Biogeochemistry of Water and Sediment in the OB and Yenisey Estuaries

Abstract

In August–September 1993 hydrochemical, hydrooptical, geochemical and biological researches were carried out in the Ob and Yenisey estuaries and adjacent regions of the Kara Sea (49-th cruise of the R/V “Dmitry Mendeleev”). The results of this expedition allow comparison of the two large estuarine systems in relation to the role of organic matter and biota in the behaviour of some elements in water, suspended matter and bottom sediments. At relatively similar hydrochemical and hydrophical conditions (the same salt wedge estuarine type, similar temperature (T) and salinity (S‰) distributions) there are significant differences in the level of dissolved carbon and nutrient concentrations (higher in the Ob estuary), and in photosynthetic activity and primary production (higher in the Yenisey estuary). The results show that biotic factors play an important role in trace metal behaviour in the water column (for both dissolved and particulate forms of elements). The influence of biotic factors is more marked in the Yenisey estuary due to higher photosynthetic activity and primary production of phytoplancton.