Lake Onego water chemical composition based on seasonal field surveys in 2019-2021

The Dataset contains the characteristics of the water chemical composition of Lake Onego (35 stations in different regions of the lake) including the lake outflow Svir' River and the estuarine area of the main tributaries of the lake (rivers Shuya, Vodla, Andoma, and Vytegra). The data were obtained in autumn 2019, spring and summer 2020, and in winter 2021. Detailed information is provided for each station of water sampling (station index, their geographic coordinates, sampling date, sampling depth, temperature, and water chemical composition). The concentration of Na+ and Cl- ions, content of organic matter (TOC, CODMn, CODCr, water color, BOD5), nutrients (PO4-P, TP, NH4-N, NO2-N, NO3-N, TN), Fe, Mn, heavy metals (Cu, Ni, Cr, Zn, Cd, Pb), total suspended solids (TSS), conductivity, and pH were measured in water samples. Analytical methods commonly accepted in hydrochemical practice were used to determine chemical parameters of the water. The hydrochemical data will enable society to understand the water quality of Lake Onego as it is the main source of freshwater. Therefore, this data can be used for comparative analysis of the hydrochemical characteristics of other large lakes.