Springs of North Ladoga Region: Isotopic-Geochemical Characteristics of Water and Risk Assessment for the Population

Natural spring waters of the Northern Ladoga region are poorly studied and are actively used for drinking and domestic purposes by the region’s population, which necessitates comprehensive isotope–geochemical investigations. Isotope measurements have shown that the range of δ18O values in spring water varies from –13.52 to –12.53‰ with corresponding δ2H values from –95.4 to –87.7‰. For comparison, in the tested rivers and streams, the δ18O values vary from –12.71 to –10.48, and δ2H, from –88.8 to –76.5. At the same time, the figurative points of the springs on the δ18O and δ2H diagram are located along the local meteoric water line, which means their meteoric origin. Estimates of the ratio of “winter” to “summer” infiltration waters in the spring water balance show that “summer feeding” dominates by ≥75%. Hydrocarbonate and calcium predominate in the ionic composition, which is very typical for ultra-fresh waters, and a distinctive feature is the relatively high content of sulfate ion, Zn, Ni, Cu, Pb, Mo, W, As, and Cd in some samples. However, due to the high rate of water exchange, the concentrations of potentially toxic elements are quite low. The assessment of non-carcinogenic risks showed that water from springs can be used by the population for drinking purposes.