Detection and Evaluation of Anthropogenic Pollution on the Basis of Geochemical Study of the Interstitial Waters of Marine and Freshwater Sediments

The chemical composition of interstitial waters from several inland seas and or water system (NPWS) exposed to anthropogenic pollution was studied. The patterns of the distribution of pollution in the Dnieper–Bug Estuary, Gelendzhik Bay of the Black Sea and in the Alexandria’s Eastern Harbor of the Mediterranean Sea were found. Most of the contamination occurs in the upper layers of bottom sediments and near mouth zones. A significant role is played by secondary contamination related to the dissolution and accumulation of metals and nutrients in the interstitial water and their migration to the water column. The estuary factor of anthropogenic pollution takes center stage according to a factor analysis for the combined impacts of potentially mobile forms of metals in the Dnieper–Bug Estuary. Studies of the Lake Pyasino pollution near Noril’sk were carried out.     

Selenium in San Francisco Bay zooplankton: Potential effects of hydrodynamics and food web interactions

The potential toxicity of elevated selenium (Se) concentrations in aquatic ecosystems has stimulated efforts to measure Se concentrations in benthos, nekton, and waterfowl in San Francisco Bay (SF Bay). In September 1998, we initiated a 14 mo field study to determine the concentration of Se in SF Bay zooplankton, which play a major role in the Bay food web, but which have not previously been studied with respect to Se. Monthly vertical plankton tows were collected at several stations throughout SF Bay, and zooplankton were separated into two operationally defined size classes for Se analyses: 73–2,000 μm, and ≥2,000 μm. Selenium values ranged 1.02–6.07 μg Se g^?1 dry weight. No spatial differences in zooplankton Se concentrations were found. However, there were inter- and intra-annual differences. Zooplankton Se concentrations were enriched in the North Bay in Fall 1999 when compared to other seasons and locations within and outside SF Bay. The abundance and biovolume of the zooplankton community varied spatially between stations, but not seasonally within each station. Smaller herbivorous-omnivorous zooplankton had higher Se concentrations than larger omnivorous-carnivorous zooplankton. Selenium concentrations in zooplankton were negatively correlated with the proportion of total copepod biovolume comprising the large carnivorous copepodTortanus dextrilobatus, but positively correlatid with the proportion of copepod biovolume comprising smaller copepods of the family Oithonidae, suggesting an important role of trophic level and size in regulating zooplankton Se concentrations.     

New data on lineament control of modern centers of methane degassing in east Asian seas

This paper reports on the heaviest submarine fluxes of natural gas bubbles (flares) that have occurred in the Sea of Okhotsk, the Laptev Sea, and Lake Baikal. It has been concluded that there is a “gas-geochemical response” of geodynamic and seismotectonic processes in the interaction of lithospheric plates. Using the example of one of the lineaments of Eastern Asia, we have shown that lineament geotectonic structures, which compose the regmatic net of the Earth, control the formation and activity of the biggest centers of methane emission, which are indicators of tectonospheric activity and hydrocarbon accumulation. Changes in the activity of these centers are informative signals of seismic fluctuations. It is concluded that Russian studies play a leading role in gas hydrate forecasts in the seas of the Eastern Arctic.     

Marine ice-rafting as a new type of sedimentogenesis in the Arctic and novel approaches to studying sedimentary processes

Research on sedimentogenesis and geochemistry of the Arctic Ocean over the last 10–20 years has allowed direct (in situ) studies to be made for all types of sedimentary matter that mix together and form the bottom deposit. Contrary to common knowledge, river sediment turned out to be insignificant; instead, more important is the dispersed sedimentary matter (suspension) from the atmosphere, cryosphere (snow, ice), marine water, riverine water, biosphere (plankton and benthos), and anthroposphere (all types of pollutants), supplemented by the endogenic mater supplied from spreading zone of the Gakkel Ridge. The mixture is dominated by sedimentary material discharged from sea ice; hence, this type of sedimentogenesis is referred to as the ice-rafted marine sedimentogenesis.Application of new methods and tools (including satellites, remote hydrooptical, hydrophysical, and hydroacoustic survey, etc.) and in situ analyses produced measurements of content, composition, and characteristics of all types of dispersed sedimentary matter, its fluxes (mg/m²/year), vectors of movement, and rates for different segments of the Arctic Ocean; observations were carried out continuously on different time scale, from hours–days to seasons and dozens of years. It is a new approach to the study of sedimentary matter that opens up new possibility for a 4D quantitative sedimentology.     

The Lomonosov Ridge as a natural extension of the Eurasian continental margin into the Arctic Basin

The inregrated geological and geophysical studies carried out in recent years in the Lomonosov Ridge and at its junction with the Eurasian shelf revealed evidence for thinned (reduced) crust in the ridge (20–25 km) and its relationship with shelf structures. We compared the parameters of deep seismic cross-sections of the shelf and Lomonosov Ridge, thus proving the existence of continental crust in the latter. Also, we analyzed the deep structure of the junction between the Lomonosov Ridge and the shelf and established a genetic geologic relationship, with no evidence that the Lomonosov Ridge moved as a terrane with respect to the shelf. In addition, seismological studies independently confirm the relationship between the Lomonosov Ridge and the adjacent shelf.The Lomonosov Ridge is a continental-crust block of a craton. The craton was reworked during the Caledonian tectonomagmatic activity with the formation of a Precambrian–Caledonian seismically unsegmented basement (upper crust) and an epi-Caledonian platform cover. Afterward, the block subsided to bathyal depths in the Late Alpine. This block and the adjacent areas of the Eastern Arctic shelf developed in the platform regime till the Late Mesozoic.     

A key Paleozoic section in the northern part of the Western Siberian Region

A few of our predecessors considered the Eastern Siberian Region to be a huge territory with similar geological history without hydrocarbon prospecting opportunities. It was also proposed to search for oil and gas in the seas of the Arctic Ocean. Not denying these search directions, we have offered to explore the Western Siberian Region by analysis of numerous deep wells, variable facial zones of Paleozoic complexes, and real prospects of searching for oil and gas fields.     

PRINCIPAL STAGES IN THE PERMIAN EVOLUTION OF ASIAN MARINE BASINS AND BRACHIOPOD FAUNA

In consequence of Hercynian folding, the Asian marine basin outlines repeatedly and essentially changed throughout the Permian. At the opening of the Sakmarian age the communication between the Arctic and Tethys marine basins was realized through the Caspian Sea region. In the middle of the Sakmarian age this channel was closed and the Arctic and Tethys seas were isolated from each other resulting in the development of various brachiopod faunas in both basins. Such an environment continued up to the beginning of the Upper Permian when a transgression of the boreal sea far to the south into the Mongolian geosyncline area and farther on into India and Burma took place. The Upper Permian marine basins of these regions became, therefore, inhabited by fauna of the Arctic type. Meanwhile the tropical forms of brachiopods did not migrate from the Tethys into the Arctic. At the beginning of the Kazanian age the sea retreated from Mongolia and the Arctic and Tethys basins became almost isolated again, their fauna growing essentially different towards the close of the Permian. In consequence of the fact that the tropical forms common in the Tethys couldn't exist through out the Permian within the present area of the Arctic, it might be assumed that the climate was most severe at the time, i.e. the region was located in the nearest proximity to the pole. At the same time the region adjacent to Japan where the North Pole moved to during the Permian (according to the opinion of most advocates of the polar migration theory) is found to be inhabited by tropical fauna. Thus analysis of the distribution of Permian fauna doesn't confirm the theory of a considerable migration of the earth's poles.—Auth. English summ.     

Acoustic evidence for shallow gas accumulations in the sediments of the Eastern Black Sea*

ABSTRACT The Black Sea contains immense gas accumulations. Exploration of gas accumulations is geologically and economically important because migration of methane in sediments may cause massive slope failures and the methane seeps may indicate deeper hydrocarbon reservoirs. Human activity both in and on the seafloor (oil industry) and natural activity (earthquakes, cyclones) trigger mechanisms for seafloor failure and gas release that may have a local and possibly global environmental impact. Recently, sonar and high‐resolution seismic surveys were carried out to obtain information about the effects of gas and gas‐filled sediments throughout the Turkish margin of the Eastern Black Sea, and shallow gas was detected on the subbottom profiler records. It continues about 25–65 m below the sea floor and is marked by bright and cloudy spots, sometimes pockmarks and acoustic voids. The lower section of the Turkish shelf is an extensive pockmarked plateau. The pockmarks are seen as circular structures with high backscattering on the sonar records.     

Lomonosov ridge and the Eastern Arctic Shelf as elements of an integrated lithospheric plate: Comparative analysis of wrench faults

The notions of deformations in the juncture area of the Eastern Arctic Shelf and Lomonosov Ridge are highly contradictory. It has been suggested that these geostructures were divided by a large right-lateral wrench fault of the transform type, which is known as the Khatanga–Lomonosov Fault. Data obtained by interpretation of the A7 profile have been compared with seismic sections crossing large-sized wrench faults in other sedimentary basins. The investigations have shown that on the A7 profile there are no structures typical of large-sized wrench faults. The Eastern Arctic Shelf and Lomonosov Ridge, which are located on the same lithospheric plate, form an integrated structure where the ridge is a natural continuation of the shelf.     

Crust of the arctic seas of Eurasia

Deep seismic studies are rather difficult in Arctic seas; it is therefore necessary to find other sources of information on the structure of the earth's crust. In this paper a number of crustal sections across the Arctic seas of Eurasia are presented. They are based on the analysis of magnetic field anomalies. Upper and lower boundaries of anomalous magnetic bodies, as well as zones where the magnetization changes rapidly in the vertical direction,indicate the position of the main seismic discontinuities. This inference has been confirmed by comparison with seismic data for the region of Okhotsk.     

Diversity and stages in evolution of conodontophorids and bivalve mollusks in Triassic seas of Siberia and the Far East

Comparative analysis of taxonomic diversity dynamics of condontophorids from Boreal (Arctic regions of Russia) and Tethyan (Northwest Pacific) paleobasins showed that they had most favorable habitat environments in tropical seas. In the Boreal realm, condontophorids went through three stages of evolution comprising probably four substages and four phases, whereas three stages with six substages and twelve phases are distinguished in the Tethyan realm. The most important abiotic factors that controlled development of conodontophorids are paleotemperature of seawater and paleogeographic settings. Renewals in taxonomic composition conodontophorids and diversification of their assemblages have been confined to moments of paleotemperature and/or sea level rise. The comparative analysis of stages in evolution of conodontophorid and bivalve assemblages has been carried out. As is established, the peak taxonomic diversity of bivalves in Boreal seas was in the Late Triassic after the diversity minimum of the Early Triassic time. In contrast, conodontophorids were most diverse in the Olenekian Age.     

The geochemical role of phyto- and zooplankton in the extraction of chemical elements from water

This paper provides for the first time comparative assessment of the contents of 70 chemical elements occurring in the aquatic environment in water, phytoplankton, and zooplankton. The assessment was made using modern highly sensitive methods. The studies were performed at Beloyarskoe Reservoir, a manmade freshwater lake situated in the Middle Urals that has been studied in detail. The chemical elements were ranked in groups differing in the accumulation coefficient (AC) values for the phyto- and zooplankton. The comparison revealed that for the vast majority of chemical elements, the AC values were higher in zooplankton (53, or 76%) than in phytoplankton (17, or 24%). The average AC values for zooplankton (∼740 000) exceeded that for phytoplankton (∼68 000) by more than 10 times. It was found that some elements had very high AC values in zooplankton compared to phytoplankton. For instance for Nb, the ratio AC_zoo/AC_phyto was 1 200 000; for B, Ta, Sn, Lu, U, 300 000–500 000; for Sb and Y, 100 000–130 000; for La and Nd, 80 000–85 000; for Mo, Cd, Pr, Gd, Dy, Sc, Se, Bi, 20 000–30 000; and for Pd, Hf, Sm, Sb, Er, As, 10 000–20 000. It is concluded that zooplankton is sometimes more suitable for the biogeochemical indication of the pollution of natural water bodies, because the AC values for most elements are much higher in zooplankton than in phytoplankton and the total plankton. Considering the high assimilability of microelements and radionuclides, the plankton may serve not only as an indication but also as the mean of regulated purification of waterbodies from these elements.     

Mesozoic marine reptiles from Spitsbergen and their ecosystems

In the Mesozoic seas, the apex predators were reptiles. From the Arctic archipelago of Svalbard, the Spitsbergen Mesozoic Research Group has excavated numerous well preserved marine reptile skeletons in order to understand the biology of these animals and the environment they lived in. The work of eleven field seasons has made this one of the largest and most productive palaeontological research projects in the high Arctic world‐wide. The initial eight seasons focused on one of the richest occurrences of Late Jurassic—earliest Cretaceous (c. 150–139 Ma) marine reptiles in the world, and nearly sixty specimens have been collected, together with a diverse assemblage of invertebrates, some of which are associated with methane seeps. The last three seasons were spent investigating events further back in time, as Spitsbergen preserves the remains from some of the first marine reptile radiations in the wake of the most devastating extinction in the history of the Earth, at the Permian–Triassic boundary (c. 252 Ma).     

Clay Minerals in Sediments of the Arctic Seas

The distribution of clay minerals in recent sediments on the Arctic shelf off the Eurasian and North American continents is considered. Prominence is given to the East Siberian and Laptev seas. The illite belt established on the basis of the composition of clay minerals in seven Arctic seas stretches from the Beaufort Sea to the White Sea and reveals a mineralogical zonality. The belt can be devided into smectite and chlorite provinces. Factors governing the formation of the Arctic illite belt and features of the distribution of individual clay minerals are discussed. The identification of the illite belt in sediments on the Arctic shelf complements the system of planetary latitudinal zones of clay minerals formulated by previous researchers.     

The dynamics and structure of plasma inhomogeneities in the Crab Nebula

The results of studies of the dynamics and structure of plasma inhomogeneities in the Crab Nebula carried out during 2002–2015 at 111 MHz on the Large Phased Array of the Pushchino Radio Astronomy Observatory are presented. Giant pulses of the pulsar PSR B0531+21 were observed and analyzed using specialized software designed to enable characterization of the scattering of a pulse via modeling of its passage through the scattering medium. The results of this analysis for the scattering of giant pulses are compared to variations in the dispersion measure, derived using data from Jodrell Bank Observatory (United Kingdom). Numerous non-stationary events associated with enhanced scattering are identified during the indicated period. The strongest scattering was observed during 2012–2014. The corresponding data are interpreted as eclipses of the pulsar by filaments in the Crab Nebula. A correlation between the variations in the scattering and dispersion measure is observed.     

中国海域表层沉积物分布规律及沉积分异模式

中国海域拥有宽广的大陆架，同时还有陆坡和深海盆，有众多河流入海并输入巨量的陆源物质，沉积物记录了海陆变迁、环流变化、海平面升降、物质输送和气候变化等环境信息。沉积物的粒度特征可以反映沉积动力、物质来源和搬运距离等，可以通过沉积物粒度组成、参数及各种图解来研究沉积环境的变化。前人对中国海域表层沉积物的粒度分布特征展开了大量的研究，取得了丰富的研究成果，但这些研究多集中在某一海域或区域，缺乏对整个中国海域的表层沉积物类型的宏观系统认识。本文基于中国地质调查局“1：100万海洋区域地质调查项目”获取了中国海域4300个海底表层沉积物样品，通过沉积物粒度分析，结合前人已发表资料，对中国海域表层沉积物的沉积类型特征、物质来源和运移模式等开展了系统的研究。本文把浅海和半深海沉积物按照含砾石和不含砾石主要划分出5个和7个沉积物类型，深海沉积物主要划分了9个沉积类型，研究结果表明：中国海域表层沉积物沉积类型多样、来源复杂，主要受控于物质来源、水动力条件和地形地貌的变化，在东部海域总体呈现“大江大河-宽缓陆架-残留慢速沉积”的条带状沉积分异模式，而在南部海域呈现的是“短源性河流-多类型陆架-重力流快速沉积”的环带状沉积分异模式。本文的结果对研究中国海域沉积物的宏观分布规律提供了基础资料，对理解海洋沉积动力过程具有重要意义，同时沉积物粒度的特征对海底砂矿分布也具有指示意义。     

Technogenic Radioactivity of Waters in the Central Arctic Basin and Adjacent Water Areas

Doklady Earth Sciences - The contemporary radiation situation in the Arctic Basin and Russian Arctic seas is assessed on the basis of data from 2013 to 2017. Statistically significant differences...     

Predation by the ctenophoreMnemiopsis leidyi in Narragansett Bay,Rhode Island

The impact ofMnemiopsis leidyi as a predator was studied quantitatively to determine their feeding rates on mixed natural zooplankton. These studies showed that feeding rate was independent of food concentration, but a function of both temperature and size of ctenophore. The feeding rate (liters cleared per mg dry weight per day) ranged from about 0.01 for larger ctenophores at lower temperatures (10–15°C) to about 0.1 for smaller ctenophores at higher temperatures (20–25°C). Combining these results with ctenophore biomass estimates from three years of sampling, numerical estimates were made of zooplankton mortality due to ctenophore predation. The maximum summer cropping byM. leidyi was calculated to be an average of 5–10% per day for the bay as a whole. Although substantial, this predation pressure alone does not account for the observed summer decline of zooplankton.     

An Overview of Hydrological Characteristics and Changing Mechanism of Modern Nordic Seas Overflows

As a connection region between Arctic and North Atlantic oceans, the Nordic seas play a critical role in global climate system. The density waters overflow through Greenland-Scotland Ridge from the Nordic seas, as the main source of the North Atlantic Deep Water (NADW), which plays a key role in global ocean conveyor. The causes and processes, which give some instruction of the overflow variation are still uncertain. Based on a review of current and historical research results of modern Nordic seas overflows, hydrological and flux characteristics and variation features of overflows through three channels, which are Faroe-Shetland Channel, Iceland-Faroe Ridge and Denmark Strait, from Nordic sea were addressed separately. The origins of overflows water and factors and physical processes that may have impact on the three overflows were also analyzed separately. Intense mixing in overflow through Faroe-Shetland Channel was discussed. At last, the changing mechanism of the whole overflow from Nordic seas and relationships among overflows through different channels were summed up. The aim of this paper is to give some instructions and research directions to the internal readers.