Preliminary statistical relationship between heavy metals in Lower Danube sediments

Abstract

Sediment quality is an important indicator in establishing the ecological status of aquatic ecosystems. Heavy metals are considered toxic and persistent substances that accumulate in the biotic and abiotic components of aquatic ecosystems, especially in sediments. This study presents research on the spatial distribution of 5 heavy metals (Cr, Ni, Cu, Zn, Pb) measured in the Lower Danube surface sediments on the adjacent segment of Tulcea County in the summer of 2019. Moreover, the statistical relationship between the heavy metals mentioned above was studied using preliminary statistical analysis methods, namely Pearson Correlation matrix and Cluster Analysis. Concentrations of the five heavy metals studied were determined using the X-ray fluorescence (XRF) technique. The results of this study indicated the following falling trend of average heavy metal concentrations Cr>Zn>Ni>Cu>Pb. Positive correlations were found between Cu-Ni (r = 0,89), Zn-Ni (r = 0,80), Zn-Cu (r = 0,90), Pb-Ni (r = 0,88), Pb-Cu (r= 0,76), Pb-Zn (r = 0,82) pairs.