Oral Presentation Australasian Groundwater Conference 2017

The CSIRO noble gas facility: new technology and first applications in QLD, NT and WA (#128)

Axel Suckow 1
  1. CSIRO, Urrbrae, SA, Australia

CSIRO has pioneered the application of environmental tracers in groundwater, surface water and aquitard pore water. The latest advancement involved the development of the first and only laboratory on the southern hemisphere to measure all stable noble gases (He, Ne, Ar, Kr, Xe) in (ground)water samples operational since 2017. We also developed the sampling and preparation capacity for radioactive noble gas isotopes (85Kr, 39Ar, 81Kr).

Noble gases are the most versatile environmental tracer in groundwater. They allow estimating flow velocities on time scales from years (85Kr), centuries (39Ar), millennia (4He), up to one million years (81Kr) and beyond (4He, 40Ar, 21Ne, 134Xe, 136Xe). Knowledge of flow velocities is indispensable when managing groundwater as a resource for drinking water, agriculture, industry and mining. Noble gases also allow for the reconstruction of infiltration conditions (i.e., temperature, salinity and altitude). Infiltration processes, such as recharge after flooding a dry riverbed or constant infiltration from a permanently losing stream, can also be identified using noble gases. Noble gases assess groundwater flow systems, surface water – groundwater interactions, groundwater – seawater interactions, aquitard permeability and inter-aquifer connectivity.

We demonstrate the capabilities of the new facility, designed specifically for Australian groundwater conditions, including high concentrations of reactive gases (CH4) and helium. The first analysed datasets will be presented, including CSIRO projects in the Surat Basin, QLD, aquifers in Northern Australia (NT and WA) and Rottnest Island, WA. We invite cooperation in the use of noble gases as a palaeoclimate tool to derive a record of soil temperatures over the last ice age and in the use of radioactive noble gases, 39Ar delivering the only dating tool for the important time scale of centuries.

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