The degradation of submarine permafrost and the destruction of hydrates on the shelf of east arctic seas as a potential cause of the “Methane Catastrophe”: some results of integrated studies in 2011     

V. I. Sergienko  L. I. Lobkovskii  I. P. Semiletov  O. V. Dudarev  N. N. Dmitrievskii  N. E. Shakhova  N. N. Romanovskii  D. A. Kosmach  D. N. Nikol’skii  S. L. Nikiforov  A. S. Salomatin  R. A. Anan’ev  A. G. Roslyakov  A. N. Salyuk  V. V. Karnaukh  D. B. Chernykh  V. E. Tumskoi  V. I. Yusupov  A. V. Kurilenko  E. M. Chuvilin  B. A. Bukhanov 《Doklady Earth Sciences》2012,446(1):1132-1137

On the basis of the analysis of published data and in the course of the authors’ long-term geochemical and acoustic surveys performed in 1995–2011 on the East Siberian shelf (ESS) and aimed to research the role of the Arctic shelf in the processes of massive methane outbursts into the Earth’s atmosphere, some crucially new results were obtained. A number of hypotheses were proposed concerning the qualitative and quantitative characterization of the scale of this phenomenon. The ESS is a powerful supplier of methane to the atmosphere owing to the continued degradation of the submarine permafrost, which causes the destruction of gas hydrates. The emission of methane in several areas of the ESS is massive to the extent that growth in the methane concentrations in the atmosphere to values capable of causing a considerable and even catastrophic warning on the Earth is possible. The seismic data were compared to those of the drilling from ice performed first by the authors in 2011 in the southeastern part of the Laptev Sea to a depth of 65 m from the ice surface. This made it possible to reveal some new factors explaining the observed massive methane bursts out of the bottom sediments.  相似文献   

Still talking about oil     

Viktor Sebek 《Marine pollution bulletin》1979,10(5):121-122

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Stream water geochemistry from selected catchments on the Kola Peninsula (NW Russia)and in neighbouring areas of Finland and Norway: 1. Elements levels and sources     

Patrice de Caritat  Clemens Reimann  Matti Äyräs  Heikki Niskavaara  Viktor A. Chekushin  Vladimir A. Pavlov 《Aquatic Geochemistry》1996,2(2):149-168

The pH, electrical conductance and concentration of six anions and 33 cations were determined in stream waters sampled in 1994 from eight arctic catchments on and adjacent to the Kola Peninsula (Russia, Finland and Norway). The catchments are located at various distances (5–300 km) from the major industrial emissions centres of Monchegorsk, Nikel and Zapoljarniy in Russia. The source of the elements can be (1) natural, marine (sea spray), (2) natural, geogenic (blowing soil/dust, till, bedrock), and/or (3) anthropogenic, industrial (emissions from smelters, dust from mining, etc.), each source showing a distinct signature. The median concentration of many contaminants can vary by up to three orders of magnitude from polluted to remote locations, and the concentration ranges observed in different catchments often do not overlap. This implies that contamination falls sharply with distance from source, but is quite profound and lasting close to the emission centres. Elevated trace metal contents in the most polluted streams indicates that deposited contaminants are transferred to the aquatic ecosystem, and eventually can reach the ocean.  相似文献   

Stream water geochemistry from selected catchments on the Kola Peninsula (NW Russia) and in neighbouring areas of Finland and Norway: 2. Time-series     

Patrice de Caritat  Clemens Reimann  Matti Äyräs  Heikki Niskavaara  Viktor A. Chekushin  Vladimir A. Pavlov 《Aquatic Geochemistry》1996,2(2):169-184

Stream water composition, measured weekly for 8–9 months in 1994 in three arctic catchments on and around the Kola Peninsula (Russia, Finland and Norway), is presented in the form of time-series. In all three catchments, snowmelt causes a major dilution of the stream water, as reflected by marked dips in electrical conductance. In the most polluted catchment (C2), the snowmelt flood (the major hydrological event at these latitudes) is reflected in the stream water by a pH dip and a pulse in technogenic heavy metals (Cu, Ni, etc.), Al and S. This results from melting of the snow laden with heavy metals and sulphate, and from leaching of the topsoil layer. In the most pristine catchment (C8), snowmelt causes no heavy metal pulse (remote location) but yields an increase in stream water Al (acidic lithology/overburden). In the intermediate catchment (C5), very subdued heavy metal and S increases are noticeable in the stream water, whilst its pH increases steadily until summer (basic lithology). Some elements (Cl, S) may be mobilised out of the snowpack before its complete thawing and reach the stream 1–2 weeks ahead of the heavy metals. The substrate (soil, overburden and bedrock) of a catchment controls to a large extent its ability to buffer acid inputs.  相似文献   

New trends in compensation for oil pollution damage : Amoco Cadiz legal proceedings and the 1984 diplomatic conference on liability and compensation     

Rouchdy Kbaier  Viktor Sebek 《Marine Policy》1985,9(4):269-279

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Lateral and vertical juxtaposition of matrix‐rich and matrix‐poor lithologies caused by particle settling in mixed mud–sand deep‐marine sediment suspensions     

Katrina Angus  Robert William Charles Arnott  Viktor Terlaky 《Sedimentology》2019,66(3):940-962

Sandy sedimentary rocks rich in detrital matrix (>10% silt/clay) have long been recognized in the ancient sedimentary record, and nowhere more commonly than in deep‐marine turbidite systems. Despite this, their depositional mechanisms remain poorly understood, in part because these rocks, which are enriched in fine‐grained sediment, are often poorly exposed in outcrop or are confined to observation in core. Matrix‐rich strata in the Neoproterozoic Windermere Supergroup, in contrast, are very well‐exposed and show systematic changes in lithofacies over distances of several tens to a few hundreds of metres along‐strike. Notably, these strata are observed in both basin floor and continental slope deposits, suggesting that their occurrence and systematic lithological arrangement is related to mechanistic, rather than palaeogeographic, controls. Specifically, the facies transect consists of structureless, clayey sandstone that transforms along‐strike to a two‐layer deposit with the development of an upper, planar‐based, markedly more matrix‐rich layer. Further along‐strike, the basal clayey sandstone thins and eventually pinches out, leaving only the (upper) sandy claystone layer, which in turn thins along‐strike and then pinches out. These systematic changes in lithology, but more specifically the distribution of clay, is interpreted to form a depositional continuum related to particle settling in a horizontally advecting, high concentration particle suspension formed along the margins of an avulsion‐related high‐energy turbulent suspension.  相似文献   

The effect of periphyton on the light environment and production of Potamogeton perfoliatus L. in the mesotrophic basin of Lake Balaton     

Viktor R. Tóth 《Aquatic Sciences - Research Across Boundaries》2013,75(4):523-534

Light within the littoral zone affects the productivity and interaction between periphyton and its macrophyte substrate. The effect of periphyton on macrophyte photosynthesis, seasonal variation and vertical distribution of periphyton on artificial substrates (plastic strips), and the effect of periphyton on the light environment was studied in Lake Balaton. Data showed that an average of 4.1 ± 0.4 mg (dry weight) cm^?2 of periphyton had accumulated on the plastic strips after 8.8 ± 0.4 days. This biomass corresponded to 294 ± 30 μg m^?2 chl-a of epiphytic algae and blocked 92.3 ± 0.8 % of the depth specific radiation. Seasonal variation and specific vertical distribution of periphyton were observed. The most active time of periphyton accumulation corresponded to spring up until mid-June. Later in the year, the amount of periphyton significantly decreased. The optimal conditions for periphyton accumulation were at 30–40 cm depth. Most of the light reaching the adaxial leaf surface was attenuated by periphyton, decreasing the production of Potamogeton perfoliatus by 60–80 %. This increased the importance of backscattered light that corresponded to 10–15 % of the macrophyte production. A smaller part of the periphyton consisted of precipitated inorganic material, while epiphytic algae, making up the majority of the periphyton, were connected to both benthic (dominantly benthic penales) and pelagic (very close seasonal dynamics of pelagic and epiphytic biomass) algae. Periphyton affects macrophyte production especially in spring and in the upper water layers even in a mesotrophic water body. This increases the importance of the light absorbed through the abaxial side of the leaf and confirm the role of periphyton in transition from clear to turbid water states.  相似文献   

Radiological aspects of red mud disaster in Hungary     

Tibor Kovács  Zoltán Sas  Viktor Jobbágy  Anita Csordás  Gábor Szeiler  János Somlai 《Acta Geophysica》2013,61(4):1026-1037

One of the most severe industrial catastrophes happened in Kolontár, Hungary, on 4 October 2010. Red mud (bauxite residue) broke through the eroded wall of the red mud reservoir pond “Number X” and flooded the surrounding area. This led to the instant death of 10 people and the injury of more than 100 people. Red mud is enriched in radium and thorium isotopes; therefore, there is a chance that this flooding will increase radionuclide concentrations of soils and also in air. In this study we have examined the site to assess the realistic radiological risks. For the risk assessment the following parameters were determined: gamma dose rate, radon concentration, radionuclide concentration of red mud and air dust concentration. It was found that the radiation dose exposure resulting from red mud contamination was < 0.045 mSv y^?1 (excluding radon), which can be considered negligible when compared to the average annual effective dose from natural sources (2.4 mSv y^?1).  相似文献   

Vegetation and climate history in the Laptev Sea region (Arctic Siberia) during Late Quaternary inferred from pollen records     

Andrei A. Andreev  Lutz Schirrmeister  Pavel E. Tarasov  Andrey Ganopolski  Viktor Brovkin  Christine Siegert  Sebastian Wetterich  Hans-Wolfgang Hubberten 《Quaternary Science Reviews》2011,30(17-18):2182-2199

Paleoenvironmental records from a number of permafrost sections and lacustrine cores from the Laptev Sea region dated by several methods (¹⁴C-AMS, TL, IRSL, OSL and ²³⁰Th/U) were analyzed for pollen and palynomorphs. The records reveal the environmental history for the last ca 200 kyr. For interglacial pollen spectra, quantitative temperature values were estimated using the best modern analogue method. Sparse grass-sedge vegetation indicating arctic desert environmental conditions existed prior to 200 kyr ago. Dense, wet grass-sedge tundra habitats dominated during an interstadial ca 200–190 kyr ago, reflecting warmer and wetter summers than before. Sparser vegetation communities point to much more severe stadial conditions ca 190–130 kyr ago. Open grass and Artemisia communities with shrub stands (Alnus fruticosa, Salix, Betula nana) in more protected and moister places characterized the beginning of the Last Interglacial indicate climate conditions similar to present. Shrub tundra (Alnus fruticosa and Betula nana) dominated during the middle Eemian climatic optimum, when summer temperatures were 4–5 °C higher than today. Early-Weichselian sparse grass-sedge dominated vegetation indicates climate conditions colder and dryer than in the previous interval. Middle Weichselian Interstadial records indicate moister and warmer climate conditions, for example, in the interval 40–32 kyr BP Salix was present within dense, grass-sedge dominated vegetation. Sedge-grass-Artemisia-communities indicate that climate became cooler and drier after 30 kyr BP, and cold, dry conditions characterized the Late Weichselian, ca 26–16 kyr BP, when grass-dominated communities with Caryophyllaceae, Asteraceae, Cichoriaceae, Selaginella rupestris were present. From 16 to 12 kyr BP, grass-sedge communities with Caryophyllaceae, Asteraceae, and Cichoriaceae indicate climate was significantly warmer and moister than during the previous interval. The presence of Salix and Betula reflect temperatures about 4 °C higher than present at about 12–11 kyr BP, during the Allerød interval, but shrubs were absent in the Younger Dryas interval, pointing to a deterioration of climate conditions. Alnus fruticosa, Betula nana, Poaceae, and Cyperaceae dominate early Holocene spectra. Reconstructed absolute temperature values were substantially warmer than present (up to 12 °C). Shrubs gradually disappeared from coastal areas after 7.6 kyr BP when vegetation cover became similar to modern. A comparison of proxy-based paleoenvironmental reconstructions with the simulations performed by an Earth system model of intermediate complexity (CLIMBER-2) show good accordance between the regional paleodata and model simulations, especially for the warmer intervals.  相似文献   

Magneto-Acoustic Waves in Compressible Magnetically Twisted Flux Tubes     

Robert Erdélyi  Viktor Fedun 《Solar physics》2010,263(1-2):63-85

The oscillatory modes of a magnetically twisted compressible flux tube embedded in a compressible magnetic environment are investigated in cylindrical geometry. Solutions to the governing equations to linear wave perturbations are derived in terms of Whittaker’s functions. A general dispersion equation is obtained in terms of Kummer’s functions for the approximation of weak and uniform internal twist, which is a good initial working model for flux tubes in solar applications. The sausage, kink and fluting modes are examined by means of the derived exact dispersion equation. The solutions of this general dispersion equation are found numerically under plasma conditions representative of the solar photosphere and corona. Solutions for the phase speed of the allowed eigenmodes are obtained for a range of wavenumbers and varying magnetic twist. Our results generalise previous classical and widely applied studies of MHD waves and oscillations in magnetic loops without a magnetic twist. Potential applications to solar magneto-seismology are discussed.  相似文献