SPATIAL DISTRIBUTION OF CADMIUM, NICKEL AND LEAD IN SOIL HUMUS HORIZON IN THE MIDDLE PART OF WIELKOPOLSKA REGION

The aim of the investigations was to determine total quantities of cadmium, nickel and lead in the humus horizon of arable lands situated in the middle parts of the Wielkopolska region against the backdrop of their physical and chemical properties. The area of studies was represented by 1439 mean soil samples. The collected material, after drying at room temperature and sieving it through a 2 mm mesh sieve, was used to determine the total metals content by the atomic absorption spectrometry (AAS) method following its mineralisation in aqua regia (HCl:HNO(3) = 3:1). Spatial distribution of Cd, Ni i Pb was investigated using statistics and geostatistics techniques. Geostatistical analyses were carried out, including spatial autocorrelation and theoretical semivariograms and the maps were produced. On the basis of the obtained analytical results, it was found that the determined mean Ni (5.0 mg.kg(-1)) and Pb (16.1 mg.kg(-1)) quantities in the arable soils indicate their natural content in soils. On the other hand, the mean total Cd content of the order of 0.68 mg.kg(-1) indicates an elevated concentration of this metal in the examined topsoil. The performed statistical analysis shows that the observed spatial variability of the examined metals depended, primarily, on the geographic location.