Evaluation of the concentrations of trace elements in stream sediments by factor and cluster analysis and the sequential extraction procedure

Surface stream sediments containing Ag, As, Be, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn in the silt-clay size category have been mapped for the Czech part of the Elbe River. A six-step sequential extraction technique and statistical factor analysis were used to identify three dominant types of components of sediments. The first three factors accounted for 78% of the total variance. Low communality can be seen only for Ag (42%), higher for Be and Mn (62–65%) and, for the other elements, the determined factors account for 73–95% of their variance. More than 70% of the total metals in the sediments are potentially reactive with a decrease in pH or under oxidizing or reducing conditions. Cluster analysis was used to determine possible sources of the contamination.