Silicon in ultrafresh groundwater: a case study of the Imandra Lake catchment, The Kola Peninsula

The ultrafresh groundwater (with TDS values less than 200 mg/L) of the Imandra Lake catchment, Kola Peninsula, is from an intensive water exchange zone, where the water has a short period of contact with the rock. Therefore, the considered water is at the initial stages of the water-rock interaction. The water is saturated with respect to oxides and hydroxides of aluminium and iron. In the groundwater of the Imandra Lake catchment area, the silicon concentrations significantly exceed the concentrations of magnesium and especially potassium. Nevertheless, water is undersaturated with respect to with respect to silicon oxides. The shown enrichment of water with cations is explained by time of water-rock interaction.