title: Dissolved radon and uranium in groundwater in a potential coal seam gas development region (Richmond River Catchment, Australia).
abstract: The extraction of unconventional gas resources such as shale and coal seam gas (CSG) is rapidly expanding globally and often prevents the opportunity for comprehensive baseline groundwater investigations prior to drilling. Unconventional gas extraction often targets geological layers with high naturally occurring radioactive materials (NORM) and extraction practices may possibly mobilise radionuclides into regional and local drinking water resources. Here, we establish baseline groundwater radon and uranium levels in shallow aquifers overlying a potential CSG target formation in the Richmond River Catchment, Australia. A total of 91 groundwater samples from six different geological units showed highly variable radon activities (0.14-20.33 Bq/L) and uranium levels (0.001-2.77 μg/L) which were well below the Australian Drinking Water Guideline values (radon; 100 Bq/L and uranium; 17 μg/L). Therefore, from a radon and uranium perspective, the regional groundwater does not pose health risks to consumers. Uranium could not explain the distribution of radon in groundwater. Relatively high radon activities (7.88 ± 0.83 Bq/L) in the fractured Lismore Basalt aquifer coincided with very low uranium concentrations (0.04 ± 0.02 μg/L). In the Quaternary Sediments aquifers, a positive correlation between U and HCO3(-) (r(2) = 0.49, p < 0.01) implied the uranium was present as uranyl-carbonate complexes. Since NORM are often enriched in target geological formations containing unconventional gas, establishing radon and uranium concentrations in overlying aquifers comprises an important component of baseline groundwater investigations.
authors: School of Environmental Science and Management, Southern Cross University, Lismore, NSW, 2480, Australia; National Marine Science Centre, School of Environment, Science and Engineering, Southern Cross University, Lismore, NSW, 2480, Australia. Electronic address: marnieatkins1@gmail.com.
authors: Marnie L
authors: ML
authors: Atkins
authors: School of Environmental Science and Management, Southern Cross University, Lismore, NSW, 2480, Australia; National Marine Science Centre, School of Environment, Science and Engineering, Southern Cross University, Lismore, NSW, 2480, Australia.
authors: Isaac R
authors: IR
authors: Santos
authors: School of Environmental Science and Management, Southern Cross University, Lismore, NSW, 2480, Australia; National Marine Science Centre, School of Environment, Science and Engineering, Southern Cross University, Lismore, NSW, 2480, Australia.
authors: Anita
authors: A
authors: Perkins
authors: School of Environmental Science and Management, Southern Cross University, Lismore, NSW, 2480, Australia.
authors: Damien T
authors: DT
authors: Maher
mesh_terms: D000066428:Coal Industry; D060587:Groundwater / Q000032:analysis*; D009517:New South Wales; D061329:Oil and Gas Fields; D011834:Radiation Monitoring; D011886:Radon / Q000032:analysis*; D014501:Uranium / Q000032:analysis*; D014875:Water Pollutants, Radioactive / Q000032:analysis*
chemical_list: D014875:Water Pollutants, Radioactive; D014501:Uranium; D011886:Radon
keywords: Baseline research; Catchment; Coal bed methane; Groundwater; Radon; Unconventional gas; Uranium