SPATIAL DISTRIBUTION OF CHEMICAL ELEMENTS IN SOILS FROM THE SOUTHEASTERN PART OF NORTH MACEDONIA (GEVGELIJA, VALANDOVO, BOGDANCI AND DOJRAN MUNICIPALITIES)

Abstract

In this work, the contents and spatial distributions of 18 elements (Ag, Al, Ba, Ca, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, P, Pb, Sr, V, Zn) in the soils of the southeastern part of North Macedonia (Gevgelija–Valandovo–Bogdanci–Dojran region) are presented. For this purpose, a total of 86 soil samples were collected from 43 locations (43 samples of topsoil and 43 samples of subsoil). All samples were analyzsed by inductively coupled plasma with atomic emission spectrometry (ICP-AES) after complete digestion with four acids (HNO3, HF, HClO4, and HCl). The obtained results were statistically evaluated and spatial distribution maps for all analysed elements were also prepared. Factor analysis was performed to reduce the number of data used and new synthetic variables (factors) were identified. Through the application of factor analysis, three geochemical associations were identified: Factor 1 (Fe, V, Mn, Cu, Ni, Zn, and Pb), Factor 2 (Ba, Li, and K), and Factor 3 (Mg, Al, Ca, and Sr). From the obtained data and the maps of spatial distribution, it could be concluded that the occurrence of the analyzed elements is related to the lithology of the region. Namely, it was found that the content of elements of Factor 1 is higher in soils dominated by Mesozoic volcanic rocks, Quaternary alluvial sediments, and Proterozoic gneisses and Paleozoic shales; the content of elements of Factor 2 is higher in soils in the north (where Mesozoic felsic plutonites dominate) and east (where Proterozoic gneisses and Paleozoic shales dominate) of the study area; and that elements of Factor 3 are present in soils from the area dominated by Quaternary alluvial sediments, Paleozoic carbonates and shales, and Mesozoic mafic plutonites. The only exception is the fact that the P content in the topsoil from the Gevgelija and Valandovo valleys along the Vardar and Anska rivers is higher than in the subsoil samples, which is probably due to the use of phosphate artificial fertilisers in agriculture.