Original scientific paper
Lead and zinc concentration in genetic horizons of Terra rossa soil at a local scale. How these concentrations differ?
2020, 21 (3) p. 633-648
The goals of this study were to (i) determine the concentration of the Pb and Zn in Terra rossa soil, (ii) reveal its origin and (iii) establish how the concentration of these elements between genetic horizons differ. In a total of 128 soil samples collected from the genetic A and B horizon of 64 Terra Rossa soil profiles were analyzed for aqua regia soluble concentration of lead (PbA and PbB) and zinc (ZnA and ZnB) as well as soil properties: pH in KCl, CaCO3, soil organic carbon (SOC) and particle size distribution. The median value of PbA, PbB, ZnA, and ZnB were 41.6, 33.8, 106.1 and 103.8 mg/kg, respectively. The principal component analyses have shown that the Pb and Zn contribute most to the variability of A horizon and have the same and natural origin – they are accumulated by geochemical weathering and soil-forming processes. Using non-parametric techniques (the two-sided Kolmogorov-Smirnov test (K-S) and a shift function (SF) we estimated that (i) the PbA and PbB distribution differ in spread and median and
(ii) the PbB distribution need to be progressively shifted, at the whole range starting from 2.8 mg/kg for the first decile; 7.2 mg/kg for the fifth decile (median) to 12.2 mg/kg for the ninth decile to match PbA distribution. In the case of Zn, there is no evidence that the distribution of ZnA is in any way different than the distribution of ZnB. This implies that the ZnA and ZnB have a remarkably similar shape of their distribution functions and a noticeable slight shift with a value of 2.3 mg/kg at fifth decile. The analysis presented here illustrated why detailed statistical descriptions can help to better understand how and by how much lead and zinc distributions in Terra rossa genetic horizon differ.