A multivariate approach for anomaly separation of potentially toxic trace elements in urban and peri-urban soils: an application in a southern Italy area

Purpose Geogenic soil enrichment and anthropogenic pollutionby potentially toxic trace elements (PTEs) are two processesacting together. Although it is often difficult, it isnecessary to separate the two processes for risk assessmentand understanding the environmental implications. The aimofthis study was to analyse the soil concentrations of variousPTEs in a southern Italy area in order to: (1) determine theirdifferent correlation structure to isolate sources of variationacting at different spatial scales and (2) to define potentialanomalies based on the correlation structure.Materials and methods In the urban and peri-urban area ofCosenza-Rende, 149 topsoil samples were collected (0.10 m)and analysed for different elements by X-ray fluorescencespectrometry. Principal component analysis and factorial kriginganalysis were used to map the spatial distribution of PTEsin topsoil and to identify the main factors influencing theirspatial variability.Results and discussion Two groups of PTEs were identified:the first group included As, Pb and Zn; and the second oneAl, Co, Cr, Fe, La, Nb, Ni, Ti and V. The first group wasrelated to anthropogenic causes, while the second one wasmore related to parent rock composition. The regionalizedfactors at different scales of variability allowed to aggregateand summarize the joint variability in the PTEs and considerthe probable causes of soil pollution.Conclusions The study allowed analysing and quantifyingthe sources (environmental or anthropogenic) of variation ofPTEs acting at different spatial scale and defining the spatialanomalies based on the correlation structure associated atthe different spatial scales.