Damien Maher, another of the study's co-authors, 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.”
“Methane, for instance, is 100 times more powerful than carbon dioxide as a greenhouse gas, and if there are unidentified pathways for methane release this can have significant ramifications for greenhouse gas budgets.
“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.”
Mr Tait said using radon as a natural tracer offered a novel way for scientific studies to assess the impact of CSG mining on atmospheric chemistry.
The study was described during a public seminar at Southern Cross University in November 2012 and can be downloaded from the School of Environmental Science and Technology website.
The paper, ‘Enrichment of radon and carbon dioxide in the open atmosphere of an Australian coal seam gas field’ by PhD candidate Douglas Tait, Associate Professor Isaac Santos, Dr Damien Maher, PhD candidate Tyler Cyronak and undergraduate student Rachael Davis, is available at Environmental Science and Technology.
Photo: Lead author PhD candidate Douglas Tait (centre) with Dr Damien Maher, Associate Professor Isaac Santos, PhD candidate Tyler Cyronak and undergraduate student Rachael Davis.