We describe a model to predict soil-regolith thickness in a 128,000 ha study area in the central Mt Lofty Ranges in South Australia. The term soil-regolith includes the A, B, and C soil horizons to the lower boundary of the highly weathered bedrock zone (R horizon). The thickness of the soil-regolith has a major control on water holding capacity for plant growth and movement of water through the landscape, and as such, it is important in hydropedological modelling and in evaluating land suitability, e.g. for forestry and agriculture. Thickness estimates also have direct application in mineral exploration and seismic risk assessment. Geology and landscape evolution within the area is complex, reflecting the variable nature of bedrock materials, and the partial preservation of deeply weathered profiles as a consequence of weathering processes dating to the Cenozoic, or possibly older. These characteristics, together with strong climatic gradients across the area, make the study area an ideal location to understand the environmental and landscape evolution controls on weathering depth. The area also features weathered landscape analogues to many parts of southern Australia. We use a digital soil mapping piecewise linear decision tree approach to develop the model to predict soil-regolith thickness. This model is based on relationships established between 714 soil-regolith thickness measurements and 28 environmental covariates (e.g. rainfall, slope, gamma-ray spectrometry). The results establish a correlation R2 of 0.64, based on a 75:25% training:test data split. These results are encouraging, and are a significant advance over soil depth mapping by traditional soil-landscape mapping methods.

This dataset was created for the National Geochemical Survey of Australia (NGSA) to help determine the location of target sites for sampling catchment outlet sediments in the lower reach of defined river catchments. Each polygon represents a surface drainage catchment derived from a national scale 9 second (approximately 250 m) resolution digital elevation model. Catchments were extracted from an unpublished, interim version of a nested catchment framework with an optimal catchment area of 5000 km2. Only catchments from the Australian mainland and Tasmania were included. In order to generate catchments approaching the optimal area, catchments with an area of less than 1000 km2 were excluded from the dataset, while other small catchments were amalgamated, and catchments much larger than 5000 km2 were split.

The Atlas of Australian Soils (Northcote et al, 1960-68) was compiled by CSIRO in the 1960's to provide a consistent national description of Australia's soils. It comprises a series of ten maps and associated explanatory notes, compiled by K.H. Northcote and others. The maps are published at a scale of 1:2,000,000, but the original compilation was at scales from 1:250,000 to 1:500,000. Mapped units in the Atlas are soil landscapes, usually comprising a number of soil types. The explanatory notes include descriptions of soils landscapes and component soils. Soil classification for the Atlas is based on the Factual Key. This dataset has been modified to show only soil types. For more information go to http://www.asris.csiro.au/themes/Atlas.html

A new continental-scale geochemical atlas and dataset for Australia were officially released into the public domain at the end of June 2011. The National Geochemical Survey of Australia (NGSA) project, which started in 2007 under the Australian Government's Onshore Energy Security Program at Geoscience Australia, aimed at filling a huge knowledge gap relating to the geochemical composition of surface and near-surface materials in Australia. Better understanding the concentration levels and spatial distributions of chemical elements in the regolith has profound implications for energy and mineral exploration, as well as for natural resource management. In this world first project, a uniform regolith medium was sampled at an ultra-low density over nearly the entire continent, and subsamples from two depths and two grain-size fractions were analysed using up to three different (total, strong and weak) chemical digestions. This procedure yielded an internally consistent and comprehensive geochemical dataset for 68 chemical elements (plus additional bulk properties). From its inception, the emphasis of the project has been on quality control and documentation of procedures and results, and this has resulted in eight reports (including an atlas containing over 500 geochemical maps) and a large geochemical dataset representing the significant deliverables of this ambitious and innovative project. The NGSA project was carried out in collaboration with the geoscience agencies from every State and the Northern Territory under National Geoscience Agreements. .../...

Soil mapping at the local- (paddock), to continental-scale, may be improved through remote hyperspectral imaging of surface mineralogy. This opportunity is demonstrated for the semiarid Tick Hill test site (20 km2) near Mount Isa in western Queensland. The study of this test site is part of a larger Queensland government initiative involving the public delivery of 25,000 km2 of processed airborne hyperspectral mineral maps at 4.5 m pixel resolution to the mineral exploration industry. Some of the mineral maps derived from hyperspectral imagery for the Tick Hill area include the abundances and/or physicochemistries (chemical composition and crystal disorder) of dioctahedral clays (kaolin, illite-muscovite and Al smectite, both montmorillonite and beidellite), ferric/ferrous minerals (hematite/goethite, Fe2+-bearing silicates/carbonates) and hydrated silica (opal) as well as soil water (bound and unbound) and green and dry (cellulose/lignin) vegetation. Validation of these hyperspectral mineral products is based on field soil sampling and laboratory analyses (spectral reflectance, X-ray diffraction, scanning electron microscope and electron backscatter). The mineral maps show more detailed information regarding the surface composition compared with the published soil and geology (1:100,000 scale) maps and airborne radiometric imagery (collected at 200 m line spacing). This mineral information can be used to improve the published soil mapping but also has the potential to provide quantitative information suitable for soil and water catchment modeling and monitoring.

Data gathered in the field during the sample collection phase of the National Geochemical Survey of Australia (NGSA) has been used to compile the Preliminary Soil pH map of Australia. The map, which was completed in late 2009, offers a first-order estimate of where acid or alkaline soil conditions are likely to be expected. It provides fundamental datasets that can be used for mineral exploration and resource potential evaluation, environmental monitoring, landuse policy development, and geomedical studies into the health of humans, animals and plants.

Geoscience Australia and CO2CRC have constructed a greenhouse gas controlled release facility to simulate surface emissions of CO2 (and other greenhouse gases) from the soil into the atmosphere under controlled conditions. The facility is located at an experimental agricultural station maintained by CSIRO Plant Industry at Ginninderra, Canberra. The design of the facility is modelled on the ZERT controlled release facility in Montana. The facility is equipped with a 2.5 tonne liquid CO2 storage vessel, vaporiser and mass flow controller unit with a capacity for 6 individual metered CO2 gas streams (up to 600 kg/d capacity in total). Injection of CO2 into the soil is via a 120m long slotted HDPE pipe installed horizontally 2m underground. This is equipped with a packer system to partition the well into six CO2 injection chambers. The site is characterised by the presence of deep red and yellow podsolic soils with the subsoil containing mainly kaolinite and subdominant illite. Injection is above the water table. The choice of well orientation based upon the effects of various factors such as topography, wind direction, soil properties and ground water depth will be discussed. An above ground release experiment was conducted from July - October 2010 leading to the development of an atmospheric tomography technique for quantifying and locating CO2 emissions1. An overview of monitoring experiments conducted during the first subsurface release (January-March 2012), including application of the atmospheric tomography technique, soil flux surveys, microbiological surveys, and tracer studies, will be presented. Additional CO2 release experiments are planned for late 2012 and 2013. Poster presented at 11th Annual Conference on Carbon Capture Utilization & Sequestration, April 30 - May 3, 2012, Pittsburgh, Pennsylvania

Analytical data for 10 major oxides (Al2O3, CaO, Fe2O3, K2O, MgO, MnO, Na2O, P2O5, SiO2 and TiO2), 16 total trace elements (As, Ba, Ce, Co, Cr, Ga, Nb, Ni, Pb, Rb, Sr, Th, V, Y, Zn and Zr), 14 aqua regia extractable elements (Ag, As, Bi, Cd, Ce, Co, Cs, Cu, Fe, La, Li, Mn, Mo and Pb), Loss On Ignition (LOI) and pH from >3500 soil samples from two continents (Australia and Europe) are presented and compared to (1) the composition of the upper crust, (2) published world soil average values, and (3) data from other continental-scale soil surveys. It is demonstrated that average upper continental crust values do not provide reliable estimates for natural concentrations of elements in soils. For many elements there exist substantial differences between published world soil averages and the median concentrations observed on two continents. Direct comparison with other continental datasets is hampered by the fact that often mean, instead of the statistically more correct median, is reported. Using a database of the worldwide distribution of lithological units, it can be demonstrated that lithology is a poor predictor of soil chemistry. Climate-related processes such as glaciation and weathering are strong modifiers of the geochemical signature inherited from bedrock during pedogenesis. To overcome existing shortcomings of predicted global or world soil geochemical reference values, we propose Preliminary Empirical Global Soil reference values based on analytical results of a representative number of soil samples from two continents (PEGS2).

The National Geochemical Survey of Australia (NGSA) provides the first national coverage of multi-element chemistry at a continental scale. The NGSA data is an important complement to other national-scale geological and geophysical datasets, particularly the Radiometric Map of Australia. The Radiometric Map of Australia shows potassium (K) measured directly from gamma-rays emitted when 40K decays to argon (40Ar), whereas thorium (Th) and uranium (U) do not emit gamma-rays. Instead, their abundances are inferred indirectly by measuring gamma-ray emissions associated with parent radionuclides (thallium-208 for Th, and bismuth-214 for U) within their radioactive decay chains. Airborne-derived grids provide a continuous prediction of these radioelements across the Australian landscape. In contrast, the NGSA data provide a series of precise single point geochemical measurements of surface (0-10 cm) and near-surface (~60-80 cm depth) unconsolidated catchment outlet sediments.

Recently, continental-scale geochemical surveys of Europe and Australia were completed. Thanks to having exchanged internal project standards prior to analysing the samples, we can demonstrate direct comparability between these datasets for 10 major oxides (Al2O3, CaO, Fe2O3, K2O, MgO, MnO, Na2O, P2O5, SiO2 and TiO2), 16 total trace elements (As, Ba, Ce, Co, Cr, Ga, Nb, Ni, Pb, Rb, Sr, Th, V, Y, Zn and Zr), 14 aqua regia extracted elements (Ag, As, Bi, Cd, Ce, Co, Cs, Cu, Fe, La, Li, Mn, Mo and Pb), Loss On Ignition (LOI) and pH. It is useful to compare these new datasets, covering 12 million km2, with compositional estimates from other continents, the upper continental crust and, indeed, published average world soil values. Comparison with other continental datasets is hampered by differences in sampling strategies (media, depth, etc.), sample preparation (esp. sieving), sample analysis (total vs partial analysis), and data reporting (means vs medians). Overall, it appears that different continents have distinct geochemical characteristics. Using upper continental crust concentrations to estimate 'average' global soil compositions is over-simplistic and unwarranted. We propose a set of Preliminary Empirical Global Soil reference values from 2 continental-scale geochemical surveys (PEGS2) based on the median values measured for Europe and Australia, for the elements listed above. These empirical values can be significantly different to previous (theoretical) world soil values. For instance PEGS2 values are systematically lower in Al2O3, CaO, Fe2O3, P2O5, Ba and Sr than previous estimates.