VARIABILITY OF HYDROCHEMICAL PARAMETERS IN THE NORTHERN PART OF THE OB ESTUARY IN 2013-2014

The mouth of the Ob Bay, one of the largest river estuaries along the Arctic coast, represents a unique natural environment where fresh river water and seawater actively interact. It leads to the formation of complex physico-chemical gradients and promotes the transformation of chemical substances, including nutrients. This study is based on data from two expeditions covering the northern part of the Ob Estuary. The research focuses on interannual variability of hydrochemical parameters, including the distribution of nutrients (NO₃⁻, PO₄³⁻, Si), and dissolved oxygen concentrations in the Ob Estuary during the early autumn of 2013 and 2014. Special attention is paid to spatial distribution patterns of hydrochemical parameters and the identification of zones of absorption and release of dissolved silicon, phosphorus, and nitrate nitrogen. The most significant factors influencing interannual variability are differences in the river runoff volumes, the hydrodynamic structure of the water area, the formation and stability of frontal zones, and the intensity of biogeochemical processes.

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