N. A. Budantseva

Oxygen isotope composition of water and snow-ice cover of isolated lakes at various stages of separation from the White Sea

This study aimed to analyze the oxygen isotope composition of water, ice, and snow in water bodies isolated from the White Sea and to identify the structural peculiarities of these pools during the winter period. The studies were performed during early spring in Kandalaksha Bay of the White Sea, in Velikaya Salma Strait and in Rugoserskaya Inlet. The studied water bodies differ in their degree of isolation from the sea. In particular, Ermolinskaya Inlet has normal water exchange with the sea; the Lake on Zelenyi Cape represents the first stage of isolation; i. e., it has permanent water exchange with the sea by the tide. Kislo-Sladkoe Lake receives sea water from time to time. Trekhtsvetnoe Lake is totally isolated from the sea and is a typical meromictic lake. Finally, Nizhnee Ershovskoe Lake exhibits some features of a saline water body. The oxygen isotope profile of the water column in Trekhtsvetnoe Lake allows defining three layers; this lake may be called typically meromictic. The oxygen isotope profile of the water column in Kislo-Sladkoe Lake is even from the surface to the bottom. The variability of δ18O is minor in Lake on Zelenyi Cape. A surface layer (0–1 m) exists in Nizhnee Ershovskoe Lake, and the oxygen isotope variability is well pronounced. Deeper, where the freshwater dominates, the values of ?18Îvary insignificantly disregarding the water depth and temperature. This fresh water lake is not affected by the seawater and is not stratified according to the isotope profile. It is found that applying the values of ?18Î and profiles of temperature and salinity may appear as an effective method in defining the water sources feeding the water bodies isolated from the sea environment.

Water isotopic-geochemical composition in the Trekhtsvetnoe meromictic lake on the White Sea coast

The isotopic features of Lake Trekhtsvetnoe in the White Sea coast area were studied in 2012–2015 in both winter and summer. Lake Trekhtsvetnoe is a water body, separating from the sea, with constant vertical stratification throughout the observation period. Its isotopic, hydrophysical, and biological characteristics have been studied. By the isotopic profile of lake water body, three zones can be identified in the lake: (1) 0–1 m: mixolimnion zone with δ18O varying from–12 to–11.1‰; (2) 1.0–3.0 m: zone with transitional properties with δ18O varying from–11.1 to–5.5‰; (3) 3.0–7.6 m: monimolimnion zone with highest values of δ18O—from–5.5 to–4.7‰.

Isotopic and palynological compositions of a massive ice in the Mordyyakha River, Central Yamal Peninsula

The investigation objective is to study a new mas� sive ice in the Mordyyakha River valley (the Central Yamal Region), to determine the contents of stable oxygen and hydrogen isotopes in the ice, and to study pollen spectrum remains. These data are used to study the ice formation conditions and to prove that massive ice are heterogeneous and originated from lake waters. The investigated body is similar to those studied in dif� ferent Yamal regions such as Erkutayakha River valley [1], Bovanenkovo field [2], and the lower Yuribei River [3–5].

Variations in δ18O, δD, and the concentration of pollen and spores in an autochthonic heterogeneous massive ice on the Erkutayaha River in the southern part of the Yamal Peninsula

The objective of our work is to study the new mas� sive ice deposit in the valley of the Erkutayaha River in the southern part of the Yamal Peninsula, determine the concentration of stable oxygen and hydrogen iso� topes in the ice and study the pollen and spore in the ice, to determine the conditions of ice formation based on these data, and show that massive ice in these region are of the heterogeneous autochthonic type and segregation (infiltrationsegregation) and injection genesis similar to those deposits that were recently studied in the regions near Yamal, on the Bovanenkov deposit (1) close to the Harasavey (2, 3) and Marre� Sale (4) settlements. The newly investigated outcrop of massive ice is located in the southern part of the Yamal Peninsula on the left bank of the Erkutayaha River (68 о 1118 N, 68 о 5139 E). This is the southernmost among the studied massive ice in the Yamal Peninsula. A massive ice approximately 100�m long exposes in the outcrop 15-18 m high that is embedded predominantly in the layered sand. The ice massive is most completely exposed in the cirques (figure). The massive ice is located just under the layer of the seasonal melting in the central part of the cirques. Here, it is sharply ele� vated and cut most likely by the postgenetic subaquatic melting. In the apical part of the cirques, the massive ice is covered by Holocene lacustrineswamp sedi� ments approximately 1 m thick. The ice layers sharply drop on both sides of the central part and in 15 m already the cover of the ice deposit appears at a depth of 8 m. The ice in the massive ice body has a suffi� ciently different cryotexture. This is predominantly the ice of four types: (1) pure ice, dullwhite with a large amount of gas xenogenic inclusions; (2) crystal� clear transparent ice sometimes with ground inclu� sions; (3) gray layered ice with steel shimmer, the lay� ers are parallel to the slope of the upper surface of the ice deposit; (4) gray block ice deposited as tiles. We distinguished the central dislocation part in the general structure of the deposit, a stock with vertically and subvertically located ice layers (the ice here is crystalclear and dirtygray with a large amount of mineral inclusions) and two peripheral parts com� posed of horizontally layered ice (the ice here is lay� ered, predominantly gray with a steel shimmer, dull� white, and block gray). The horizontal layers of these two parts of the deposit change to sloping at the con� tact with the central stock. Such contact evidences that the ice of the central stock influences the charac� ter of the horizontally layered ice bedding.

Oxygen Isotope and Deuterium Indication of the Origin and 14C Age of the Massive Ice, Bovanenkovo, Central Yamal Peninsula

The conditions and forming time of massive ice were specified (Bovanenkovo gas condensate field, Central Yamal). Here, massive ice lies as stratums, laccoliths, stocks, and lenses. Three thousand boreholes 10–100 m in depth were analyzed. In 260 of them massive ice was broached. The ice foot is situated from 1 to 57 m deep. The maximal thickness of ice broached with boreholes came to 28.5 m; on average, it was about 8 m. The extension of massive ice is sometimes more than 2000 m, and its area is quite often more than 10 km2. According to the radiocarbon method, loams of the third terrace, containing and overlapping ice deposits, were formed from 25 000 to 20 000 years ago or somewhat later. These strongly peat loams containing massive ice formed either in shallow sea conditions or during periodical draining conditions of beaches or low laida, where organic matter appeared due to erosion and deposition and accumulated during draining and overgrowing of drains. In more inclement conditions than at present, loam deposits were frozen immediately, forming massive ice, which occupied the barely water-saturated layers. The oxygen isotope composition (δ18O) of massive ice samples varied from −12.49‰ (here and further, relative to SMOW) to −22.95‰. The deuterium concentration (δD) varied from −91.7 to −177.1‰. Deuterium kurtosis (dexc) varied from 3.4 to 10.6‰. In one seam outcrop, the content of stable isotopes varied significantly. Here, at a depth of 0.2–0.8 m, the δ18O content varied by more than 10‰ (from −12.49 to −22.75), and the δD content, from −91.7 to −171.9‰. Such variations testify about ice extraction upon freezing of water-saturated grounds in a closed system. According to palynological analysis of ice stratums, numerous remains of unicellular green algae and diatoms were revealed. It is possible that this is evidence of the existence of a fresh well, which was a source of water, feeding the layer. Most probably these were near-bottom silt waters of a large lake or desalted bay, which were frozen syngenetically. This accentuates the new type of massive ice, syncriogenic segregative ice, which probably formed 25 000–20 000 yr BP.

Oxygen isotope and deuterium composition of snow cover on the profile of Western Siberia from Tomsk to the Gulf of Ob

The purpose of this work is to study the variability of the isotope composition (δ18О, δD, dexc) of the snow cover on a long transect of Western Siberia from the southern taiga to the tundra. The study of the snow cover is of paleogeographic, paleogeocryological, and paleohydrological value. The snow cover of western Siberia was sampled on a broadly NS transzonal profile from the environs of Tomsk (southern taiga zone) to the eastern coast of the Gulf of Ob (tundra zone) from February 19 to March 4, 2014. Snow samples were collected at 31 sites. Most of the samples represented by fresh snow, i.e., snow that had fallen a day before the moment of sampling were collected in two areas. In the area of Yamburg, the snow specimens collected from the surface are most probably settled snow of different ages. The values of δ18О in the snow from Tomsk to Yamburg varied from–21.89 to–32.82‰, and the values of δD, from–163.3 to–261.2‰. The value of deuterium excess was in the range of 4.06–19.53‰.

Hydrograph separation of the Dzhankuat River, North Caucasus, with the use of isotope methods

The formation of snowmelt runoff from the Dzhankuat glacier has been considered and the hydrograph of the Dzhankuat R. has been separated with the use of isotope and ionic balance. Isotope variations of runoff at the outlet section of the Dzhankuat R. have been studied for two ablation seasons of 2013 and 2014. The separation of 2014 hydrograph was based on δ18O and mineralization values obtained for various sources of Dzhankuat R. recharge: precipitation, snow of different seasons, firn, ice, and groundwater. The isotopic separation of the hydrograph has shown that, in June, a considerable portion (15–20%) of Dzhankuat R. total runoff is due to the melting snow cover that has formed during spring snowfalls. In June, the proportion of this component in the total daily runoff can reach 36%. The contribution of the runoff originating from winter-snow melting varies from 20% in the early to 50% in the late June. In August and September, the share of groundwater varies from 30 to 100%; the share of precipitation, from 0 to 30% (on the average for the period, 6%); and the share of water from melting firn and ice, from 0 to 70% (on the average, 38.6%).

Concentration of 18O in precipitation over Moscow in 2014

The series of δ18O values is presented for all precipitation events in Moscow in 2014. Precipitation samples were taken at the observation site of the Meteorological Observatory of Lomonosov Moscow State University (MSU MO), and the isotopic analysis was carried out in the isotopic laboratory of the Department of Geography of MSU. The concentration of stable 18O in precipitation over Moscow in 2014 varied from -0.09 to -26.29‰. The maximum amplitudes of δ18O were registered in March-April and October. The pronounced interrelation was revealed between the oxygen isotopic composition of precipitation and surface air temperature (the correlation coefficient is 0.85). The computation of back trajectories of air masses and the analysis of weather charts demonstrated that the most isotopically light precipitation is typical of relatively cold air masses slowly moving over the continent during the last five days before precipitation. In this case, the ongoing condensation leads to the progressive isotopic depletion of precipitation (more and more isotope-depleted precipitation is registered). On the contrary, fast air transport from the middle and even from high latitudes of the Atlantic Ocean leads to the relatively constant of δ18O values of precipitation.

Isotope composition of a lithalsa in the Sentsa River valley (East Sayan Mountains)

The ice-rich core formation within the core of the lithalsa in the Sentsa River valley (West Buryatia) was studied. The concentrations of stable oxygen and hydrogen isotopes in the ice were determined, the plant residues in the enclosing deposits were aged. It was found that the lacustrine loams enclosing the ice body were accumulated about 4700–7000 years ago. The ice core of the lithalsa was characterized by δD values from 141.9 to–159.8‰, δ18O from–19.52 to–21‰, and dexc within 4.1–17.29‰. Small variations in the isotope composition of the ice–soil material within the lithalsa core point to its formation in an open system with water inflow from outside. The values of δ18O and δD were much closer to those for recent middle-winter and late-autumn atmospheric precipitation, as well as for riverine water, which pointed to a Holocene age of the ice.

δ18O and δD variations in Holocene massive ice in the Sabettayakha river mouth, northern Yamal Peninsula

The conditions of formation of massive ice near the South Tambey gas-condensate field in northern Yamal Peninsula are studied. It is shown that massive ice bodies up to 4.5 m thick occur in the Holocene deposits of the high laida and the first terrace. Therefore, they cannot be the remains of glaciers; they are ground ice formations. All three types of massive ice have quite various isotopic compositions: the values of δD range from–107 to–199.7, and δ18O from–15.7 to–26.48‰. Such a significant differentiation in isotopic composition is a result of cryogenic fractionation in a freezing water-saturated sediment. The most negative isotope values are even lower in this Holocene massive ice than in the Late Pleistocene ice-wedge ice of Yamal Peninsula.