[B._Beckhoff,_et_al.]_Handbook_of_Practical_X-Ray_(b-ok.org).pdf

Vincze et al 503 have shown that the accuracy of

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Vincze et al. [503] have shown that the accuracy of quantitative analysis of coal fly ash particles using µ -SRXRF and Monte Carlo simulations ranges between 5 and 30%. Typical airborne particles like fly ash particles [503] and fuel parti- cles [504] were analyzed for potentially toxic elements. Another field of appli- cation which also has the aim of tracing environmental problems is the analysis of sediment-derived particles. Os´an et al. [505] were able to learn about the ori- gin of the toxicity of river sediment pollution particles by combined µ -SRXRF and µ -XANES (X-ray absorption near-edge structure). Salbu et al. [506] de- termined the oxidation states of uranium in depleted uranium particles (av- erage size: 2 µ m or less) from soil samples by µ -XANES and µ -SRXRF. The results are fundamental for understanding the potential remobilization of U within the contaminated area. The combined study of chemical composition and speciation is of major importance in particle research as the speciation has a major influence on the transport and dissolution behavior of the metal ions from the particle, biological uptake, and the toxicity of the particle. To identify the areas of interest for µ -XANES, µ -SRXRF is commonly applied. Fluid and Melt Inclusion Analysis. Fluid and melt inclusions in mineral hosts are formed during crystal growth or crack annealing and – if their compo- sition is conserved after the time of trapping – uniquely record directly the fluid and melt phase that was present during the rock genesis. Typically, many generations of fluids are included within the same mineral host (e.g., Roedder [507]). Thus, the analysis of single inclusions allows studying the evolution of crustal rocks, element transport in the crust, and enrichment processes of economically important elements. Analysis of single inclusions is ambitious because of their small size in the micrometer range and the fact that they are shielded by their host mineral. Trace element analysis of single inclusions is possible with PIXE, LA-ICP-MS, and SRXRF. Laser ablation ICP-MS allows the multielement analysis of major and trace elements with very high accuracy and low limits of detection [508, 509]. The sensitivity varies from very high to low. Typical spot sizes have a diameter from a few to tens of micrometers. Aud´ etat et al. [510] have used LA-ICP-MS of sin- gle fluid inclusions to trace the formation of a magmatic-hydrothermal ore deposit. Heinrich et al. [511] were able to retrieve information on the metal
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676 D. Rammlmair et al. fractionation between magmatic brine and vapor using the same method. However, LA-ICP-MS is destructive and does not permit reproducibility mea- surements which are possible with PIXE and SRXRF. For inclusion studies, both methods have been proven to be complementary. The proton micro- probe was shown to be best for near-surface inclusions and light elements (Z < 22; e.g., M´ enez et al. [512, 513]). With a spatial resolution of about 2 µ m, it is well suited for element distribution maps (e.g., Kamenetsky et al. [514], Ryan et al. [515, 516]). Detection limits are in the 10 ppm range which is
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  • Spring '14
  • MichaelDudley

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