Field Portable X-Ray Fluorescence (pXRF) Spectrometry for Chemical Dust Source Characterization: Investigations of Natural and Mining-Related Dust Sources in Greenland (Kangerlussuaq Area)

In this study, we evaluate the use of field portable X-ray fluorescence (pXRF) as a screening tool for dust source characterisation at two sites in Greenland, a natural site near Kangerlussuaq influenced by dust generated by the Greenland Ice Sheet and an anorthosite mine site located 80 km from Kangerlussuaq. Measurements of ground surface samples were done ex-situ in LDPE plastic bags and in-situ at selected locations. Ex-situ measurements were done both before and after drying of samples to evaluate the effect of water content. Further, the effect of XRF cup films and LDPE bag walls was measured to enable element-specific corrections for signal attenuation of the pXRF measurements. Accuracy and precision were evaluated using a matrix blank and three different soil certified reference materials (CRMs). Finally, pXRF data from the two sites were analysed statistically by principal component analysis (PCA) and linear discriminant analysis (LDA) for the purpose of discriminating between dust sources. The pXRF results showed detectable concentrations of the elements: Al, Si, K, Ca, Fe, Sr, Zr and Ba in all samples (and P, Mn, Zn, Rb, Y, Nb, Ta, Pb and Th in some samples). Moreover, the results showed good accuracies for 21 elements in the CRMs. The PCA/LDA plots based on the pXRF data provided a good tool to discriminate between natural and mining-related dust sources and also between some specific mining-related sources. Altogether, this demonstrates that pXRF combined with multivariate statistics can be an adequate tool for fast cost-effective dust source characterisation.