The dynamics of heavy metals and metalloids accumulation in oxbow bottom sediments of the Sok River

The article analyzes the dynamics of heavy metals (V, Cr, Mn, Co, Ni, Cu, Zn, Rb, Sr, Cd, Pb) and metalloids (As, Se) accumulation in the bottom sediments of the low-flow oxbow of the Sok River. This oxbow was formed as a result of the Saratov reservoir creation and located within the Krasnoglinsky District of the Samara city. The study was conducted in 2021 and 2022. Four trial plots were established in the oxbow of the river; the control plot was a sample area allocated in the Saratov reservoir, in the immediate vicinity of the oxbow. The quantitative determination of heavy metals and metalloids content in bottom sediments was carried out using inductively coupled plasma spectrometry. The results obtained showed that specific conditions arise in each research period that affect the studied elements accumulation in the oxbow bottom sediments. These processes are influenced by the location of the sample plot in the oxbow, the flow degree, the spring flood nature, the anthropogenic transformation and the overgrowth of Typha angustifolia L. For all sample plots located in the oxbow, higher concentrations of most of nalyzed elements were detected in 2022. Heavy metals and metalloids accumulated especially actively in the bottom sediments of sample plot 4, located in the oxbow behind an artificial dam and characterized by the weakest flow. The soil cover of Samara city posesses weak and moderate effect on the quantitative characteristics of metal accumulation in the oxbow bottom sediments. Compared to the control, the studied elements accumulated more actively in the bottom sediments of all oxbow sample areas, which confirms the accumulative nature of river oxbow of varying degrees of isolation.