Assessment and analysis of metal bioaccumulation in freshwater gastropods of urban river habitats, Saint Petersburg (Russia).

The aim of this study was to analyze the content of heavy metals in the shells of freshwater gastropods Viviparus sp.; to evaluate the correlation of the trace element accumulation degree in biological objects, bottom sediments, and water, and to assess the degree of pollution of minor rivers of St. Petersburg, as well as the applicability of the studied biological objects for this. Water samples, sediment samples, and gastropods were collected in July 2019 and August 2020 at seven sampling points located at five rivers in St. Petersburg. Analysis of metals in water samples, water extract from bottom sediments, was carried out with atomic emission spectrometry. Analysis of metals in the shells of molluscs Viviparus sp. carried out with atomic absorption spectrophotometry and atomic emission spectrometry. The data obtained indicate the current contamination of the Neva River Delta with a number of metals, such as Al, Mn, Fe, Cu, and Pb, and indicate a significant accumulative capacity of bottom sediments with Zn, Pb, Ni, Cu, Mn, and Fe. Gastropods showed an ability for intensive bioaccumulation, which depended on the properties of metals, the hydrology of the river, and the characteristics of bottom sediments. It was found that for the studied environmental conditions, Sr, Fe, Cr, and Mn have the best ability to bioaccumulate in gastropod shells.