Exploring short-term soil landscape formation in the Hunter Valley, NSW, using gamma ray spectrometry

In recent years proximal soil sensing techniques have been applied to investigate the spatial distribution of soil properties as well as the patterns of soil deposition in the landscape. Here, we present the results of a soil survey conducted in a small catchment in the Hunter Valley, NSW, Australia, which was used to investigate spatial variability in the processes of short-term soil landscape formation in the study region. A vehicle-borne passive gamma-ray spectrometer was employed to explore at a high resolution the distribution of radioactive isotopes occurring naturally (40K, 238U-series, 232Th-series) and artificially produced in the soil (137Cs). Our results show that spatial patterns determined from gamma emissions from natural and artificially produced radio-isotopes in the soil do not differ as much as expected. We therefore came to the conclusion that normalizing algorithms such as baseline correction of the spectra need to be explored further, and that point data are required to validate the derived maps. From here, soil samples will be taken along toposequences to determine the concentration of the fallout radionuclide 137Cs, to better assess soil erosion and soil deposition patterns using this environmental tracer. These observations together with a high resolution digital elevation model will improve our understanding of how the landscape formed or changed in the short-term. Eventually, the collected data will give us a clear picture on the function and the response of managed soil systems to a changing environment