CHEMICAL-COMPOSITION OF BOTTOM SEDIMENTS FROM THE KARA SEA AND ESTUARIES OF OB AND YENISEI RIVERS

Chemical composition of bottom sediments collected during the 49-th cr uise of the R/V ''Dmitry Mendeleev'' in the Kara Sea and estuaries of Ob and Yenisei; rivers was under study. Processes of mechanical differ entiation of sedimentary material were of great importance during the formation of Holocene and Upper Pleistocene sediments. Both grain-size and chemical compositions of sediments significantly depend on these processes. Mechanical differentiation of estuarine sediments is higher than one of marine Upper Pleistocene sediments, but lower than that o f marine Holocene sediments. Obtained lithological and geochemical dat a showed that marine Upper Pleistocene sediments were formed in the sh allow zone of inner shelf. The contents of chemical elements accumulat ed from solution (or due to sorption or with organic matter) in reduce d estuarine muds are similar to ones of estuarine suspended matter. If sediments from the upper layer are oxidized they are enriched in a nu mber of chemical elements (at first - in Mn and in Fe, P, Ni, Co as we ll) due to their migration from sediments of the lower layer, and due to their sorption from the sea water by Fe and Mn hydroxides.