Geological controls and the impact of human society on the composition of peloids of present-day salt lakes (coastal zones of the Black, Azov, and Dead Seas)

Abstract

Modern salt lakes belong to a growing class of natural systems undergoing compositional change due to increased human activity along their shores. To understand the full consequence of anthropogenic-driven change, detailed geological and geochemical study of such salt lake systems is required. Notably further study is required of the changes recorded in the peloids (lake muds) commonly found in these salt lake systems. Differences in regional geology respectively determine the dominant sulphate mineralsalt type and chemical composition of Crimean salt lake peloids, and the chloridecarbonate mineral-salt type and chlorine-calcium composition of the Dead Sea peloids. Local geological factors furthermore influence the peloids’ geochemical and grain size characteristics: Cu-Rb-Zn-Mo-Ca-Cl association is found in Dead Sea peloids and Fe-V-Mn-Co-Y-Pb association is found in Crimean lake muds. Finally, the beddingstructure of the peloid layer affects the granulometric characteristics of the peloids. The impact of human society (e.g., the anthropogenic factor) influences the salt, granulometric and microelemental compositions of peloids. A complete lack of halite in the Lake Kuchuk-Adzhigol mud is most likely related to intensive anthropogenic desalination, as well as to the input of drainage and waste water. The coarsest muds were found in Lake Saky, which reflects changes in the hydrochemical regime of the lake. Ferrous sediments of the Cimmerian stage are widespread in the East of Crimea. Until recently, these deposits were exploited through open pit mining (e.g., the iron ore mine Kamish-Burun), which could amplify Fe-Ti-Cr-K-V-Pb-Y-Mn-As-Co association in the Lake Tobechik muds.