Mariusz Sojka*, Marcin Siepak**, Emilia Gnojska***
*Uniwersytet Przyrodniczy, Poznań
**Uniwersytet im. Adama Mickiewicza, Poznań
***Uniwersytet Przyrodniczy, Poznań

The aim of this study was the assessment of spatial variability of heavy metals concentration in the Stare Miasto pre-dam reservoir on the Powa river. Sediment samples from 16 locations were collected and analyzed for the trace metal contents (Cr, Ni, Cu, Zn, Cd and Pb), organic carbon and grain size. The variability of heavy metal concentration in bottom sediments was assessed by multivariate statistical methods like cluster analysis (CA), factor analysis (FA) and principal components analysis (PCA). They made it possible to observe similarities and differences in trace metal content in samples taken from specific locations, to identify indicators suitable for characterizing its spatial variability and to uncover hidden factors accounting for the structure of the data. Data of the grain size indicated that sandy sediments dominated in the initial part of the pre-dam reservoir were the Powa river inflow. The mean concentrations of Zn 3.38 – 21.3 was the highest followed by Pb and Ni, 0.47 – 4.96 and 0.96 – 5.25 respectively, relative to other metals. The concentrations of Cu was 1.03 – 2.88 while Cd and Cr were the least 0.02 – 0.80 and 0.06 do 0.74 respectively. Cluster analysis CA of heavy metals content in bottom sediments of the reservoir showed that 16 samples of sediments can be divided into two groups characterized by different content of heavy metals. The analysis showed that the content of Cd, Pb, Ni, Cr and Zn were associated with content of clay and organic matter, depth of sampling and the sampling distance from the inflow point of the river. The concentration of the copper was associated with sampling distance from inflow and out flow point and the content of the silt.

Słowa kluczowe
metale ciężkie; zbiornik retencyjny

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