Plitvice Lakes as a Case Study for Developing a Laboratory Model of Tufa Formation with Future Relevance to Environmental and Anthropogenic Impacts

Key physicochemical parameters of Plitvice Lakes water were monitored over a three-year period at representative locations along the lake system. In situ tufa mineralization rates were determined by using glass substrates, revealing a pronounced downstream increase: the lowest rates occurred at the lake’s source, while the highest were measured in the lake’s outflow to Korana River. Strong seasonal patterns were also evident, with maximum deposition rate during summer. In situ-formed tufa consisted predominantly of calcite and magnesium calcite, while small amounts of the metastable polymorph vaterite were occasionally detected during early mineralization stages. Diatom frustules were consistently present in all samples, highlighting the interconnected roles of biotic and abiotic factors, including hydrodynamics, temperature, and water chemistry, in regulating tufa formation. Field observations were complemented by laboratory calcium carbonate precipitation experiments conducted in artificial karst water formulated to mimic the properties of Plitvice Lakes. Structural, morphological, and chemical comparisons showed excellent agreement between natural tufa and laboratory-precipitated calcium carbonate. These results demonstrate the suitability of the proposed experimental model system for future laboratory studies aimed at disentangling the environmental and anthropogenic controls on tufa formation.