Distribution of dissolved matter in the Yenisei river estuary and adjacent water area of the Kara sea and its interannual variability

Abstract

The distribution of dissolved matter (major ions, nutrients, and trace elements) in the Yenisei River estuary and adjacent water area was studied according to the natural observations data from 20092016. These results were compared to the literature data of hydrochemical researches of this region. It was shown that transport of major ions (Na, K, Mg, Ca, SO4) and some trace elements (Li, Rb, Cs, Sr, B, F, Cr, Ge, As, Mo, U) is described by the stable in the long-term period equations of conservative mixing between riverine and seawater masses. Alkalinity also belongs to conservative components; however this parameter exhibits substantial spatiotemporal variability of the distribution caused by complex hydrological structure of the Yenisei Bay and adjoining part of the Kara Sea. Concentrations of Pmin, Si, and V in the desalinized waters of photic layer decreases seaward during vegetation period owing to uptake by phytoplankton. The losses of these elements reach 3057, 30, and 9% of their supply by river runoff, respectively. The content of dissolved Pmin and V in the intermediate and near-bottom layers of the Yenisei River estuary strongly increases with increase of salinity due to regeneration of precipitated organic matter, whereas silica remineralization is much less pronounced. Barium in the all estuary is intensively desorbed from river suspended matter in the quantity reaching 20100% of its dissolved forms input with river runoff depending on seasonal variations of chemical composition of the last. The transport of dissolved forms of heavy metals (Mn, Fe, Pb) and elements-hydrolyzates (Al, Ti, Y, La, Ce, Pr) in the mixing zone between the riverine and seawater masses is probably controlled by the coagulation and flocculation of organic and organomineral colloids, which is indicated by decrease in the concentrations of these elements at the beginning of salinization (for 2061%) with subsequent approximation to the seawater mass characteristics.