At the Environmental Tracer and Noble Gas Laboratory (former IAS, Isotope Analysis Service) we provide an extensive range of tracer analyses to study the terrestrial water cycle: aquifer and aquitard systems, groundwater - surface water interaction, infiltration conditions and flow velocities.
Land and Water Flagship provides isotope, noble gas and trace gas analyses for hydrological and environmental purposes. We have a CFC and SF6 laboratory and analytical facilities for noble gases and radioactive noble gas isotopes. We provide special expertise in multi-tracer interpretation in groundwater hydrology.
Established in 1984, we undertake several thousand different analyses per year for over 100 customers in Australia and overseas.
The major strengths of our service include:
- the provision of quality analyses for over 25 years
- backed by Australia’s premier scientific research organisation
- ongoing research and development of new analytical techniques
- only facility for noble gas measurements in water samples in the southern hemisphere
- only facility for the measurement of CFCs and SF6 in water samples in Australia
- reliable turnaround and support
- one-stop-shop for the coordination of other environmental tracers not available in-house
- collaboration with universities and Australian federal and state government departments.
Chlorofluorocarbon and Sulfur Hexafluoride analysis
We analyse groundwater samples for the presence of man-made Chlorofluorocarbon (CFC-11 and CFC-12) and Sulfur Hexafluoride (SF6).
The presence of CFCs and SF6 in the atmosphere for the last 50 years means that these compounds are now in groundwater in quantities that reflect the presence and proportions of recent recharge.
Since the 1990s, atmospheric CFC-11 and CFC-12 concentrations have leveled off and more recently have started to decrease. Atmospheric SF6 concentrations, however, continue to rise and therefore SF6 complements the CFCs and provides the largest sensitivity to most recent recharge. In aquifer and catchment characterisation, CFCs and SF6 are most favourably combined with tritium and 85Kr analyses.
Noble gases are the most versatile natural tracers for surface and subsurface waters.
We operate the only facility in the southern hemisphere to measure noble gases in water samples. At present these comprise the light noble gases helium, neon and argon. A new facility to measure all noble gas concentrations (He, Ne, Ar, Kr, Xe) with higher accuracy and precision in fully automated mode is presently under construction and will be operational in 2016.
Noble gas analyses can provide the infiltration conditions (temperature, pressure, salinity) of a groundwater sample at the time of recharge. They can indicate the amount of excess air that is trapped during infiltration at amounts indicative of the infiltration process (e.g. flood infiltration, infiltration through an unsaturated soil zone or riverbank infiltration).
They can also provide information on residence time of water in the subsurface (groundwater and aquitard pore water) by the accumulation of helium from the decay of naturally occurring uranium and thorium in the rock matrix.
222Rn and 226Ra analyses
222Rn and 226Ra form part of the decay chain for uranium bearing minerals. They are often found in higher concentrations in groundwater than in surface water because groundwater has more contact with uranium and radium bearing rocks than surface water. 222Rn and 226Ra can be used to identify areas of input of groundwater into streams and rivers.
We use the PET method (developed by CSIRO) which allows more accurate measurements of 222Rn and 226Ra concentrations in surface water samples. This method is often used in groundwater-surface water interaction studies.
We also serve as a one-stop shop for other analyses that we outsource to cooperating laboratories with the most reliable measurement techniques and a known record of quality control and quality assurance.
These services include:
- Analyses of the stable isotopes of water (18O and 2H) in water samples, plant material and soil. For groundwater we also provide analysis of the stable isotopes of nitrate (18O and 15N on NO3) and sulfate (18O and 34S on SO4).
- Through our co-operators we also provide analysis of tritium (3H). Tritium is more reliable for characterising young groundwater compared to CFCs and SF6 and complements the latter during the analysis of young groundwater flow systems.
- Through our collaborating laboratories we provide Accelerator Mass Spectrometric (AMS) analysis of 14C, 13C and 36Cl to assess time scales of old groundwater.
- We can provide large volume gas sampling from groundwater, sample preparation to extract the Ar and Kr fraction, and through collaborating overseas laboratories also the analysis of the radioactive noble gas isotopes 85Kr, 39Ar and 81Kr. These provide the most reliable tracer system to assess time scales of decades, centuries and millions of years in groundwater.