How analysing ancient waters helps secure our future
The Atom Trap Trace Analysis facility: a game changer
In September this year, Australia’s national science agency, CSIRO, and the Institute for Photonics and Advanced Sensing opened a new facility at the University of Adelaide that would ultimately help protect Australia’s precious groundwater into the future. A collaboration between CSIRO and the University of Adelaide, the Atom Trap Trace Analysis (ATTA) facility uses advanced laser physics to count individual atoms of noble gases, specifically as Argon and Krypton, that are naturally found in groundwater. This is the first ATTA facility in the Southern Hemisphere and it complements an existing Noble Gas Facility at CSIRO’s Waite campus in Adelaide.
“The new ATTA facility is a game changer,” says CSIRO Senior Principal Research Scientist Dr Dirk Mallants.
“Measuring ultra-low concentrations of these radioactive noble gases allows researchers to not only determine how old groundwater is, from decades and centuries up to one million years, but where it comes from and what the natural recharge rates are.”
Just three labs in the world have this noble gas tracing capacity including labs in Germany and China.
Dr Mallants said this standard of analysis would previously take up to one month but can now be done in a day.
“We have gone from processing a dozen samples a year to potentially hundreds,” he says.
“Because noble gases don’t easily react chemically, they are the gold standard for environmental tracers to track groundwater movements,” says Professor Andre Luiten, Director of The University of Adelaide’s Institute for Photonics and Advanced Sensing which houses the ATTA facility.
Tracing water for development here and overseas
Being able to adequately determine the rate aquifers will naturally replenish quickly is essential to providing advice on decisions about sustainable extraction. This is critical where development of any kind might use or impact groundwater systems – from urban development where groundwater systems are used to supply communities, to agricultural and mining development.
“In countries like Chile where CSIRO has already completed some groundwater analysis, there are many users including mining, agriculture and wineries all tapping into the same groundwater resource,” Dr Mallants says.
“It’s essential in these regions that we answer the big questions like what is the natural rate these aquifers get replenished and how much water can people sustainably take.”
This detailed analysis enables countries to build more robust aquifer models to underpin important decisions about water usage.
Securing the future of our groundwater
Back on the home front, sustainable and reliable groundwater remains an increasing challenge in Australia. A flat and dry content, Australia’s slowly moving groundwater can be up to two million years old, some of the oldest water on the planet.
Australia relies on its groundwater for 30 per cent of its water supply for human consumption, stock watering, irrigation and mining. With climate change and periods of prolonged drought, surface water is becoming increasingly more unreliable and the use of groundwater is rising. Good groundwater analysis is critical where development of any kind might use or impact groundwater systems – from urban development where groundwater systems are used to supply communities, to agricultural and mining development.
An example of where noble gas analysis has triggered an industry to think differently about how groundwater behaves, and what that then means for groundwater management, is in Queensland’s Surat Basin.
Groundwater in the Surat Basin, Queensland
CSIRO’s Gas Industry Social and Environmental Research Alliance (GISERA) analysed groundwater flow and velocity for two major aquafers in the Basin. The GISERA project used tracer information from several field trips to improve the understanding of water in the Hutton Sandstone and Precipice Sandstone aquifers. These are the first and second major aquifers below the Walloon Coal Measures which is the focus of coal seam gas development.
The aquifers are key regional aquifers supplying farm wells. They provide recharge to the Great Artesian Basin, and the Precipice Sandstone serves as aquifer for re-injection of treated coal seam gas water. CSIRO discovered flow rates and recharge in the Precipice Sandstone were higher than in the Hutton Sandstone, concluding that the Hutton Sandstone aquifer was replenishing at a lower rate than initially thought. This made the system more vulnerable to groundwater extraction, so further investigation was needed to determine how connected the Walloon Coal Measures was to the Hutton Sandstone aquifer.
Origin Energy Groundwater Manager Andrew Moser says CSIRO’s comprehensive groundwater analysis was invaluable to the project.
“Our experience using a variety of methods and the expertise of CSIRO shows that if you can incorporate appropriate isotope studies from the very start of a project, you can cost effectively test system scale hypotheses, and often gain a wider understanding of hydrogeological process than using many conventional tools,” Mr Moser says.
Groundwater in Western Australia
In the west, CSIRO’s groundwater team used tracers to better understand groundwater resources to support several developments, including irrigated agriculture in the Peel region, south of Perth.
Funded by the Western Australian Government, the team assessed recharge rates and connectivity between different aquafers. Over the past decades, groundwater abstraction has resulted in declining groundwater levels. In addition, the region has been affected by climatic changes with rainfall reduced by 18 per cent from 1961 to 2016, and an even more pronounced reduction in seasonal streamflow.
The study provided new knowledge that partly confirmed and improved an existing conceptual hydrogeological model. Researchers found different aquifers were relatively well connected in the eastern part of the area but quite separate in the west. Recharge rates and fluxes were estimated and mapped for several parts of the groundwater system.
Dr Mallants says the new technology has supported the development of a greater level of groundwater analysis not previously available in Queensland and Western Australia.
“We can now with certainty measure the rate an aquifer is being replenished or answer categorically whether it is connected to another aquifer,” he says.
However, Dr Mallants and his team believe when it comes to helping Australia and overseas countries achieve a better “water balance”, the technology is forever evolving.
“The work is not finished. Each time we advance our understanding, we identify another knowledge gap,” he says.
“Future research will focus on systematic ways we can reduce these uncertainties.”
In the meantime, Australia has taken a huge leap in protecting and sustaining its groundwater for future generations.