Structural-functional Features Of Landscapes With Active Thermocarst In The Northern Taiga Of Western Siberia

Abstract

A. G. Lim, S. V. Loiko, I. V. Kritckov, D. M. Kuzmina

In the article, the main results of the study of dissolved greenhouse gases (CO2, CH4), dissolved organic carbon (DOC) and colloidal trace elements-metals in surface and soil waters of hollows, depressions, permafrost subsidences are considered. These waters were sampled in areas with active and stable permafrost thawing in Western Siberia. It is found that these zones of active termokarst are mainly located on the slopes and the bottoms of the upper reaches of rivers, which drain the interfluve. Active thawing of flat mound bogs leads to the appearance of numerous hollows, depressions and thermokarst subsidences, especially on the border between forest and fens. This is related to the additional heat input from the flowing water and causing the thawing deep permafrost on the edges of ridges occupied by the forest. Increase in specific conductivity (S.C.) in the smallest water bodies and supra-permafrost water is accompanied by a significant increase in concentrations of DOC, P, K, Cu, Zn, Mo and Ba. It has been found that small hollows and subsidence (< 10 – 100 м²) are characterized by much higher concentrations of DOC and CO2 (p < 0.05) in comparison with large depressions and thermokarst water bodies. There is also a decrease of CH4 concentration with an increase in the size of water bodies (p < 0.05), despite the fact that the data dispersion reaches 3 orders in small (<100 – 300 m²) water bodies of the where located zones active termokarst landscape, concentrations of DOC, CO2 and CH4 are significantly higher (p <0.05) than in the previously studied water bodies formed under conditions of a stable state of permafrost in areas of Nojabrsk and Khanymey. Waters of the active thawed of permafrost peat landscapes are usually rich in oxygen (saturation in the range of 30 ≤ O2 ≤ 105 %) and approximately 0.5 unit’s pH more acidic than areas with a stable state of permafrost. Many major and trace elements show a statistically significant decrease in concentration from very small water bodies (< 10 m²) to larger thermokarst waters. By the results of carried out research we can say that in the landscapes with active termokarst there will be direct mobilization of soil water in the hydrological network (rivers and lakes) with a minimal transformation of the water composition within the catchment area.

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