Composition of suspended matter, bottom sediments, and interstitial waters from the Caspian Sea

Isotopic compositions of organic (d13C Corg) and carbonate (d13C Ccarb) carbon were analyzed in suspended matter and bottom sediments from the North and Middle Caspian Basins. Isotopic composition of Corg was used for assessing proportions of allochthonous and autochthonous particulate organic matter. Difference between d13C Corg values in surface layer bottom sediments and suspended matter is explained by aerobic and anaerobic diagenetic transformations. Isotopic composition of Corg in bottom sediments may be used as a tool for reconstructing Quaternary transgressive-regressive history of the Caspian Sea.