Dynamics of dissolved inorganic carbon in the Yenisey gulf during open water period

Abstract

On the materials of several SIO RAS cruises and archival hydrological and hydrochemical data, the dynamics of dissolved inorganic carbon in the Yenisey Gulf was investigated. There are 3 main areas, where mass sedimentation of suspended matter and oxidation of organic matter (OM) in the upper sediment layer takes place. The first region of oxidation of OM was south of 72 N, its existence is associated with mass sedimentation of dissolved and suspended matter on the geochemical barrier. Two other areas of decomposition of the OM (elevated dCtot) are located downstream (between 73 and 74 and north of 75 N) and most likely originated at the orographic barrier, where the change in the dynamic characteristics of the riverine flow and the topography of the bay bottom creates conditions for sedimentation. Comparison of the difference in the observed Ctot value with the AOU value showed that in 1993, the change in the Ctot content was provided by the oxidation processes of OM. In 2011, carbon emission into water was most likely associated with the transformation of mineral suspension and/or carbon exchange in bottom water with bottom sediments. In 2016, a decrease in the Ctot content was observed almost everywhere in bottom layer. It is most realistic to assume that such a distribution is associated with carbon sorption on suspensions. Despite the many similar features of the distribution of hydrochemical characteristics in the bay, the change in the content of dissolved inorganic carbon in the investigated area has differed greatly in different years. In our opinion, the reason for the fact is the variability of the discharge of the Yenisey River in different years.