TY - JOUR
T1 - Investigating Metals and Metalloids in Soil at Micrometric Scale Using µ-XRF Spectroscopy
T2 - A Case Study
AU - Barbosa, Sofia
AU - Dias, António
AU - Pacheco, Marta
AU - Pessanha, Sofia
AU - Almeida, J. António
N1 - Funding Information:
info:eu-repo/grantAgreement/FCT/6817 - DCRRNI ID/UIDB%2F04035%2F2020/PT#
This research was funded by FCT-Fundação para a Ciência e a Tecnologia, Portugal, grant number UID/FIS/04559/2020.
Publisher Copyright:
© 2023 by the authors.
PY - 2023/1/2
Y1 - 2023/1/2
N2 - Micrometric 2D mapping of distinct elements was performed in distinct soil grain-size fractions of a sample using the micro-X-ray Fluorescence (µ-XRF) technique. The sample was collected in the vicinity of São Domingos, an old mine of massive sulphide minerals located in the Portuguese Iberian Pyrite Belt. As expected, elemental high-grade concentrations of distinct metals and metalloids in the dependence of the existent natural geochemical anomaly were detected. Clustering and k-means statistical analysis were developed considering Red–Green–Blue (RGB) pixel proportions in the produced 2D micrometric image maps, allowing for the identification of elemental spatial distributions at 2D. The results evidence how elemental composition varies significantly at the micrometric scale per grain-size class, and how chemical elements present irregular spatial distributions in the direct dependence of distinct mineral spatial distributions. Due to this fact, elemental composition is more differentiated in coarser grain-size classes, whereas griding-milled fraction does not always represent the average of all partial grain-size fractions. Despite the complexity of the performed analysis, the achieved results evidence the suitability of µ-XRF to characterize natural, heterogeneous, granular soils samples at the micrometric scale, being a very promising investigation technique of high resolution.
AB - Micrometric 2D mapping of distinct elements was performed in distinct soil grain-size fractions of a sample using the micro-X-ray Fluorescence (µ-XRF) technique. The sample was collected in the vicinity of São Domingos, an old mine of massive sulphide minerals located in the Portuguese Iberian Pyrite Belt. As expected, elemental high-grade concentrations of distinct metals and metalloids in the dependence of the existent natural geochemical anomaly were detected. Clustering and k-means statistical analysis were developed considering Red–Green–Blue (RGB) pixel proportions in the produced 2D micrometric image maps, allowing for the identification of elemental spatial distributions at 2D. The results evidence how elemental composition varies significantly at the micrometric scale per grain-size class, and how chemical elements present irregular spatial distributions in the direct dependence of distinct mineral spatial distributions. Due to this fact, elemental composition is more differentiated in coarser grain-size classes, whereas griding-milled fraction does not always represent the average of all partial grain-size fractions. Despite the complexity of the performed analysis, the achieved results evidence the suitability of µ-XRF to characterize natural, heterogeneous, granular soils samples at the micrometric scale, being a very promising investigation technique of high resolution.
KW - soil matrix
KW - metal distribution per grain fraction
KW - micro-X-ray elemental mapping
KW - RGB clustering image analysis
KW - k-means
UR - http://www.scopus.com/inward/record.url?scp=85166591623&partnerID=8YFLogxK
U2 - 10.3390/eng4010008
DO - 10.3390/eng4010008
M3 - Article
AN - SCOPUS:85166591623
SN - 2673-4117
VL - 4
SP - 136
EP - 150
JO - Eng
JF - Eng
IS - 1
ER -