Magnetic and geochemical properties of Zagreb city area soils

Abstract The study was performed to get the first insight of distribution of the low field volume magnetic susceptibility (MS) throughout the Zagreb city area, based on in-situ field measurements on 125 locations. 25 most interesting locations were selected for soil sampling and geochemical content was determined using ICP-OES method. A geostatistical approach was applied on MS and geochemical results. Median value of 0.245 x 10− 3 SI units, obtained by in-situ measurements is proposed to be used as relevant average value of MS in Zagreb area. Mean concentrations of heavy metals measured in Zagreb soils are following: Pb (36.82 µg/g), Zn (87.77 µg/g), Cu (30.84 µg/g), Cd (0.66 µg/g), Cr (29.04), Co (11.89) and Ni (28.40). Those concentrations are relatively low in comparison with Croatian legislation and with Europe and world average. Boxplot analysis showed that 45% of studied elements do not show any anomaly (Al, Ca, Cu, Fe, K, Li, Mg, Ni and Pb) and most of them have regular normal distribution. The rest of other elements mostly show only one weak anomaly. Boxplot analysis confirmed element anomalies are located at the same sampling points where MS anomalies are located. Statistical correlations between MS in-situ measurements and analyzed elements are following: Cd (0.52), Co (0.54), Fe (0.35), Mn (0.74), Na (0.45), Pb (0.48), Sb (0.63) and Zn (0.75). In-situ MS measurements proved to be an efficient tool for initial screening of a large area in terms of elevated heavy elements concentrations, enabling cheap and fast assessment of state of environment.