Laser isotope mass spectrometry technology for groundwater research in Australia

Posted 19 August 2013

Picarro Cavity Ring-Down Spectrometer

Laser isotope mass spectrometry is the next-generation technology for measuring environmental isotopes, and the Groundwater Education Investment Fund (GEIF) has invested in a suite of instruments to enable state-of-art research capabilities for groundwater research in Australia.

The ability to measure oxygen and hydrogen isotopes in liquid water and water vapour is of great value in both field and laboratory settings.

In the field, water vapour analyses help quantify the water budget as they can constrain water loss incurred due to evapotranspiration from vegetation. In the laboratory, the ancient pore water can be measured in aquitard material and can characterise water movement in aquitards through the vapour equilibrium technique.

Laser isotope mass spectrometry can also be used for isotope analysis of the carbon contained in dissolved organic and inorganic carbon and gaseous methane.

One of the main benefits of a method for the routine measurement of liquid water samples by isotope mass spectrometry is the high sample throughput and turn-key operation. This permits the design of groundwater research projects using water isotopes at a larger scale than previously possible.

Isotope analysis

The ‘iTOC’ is a combined dissolved organic carbon and isotope analyser which provides high throughput and turn-key analysis of the carbon isotopic composition of dissolved organic carbon in groundwater. This is the first instrument of its kind in Australia. The carbon isotope gaseous methane analyser enables researchers to distinguish between sources of gaseous methane, which is useful for environmental monitoring in regions where unconventional gas extraction occurs.

Our laser isotope mass spectrometers have been utilised by researchers from the University of New South Wales, the National Centre for Groundwater Research and Training and ANSTO.

They have been used in the field at the Wellington GEIF site, in the laboratory for analysing cores from the Namoi GEIF site, and have helped leverage research projects funded by the Australian Research Council and Cotton RDC.

X-ray fluorescence core scanning

X-ray fluorescence core scanning provides a unique facility for the geochemical analysis of geological cores. The ITRAX core scanner provides X-ray images of geological cores, high resolution optical surface scans, and X-ray fluorescence elemental analysis at 100 micron resolution. The core scanner can be used to characterise geological cores with rapid sample throughput and turnkey operation

Organic matter characterisation

Groundwater organic matter characterisation is facilitated by the state-of-art Aqualog instrument. Originally the first in Australia, this instrument is field portable and provides rapid characterisation of dissolved organic matter by fluorescence and ultraviolet-visible spectroscopy. In collaboration with researchers from the University of Queensland, University of Western Australia and CSIRO, it has been used extensively in the field for identifying surface-groundwater connectivity at the Namoi and Wellington GEIF sites and characterising organic matter in the Queensland Sand Islands and the Gnangara Mound in Western Australia.

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