Distribution of trace elements in sediments and soil from Crn Drim River Basin, Republic of Macedonia

Abstract

A systematic study was carried out to investigate the distribution of chemical elements in the sediment and soil samples collected from Crn Drim River Basin, Republic of Macedonia. For this purpose, 18 samples of river sediment, 19 samples of lake sediment, 16 samples of surface (0–5 cm) and 16 samples of bottom (20–30 cm) soil were collected within the basin. From the sewerage systems in the towns of Resen, Ohrid, Struga and Debar, 11 samples of urban sediment were collected. The determination of the content of 22 elements was performed by using inductively coupled plasma atomic emission spectrometry. Cluster and factor analyses were applied in order to show the associations of chemical elements. According to a correlation coefficient matrix of all sediment samples, a strong correlation (over 0.70) was identified between the content of the following elements: Zn–Cu, Ni–Cr, V–Fe, Sr–Ca, Fe–Cr, P–Cu, Ni–Cu, Zn–P and V–Cr. Factor analysis of the data resulted in three factors: Factor 1 (Fe, V, Al, Mn, Li), Factor 2 (Zn, Cu, Ag, Pb) and Factor 3 (Co, Ni, Cr). The elements included in factors F2 and F3 were internally correlated and belong to one cluster. Comparative statistics with three methods [t test, F ratio and R(T/B)] showed no difference between the distribution of various chemical elements in top (T) and bottom (B) soil samples. The results show that the samples of urban sediment have a high content of heavy metals, which represent a risk to the environment and the river basin of Crn Drim, especially for the natural Prespa and Ohrid lakes.