Background limit of Zn and Hg in soils of Eastern Serbia

Abstract

The objective of the present study was to point out different approaches for background limits assessment of Zn and Hg. Background limits obtained by graphical methods (cumulative probability plot-CDF and boxplot) were similar for Zn (about 100 mg/kg-1), while background limits for Hg were different (from 0.2 mg kg-1 to 0.3 mg kg-1). For three empirical methods, besides natural data, log-transformed ones were used. Results from log-transformed limits were higher than from natural (except classical methods for Hg). The most of the territory of Eastern Serbia has low content of these elements, whose background limits calculated using log-transformed data by [Median+2MAD] methods (73 mg kg-1 for Zn and 0.15 mg kg-1 for Hg) are the most suitable (MAD-median of the absolute deviations from the data?s median). On the part of area with elevated elements content, background limits were determined using log-transformed data by methods with the highest values: for Zn it was [Mean+2Sdev], and for Hg boxplot (166 mg kg-1 and 0.41 mg kg-1 for Zn and Hg respectively).U radu su istrazivane razlicite metode odredjivanja gornje granice prirodnog nivoa Zn i Hg. Granica prirodnog nivoa odredjena grafickim metodama (CDF i boxplot) je ista za Zn (100 mg kg-1), dok se razlikuje za Hg (od 0,2 mg kg-1 do 0,3 mg kg-1). Za tri empirijske metode, pored prirodnih, korisceni su i logtransformisani podaci. Log-transformisane vrednosti su vece od prirodnih (osim kod klasicne metode za Hg). Najveci deo teritorije istocne Srbije ima nizak sadrzaj ovih elemenata, gde je granica prirodnog nivoa izracunata metodom [Median+2MAD] najprikladnija. Na delu teritorije sa povecanim sadrzajem elemenata, vise odgovara granica prirodnog nivoa odredjena metodama: [Mean+2Sd] za Zn i box-plot ?gornji brk? za Hg.