Abstract
Abstract. This work describes the hydrochemical composition of thermokarst lake and pond ecosystems, which are observed in various sizes with different degrees of permafrost influence and are located in the northern part of western Siberia within the continuous and discontinuous permafrost zones. We analysed the elemental chemical composition of the lake waters relative to their surface areas (from 10 to 106 m2) and described the elemental composition of the thermokarst water body ecosystems in detail. We revealed significant correlations between the Fe, Al, dissolved organic carbon (DOC) and various chemical elements across a latitude gradient covering approximately 900 km. Several groups of chemical elements that reflect the evolution of the studied water bodies were distinguished. Combining the data for the studied latitude profile with the information available in the current literature demonstrated that the average dissolved elemental concentrations in lakes with different areas depend specifically on the latitudinal position, which is presumably linked to (1) the elements leached from frozen peat, which is the main source of the solutes in thermokarst lakes, (2) marine atmospheric aerosol depositions, particularly near the sea border and (3) short-range industrial pollution by certain metals from the largest Russian Arctic smelter. We discuss the evolution of the chemical compositions observed in thermokarst lakes during their formation and drainage and predict the effect that changing the permafrost regime in western Siberia has on the hydrochemistry of the lakes.
Highlights
The wetland ecosystems of the sub-Arctic region of western Siberia act as unique natural indicators of climate change because these ecosystems are the most sensitive toward changes in the natural environment
Based on recently collected data, we study the chemical composition of the thermokarst lakes and ponds along a 900 km gradient of climate, vegetation and permafrost coverage to answer the following questions: 1. Do the variations in the chemical composition of lake water chemical composition as a function of the surface area of the lake in the continuous permafrost zone follow the trends established in the discontinuous and sporadic zone?
Within the continental permafrost zone of the thermokarst lakes, we observe a systematic evolution of the chemical composition of the water bodies while their ecosystems develop from small permafrost subsidence, depressions and ponds to large thermokarst lakes
Summary
The wetland ecosystems of the sub-Arctic region of western Siberia act as unique natural indicators of climate change because these ecosystems are the most sensitive toward changes in the natural environment. Most studies on thermokarst, the thawing of ice-rich permafrost or the melting of massive ground ice (i.e. Jorgenson et al, 2008), have been performed in Canada, Alaska, Mongolia, China, Antarctica and eastern Siberia (see Kokelj and Jorgenson (2013) for a review and Boike et al (2013) for a description of the Lena River Delta Observatory). Relatively little attention has been paid to the vast area of the western Siberian lowlands (WSL),where the largest resources of potentially unstable frozen peat are concentrated. Most studies in this region were related to greenhouse gases, CH4, and their release to the atmosphere from the surface of the thermokarst lakes (Walter et al, 2006, 2008) and other forms of permafrost thaw (Walter Anthony et al, 2012). Thermokarst lake formation is a dominant mode of permafrost degradation involving a surface disturbance, melting ground ice, surface subsidence and water impoundment
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