Inter-decadal changes in the water layer of Atlantic origin and freshwater content (FWC) in the upper 100 m layer were traced jointly to assess the influence of inflows from the Atlantic on FWC changes based on oceanographic observations in the Arctic Basin for the 1960s – 2010s. For this assessment, we used oceanographic data collected at the Arctic and Antarctic Research Institute (AARI) and the International Arctic Research Center (IARC). The AARI data for the decades of 1960s – 1990s were obtained mainly at the North Pole drifting ice camps, in high-latitude aerial surveys in the 1970s, as well as in ship-based expeditions in the 1990s. The IARC database contains oceanographic measurements acquired using modern CTD (Conductivity – Temperature – Depth) systems starting from the 2000s. For the reconstruction of decadal fields of the depths of the upper and lower 0 °С isotherms and FWC in the 0–100 m layer in the periods with a relatively small number of observations (1970s – 1990s), we used a climatic regression method based on the conservativeness of the large-scale structure of water masses in the Arctic Basin. Decadal fields with higher data coverage were built using the DIVAnd algorithm. Both methods showed almost identical results when compared.  The results demonstrated that the upper boundary of the Atlantic water (AW) layer, identified with the depth of zero isotherm, raised everywhere by several tens of meters in 1990s – 2010s, when compared to its position before the start of warming in the 1970s. The lower boundary of the AW layer, also determined by the depth of zero isotherm, became deeper. Such displacements of the layer boundaries indicate an increase in the volume of water in the Arctic Basin coming not only through the Fram Strait, but also through the Barents Sea. As a result, the balance of water masses was disturbed and its restoration had to occur due to the reduction of the volume of the upper most dynamic freshened layer. Accordingly, the content of fresh water in this layer should decrease. Our results confirmed that FWC in the 0–100 m layer has decreased to 2 m in the Eurasian part of the Arctic Basin to the west of 180° E in the 1990s. In contrast, the FWC to the east of 180° E and closer to the shores of Alaska and the Canadian archipelago has increased. These opposite tendencies have been intensified in the 2000s and the 2010s. A spatial correlation between distributions of the FWC and the positions of the upper AW boundary over different decades confirms a close relationship between both distributions. The influence of fresh water inflow is manifested as an increase in water storage in the Canadian Basin and the Beaufort Gyre in the 1990s – 2010s. The response of water temperature changes from the tropical Atlantic to the Arctic Basin was traced, suggesting not only the influence of SST at low latitudes on changes in FWC, but indicating the distant tropical impact on Arctic processes. 

The purpose of the paper is to analyze the spatial-temporal variability of the time of stable ice formation in the Russian Eastern Arctic seas (the Laptev Sea, the East-Siberian Sea, the Chukchi Sea) in autumn period during 1942–2018, as well as the climatic changes for the last 20 years. The specialized information archive containing the dates of stable ice formation in the elements of regular grid (5 degrees along the parallel and 1 degree along the meridian) based on the AARI observations and satellite imagery was developed. The archive covers 2.2 million km2 of the Arctic area.  During the period from 1942 to 2018 one can reveal 4 consecutive climatic periods: mean dates of ice formation (1942–1953), anomaly early dates of ice formation (1954–1988), mean dates of ice formation (1989–2002) and anomaly late dates of ice formation (2003–2018). Notice that the ice formation regime in the 21st century, by its abnormality, differs radically from that in the 20th one. For the total area of three seas, the mean date of ice formation in the 21st century became 21 days later than in the 20th one. The most significant changes (up to 45 days) take place in the Chukchi Sea. The transformation of the ice formation regime typical for the 1942–2002 to the regime of 2003–2018 happened rather quickly — approximately within 5 years. The anomaly late time of ice formation began in the Chukchi Sea in 2003, and then this anomaly propagated to the East-Siberian Sea (in 2005) and to the Laptev Sea (in 2009). The 16-year period of anomaly late ice formation consists of three 5–6-year periods depending on location of the maximum anomalies: 2003–2008 (the Chukchi Sea), 2009–2013 (the Laptev Sea), and 2014–2018 (the Chukchi Sea again). As a consequence, the period of autumn warming, which has begun in 2003, is going on till present, and the latest date of ice formation in the eastern Arctic seas for the entire 77-year period was registered just in 2018. 

In August-September 2018, on the route of the expedition “Arctic-2018” (R/V “Akademik Tryoshnikov”) in the Arctic Ocean we carried out the following cycle of measurements of aerosol characteristics: aerosol optical depth (AOD) of the atmosphere in the wavelength range of 0.34–2.14 μm, number concentrations of particles with diameters of 0.4–10 μm, and mass concentration of absorbing substance (black carbon) in the near-ground layer. The optical and microphysical characteristics of aerosol were measured using portable sun photometer SPM, photoelectric particle counter AZ-10, and aethalometer MDA. Analysis of the measurements showed that aerosol and black carbon concentrations are maximal in the atmosphere of the Barents Sea and especially in its southern part, subject to outflows of fine aerosol from the north of Europe. The average aerosol characteristics near Kola Peninsula had been 7.2 cm^–3 for aerosol concentration, 167 ng/m³ for black carbon concentration, and 0.16 for AOD (0.5 μm). To estimate the specific features of the spatial variations in aerosol over the Arctic seas of Russia, we generalized the measurements in nine (2007–2018) expeditions. All aerosol characteristics are found to decrease from west toward east in the average spatial distribution. The average concentrations of aerosol are 3.5 cm^–3, black carbon concentrations are 41.2 ng/m³, and AOD (0.5 μm) values are 0.080 over the Barents Sea; and they decrease to 1.96 cm–3, 24.3 ng/m³, and 0.039 respectively over the East Siberian Sea. The decreasing tendency in the northeastern direction is noted in more detailed latitude-longitude distributions of aerosol characteristics in the atmosphere over the Barents and Kara Seas.

The article presents the results of measurements of the principal ions content, electrical conductivity and pH for 13 lakes and small (temporary) water ponds in the east part of the Thala Hills, Enderby Land, East Antarctica. Water sampling was carried out by participants of the seasonal Belarusian Antarctic expeditions in the period from 2011 to 2018. The purpose of the study is the evaluation of the hydrochemical composition of lakes and temporary ponds of the Thala Hills (on an example of the Vecherny Oasis), identification of natural and anthropogenic factors which determine the variability of the hydrochemical parameters for assessment of vulnerability of lakes and temporary ponds to anthropogenic impacts and climate change. It is shown that the waters of the lakes of this region are low mineralized with the sum of ions within the range of 10.6–87.5 mg/l (the average is 34.5 mg/l), electrical conductivity — 19.3–130.0 μS/cm (61.3 μS/cm). The water is characterized as slightly acidic and neutral. The waters of small (temporary) ponds are characterized by greater variability of hydrochemical parameters in comparison with lakes: the sum of ions is in the range of 6.7–915.0 mg/l (the average is 158.0 mg/l), the electrical conductivity is 4.6–1663.0 μS/cm (the average is 267.0 μS/cm). Coefficients of variation for most compounds in the waters of temporary ponds exceed 100 %. In most cases the predominance of sodium and chloride ions was established, which indicates the influence of marine aerosols on chemical composition of water lakes and temporary ponds. Elevated concentrations of mineral elements in the water of temporary ponds are caused by the lack of flow and, and as a consequence of thies, the accumulation of salts as a result of evaporation. 

Measurements of surface ablation in 2016–2018 on the neighboring glaciers Aldegondabreen, Austre and Vestre Grønfjordbreen (West Spitsbergen) revealed significant differences in its magnitude both within the same altitude zones for one year, and on an interannual scale. Comparison of the region’s common variations in climatic conditions (air temperature, rainfall) and ablation data showed a significant contribution of the following additional factors of melting: aspect, size, altitude range, surface slope, the rocky bordering of glaciers. The maximum ablation were measured on the Aldegondabreen (with the smallest area and altitude range), which has a northeastern aspect; the average value over three years of observations was 1947 mm w.e. Austre Grønfjordbreen and Vestre Grønfjordbreen had in 2016–2018 average ablation values 1512 and 1385 mm w.e., respectively. The largest Vestre Grønfjordbreen has the lowest values of average ablation also because it lies higher then neighboring glaciers. Interannual variations of mean ablation in the same altitudinal zones show: the minimum scatter of values for the Aldegondabreen (130–370 mm w.e.); higher scatter of values for the Austre Grønfjordbreen (200–450 mm w.e.); the maximum scatter of values for the Vestre Grønfjordbreen (from 400–600 mm w.e. in most altitude zones to 1000 mm w.e. at altitudes of 250–350 m). Due to the influence of additional factors, the maximum average ablation was observed on the Aldegondabreen in 2016, on the Vestre Grønfjordbreen in 2017, and on the Austre Grønfjordbreen in 2017 and 2018. The results of the study indicate the need to take into account the contribution of these factors to the ablation parameters of the region’s glaciers in model calculations, as well as the relevance of a detailed study of the distribution of solar radiation on glaciers.

Peterman Island is located in the archipelago of the Wilhelm Islands on the west coast of the Antarctic Peninsula (Graham Land). It is composed of gabbroids and granitoids of the Andean complex, which formed almost 100 million years later than the volcanic group of the Antarctic Peninsula. To clarify their genesis and geodynamic conditions of formation, gabbroids of the Andean complex are of particular interest, since the petrological models of their formation are well developed. Gabbroid intrusions comprise small bodies that are widespread along the Antarctic Peninsula. Among them stand out olivine gabbros, normal gabbros, norites and hornblende gabbros. Also are found small bodies of melanogabbro-pegmatites and intramagmatic dykes, that are associated with the manifestations of ore mineralization of magnetite, ilmenite and sulfides. For this reason, they are of interest for both the minerals search and for solving the question of their genesis. To this end, we performed geochemical studies of Peterman Island gabbroids. Gabbroids of Peterman Island are represented by amphibolized medium-grained gabbro with hypidiomorphic texture. Among them, xenoliths of thinly stratified gabbroids 3 × 8 m in size were found, which are characteristic of stratified intrusions, for example, Stillwater, Bushveld, etc. Gabbroids of Peterman Island have low content of silica and potassium and according to the petrochemical characteristics correspond to peridotite gabbro. They have low contents of Cr, Ni, V and high strength lithophilic Y and Nb elements. Gabbroids have been crystallized from basic magma, differentiated in the intermediate crustal magma chambers. Positive anomalies of Sr, Eu, and Ti in the multielement diagrams and positive anomalies of europium Eu/Eu* suggest the accumulation of plagioclase and apparently, ilmenite in the magmatic chamber. The primary magma source for gabbroids was probably the primitive mantle (PM). Gabbroids are contaminated with crustal matter. This contamination is probably due to their regressive metamorphism, caused by the introduction of later intrusions of Andean complex granitoid. Finely layered xenolithic gabbroids do not differ from other homogeneous gabbros of Peterman Island in terms of chemical composition.This xenolith most likely represents a part (fragment) of the wall of the magma chamber in which the differentiation of the initial main magma took place. According to the obtained geochemical data, a wide range of compositions of the Andean complex gabbroids formed as a result of crystallization differentiation of magma melted from rocks of the composition of the primitive mantle (PM) in crustal magma chambers, which also resulted in the accumulation of ore elements — V, Co, and Cu in the residual magmatic melts.

In order to assess the current state of the ecosystem of the southeast of the Onega Bay of the White Sea affected by fuel oil spill in 2003, the accumulation of petroleum hydrocarbons was analyzed by the dominant species of aquatic organisms collected on the littoral of the most polluted coast in the areas of Purnem and Lyamts villages. In 2012, samples of aquatic organisms were taken in an area where all the species discussed in this work are represented on a small area: bivalved mollusks, attached molluscs, gastropods, polychaetes. In 2013 and 2018, samples of hydrobionts were additionally selected, in the three-kilometer strip of the coast on either sides of the givin point. In 2012 and 2013, high concentrations of HC in the tissues of bivalves were recorded. In 2018, the concentrations of hydrocarbons in the tissues of the studied hydrobionts were comparable to background values. A non-parametric test of Mann-Whitney showed a significant decrease in НС in mussel tissue from 2013 to 2018, at a significance level of 0.05. Taking into account the low levels of HC in the aqueous medium (less than 1 MPC of fishfarm) and in bottom sediments (from 0.34 to 9.03 mg/kg, the median of 1.41 mg/kg) in 2018, and is comparable with the background contents of hydrocarbons in tissues of aquatic organisms. We can conclude that after 15 years of the fuel oil spill, the condition of the Cape Deep ecosystem in terms of the content of hydrocarbons returns to the baseline state, continuing emissions of oil-sand lumps do not adversely affect the ecosystem. Based on the work done, it can also be concluded that ecotoxocological methods are priority in assessing the prolonged (or delayed) accidental impact of heavy petroleum products on aquatic ecosystems. The conclusion about the presence or absence of a negative impact on the aquatic ecosystem of hydrocarbons, based solely on the analysis of abiotic components, may not be sufficiently informative because it does not take into account the accumulative and deferred effects, especially manifested in the cold Arctic waters.