HEAVY-METALS IN RIVER SEDIMENTS - A CHEMOMETRICAL EVALUATION

First results are presented to support decisions within projects of re cultivation in the Merseburg region. From two places of the river Lupp e eight sediment samples were taken at four different days. The total concentrations of Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn were determined b y ICP-AES after digestion with aqua regia both in the gross samples an d in four particle size fractions obtained by wet sieving. Subsequentl y each fraction was split into six classes by a sequential extraction to characterise the pattern of heavy metal binding form. Questions abo ut the difference of the regions, the importance of the particle size fractions, the mobility of the metals, and the influence of the season al factor were tried to answer by the help of chemometrical methods. I t was possible to show that the two sampling places situated only abou t 7 km from each other have different total metal concentrations as we ll as different binding form patterns. The trend of the heavy metal en richment in the smallest particle size fraction can easily be seen in two-dimensional diagrams, but could in general not be confirmed statis tically for all metals. The consideration of all four factors together (region, particle size fraction, mobilisation class, and time) shows the significant influence caused by all factors and all interactions. Multivariate covariance analysis is used to include also the influence of sampling conditions.