SPATIAL-TEMPORAL VARIABILITY OF HYDROCHEMICAL CHARACTERISTICS OF THE GULF OF OB AND TAZ BAY

The Gulf of Ob and Taz Bay are components of a special geographical object — Ob-Tar estuarine area. They are intensively used by companies, which produce natural gas and oil in the Yamal Region. The aim of the study is to assess the spatial patterns and temporal dynamics of the priority hydrochemical characteristics of the Gulf of Ob and Taz Bay. The data of the Arctic estuarine expeditions (1968—1989) and complex expeditions (2012—2013), organized by the Arctic and Antarctic Research Institute, are used as the research materials
The authors have analyzed hydrochemical characteristics: pH, salinity, dissolved oxygen, silicon and phosphorus compounds. In summer-autumn period 2012—2013 there was a significant seawater intrusion to the south of the Gulf of Ob, caused by a small runoff of rivers the in these dry years. Dissolved oxygen distribution is determined by seasonal variability. In summer-autumn period the average values of more than 7 mg/l were observed. In winter, in the southern part of Gulf of Ob and Taz Bay there was an extreme oxygen deficit, dissolved oxygen values dropped below 1 mg/l. A tendency for a decrease in the content of silicon and phosphorus compounds from south to north was noted. Concentrations of phosphorus-containing compounds in the whole water area were low.
The condition of Taz Bay and southern part of the Gulf of Ob is mainly determined by the river runoff and the hydrochemical regime in the area. In the period of high waters the regime has features inherent to rivers, and in the period of low flows — to lakes and reservoirs. Large-scale interference in the ecosystem of Ob-Taz estuarine area recently requires regular hydrological-ecological observations at coastal stations and along the water area sections.

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