Relation between air and soil pollution based on statistical analysis and interpolation of Nickel (Ni) and Lead (Pb): Case study of Zagreb, Croatia.

Purpose. This paper focuses on the comparison of Ni and Pb concentrations in air and soil pollution in the Zagreb area. Due to the very limited amount of publicly available data from soil analysis samples, 2016 and 2019 were chosen as the best possible indicators of related changes in metal concentrations in soil and air. Methods. Testing the normality of Ni and Pb concentrations in the total deposited matter (TDM) confirmed the feasibility of using two parametric statistical tools - the Pearson correlation coefficient and the t-test. The Inverse Distance Weighting (IDW) interpolation method was selected as the best approach for a small number of measurements. Findings. The insufficient amount of data is the main shortcoming for urban health policy in a large area like Zagreb. The small number of air measurement stations and especially soil sampling sites cannot lead to any reliable conclusions about urban pollutants, their activity over time and direct links to soil toxic degradation based on statistical or geological methods and analyses. However, there is no doubt that urban pollution sources fill the soil with accumulated toxic elements such as Ni and Pb, especially in suburban areas located along the paths of the dominant wind directions. Originality. This is an original research that for the first time statistically analyzes and maps publicly available air and soil pollution data for the period 2016-2019. Practical implications. This research is a necessary step in determining the future planning of air and soil measurement stations in the Zagreb urban area. [ABSTRACT FROM AUTHOR]