geochemistry
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Legacy product - no abstract available
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Catchment outlet sediments (0-10 cm depth, sieved to <2 mm) collected at a very low density over most of the Australian continent have been analysed using the Mobile Metal Ion (MMI®) partial extraction technique. Of the 54 elements analysed, eight are generally regarded as essential nutrients for plant growth: Ca, Cu, Fe, K, Mg, Mn, P and Zn. For these, 'bioavailability', defined here as the ratio of the partial digest concentration to the total concentration, has been investigated. This estimation of 'bioavailability' gives results comparable with standard agricultural measurements. Average 'bioavailability' ranges from 15.0% for Ca to 0.1% for Fe. Smoothed (kriged) colour contour maps for continental Australia have been produced for these eight nutrients and interpreted in terms of lithology (e.g., presence of carbonates in the MMI® Ca map), mineralization (e.g., well known and possibly less known mineral districts in the Cu, P and Zn maps), environmental processes (e.g., salinity in K map, weathering and acid generation in Fe map) and agricultural practices (e.g., application of fertilizers in P and Zn maps). This first application of a partial extraction technique at the scale of a continent has yielded meaningful, coherent and interpretable results.
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Legacy product - no abstract available
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Legacy product - no abstract available
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Legacy product - no abstract available
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Legacy product - no abstract available
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There is a general acceptance amongst the analytical community that geological materials must be reduced to less than 75 microns grain size to reduce particle-size effects and to reduce minerals sufficiently to provide a representative analysis of the sample. This study examines several aspects of this assumption, by comparing the XRF analysis of pressed powder pellets and fused glass discs of the same samples in coarse- and fine-grained form; quantifying the grain-size difference between these samples by laser particle size analysis. An examination of the effect that overloading a grinding head can have on the efficiency of grinding was also carried out. Coarse- and fine-grained aliquots of the same samples were pressed into powder pellets and trace elements analysed by a Philips PW2404 X-ray Fluorescence spectrometer. These same samples were fused into Lithium meta/tetra Borate discs and analysed for major elements by XRF. A sub-sample of this glass disc was acid-digested and trace elements analysed on an Agilent 7500CE ICP-MS. Results obtained were compared. Grinding head efficiency was examined by pulverising increasing weights of the same rock sample in a Rocklabs TC-200 Tungsten Carbide grinding head in a Rocklabs Standard Ring Mill. The same methodology as outlined above was then used to analyse the fractions and compare the results. A Malvern 2000E Laser Particle Size analyser was used to quantify the grain size of the samples analysed. Analytical results will be presented, highlighting the effects of the varying grain size.
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Legacy product - no abstract available
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Legacy product - no abstract available
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Legacy product - no abstract available