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A comparative description of sedimentary matter in the snow–ice cover of the Circumpolar Arctic and fast ice of the Antarctic is given. The main distribution patterns of dispersed sedimentary matter in the marine cryosystem of snow–sea ice–ice water of the Arctic and Antarctica are obtained. Sedimentary matter fluxes from the bottom of sea ice to the ocean bottom are calculated.

We studied sedimentation processes in the Lofoten Basin of the Norwegian Sea based on data of the Automatic Deep-Sea Sedimentation Observatory (ADSO) deployed for a year (August 2017–July 2018). The article presents estimates of the vertical fluxes of total sedimentary material, organic carbon (Corg), calcium carbonate (CaCO3), biogenic silica (SiO2bio), aluminum, and the particles of planktonic origin (pteropods, foraminifera, fecal pellets, necrozooplankton). The seasonal pattern of total vertical flux is characterized by a unimodal distribution with a maximum in September 2017 (191 mg dry weight m–2 day–1) in the 0–500 m surface water layer. The total flux decreases markedly from November and reaches the minimum (2.6 mg m–2 day–1) in March–April 2018. The maximum Corg flux values (5.2 mg C m–2 day–1), CaCO3 (178 mg CaCO3 m–2 day–1), and SiO2bio (9.1 mg SiO2bio m–2 day–1) are observed in autumn. The value of fluxes and the portion of lithogenic material in it are higher at a depth of 2950 m due to redeposition from the nepheloid layer. The amplitude of flux variations during the year is noticeably smaller at this depth. The highest fluxes are related to the maass sedimentation of juvenile pteropods Limacina retroversa. The contribution of pteropods to vertical fluxes in autumn is 60–100% for CaCO3 and 56–73% for Corg. The contribution of foraminifera to the total CaCO3 flux does not exceed 6% and only reaches 60% at a depth of 550 m in October. The flux of fecal pellets, where ostracod pellets dominate, varies from

—The distribution of Sc, Co, Hf, Cr, Th, and rare-earth elements in samples of surface sediments collected during cruises 67th and 68th of the R/V Akademik Mstislav Keldysh in the Barents Sea and in its bays is analyzed. The results obtained suggest that the predominant part of the bottom sediments of the Barents Sea is composed of thin-grained siliciclastics that was supplied with suspended particulate matter of the North Cape (Atlantic) Current through the erosion of the northwestern Scandinavian coasts and some seafloor areas. Some sediments in the northern part of the sea were formed through the erosion of rocks of the Novaya Zemlya and Franz Josef Land. A certain role in their formation was probably played by material from Svalbard as well as by the Pechora River suspended particulate matter. The established isotopic characteristics (eNd, 207Pb/206Pb and 87Sr/86Sr) of surface sediments suggest that the main contribution to the formation of bottom sediments of the central Barents Sea was made by rocks of the mainland part affected by the North Cape Current. The comparison of the 87Sr/86Sr values ​​in the surface sediments of the central part of the Barents Sea and in the ice-rafted sediments carried by the Transpolar Drift showed their significant difference. This suggests a reatively small contribution of ice-rafted material to the formation of surface sediments of the Barents Sea.

A new approach has been applied to studying marine sedimentation using dispersed sedimentary material in sediment traps compared to the surface layer of bottom sediments. Based on long-term studies of a small sea of the Arctic Ocean, it was possible to establish new sedimentary patterns in the conditions of the Subarctic and Arctic zones. The monthly, seasonal, and long-term dynamics of the main components of fluxes of dispersed sedimentary material have been studied. The marine stage of sedimentation of the main components of dispersed sedimentary material over time is discussed; it is shown that the biogenic component of the flux decreases by an order of magnitude when passing from dispersed to concentrated forms. The average values of the vertical fluxes are calculated: the total and those of the contributions of the main biogenic and terrigenous components per 1 m2 of the bottom and over the entire deep sea area of the White Sea.

The multidisciplinary expedition “European Arctic-2020” on board the R/V Akademik Mstislav Keldysh took place from July 31 to August 26, 2020. The investigations were carried out in the Norwegian Sea on the Mohns Mid-Oceanic Ridge (including the hydrothermal activity zone near Jan Mayen), near gas seeps in the Storfjord Trough, on the polar front in the Barents Sea, and on the continental slope of the Arctic Ocean at the drift ice boundaries at 83°18′ N.

We discuss the preliminary results of the plume and bottom sediments studies of the Trollveggen hydrothermal vent field based on data from the 68th cruise of the RV Akademik Mstislav Keldysh. The hydrothermal vent field is located to the east of the axial zone of the slow-spreading Mohn Ridge close to the Jan Mayen hotspot at a depth of about 550 m (7118 'N, Norwegian-Greenland Basin). The plume of the hydrothermal vent field was characterized by a weak distribution in the water column, anomalies of temperature, density and salinity, a moderate concentration of methane and a low concentration of suspended particulate matter near the bottom. The enrichment of bottom sediments with barium, strontium and some sulfide forming elements (zinc, lead, copper, molybdenum) was shown. Two mineral associations of hydrothermally modified bottom sediments were revealed: pyrite and barite-marcasite. The temperature of hydrothermal fluids was established by the method of thermal and cryometric studies of gas-liquid fluid inclusions in barite (128260C) and using the FeSZnS equilibrium diagram of sulfide minerals (130290C). Our data were close to the data of direct measurements of fluid temperature [28]. We made a comparison of the hydrothermal mineralization of the Trollveggen vent field and the previously studied fields of the Mid-Atlantic Ridge located near the Azores hotspot. As a result we confirmed the influence of ocean depth and PT-conditions on the formation of hydrothermal deposits.

The paper presents the results of a study of the concentrations of black carbon in the marine boundary layer over the Baltic and North Seas, the North Atlantic, the Norwegian, the Barents, the Kara and the Laptev seas from June 30 to September 29, 2017 in the 68th and 69th voyages of research vessel "Akademik Mstislav Keldysh". Black carbon has a significant impact on climate change and the degree of pollution of the Arctic. Black carbon is formed as a result of incomplete combustion of fossil fuels (primarily coal, oil) and biomass or biofuel. It consists of submicron particles and their aggregates and can be transported a great distance from the source. Samples were taken by pumping air for 46 hours through quartz filters Hahnemule at an altitude of 10 m above sea level in a headwind to prevent smoke of the vessel from entering the filters. Subsequently, the black carbon content was determined in the laboratory by the aetalometric method. The backward trajectories of the air mass transfer and the black carbon particles transported by them to the sampling points were calculated using the HYSPLIT (Hybrid Single-Particle Lagrangian Integrated Trajectory) model at http://www.arl.noaa.gov/ready.html. The conducted studies show low values of black carbon concentrations (50 ng/m3) along the expedition route when air masses came from the background areas of the North Atlantic and the Arctic. High concentrations of black carbon (100200 ng/m3 and higher) are characteristic for areas with active navigation (the South-Eastern Baltic, the North Sea) and near ports (eg Reykjavik), as well as for incoming air masses from the industrialized regions of Europe to South-Eastern Baltic and from areas of oil and gas fields where associated gas is flared (the North, the Norwegian and the Kara seas).

The article discusses the preliminary results of plume and bottom sediment studies of the Trollveggen hydrothermal vent field based on data from cruise 68 of the R/V Akademik Mstislav Keldysh. The hydrothermal vent field is located east of the axial zone of the slow-spreading Mohn Ridge near the Jan Mayen hotspot at a depth of about 550 m (71°18′ N, Norwegian–Greenland Basin). The hydrothermal vent field plume was characterized by a weak distribution in the water column; temperature, density, and salinity anomalies; a moderate methane concentration; and a low concentration of suspended particulate matter near the bottom. The enrichment of bottom sediments in barium, strontium, and some sulfide-forming elements (zinc, lead, copper, and molybdenum) was shown. Two mineral assemblages of hydrothermally modified bottom sediments were revealed: pyrite and barite–marcasite. The temperature of hydrothermal fluids was established by thermal and cryometric studies of gas–liquid fluid inclusions in barite (128–260°С); the FeS–ZnS equilibrium diagram of sulfide minerals was also used (130–290°С). Our data were close to direct fluid temperature measurement data [28]. We compared the hydrothermal mineralization of the Trollveggen vent field and earlier studied fields of the Mid-Atlantic Ridge located near the Azores hotspot. As a result, we confirmed the influence of ocean depth and PT conditions on the formation of hydrothermal deposits.

The article presents the results of a study of black carbon concentrations in the atmospheric boundary layer over the Baltic and North seas, the North Atlantic, and Norwegian, Barents, Kara, and Laptev seas from June 30 to September 29, 2017, on cruises 68 and 69 of the R/V Akademik Mstislav Keldysh. Black carbon has a significant impact on climate change and pollution in the Arctic. It forms as a result of incomplete combustion of fossil fuels (primarily coal and oil) and biomass or biofuels. It consists of submicron particles and their aggregates and can be transported long distances from their source. Samples were taken by pumping air for 4–6 h through Hahnemule quartz filters at a height of 10 m above sea level in a headwind to prevent exhaust from the smokestack from entering the filters. The black carbon content was subsequently determined in a laboratory with an aethalometer. The backward trajectories of air mass transfer and the transported black carbon particles to the sampling points were calculated by the HYSPLIT (Hybrid Single-Particle Lagrangian Integrated Trajectory) model on the NOAA website at http://www.arl.noaa.gov/ready.html. Studies show low black carbon concentrations (

Marine sediments and samples of suspended particulate matter from the North Atlantic were studied. It is shown that modern sedimentation in this area is controlled mainly by the efficiency of autochthonous marine phytoplankton and sediment supply by the system of near-bottom currents, as well as by means of the ice-rafting. The studied sediment sections were formed in the North Atlantic during the Middle Pleistocene to Holocene. The highest sedimentation rate, up to 58.3 cm/kyr, is established for AI-3359 core, collected in the area of the Gardar and Bjorn Drifts. This makes the core very interesting for detailed paleoreconstructions. AI-3378 and AI-3415 cores are characterized by low sedimentation rates. Nevertheless, they are of interest for spatial paleoreconstructions on a continuous timeline. The general pattern is established for the first time for the sediments from the central North Atlantic: biogeochemically significant processes are detected only in the thin surface layer (0–2 cm) and almost completely cease at depths of 90–180 cm. The processes are probably controlled by the position of the sampling stations and the composition of organic matter (OM) but not related to the age of the sedimentary layer. The low microbial activity in the sediments is most likely the result of a lack of OM.

Direct determinations of the dispersed sedimentary matter in the snow-ice cover near the North Pole are carried out. The composition of sedimentary material in the snow-ice cover was studied at the maximum for the high latitudes of the Northern Hemisphere distance from the continents, the vertical fluxes of matter from the under-ice layer were determined. These data were obtained using sediment traps. For snow and ice investigations melt waters of large volume were studied. It was found that dispersed sedimentary matter of aeolian genesis is of primary importance in snow and sea ice.

New data on the particle fluxes of sedimentary matter and its main components at the meridional section along 59°30' N in the North Atlantic under the influence of multidirectional transfer of water masses are given. The material for the study was collected for two years from July 2015 to July 2017 using sediment traps installed as part of four automatic deep-water sedimentary observatories. In the subsurface layer, the annual variation of the fluxes and the change in the composition of the sinking matter are determined by the primary production. Near-bottom fluxes of sedimentary matter on the slopes of the Reykjanes ridge are formed under conditions of water masses and, respectively, suspended particulate matter transfer in a south-westerly direction along the ridge from the Iceland-Faeroe and Greenland-Iceland rises. There is a reverse directional transfer of matter at the foot of the European continental slope. The composition of the sinking matter is dominated by the biogenic component, the proportion of which decreases with depth due to dissolution, and in winter due to the weakening of the biological activity of the upper active layer. The role of lithogenic matter is maximal in the bottom layer, including due to the supply of material from the bottom.

New data are presented on sedimentary matter fluxes and its main components along a meridional transect (59°30′ N) in the North Atlantic under the effect of multidirectional transport of water masses. The material for the study was collected July 2015 to July 2017 using sediment traps installed as parts of four automatic deep-water sedimentary observatories. In the subsurface layer, the annual variation in fluxes and composition of sinking material are determined by primary production. Bottom sedimentary material fluxes on the slopes of the Reykjanes Ridge are formed under conditions of transport of water masses and, accordingly, suspended particulate matter to the southwest along the ridge from the Iceland–Faroe and Greenland–Iceland rises. There is back transfer of material at the foot of the European continental slope. Sinking material is dominated by the biogenic component, the proportion of which decreases with depth due to dissolution and to less biological activity in the upper layer in winter. The role of lithogenic material is maximum in the bottom layer, where material is additionally supplied from the bottom.

The first data on a long-term study of the Volga River marginal filter are reported. The concentrations of suspended particulate matter, particulate chemical elements, and trace elements are considered. The ratios of suspended particulate matter enrichment in chemical elements in relation to the upper lithosphere are calculated, as well as their interrelations at different stages of the marginal filter. It is shown that sedimentary material delivered to the sea with river runoff changes radically, both quantitatively and qualitatively.

The species composition and biomass of phytoplankton, as well as hydrological characteristics, were estimated during four spatial surveys in the Subarctic tidal Kem’ River estuary and adjacent area of Onega Bay (White Sea, Russia) in June–July 2008–2011. The study area was divided into the zones (river, transition, and marine), based on salinity variation of the surface water layer. In total, 318 species of phytoplankton were recorded, 143 species were found in the river zone, 225 in the transition zone, and 106 in the marine zone. Diatoms were represented by the greatest number of species in all zones. The highest phytoplankton biodiversity in the surface layer was found in the transition zone. The averages of total phytoplankton biomass in the surface layer (B0) in different years varied as 2.8–16.9 mgC/m3. Although B0 did not differ significantly between zones (except 2011, when B0 was the highest in the river zone), the dissimilarity in the phytoplankton community structure in the river, transition and marine zones was 61–95%. The similarity of phytoplankton at stations of each zone was poor (22–53%); the lowest values were observed in the transition zone. It is postulated that the tidal cycle determines the spatial and temporal heterogeneity of the phytoplankton composition, structure, and abundance in the Kem’ River estuary in summer.

—Dispersed sedimentary material in the snow and ice cover is directly determined near the North Pole. The composition of sedimentary material in the snow and ice cover was studied at the maximum distance from continents in the high latitudes of the Northern Hemisphere, and the vertical fluxes of material from the underice layer were determined. These data were obtained using sediment traps; for snow and ice, using large volumes of melt water. It was found that dispersed aeolian sedimentary material is of primary importance in snow and sea ice.

The first results of the multidisciplinary expedition aboard the RV «Akademik Mstislav Keldysh» to the North Atlantic in July 2017 are given. Continuation of deep convection in the Irminger Sea to a depth of 1500 m, which began in 2015, is discovered. New information is provided on the structure of the main jets of the North Atlantic Current in the Iceland basin and in the Irminger Sea (Irminger Current), as well as the East Greenland Current. New samples of atmospheric aerosols, suspended particulate matter and bottom sediments are collected. New data on the particle fluxes have been obtained using sediment traps.

The Co, Hf, Ce, Cr, Th, and REE characteristics are analyzed for modern sediments collected by a bottom grab during the 67th and 68th cruises of R/V Akademik Mstislav Keldysh and samples taken in the Barents Sea bays and inlets. Our results indicate that most modern bottom sediments are composed of fine siliciclastic material enhanced with a suspended matter of the North Cape current, which erodes the western coast of Scandinavia, and due to bottom erosion of some marine areas, as well as erosion of rock complexes of the Kola Peninsula, Novaya Zemlya, and Franz Josef Land (local provenances). Material from Spitsbergen also probably played a certain role. In the southern part of the Barents Sea, clastic material is carried out by Pechora River.

The isotopic characteristics (eNd, 207Pb/206Pb, and 87Sr/86Sr) of the modern bottom sediments sampled in the Barents Sea during the 67th voyage of the R/V Akademik Mstislav Keldysh are considered. It is shown that the major contribution to the formation of the sediments in the central Barents Sea is made by rocks of the North European continental margin, which are found in the zone of influence of the North Cape Current. The values of eNd, 87Sr/86Sr are lower in the bottom sediments of this part of the sea than the corresponding characteristics of sedimentary material incorporated into ices and carried by the Transpolar Drift Stream. This allows one to conclude that such material has not contributed much to the sedimentation in the Barents Sea.

For the first time, vertical and lateral distribution patterns of mercury in White Sea bottom sediments have been determined. An abrupt change in the nature of mercury concentrations has been revealed, with a general tendency to decrease with depth. Natural variations in mercury concentrations within 0.01–0.03 µg/g dry weight (dw) have been established. An upper value of 0.03 µg/g dw is taken for the natural background content of the element. The distribution of mercury concentrations in the sequence of bottom sediments is influenced by both anthropogenic and natural factors and processes. With distance from the marine–estuary boundary of the Northern Dvina River, the river’s role in supplying mercury to the White Sea is reduced, and global and regional atmospheric mass transfer take over. The mercury content is used as an indicator of landslide processes in Kandalaksha Gulf of the White Sea. The accumulation chronology of mercury in White Sea sediments is studied, and the proportion of anthropogenic mercury is calculated.

Snowpack exhibits properties that make it a unique natural archive of airborne pollution. The data on insoluble particles in the Ob River catchment (Western Siberia) snowpack are limited. Insoluble particles in the snowpack of Western Siberia were studied at 36 sites on a 2800 km submeridional profile from the city of Barnaul to Salekhard in February 2020. Snow samples were collected over the full depth of the snow core, from the surface of the snow cover to the boundary with soil, except for the lower 1&ndash, 2 cm. After the filtration of melted snow through a 0.45-&micro, m membrane, the particle composition was studied using a scanning electron microscope with an energy microprobe. In the background areas, the concentration of insoluble particles in the snow was below 2 mg/L. Significantly higher particle concentrations were encountered near cities and hydrocarbon production areas. Particulate matter in snow mainly consists of biogenic and lithogenic particles mixed with anthropogenic particles (ash and black carbon aggregates). The proportion of anthropogenic particles increases near cities and areas of active hydrocarbon production.

The dispersed sedimentary material in the snow–ice cover near the North Pole was analyzed directly for the first time. The composition of sediments in the snow–ice cover and vertical fluxes of the material from the ice water layer were studied at the maximal distance for the Northern Hemisphere from the continents. The data were obtained by sedimentation traps (for water) and in large volumes of melt water (for snow and ice). It has been revealed that the dispersed sedimentary material of aeolian genesis plays the leading role in snow and sea ice.

The distribution of suspended particulate matter (SPM) and chlorophyll a in the Caspian Sea water column from April to November in 2008–2016 is analyzed. It is shown that the spatiotemporal variability of SPM concentration is defined by its sources, especially by the autochthonous (primary production) and allochthonous (particulate river runoff, aerosols) components. The effect of marginal filters of rivers on the volume of coming allochthonous SPM is considered. It is revealed that chlorophyll a is a reliable marker of the autochthonous component of SPM and biogenic sedimentation conditions. The stable vertical stratification defines the distribution of allochthonous and autochthonous SPM in the water column. Vertical profiles of these SPM components in the active layer (its thickness is usually up to ~60 m, more rarely to ~100 m) of the sea are similar in April and October-November and differ much in May-September.

The contribution of different geochemical processes in the accumulation of metals in dispersed sedimentary matter collected by ADOO was estimated for the first time for the White Sea system. The contents of Al, Fe, Cr, Ni, Со, and Мо (from 60 to 90% of the total content) are mainly controlled by terrigenous processes. The group of geochemically mobile elements includes Mn, Cu, Pb, and Cd; the sum of their forms 1–3, which include the contribution of absorption−desorption and formation of authigenic hydroxides and organic compounds, accounts for, on average, from 52 to 83 Mn %. With increasing water depth, the fraction of the lithogenic form remains either constant or increases insignificantly. In contrast, Mn shows a sharp increase in geochemically mobile forms, heavy metals (Pb, Cu, Mo, Co, and Cd) of which are associated with.

Based on long-term studies of a small sea in the Arctic Ocean, new regularities in the sedimentary process under the conditions of Arctic sedimentogenesis were established. The quantitative transition of particulate sedimentary materials into the concentrated forms (bottom sediments) in the White Sea follows the linear dependence with a local maximum in the deep nepheloid layer. Marginal filters (Severnaya Dvina River, etc.), which are areas of ultrarapid sedimentation, were distinguished. The long-term data on the concentration of suspension and fluxes of particulate sedimentary material clearly indicate stable annual nepheloid layers, i.e., the distribution of particulate forms of sedimentary material (suspension) in the water column proceeds by new regularities, which may be distinguished ever more clearly.

The first data on the concentrations, fluxes, and mineral and chemical compositions of aerosols from the near-water surface layer of the Caspian Sea are presented. It is shown that the aerosol fluxes onto the sea surface are comparable to the fluxes of a lithogenic substance in a water column. The mineral and chemical compositions of aerosols depend on the carrying air masses that pass through different regions. The coefficients of enrichment of aerosols with chemical elements relative to the upper lithosphere and their correlation relationships are studied.

We discuss the measurements of black carbon concentrations in the composition of atmospheric aerosol over the seas of the North Atlantic and European sector of the Arctic Ocean (21 expeditions in 2007–2020). The black carbon concentrations were measured by an aethalometer and filter method. The comparison of the two variants of the measurements of the black carbon concentrations showed that the data acceptably agreed and can be used jointly. It is noted that the spatial distribution of black carbon over the ocean is formed under the influence of outflows of air masses from the direction of continents, where the main sources of emission of absorbing aerosol are concentrated. We analyzed the statistical characteristics of black carbon concentrations in five marine regions, differing by the outflows of continental aerosol. The largest black carbon content is a salient feature of the atmosphere of the North and Baltic Seas, surrounded by land: average values of concentrations are 210 ng/m3, and modal values are 75 ng/m3. In other regions (except in the south of the Barents Sea), the average black carbon concentrations are 37–44 ng/m3 (modal concentrations are 18–26 ng/m3). We discuss the specific features of the spatial (latitude-longitude) distributions of black carbon concentrations, relying on ship-based measurements and model calculations (MERRA-2 reanalysis data). A common regularity of the experimental and model spatial distributions of black carbon is that the concentrations decrease in the northern direction and with the growing distance from the continent: from several hundred ng/m3 in the southern part of the North Sea to values below 50 ng/m3 in polar regions of the ocean.

The role of zooplankton in the vertical mass flux in the Kara and Laptev seas was studied during cruise 63 of the R/V Akademik Mstislav Keldysh in August–October 2015. Mass fluxes were estimated using sediment trap samples. The maximum values of the total vertical flux (19600 mg m−2 day−1) and particulate organic carbon (POC) flux (464 mg C m−2 day−1) were measured close to the Lena River Delta in the Laptev Sea. In the Kara Sea, the total flux (80–2700 mg m−2 day−1) and the POC flux (17–130 mg C m−2 day−1) were substantially higher than the estimates published earlier. The fecal pellet flux varied from 2 to 92 mg C m−2 day−1 and made up 4–190% of the total organic carbon flux. The mineral composition of fecal pellets largely mirrored that of suspended particulate matter. Clay minerals in the fecal pellets were more abundant than in particulate matter in the areas with noticeable freshwater impact. The flux of zooplankton carcasses varied from 0.1 to 66.4 mg C m−2 day−1 and made up 0.2–72% of total POC flux. The results are discussed in relation to the abundance and composition of zooplankton, the concentration and composition of suspended particulate matter, hydrophysical conditions, and methods of sample preparation for analysis.

The results of long-term investigations in a small sea of the Arctic Ocean served as a basis for revealing new regularities characteristic of the sedimentary process in the Subarctic and Arctic zones. The monthly, seasonal, and multiyear dynamics of the main components of dispersed sedimentary matter fluxes are analyzed by defining the marine sedimentation stage. It is shown that the biogenic constituent of the flux decreases by an order of magnitude at its transition from dispersed to concentrated forms. The average values of the vertical flux are calculated including the total sedimentary matter and the contribution of main biogenic and terrigenous components per m2 of the bottom and the entire deep area of the White Sea.

The work reports the results of the measurements of particulate matter (PM), organic (OC) and elemental (EC) carbon mass concentrations, and carbon isotope composition (δ13С) in atmospheric aerosol sampled along the route of the research vessel “Academician Mstislav Keldysh” (71 voyage). The measurements were carried out over the Baltic Sea – the North Sea – the North Atlantic – the Norwegian Sea – the Barents Sea from June to August 2018. The increased OC, EC concentrations and the high δ13С value in the samples collected off the coast of Greenland are shown to be not due to marine origin, but due to the transfer of atmospheric aerosol formed in Canada during biomass burning (forest fires).

The relation of nonferrous metals and other elements to the main mineral phases in iron–manganese ore is a matter of interest in theoretical and practical terms and has long been discussed by experts. However, opinions on this issue diverge due to the vast variety of conditions of ore formation. This is particularly applicable to ferromanganese nodules of the Kara Sea. The results published here demonstrate that the ferromanganese nodules of the Arctic seas accumulate the same range of elements as pelagic ocean nodules, but in different concentrations and proportions: the contents of most ore elements is decreased by a significant influx of clastic material.

Trawling of the bottom in the northeastern Kara Sea during cruise 125 of the R/V Professor Shtokman in 2013 recovered a block of cavernous, partly phosphatized carbonate rock consisting of biogenic carbonate material and partly crystallized diagenetic calcite. The fauna remains are mainly Oligocene–Pliocene planktonic and benthic foraminifers, with less common Oligocene–Miocene coccoliths and single wormlike organisms. Part of the phosphatized material in caverns is impregnated by manganese and iron oxides and enriched in heavy and trace metals. According to the oxygen isotopic composition, this rock formed under moderate temperature conditions. In terms of morphology, mineralogy, and the abundance of organic remains, the block is comparable to methanogenic carbonates found in other parts of the ocean, but shows no isotopically light carbon signatures typical of methane activity. This indicates the diversity of the carbon isotope composition of the Arctic carbonates.

The features of the distribution of some rare and trace elements in modern bottom sediments of the Caspian Sea have been studied from samples collected during cruises 35, 39, and 41 of the R/V Rift and the cruise of the R/V Nikifor Shurekov in 2013. It was established that bottom sediments in different areas of the Caspian Sea vary to some degree in the contents of Zr, Hf, Th, V, Cr, Co, Ni, Cu, Sr, and Ba in comparison to suspended matter discharged by the Volga River and rivers originating in the Caucasus. As follows from the results of a comparison of the geochemical features of modern bottom sediments of the Volga River delta and different sedimentary subsystems of the Caspian Sea with the chemical composition of Middle Archean granitoids and Paleozoic and Mesozoic–Cenozoic basalts, which are regarded as geochemical images of such provenance areas as the basement of East European Platform, Urals, and Caucasus, none of these regions is considered the dominant provenance area for all sedimentary subsystems of the Caspian Sea region. Here, the revealed similarity between modern bottom sediments of the northern, central and southern Caspian Sea regions, the Volga River delta, and Post-Archean average Australian shale (PAAS) in some parameters, including REE spectra, assumes that the Volga River discharge plays a dominant role in the formation of the geochemical image of Caspian Sea subsystems. The role of clastics, including the fine-grained fraction, which is supplied to the Caspian Sea from the Caucasus region and Elburz Mountains, is insignificant already in the coastal area, which is determined both by influence of the marginal filter (MF) and large-scale cholestatic current circulation.

The material for our study was collected in the White Sea during 22 interdisciplinary expeditions organized by the Shirshov Institute of Oceanology, Russian Academy of Sciences (IO RAS), in 2000–2014. The researches were carried out mostly in June–August; however we have some samples for autumn–winter and early spring seasons. Here, we report the concentration of suspended particulate matter (SPM), its composition and properties, as well as their changes due to natural zoning and local conditions. This paper discusses the features in the distribution of SPM concentration, grain-size, mineral, and major phase composition. As far as possible, we involved our own and other published data on hydrology, bottom morphology, and particulate and dissolved river runoff from the catchment area, abundance and composition of marine phyto- and bacterioplankton. This new knowledge has been used to describe particles dispersion system of the White Sea, which forms a giant reservoir of micro- and nanoparticles, using terms adopted in sedimentology and oceanography.

In this chapter we summarize results of aerosol studies over the White Sea and its coasts; we also analyze contribution of different anthropogenic constituents from European industrial cities and areas into studied aerosol composition. We estimated the degree of anthropogenic influence of these sources on the atmosphere and the terrestrial environment in this region. Data on airborne heavy metal accumulation in natural archives (snow cover, lichens, lake sediments) are generalized. The most significant source regions for some anthropogenic components depositing on the White Sea surface from atmosphere are revealed. Annual average (for 2000s) fluxes of anthropogenic Cu, Ni, Pb, Fe, Al, and black carbon incoming to the White Sea waters from various regions are evaluated. Studied element concentrations in the White Sea aerosols are generally on the level typical for other Arctic regions. In the Kandalaksha Bay, we traced the air mass arrival from metallurgical facilities of Murmansk Region. Elevated concentrations of heavy metals and black carbon were found in vicinity of industrial urban agglomeration of Arkhangelsk. For the first time, we assess contribution of Kostomuksha field (Karelia Republic) surface mining into Fe and Al fluxes (these elements are of both lithogenic and anthropogenic origin) on the White Sea surface which are comparable to contribution of the other source regions.

A new approach using dispersed sedimentary matter of the water column captured by sediment traps in comparison with its consolidated form (surface layer of the bottom sediments) was applied to study sedimentation in the White Sea. The results of long-term investigations in a small sea of the Arctic Ocean served as a basis for revealing new regularities characteristic of the sedimentary process in the Subarctic and Arctic zones. The monthly, seasonal, and multiyear dynamics of the main components of dispersed sedimentary matter fluxes were analyzed by defining the marine sedimentation stage. It was shown that the biogenic constituents of the particle flux while its transition from the dispersed form to consolidated one decreased by an order of magnitude. The average values of the vertical flux were calculated including the total sedimentary flux and the contribution of main biogenic and lithogenic constituents per m2 of the bottom area of the White Sea.

The White Sea is an inner subarctic marine basin where sedimentation is known to be influenced by mostly terrigenous processes. In the catchment area of the White Sea, a lot of the mining, manufacture, and pulp and paper industry plants are located whose solid and liquid wastes contain heavy metals, including the toxic ones. Through the solid and dissolved river runoff, atmospheric fluxes, and coastal abrasion, heavy metals enter the seawater where they are involved in various biogeochemical processes before to be precipitated on the sea floor. Many studies of marine sedimentation concern total metal concentration; meanwhile, an assessment of contribution of different biogeochemical processes stays incomplete. In this chapter, we try to evaluate the partitioning among the different forms (speciation) of heavy metals that reflect principal processes of their accumulation in the modern bottom sediments of the White Sea. We study both the rock-forming (Al, Fe, Mn) and trace elements (Mo, Cr, Ni, Co, Cu, Pb, Cd, and As) by use of a modified method of selective sequential chemical leaching.

Interest in the study of subarctic areas of the Earth increases year by year, due to the accelerating pace of development of high latitudes and increasing anthropogenic pressure. In parallel with these processes, there is a growing need to study the behavior of substances of the first class of danger in the natural objects of the region. This article summarizes and analyzes data on Hg content in bottom sediments of the White Sea and rivers of its basin. The influence of the river flow of the Northern Dvina, Kyanda, and Kem Rivers on the formation of Hg concentrations in the bottom sediments of the White Sea, Dvinsky, and Onega bays has been studied.

A new approach using dispersed organic matter of the water column in sedimentation traps in comparison with the surface layer of the bottom sediments is applied for the study of marine sedimentation. This approach provides the opportunity for an in situ (by fluxes of sedimentary matter in the water column) study of modern sedimentation in the surface layers of the bottom sediments and tracing the changes in the environment and climate at a new technological level. This also allows us to choose the reverse task: to reconstruct the fluxes of the matter and chemical elements in ancient seas by the rates (or absolute masses) of sedimentation.

The suspended particulate matter (SPM) distribution in the water column of the Kara Sea including the Ob and Yenisei river estuaries was investigated in September 2007 and 2011, i.e., during periods of the maximum reduction of drift ice in the Arctic Ocean. The increased SPM concentrations in the surface layer of the Ob Estuary (26 and 16 mg/L on average in the fresh and saline (3–10 psu) water, respectively) were revealed in 2007 as compared with its values available from previous publications. The SPM concentrations and share of the terrigenous component in the latter in the Ob Estuary (2007) was =10 times higher than in the estuary of the Yenisei River (2011). The SPM concentration decreased exponentially in response to fresh and saline water mixing in the marginal filter (MF) areas of these rivers. The main transformation of the SPM composition at the transition from estuary to shelf waters took place within the salinity frontal zone (coagulation and sorption stage of the MF). The impact of terrigenous material on marine SPM composition in 2011 decreased in the northerly direction. The anomalous desalination of the sea surface layer in 2007 resulted in significant lightening of the organic carbon isotopic composition in the western part of the Kara Sea. This means that the impact of terrigenous material on SPM composition insignificantly decreased in the northerly direction. It was shown that mineral matter was distributed from the northeastern extremity of the Novaya Zemlya Archipelago in the northeasterly direction. At the same time, mineral particles transported by rivers from West and East Siberia prevail in the terrigenous SPM constituent in the Kara Sea up to 76°30′ N. Our data indicated that the processes of cross-shelf SPM transport in the Kara Sea were controlled by bottom topography.

The spatial and temporal variations in SPM concentration in the White Sea, Russia, are directly (mineral particles from the water basin) or indirectly ("blossom" of diatoms due to supply of nutrients) caused by river runoff. Interannual variations in SPM concentration for the White Sea are low and do not exceed 18% (2003–2010); hence, they are statistically insignificant.

The distribution of suspended particulate matter (SPM) concentration in the Kara Sea was analysed based on ship and satellite data during the lowest ice cover periods in the Arctic (2007 and 2011). The distance of the river runoff with terrigenous SPM was recognized up to at least 76–76.5° N on the basis of isotope data and SPM concentrations and composition. The complex studies of SPM in the water column and in the benthic boundary layer provided new information about the supply and transformation of particles in the marine ecosystem.

The results of black carbon (BC) studies in the marine boundary layer over the White, Barents and Kara seas in August–September 2007, snow, ice and under-ice water were studied in the vicinity of the North Pole during the Pan-Arctic Ice Camp Expedition (PAICEX) In April 2008 and modeling of transport of air masses and pollution in the Russian Arctic are presented in this chapter. It is shown that aeolian and ice transport of matter plays an important role in the fate of black carbon, heavy metals and other contaminants in the Arctic.