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Studies of permafrost agradation within peat mires leading to palsa growth and palsa dynamics during the Holocene are important for predicting the future of permafrost in a changing climate. The radiocarbon age of peat cover and stable isotope composition of the ice cores of palsas near Eletsky settlement, north‐east of the European part of Russia, were studied. Palsa growth was the most active between 8 and 5 cal ka BP. The main sources for ice core formation were precipitation‐fed surface and suprapermafrost waters. It is assumed that the isotope composition of the initial water was isotopically depleted compared with modern surface waters, which may be explained by general climate cooling during earlier stages of palsa growth (response to the 8.2 ka cooling event). The ice cores of the studied palsas were formed during the freezing of water in semi‐closed conditions, mainly by the segregation mechanism during permafrost agradation, thickness of the ice lenses and ice volume could depend on freezing rates and water supply. The upper part of the palsa ice core experienced deep thawing and could be saturated with meteoric water; repeated freezing of this part of the ice core likely occurred in closed system conditions. [ABSTRACT FROM AUTHOR]

The study presents a dataset on long-term complex glaciological, hydrological, meteorological observations and isotopes sampling in an extremely underreported alpine zone of the North Caucasus. The Djankuat research basin is of 9.1 km², situated on elevations between 2500-4000 m, by 30 % covered with glaciers. The biggest in the basin - the Djankuat glacier was chosen as representative of the central North Caucasus during the International Hydrological Decade and is one of 30 "reference" glaciers in the world that have annual mass balance series longer than 50 years (Zemp et al., 2009). The dataset covers 2007-2017 and contains the result of yearly measurements of snow thickness and density; dynamics of snow and ice melting; measurements of water runoff, conductivity, turbidity, temperature, δ18O, δ²H on the main gauging station (844 samples in sum) with a one-hour or several-hours step depending on the parameter; data on δ18O and δ²H sampling of liquid precipitation, snow, ice, firn, groundwater in different parts of the watershed regularly in time during melting season (485 samples in sum); precipitation amount, air temperature, relative humidity, shortwave incoming and reflected radiation, longwave downward and upward radiation, atmospheric pressure, wind speed and direction - measured on several automatic weather stations within the basin with 15 min - one-hour step; gradient meteorological measurements to estimate turbulent fluxes of heat and moisture, measuring three components of wind speed at a frequency of 10 hertz to estimate the turbulent impulse heat fluxes over the glacier surface by the eddy covariance method. All the observations were done during ablation period (June-September) and were interrupted in winter. The dataset was published on knb.ecoinformatics.org long-term repository doi: https://doi.org/10.5063/F1H1307Q and will be further updated. The dataset can be useful for developing and verifying hydrological, glaciological and meteorological models for high elevation territories, to study impact of climate change on hydrology of mountain regions, using isotopic and hydrochemical approaches to study mountain territories. As the dataset includes the measurements of hydrometeorological and glaciological parameters during the catastrophic proglacial lake outburst in the neighboring Bashkara valley in September 2017, it is a valuable contribution to the study of this dangerous hydrological phenomena. [ABSTRACT FROM AUTHOR]

Perennial frost mounds identified as lithalsas occur in the Sentsa River valley of the Eastern Sayan Mountains, Russia. We report the first detailed study of permafrost in this region, based on analysis of the cryostructure and distribution of stable isotopes of oxygen and hydrogen, and ion concentrations from the ice-rich cores of two lithalsas 3-7 m high. Their main cryostructures are reticulate and lenticular, with visible ice contents exceeding 50-60%. The vertical and lateral distribution of δ18О and δD values show a step-by-step mechanism of lithalsa growth: in the first stage a large lithalsa formed, and in the second stage a small lithalsa formed. The more negative isotope values of ice in the large lithalsa ice probably resulted from gradual release of isotopically depleted water from the central to peripheral part of the massif during ice segregation in water-saturated fine-grained lake sediments. Minor variations of isotope values suggest intensive recharge of lake-fen and meteoric water supply during freezing and lithalsa growth. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]