Browsing by Author "Milham, PJ"

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    Can synchrotron micro-x-ray fluorescence spectroscopy be used to map the distribution of cadmium in soil particles?
    (CSIRO Publishing, 2007-10-30) Milham, PJ; Payne, TE; Lai, B; Trautman, RL; Cai, ZH; Holford, P; Haigh, AM; Conroy, JP
    Plants take up cadmium (Cd) from the soil, and the concentration of Cd in some plant products is a health concern. Plant uptake of Cd is poorly predicted by its concentration in soils; consequently, there is interest in the binding and distribution of Cd in soil. Synchrotron micro-X-ray fluorescence spectroscopy (micro-XRFS) is the most sensitive method of observing this distribution. We used beam-line 2-ID-D of the Advanced Photon Source (APS), Argonne, to test whether this technique could map the Cd distribution in 5 soils from Greater Sydney that contained 0.3-6.4 mg Cd/kg. A subsample of one soil was spiked to contain similar to 100 mg Cd/kg. Cadmium was readily mapped in the Cd-enriched subsample, whereas in the unamended soils, only one Cd-rich particle was found; that is, sensitivity generally limited Cd mapping. We also examined a sample of Nauru phosphorite, which was a primary source of much of the Cd in farm soils on the peri-urban fringe of Greater Sydney. The phosphorite contained similar to 100 mg Cd/kg and the Cd was relatively uniformly distributed, supporting the findings of an earlier study on an apatite from Africa. The micro-XRFS at beam-line 2-ID-D of the APS can be reconfigured to increase the sensitivity at least 10-fold, which may allow the distribution of Cd and its elemental associations to be mapped in particles of most agricultural soils and facilitate other spectroscopic investigations. © 2007, CSIRO Publishing