Variability in the Chemical Composition of Spring Waters in the Postomia River Catchment (Northwest Poland)

The paper presents the results of physicochemical analyses of spring waters in the Postomia River valley (Northwest Poland). Multivariate statistical methods, i.e., cluster analysis (CA) and principal component analysis (PCA) were used to assess the spatial distribution of similarities and differences in the concentrations of individual elements. Concentrations of macro elements (MEs), trace elements (TEs) and rare-earth elements (REEs) were analysed concerning the spring’s typology, land use structure and the distance from roads. The results showed that the springs waters are of the Ca2+-HCO3− and Ca2+-HCO3−-SO42− types, medium hardness and low mineralisation. The study revealed differences between valley springs and scarp-foot springs in terms of electrical conductivity and concentrations of F−, SO42−, NO3−, Mg2+, Ba, Zn, and U. Greater variability was observed between the physical and chemical conditions of the spring waters due to their location in terms of land use. Springs located in agricultural areas had lower pH values than those in other areas, and higher NO3− concentrations. The pH values and concentrations of Fe, Mo, Rb, and Th in urban areas were higher than in agricultural areas. Moreover, the concentrations of F−, Cl−, K+, Na+, Mo, Sb, Se, and Sr were higher in urban areas than in forested areas. The study shows that only HCO3− values and SO42− concentrations were related to the distance from the road network. The concentrations of Cl−, SO42−, and K+ were higher in the waters of springs located more than 50 m from the road network. The Ca and PCA analysis did not permit the identification of a single dominant origin of pollutants, suggesting an interaction of different types of pollution sources