A multivariate approach to study the geochemistry of urban topsoil in the city of Tampere, Finland

Risk assessment of potentially toxic elements (PTEs) requires to separate their geogenic soil enrichment and anthropogenic pollution since they are two processes acting together and causing elevated concentrations of PTEs in urban topsoil. The study was aimed to analyse and compare the concentrations of various potentially harmful geochemical elements in the urban soils of the city of Tampere (Finland) to determine their spatial relations by modelling their coregionalization to isolate and display sources of variation acting at different spatial scales and define potential spatial anomalies based on the correlation structure associated at the different spatial scales. Principal Component Analysis (PCA) and Factorial Kriging Analysis (FKA) were used to analyse the geochemical data set. Principal Component Analysis (PCA) allowed to identify two groups of geochemical elements whereas FKA enabled to distinguish the correlation structure of the multivariate data at different spatial scales and to summarize the main features of the data at each spatial scale and to take into account different sources of geochemical elements concentrations. Such concentrations in topsoil of the Tampere city were explained by both geogenic and anthropogenic sources.