New Data on Paleogeography of Quaternary Coast Sediments of the Rivers of the European North of Russia Using Isotope-Geochemical Methods

(1) Background: The Quaternary river bank deposits of the European North of Russia contain several mollusk fossils that can give important past-climate information which is relevant to understand the evolution of climate in the Holocene period and predict future scenarios on climate change. (2) The purpose of the research: reconstruction of the main physical and chemical parameters of the habitat of mollusks based on the determination of the species of mollusks and the study of the isotope-geochemical composition of shells and their host deposits. (3) Object of study: Quaternary deposits of coastal outcrops of the rivers of the European North of Russia: Pechora Sula, Peza, bivalve shells, and their fragments. (4) Results: The revealed macrofauna complexes represented by bivalves (Arctica islandica, Hiatella arctica, Mytilus edulis, Tridonta borealis, Mya truncata, Neptunea despecta) were determined and the variations of δ13C and δ18O (‰) isotopes in the studied fossil bivalve shells were calculated. The data on the concentrations of chemical elements in fossil shells were determined and summarized. The content of elements in mollusk shells varied within the following limits: Fe 101.7−403.3 µg/g (Vastyansky Kon’, river Pechora), Mg 0.38–2.61 µg/g (Vastyansky Kon’, river Pechora), Ba 18.27–60.44 µg/g (village Oksino-River Sula), and Sr 1128.3–2275.34 µg/g (Vastyansky Kon’-village Oksino, river Pechora). The ratio between the elements varies within Ba/Sr 0.011–0.041 (village Oksino- River Sula) and Mg/Fe 0.01–0.15 (Vastyansky Kon’- village Oksino, river Pechora)

Isotope Signs (234U/238U, 2H, 18O) of Groundwater: An Investigation of the Existence of Paleo-Permafrost in European Russia (Pre-Volga Region)

The isotopic (234U/238U, 2H, 18O) and chemical composition of groundwater on the right bank of the Volga River along the middle reach (European Russia) was studied down to a depth of 400 m. These data allow diagnosis of the presence of a three-component mixture. The first component is modern/young fresh recharge water of the Holocene age. It has the isotopic composition of water δ18O → −12.9 ‰ and δ2H → −90 ‰, close to modern precipitations, and the equilibrium isotopic composition of uranium 234U/238U → 1 (by activity). The second component is slightly salted water of the late or postglacial period with δ18O → −17.0 ‰ and δ2H → −119 ‰, and a small excess of uranium-234 234U/238U ≈ 4. The third component is meltwater formed as result of permafrost thawing. It is brackish water with δ18O ≈ −15.0 ‰ and δ2H ≈ −110 ‰, and a maximum excess of uranium-234 234U/238U ≈ 15.7. The salinity of this water is associated with an increase of the SO42−, Ca2+ and Na+ content, and this may be due to the presence of gypsum in water-bearing sediments, because the solubility of sulfates increases at near-zero temperature. We explain the huge excess of uranium-234 by its accumulation in the mineral lattice during the glacial age and quick leaching after thawing of permafrost

Contribution of the atmospheric channel to lead contamination of soils in the Arctic territories

Although the Arctic territories have long been considered “the gold standard of purity”, global climate change and environmental pollution are having a significant impact on the state of Arctic ecosystems. In particular, industrial complexes combined with transboundary transport are having a negative impact. The aim of this work is to determine the contribution of atmospheric Pb to the contamination of soils of the Arctic territories using the trajectory statistics method which combines correlation and factor statistical processing approaches while taking the actual lead content in the upper soil horizon into account. In order to assess the transfer of pollutants, an analysis of multiannual air mass tracts and impurity transfer trajectories to certain points was carried out. The objects of study are the soil of the Khorey-Ver settlement, the basin of the Shapkin and Sula rivers, northeastern and southern Svalbard and the islands of the Southern Archipelago of Novaya Zemlya. It was established that the primary contribution to airborne pollution of the Nenets Autonomous District (NAO) during the summer period comes from sources located within a radius of about 400 km. Aerogenic influence of the mainland on the territory of Svalbard is practically absent, with the main atmospheric transport of substances coming from nearby marine areas. The transfer of impurities from the mainland to the Novaya Zemlya District is also insignificant. During the summer months, there is practically no airborne lead contamination of the island territories. Some influences on the territory of Novaya Zemlya and the NEO can be traced to sources on the Kola Peninsula, the coasts of the Barents and Kara seas, as well as long-distance transport from the southern regions. On the territory of the NAO, the number of heavy metal (HM) precipitations increases from west to east, possibly indicating a stronger impact of emissions from the Norilsk industrial hub than from the enterprises of the Kola Peninsula on this territory. In terms of seasonal dynamics, the island points are characterised by an increase in HM fluxes during the winter period; conversely, for the NAO territory, such an increase takes place during the summer. This discrepancy is primarily due to the changing nature of the atmospheric circulation

134Cs, 137Cs, 40K, 232Th, 226Ra in bottom sediments of the Dvina Bay on the White Sea (the Suhoe Sea Gulf)

The Suhoe Sea Gulf is a unique White Sea water body. Taking into account the risk of contamination of the White Sea with radionuclides as a result of the activities of the domestic and foreign nuclear industry and considering the plans to construct a deep-water part of the Arkhangelsk port on the Kuya River, the content and distribution patterns of natural and man-made radionuclides in the bottom sediments of the Suhoe Sea Gulf need to be studied. The specific activity of radionuclides was measured using a PROGRESS-2000 gamma spectrometer. Statistical processing of the data was performed using the STATISTICA (data analysis software system), version 10 software by StatSoft, Inc. (2011). The average specific activity of 226Ra, 232Th and 40K was 6.5 ± 1.4, 14.2 ± 4.3, 416 ± 89, accordingly. 134Cs and 137Cs were detected in 4 and 5 samples with a mean specific activity value of 3.3 ± 1.6 and 3.5 ± 1.1, respectively. The highest specific activity values of 40K are confined to the pelitic deposits. The main driving force in the processes of accumulation and redistribution of 232Th is gravitational water accumulation and mechanical transfer. The measured values of the specific activity of radionuclides do not exceed those previously determined by other authors in the bottom sediments of the White Sea. Correlation analysis showed a significant relationship between the content of 134Cs and 137Cs (0.77, p = 0.05), 232Th and 40K (0.67, p = 0.05) and 137Cs and 40K (0.84, p = 0.05). Factor analysis allowed two groups of radionuclides to be identified, their content being is determined by different processes: 134Cs, 137Cs, and 40K are jointly controlled by the most powerful factor (50%) and 232Th is affected by the weaker factor (29 %). Both factors are based on natural processes of radionuclide receipt and redistribution: the first factor reflects the ability of bottom sediments to adsorb 40K and isotopes of cesium, which are similar in chemical properties, and the second one reflects the natural process of removal by rivers of 232Th with terrigenous material

Spatial distribution of natural and anthropogenic radionuclides in the soils of Naryan-Mar

The objective of the research is to identify the main patterns of spatial distribution of natural and anthropogenic radionuclides (RN) in Naryan-Mar. Urban soils are formed by means of natural soil transformation with the participation of technogenic sedimentogenesis, which leads to disturbance of natural RN migration processes and contributes to the complex structure of natural and anthropogenic RNs contamination of tundra soils. The specific activity of anthropogenic (134Cs, 137Cs) and natural (226Ra, 232Th, 40K) RNs in Naryan-Mar soil was determined. The local low-intensity anomalies (LLIA) of anthropogenic RNs result from transboundary transfer; 134Cs and 137Cs are concentrated in soils with a well-shaped vegetable layer. 226Ra and 232Th LLIAs are confined to regions with stone buildings. 40K LLIAs are conditioned by high density of grassland vegetation involving 40K in the biological cycle. The statistical manipulation of the acquired data involved correlation and factor analysis techniques. The statistical analysis demonstrated a moderate and salient correlation between the content of 232Th and 40K in the soils of the areas built up with wooden houses and the soils of the recreation area, respectively. There is a salient correlation between the content of 134Cs and 40K as well as between 134Cs and 232Th in the soils of the recreation area. The area occupied by technological buildings demonstrates salient and high negative correlations between the content of 226Ra and radionuclides of 40K and 234Th. The multidirectional nature of the 226Ra and 232Th accumulation processes can be explained by their different mobility in the environment. A factor analysis of the specific activities of the radionuclides in the soils (based on the varimax method) revealed that the strongest factor (28%) conjointly regulates the 134Cs and 40K content, which testifies to their affiliation to non-mobile cationogenic elements. The second factor (25%) identified through an analysis of the overall data array may signify that organic matter plays a major role in the 137Cs retention

The evolution of the ecosystems of thermokarst lakes of the Bolshezemelskaya tundra in the context of climate change

In the conditions of climate warming, the thawing of permafrost can provoke the formation of new thermokarst lakes and subsidence, which facilitates the removal of organic matter from thawed peat into natural waters. Hydrochemical studies of surface waters of the Bolshezemelskaya tundra have demonstrated the exponential dependence of the physicochemical parameters on the size of the water body (peat subsidence, thaw ponds, small lakes, thermokarst lakes). The hydrochemical features of thermokarst lakes of the Bolshezemelskaya tundra are determined by high content of DOC, surface runoff and the thickness of peat deposits. Measurements of concentrations and fluxes of methane showed that all studied water bodies of the Bolshezemelskaya tundra are oversaturated with CH4, and depressions, subsidence, and small water bodies (<100 m2) are characterized by the highest concentrations of DOCs. The contribution of these small reservoirs to the total coverage of the surface of the Bolshezemelskaya tundra area is significant, and their consideration can greatly change the assessment of methane fluxes from the arctic tundra

New paleogeography data of the eastern coast of Green fjord (West Spitsbergen Island) based on research of the holocene deposits on Finneset cape with use of isotope-geochemical methods

Актуальность исследования заключается в определении возраста моллюсков в заливе Грен-фьорд на архипелаге Шпицберген и физико-химических параметров среды их обитания в условиях угрозы разрушения геологических обнажений с находящимися в них моллюсками и костным материалом птиц и рыб в результате активно развивающихся процессов береговой термоабразии и техногенной нагрузки комбината «Арктикуголь». Цель: реконструкция основных физико-химических параметров среды обитания моллюсков в голоцене на основе определения видовой принадлежности моллюсков и изучения изотопно-геохимического состава раковин и вмещающих их горных пород. Методы: определение видовой принадлежности раковин моллюсков с использованием морфологического метода; разложение образцов раковин путем кислотного вскрытия; определение содержания макро- и микроэлементов на масс-спектрометре с индуктивно связанной плазмой Aurora Elite фирмы Bruker (Германия) и на волнодисперсном рентгенфлуоресцентном спектрометре LabCenter XRF-1800; определение отношений стабильных изотопов на масс-спектрометре Finningan МАТ253; определение возраста раковин моллюсков на жидкостном низкофоновом сцинтилляционном счетчике. Объекты: четвертичные отложения берегового клифа мыса Финнисет (залив Грён-фьорд, арх. Западный Шпицберген), раковины двустворчатых моллюсков и их фрагменты Результаты. Определены обнаруженные комплексы макрофауны, представленные двустворчатыми моллюсками (Hiatella arctica, Mytilus edulis, Tridonta borealis, Mya truncata). Впервые для мыса Финнисет установлен возраст ископаемых раковин морских моллюсков, который составляет от 7970 до 8050 кал. лет. Установлено, что моллюски, найденные в нижних слоях, обитали в более теплой среде чем те, что обнаружены в вышележащих. Реконструированы редокс-условия с помощью соотношения Ni/Co в пределах от 1,5 до 9 единиц и V/Cr менее 2 единиц. Определено содержание U, которое изменяется в диапазоне от 0,2 мг до 4 мг. Анализ отношения Сu/Cr в разрезе показал, что расстояние от области сноса до области осадконакопления изменялось незначительно. Содержания Zn в горной породе свидетельствует о временной регрессии моря и преобладании континентального режима осадконакопления над морским. Определение концентраций Mn в раковинах моллюсков показало, что они обитали в прибрежно-морской зоне с высоким содержанием кислорода.The relevance of the research consists in determining the age of mollusks in the Green fjord bay of West Spitsbergen Island and physical and chemical parameters of their habitant environment in conditions of the threat of destruction of geological outcrops as a result of actively developing processes of coastal thermo-abrasion and man-made load of «Arcticugol» combine. The main aim of the research is to reconstruct physical and chemical parameters of mollusks habitant environment in Holocene based on determination of mollusks species and research of isotope-geochemical composition of shells and their host rocks. Methods. Mollusk species were identified using morphological method and decomposition of shell samples - by acid dissection. Content of microelements and microelements was determined on Aurora Elite inductively coupled plasma mass spectrometer (Bruker, Germany) and on LabCenter XRF-1800 wavelength X-ray fluorescence spectrometer and stable isotope ratios - on Finningan MAT253 mass spectrometer. Age of mollusk shells was identified on liquid low-background scintillation counter. Objects of the research are quaternary sediments of the coastal cliff of Finniset cape (Green fjord bay, West Spitsbergen Island), shells of bivalve mollusks and their fragments. Results. The authors have identified the detected macrofauna complexes represented by bivalve mollusks (Hiatella arctica, Mytilus edulis, Tridonta borealis, Mya truncata) and the age of fossil shells of marine mollusks for Finniset cape, which are from 7970 to 8050 years old. It was established that the mollusks found in lower layers lived in a wormer climate than those found in the overlying layers. The authors reconstructed redox conditions using Ni/Co ratios ranging from 1,5 to 9 units and V/Cr less than 2 units. Content of the U was detected in range from 0,2 mg to 4 mg. An analysis of the Cu/Cr ratio in the outcrop shows that the distance from the area of denudation to the sedimentation area changed insignificantly. Zn concentration in sediments indicates the temporal regression of the sea and predominance of continental sedimentary regime over sea regime. Determination of Mn content in mollusk shells shown, that they lived in coastal-marine zone with high oxygen content