Seasonal and Annual Fluxes of Nutrients and Organic Matter from Large Rivers to the Arctic Ocean and Surrounding Seas   总被引：3，自引：0，他引：3  

Robert Max Holmes  James W. McClelland  Bruce J. Peterson  Suzanne E. Tank  Ekaterina Bulygina  Timothy I. Eglinton  Viacheslav V. Gordeev  Tatiana Y. Gurtovaya  Peter A. Raymond  Daniel J. Repeta  Robin Staples  Robert G. Striegl  Alexander V. Zhulidov  Sergey A. Zimov 《Estuaries and Coasts》2012,35(2):369-382

River inputs of nutrients and organic matter impact the biogeochemistry of arctic estuaries and the Arctic Ocean as a whole, yet there is considerable uncertainty about the magnitude of fluvial fluxes at the pan-Arctic scale. Samples from the six largest arctic rivers, with a combined watershed area of 11.3?×?10⁶?km², have revealed strong seasonal variations in constituent concentrations and fluxes within rivers as well as large differences among the rivers. Specifically, we investigate fluxes of dissolved organic carbon, dissolved organic nitrogen, total dissolved phosphorus, dissolved inorganic nitrogen, nitrate, and silica. This is the first time that seasonal and annual constituent fluxes have been determined using consistent sampling and analytical methods at the pan-Arctic scale and consequently provide the best available estimates for constituent flux from land to the Arctic Ocean and surrounding seas. Given the large inputs of river water to the relatively small Arctic Ocean and the dramatic impacts that climate change is having in the Arctic, it is particularly urgent that we establish the contemporary river fluxes so that we will be able to detect future changes and evaluate the impact of the changes on the biogeochemistry of the receiving coastal and ocean systems.  相似文献   

Uranium in Saline Lakes of Mongolia and Adjacent Areas     

Vitaly ISUPOV  SODOV Ariunbileg  Svetlana SHATSKAYA  Marina KOLPAKOVA  Ljudmila RAZVOROTNEVA  Alexander VLADIMIROV  Stepan SHVARTSEV  Leonid KUIBIDA  Sergey KRIVONOGOV  Ekaterina MOROZ 《《地质学报》英文版》2014,88(Z1):137-138

正1 Introduction Increasing demand for uranium raw materials for the nuclear industry has stimulated interest in non-traditional sources,including hydromineral ones[Qin,2009].Those are saline lakes located in the uranium ore districts.Accumulation of uranium in such lakes results from the leaching of uranium from the rocks by surface and ground  相似文献   

Geochemistry of Fe-Mn deposits of the Atlantic Ocean (Strakhov Basin,Elena Seamount,and Cape Verde Quadrangle)     

O. A. Korotkina  L. N. Kogarko  E. S. Bazilevskaya  I. V. Kurbakova 《Geochemistry International》2010,48(12):1166-1176

Fe-Mn deposits for this research were sampled at the floor of the Atlantic Ocean in the Cape Verde Quadrangle, Elena Seamount, and Strakhov Basin. The samples were analyzed for major components and for Ni, Co, Cu, P, S, and other trace elements by ICP-AES. Common features in the distribution of REE (high positive Ce anomalies) were discovered, and trends in the distribution of elements with depths are revealed. As, Pb, Sr, Co, and Pt are prone to accumulate in shallower water areas, whereas Cu and Li are enriched at deeper water territories. The samples are analyzed in compliance with Andreev’s classification, and their noble metal composition is determined.  相似文献   

On the extension of the wind profile over homogeneous terrain beyond the surface boundary layer   总被引：7，自引：5，他引：2  

Sven-Erik Gryning  Ekaterina Batchvarova  Burghard Brümmer  Hans Jørgensen  Søren Larsen 《Boundary-Layer Meteorology》2007,124(2):251-268

Analysis of profiles of meteorological measurements from a 160 m high mast at the National Test Site for wind turbines at Høvsøre (Denmark) and at a 250 m high TV tower at Hamburg (Germany) shows that the wind profile based on surface-layer theory and Monin-Obukhov scaling is valid up to a height of 50–80 m. At higher levels deviations from the measurements progressively occur. For applied use an extension to the wind profile in the surface layer is formulated for the entire boundary layer, with emphasis on the lowest 200–300 m and considering only wind speeds above 3 m s^?1 at 10 m height. The friction velocity is taken to decrease linearly through the boundary layer. The wind profile length scale is composed of three component length scales. In the surface layer the first length scale is taken to increase linearly with height with a stability correction following Monin-Obukhov similarity. Above the surface layer the second length scale (L _MBL ) becomes independent of height but not of stability, and at the top of the boundary layer the third length scale is assumed to be negligible. A simple model for the combined length scale that controls the wind profile and its stability dependence is formulated by inverse summation. Based on these assumptions the wind profile for the entire boundary layer is derived. A parameterization of L _MBL is formulated using the geostrophic drag law, which relates friction velocity and geostrophic wind. The empirical parameterization of the resistance law functions A and B in the geostrophic drag law is uncertain, making it impractical. Therefore an expression for the length scale, L _MBL , for applied use is suggested, based on measurements from the two sites.  相似文献   

Probing deep weathering in the Shale Hills Critical Zone Observatory,Pennsylvania (USA): the hypothesis of nested chemical reaction fronts in the subsurface   总被引：1，自引：0，他引：1  

Susan L. Brantley  Molly E. Holleran  Lixin Jin  Ekaterina Bazilevskaya 《地球表面变化过程与地形》2013,38(11):1280-1298

Weathering is both an acid‐base and a redox reaction in which rocks are titrated by meteoric carbon dioxide (CO₂) and oxygen (O₂). In general, the depths of these weathering reactions are unknown. To determine such depths, cuttings of Rose Hill shale were investigated from one borehole from the ridge and four boreholes from the valley at the Susquehanna Shale Hills Observatory (SSHO). Pyrite concentrations are insignificant to depths of 23 m under the ridge and 8–9 m under the valley. Likewise, carbonate concentrations are insignificant to 22 and 2 m, respectively. In addition, a 5–6 m‐thick fractured layer directly beneath the land surface shows evidence for loss of illite, chlorite, and feldspar. Under the valley, secondary carbonates may have precipited. The limited number of boreholes and the tight folding make it impossible to prove that depth variations result from weathering instead of chemical heterogeneity within the parent shale. However, carbonate depletion coincides with the winter water table observed at ~20 m (ridge) and ~2 m depth (valley). It would be fortuitous if carbonate‐containing strata are found under ridge and valley only beneath the water table. Furthermore, pyrite and carbonate react quickly and many deep reaction fronts for these minerals are described in the literature. We propose that deep transport of O₂ initiates weathering at SSHO and many other localities because pyrite commonly oxidizes autocatalytically to acidify porewaters and open porosity. According to this hypothesis, the mineral distributions at SSHO are nested reaction fronts that overprint protolith stratigraphy. The fronts are hypothesized to lie subparallel to the land surface because O₂ diffuses to the water table and causes oxidative dissolution of pyrite. Pyrite‐derived sulfuric acid (H₂SO₄) plus CO₂ also dissolve carbonates above the water table. To understand how reaction fronts record long‐term coupling between erosion and weathering will require intensive mapping of the subsurface. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Where fast weathering creates thin regolith and slow weathering creates thick regolith     

Ekaterina Bazilevskaya  Marina Lebedeva  Milan Pavich  Gernot Rother  Dilworth Y. Parkinson  David Cole  Susan L. Brantley 《地球表面变化过程与地形》2013,38(8):847-858

Weathering disaggregates rock into regolith – the fractured or granular earth material that sustains life on the continental land surface. Here, we investigate what controls the depth of regolith formed on ridges of two rock compositions with similar initial porosities in Virginia (USA). A priori, we predicted that the regolith on diabase would be thicker than on granite because the dominant mineral (feldspar) in the diabase weathers faster than its granitic counterpart. However, weathering advanced 20× deeper into the granite than the diabase. The 20 × ‐thicker regolith is attributed mainly to connected micron‐sized pores, microfractures formed around oxidizing biotite at 20 m depth, and the lower iron (Fe) content in the felsic rock. Such porosity allows pervasive advection and deep oxidation in the granite. These observations may explain why regolith worldwide is thicker on felsic compared to mafic rock under similar conditions. To understand regolith formation will require better understanding of such deep oxidation reactions and how they impact fluid flow during weathering. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Freeze–thaw processes degrade post-fire water repellency in wet soils     

Ekaterina Rakhmatulina  Sally Thompson 《水文研究》2020,34(26):5229-5241

Wildfires are a cause of soil water repellency (hydrophobicity), which reduces infiltration whilst increasing erosion and flooding from post-fire rainfall. Post-fire soil water repellency degrades over time, often in response to repeated wetting and drying of the soil. However, in mountainous fire-prone forests such as those in the Western USA, the fire season often terminates in a cold and wet winter, during which soils not only wet and dry, but also freeze and thaw. Little is known about the effect of repeated freezing and thawing of soil on the breakdown of post-fire hydrophobicity. This study characterized the changes in hydrophobicity of Sierra Nevada mountain soils exposed to different combinations of wet–dry and freeze–thaw cycling. Following each cycle, hydrophobicity was measured using the Molarity of Ethanol test. Hydrophobicity declined similarly across all experiments that included a wetting cycle. Repeated freezing and thawing of dry soil did not degrade soil water repellency, but freeze–thaw cycles decreased hydrophobicity in wet soils. Total soil organic matter content was not different between soils of contrasting hydrophobicity. Macroscopic changes such as fissures and cracks were observed to form as soil hydrophobicity decayed. Microscopic changes revealed by scanning electron microscope imagery suggest different levels of soil aggregation occurred in samples with distinct hydrophobicities, although the size of aggregates was not clearly correlated to the change in water repellency due to wet–dry and freeze–thaw cycling. A 9-year climate and soil moisture record from Providence Critical Zone Observatory was combined with the laboratory results to estimate that hydrophobicity would persist an average of 144 days post-fire at this well-characterized, typical mid-elevation Sierra Nevada site. Most of the breakdown in soil water repellency (79%) under these climate conditions would be attributable to freeze–thaw cycling, underscoring the importance of this process in soil recovery from fire in the Sierra Nevada.  相似文献   

Cellular Response to Cu‐ and Zn‐Induced Oxidative Stress in Aspergillus fumigatus Isolated From Polluted Soils in Bulgaria          下载免费PDF全文

Ekaterina Krumova  Nedelina Kostadinova  Jeny Miteva‐Staleva  Vitalii Gryshko  Maria Angelova 《洁净——土壤、空气、水》2016,44(6):657-666

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Organizing earth observation data inside a spatial data infrastructure     

Markus Innerebner  Armin Costa  Ekaterina Chuprikova  Roberto Monsorno  Bartolomeo Ventura 《Earth Science Informatics》2017,10(1):55-68

Scientists as well public institutions dealing with geospatial data often work with a large amount of heterogeneous data deriving from different sources. Without a well-defined, organized structure they face problems in finding and reusing existing data, and as consequence this may cause data inconsistency and storage problems. A catalog system based on the metadata of spatial data facilitates the management of large amount of data and offers service to retrieve, discover and exchange geographic data in an quick and easy fashion. Currently, most online catalogs are more focusing on the geographic data and there has been only few interests in catalogizing Earth observation data, in which in addition the acquisition information matters. This article presents an automatic metadata extraction approach that creates from different optical data deriving from various satellite missions of scientific interest (i.e. MODIS, LANDSAT, RapidEye, Suomi-NPP VIIRS, Sentinel-1A, Sentinel-2A) metadata information, based on an extended model of the standard ISO 19115. The XML schema ISO 19139-2 with the support of gridded and imagery information defined in ISO 19115-2 was examined, and based on the requirements of experts working in the research field of Earth observation the schema was extended. The XML schema ISO 19139-2 and its extension has been deployed as a new schema plugin in the spatial catalog Geonetwork Open Source in order to store all relevant metadata information about satellite data and the appropriate acquisition and processing information in an online catalog. A real-world scenario that is productively used in the EURAC research group institute for Applied Remote Sensing illustrates a workflow management for Earth observation data including data processing, metadata extraction, generation and distribution.  相似文献   

Applied model for the growth of the daytime mixed layer   总被引：5，自引：2，他引：5  

Ekaterina Batchvarova  Sven-Erik Gryning 《Boundary-Layer Meteorology》1991,56(3):261-274

A slab model is proposed for developing the height of the mixed layer capped by stable air aloft. The model equations are closed by relating the consumption of energy (potential and kinetic) at the top of the mixed layer to the production of convective and mechanical turbulent kinetic energy within the mixed layer. By assuming that the temperature difference at the top of the mixed layer instantaneously adjusts to the actual meteorological conditions without regard to the initial temperature difference that prevailed, the model is reduced to a single differential equation which easily can be solved numerically. When the mixed layer is shallow or the atmosphere nearly neutrally stratified, the growth is controlled mainly by mechanical turbulence. When the layer is deep, its growth is controlled mainly by convective turbulence. The model is applied on a data set of the evolution of the height of the mixed layer in the morning hours, when both mechanical and convective turbulence contribute to the growth process. Realistic mixed-layer developments are obtained.  相似文献