engleski

Tufa and lake sediment formation

In the Plitvice Lakes area tufa, a freshwater calcium carbonate, precipitates very intensively in presence of macrophites and microphites forming spectacular waterfalls and barriers. Barrier deposits form dams, behind which the lakes of the Plitvice complex are situated. At the same time calcium carbonate precipitates as fine-grained lake sediment at the bottom of the lakes. In the first step of the geochemical process of tufa and lake sediment formation, the rain water dissolves CO2 produced by the decomposition of organic matter and by root respiration in the topsoil. Percolating water rich in CO2 dissolves carbonate rocks and forms bicarbonate. When water containing calcium and bicarbonate ions emerges in the form of a karst spring, precipitation of calcium carbonate occurs either due to degassing of CO2 from solution or by evaporation. Precipitation of carbonates in the form of lake sediment or tufa depends on the physico-chemical conditions of the water. It is enhanced by the photosynthetic activity of aquatic primary producers (algae, bacteria and plants) indicating that the interaction between atmosphere and biosphere determines the CO2 – HCO3 – CaCO3 system.

Plitvice Lakes, karst, project STRAVAL, tufa, lake sediments

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