Assessing Long-Term Variations of pH in Caucasian Lakes by Bioindication Method (Diatom Analysis)

The processes of possible long-term variations of pH in Caucasian lakes were analyzed based on a study of lacustrine sediments from five small lakes of the Western and Central Caucasus. The study was focused on diatom complexes examined in core columns of bottom sediments. The values of pH were reconstructed using the authors’ principle of unification of hydrological characteristics. The study used the results of isotopic dating. Series of numerical values of pH with lengths from 2000 to 130 years were constructed for the examined lakes. The reconstructed series of pH values show no appreciable changes in the lakes of the Western Caucasus and suggest pronounced processes of alkalinization in the lakes of the Central Caucasus.