Scientific publications

The article presents the results of the analysis of the redistribution of heavy metals (Cd, Pb, Co, Cu, Ni, Zn, Cr, and Mn) in bottom sediments of beaver ponds in small rivers in the north of the Pre-Volga Region of the Republic of Tatarstan. The results indicate a relatively uniform spatial distribution of the metals in the river sediments, except for Co, Zn, and Cr total concentrations, as well as labile forms of Cd and Zn. Their content in the sediments was higher in the upper and middle reaches compared with the lower reaches. The distribution of gross and labile forms of heavy metals in top-core sediments of beaver ponds is also uniform, except for Cd and Pb. The deeper strata of sediments in the pond’s fluctuating backwater region show a weak tendency towards a decrease in the metal content, whereas the distribution of the gross content of heavy metals in the middle part of the ponds has no contrast. The tendency in the near-dam region is multidirectional: an increase in the gross content and a decrease in labile forms in the sediments with depth. The total content of heavy metals correlates with the grain size composition of the sediments and their organic matter content. Statistically significant factors in the distribution of labile forms of heavy metals are the distance to the river mouth, the length of beaver dams and ponds, and the content of organic matter in the beaver pond sediments.