ANSTO's research capabilities, led by the OPAL nuclear research reactor and associated instruments provide access to users investigating areas as diverse as materials, life sciences, climate change and mining/engineering.
Ice sheets and micro-carbon studies
In this area, cosmogenic radionuclides are used to study climate change and solar variability.
| ANSTO team celebrates drilling to 200 metres in the Antarctic ice sheet at Law Dome. |
Ice sheets and micro-carbon studies broadly involves the application of isotopes, commonly measured by accelerator mass spectrometry (AMS), to atmospheric and climate studies on gases and chemicals in ice sheets.
Ice sheets provide long, continuous records of changes in the composition of the Earth's atmosphere, and changes in the production rates of cosmogenic radionuclides. These radioactive isotopes are produced by the cosmic radiation that continually bombards the Earth. One such radionuclide is radiocarbon 14C, often used by archaeologists and anthropologists for dating artefacts and establishing time scales.
Radiocarbon also provides valuable information on changes in the carbon cycle, particularly those changes caused by variations in climate. Other isotopes of interest include the radioactive beryllium isotopes, 7Be and 10Be, also naturally produced in the Earth's atmosphere by cosmic radiation.
New methods for preparing samples
Common atmospheric carbonaceous gases include carbon monoxide (CO), carbon dioxide (CO2) and methane (CH4). In today's atmosphere, the average concentration of these gases is 50 ppb (parts per billion), 385 ppm (parts per million) and 1745 ppb respectively. Concentrations have varied in the past, however the concentration of the greenhouse gases CO2 and CH4 are higher than they have been for the last 800,000 years, yet together they represent less than 0.04 per cent of atmospheric gas.
This means that the samples of these gases taken from the ice sheet are severely restricted in size, even for a super-sensitive technique like AMS where individual atoms are counted by the accelerator. For this reason, as well as to advance other projects, we have been exploring new methods for preparing ultra-small carbon samples at ANSTO.
Specific studies
Within this group are a number of specific studies, including:
- Radiocarbon bomb pulse for tuning firn air diffusion models
- Using radiocarbon to understand sources of atmospheric methane
- Radiocarbon monitoring: atmospheric variability and geo-sequestration
- The production of 14C in-situ in ice sheets and air cylinders
- Laser heated micro-furnace for the production of ultra-small graphite samples
- Radio-beryllium to study transport and deposition and solar variability.