Photometric and Spectral Studies of the Object EG And     

I. N. Kondratyeva  F. K. Rspaev  I. V. Reva  M. A. Krugov 《Astrophysics》2018,61(3):310-323

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Stable isotopes of water show deep seasonal recharge in northern bogs and fens          下载免费PDF全文

Zeno F. Levy  Donald I. Siegel  Soumitri S. Dasgupta  Paul H. Glaser  Jeffrey M. Welker 《水文研究》2014,28(18):4938-4952

Ground water recharge is assumed to occur primarily at raised bog crests in northern peatlands, which are globally significant terrestrial carbon reservoirs. We synoptically surveyed vertical profiles of peat pore water δ¹⁸O and δ²H from a range of bog and fen landforms across the Glacial Lake Agassiz Peatlands, northern Minnesota. Contrary to our expectations, we find that local‐scale recharge penetrates to not only the basal peat at topographically high bog crests but also transitional Sphagnum lawns and low‐lying fen water tracks. Surface landscape characteristics appear to control the isotopic composition of the deeper pore waters (depths ≥0.5 m), which are partitioned into discrete ranges of δ¹⁸O on the basis of landform type (mean ± standard deviation for bog crests = ?11.9 ± 0.4‰, lawns = ?10.6 ± 0.1‰, fen water tracks = ?8.8 ± 1.0‰). Fen water tracks have a shallow free‐water surface that is seasonally enriched by isotope fractionating evaporation, fingerprinting recharge to underlying pore waters at depths ≥3 m. Isotope mass balance calculations indicate on average 12% of the waters we sampled from the basal peat of the fen water tracks was lost to surface evaporation, which occurred prior to advection and dispersion into the underlying formation. These new data provide direct support for the hypothesis that methane production in deeper peat strata is fuelled by the downward transport of labile carbon substrates from the surface of northern peat basins. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Regional‐scale mapping of groundwater discharge zones using thermal satellite imagery          下载免费PDF全文

G. Z. Sass  I. F. Creed  J. Riddell  S. E. Bayley 《水文研究》2014,28(23):5662-5673

Mapping groundwater discharge zones at broad spatial scales remains a challenge, particularly in data sparse regions. We applied a regional scale mapping approach based on thermal remote sensing to map discharge zones in a complex watershed with a broad diversity of geological materials, land cover and topographic variation situated within the Prairie Parkland of northern Alberta, Canada. We acquired winter thermal imagery from the USGS Landsat archive to demonstrate the utility of this data source for applications that can complement both scientific and management programs. We showed that the thermally determined potential discharge areas were corroborated with hydrological (spring locations) and chemical (conservative tracers of groundwater) data. This study demonstrates how thermal remote sensing can form part of a comprehensive mapping framework to investigate groundwater resources over broad spatial scales. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

The impact of rural land management changes on soil hydraulic properties and runoff processes: results from experimental plots in upland UK          下载免费PDF全文

M. R. Marshall  C. E. Ballard  Z. L. Frogbrook  I. Solloway  B. Reynolds  H. S. Wheater 《水文研究》2014,28(4):2617-2629

To develop an evidence base to help predict the impacts of land management change on flood generation, four experimental sites were established on improved grassland used for sheep grazing at the Pontbren catchment in upland Wales, UK. At each site, three plots were established where surface runoff was measured, supplemented by measurements of soil infiltration rates and soil and vegetation physical properties. Following baseline monitoring, treatments were applied to two of the plots: exclusion of sheep (ungrazed) and exclusion of sheep and planting with native broadleaf tree species (tree planted), with the third plot acting as a control (grazed pasture). Due to a particularly dry summer that occurred pre‐treatment, the soil hydrological responses were initially impacted by the effects of the climate on soil structure. Nevertheless, treatments did have a clear influence on soil hydrological response. On average, post‐treatment runoff volumes were reduced by 48% and 78% in ungrazed and tree‐planted plots relative to the control, although all results varied greatly over the sites. Five years following treatment application, near‐surface soil bulk density was reduced and median soil infiltration rates were 67 times greater in plots planted with trees compared to grazed pasture. The results illustrate the potential use of upland land management for ameliorating local‐scale flood generation but emphasise the need for long‐term monitoring to more clearly separate the effects of land management from those of climatic variability. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Long‐term monitoring of a mercury contaminated estuary (Ria de Aveiro,Portugal): the effect of weather events and management in mercury transport          下载免费PDF全文

J. P. Coelho  P. Pato  B. Henriques  A. Picado  A. I. Lillebø  J. M. Dias  A. C. Duarte  M. E. Pereira  M. A. Pardal 《水文研究》2014,28(2):352-360

The main aim of this research was to assess the mercury transport from an estuarine basin with a background of anthropogenic contamination during a spring tidal cycle (year 2009) and compare it with two previous tidal cycles (years 1994 and 1999), as part of a long‐term monitoring program. Results showed that effective mercury transport occurs both in the dissolved and particulate fractions (0.18 and 0.20 kg per tidal cycle, respectively), and despite an overall decrease in environmental contamination, results more than double previous findings on particulate transport in the system. These findings result essentially from changes in the tidal prism (net export of 2 million m³ of water), given that both dissolved and particulate concentrations did not increase over time. Hydrodynamic simulations were performed to evaluate the effect of physical disturbance (dredging) and weather events (increased freshwater flow) in these processes, and results suggest the increased freshwater flow into the system as the main forcing function for the mercury transport increment. These results highlight the importance of long‐term monitoring programs, since despite an overall improvement in local contamination levels, the enhancement of transport processes through hydrological changes increases environmental pressure away from the contamination source. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Role of Averaging in Statistical Analysis of Solar Wind Data from the DSCOVR Spacecraft for the First Year of Operation     

Veselovsky  I. S.  Kaportseva  K. B. 《Geomagnetism and Aeronomy》2019,59(3):257-264

Geomagnetism and Aeronomy - The results from a statistical analysis of solar wind data obtained near the Earth’s orbit by the DSCOVR spacecraft for the period of one year starting August 2016...  相似文献   

Study of the Galactic Rotation Based on Masers and Radio Stars with VLBI Measurements of Their Parallaxes     

Bobylev  V. V.  Krisanova  O. I.  Bajkova  A. T. 《Astronomy Letters》2020,46(7):439-448

Astronomy Letters - Based on published data, we have produced a sample of 256 radio sources whose trigonometric parallaxes and proper motions were measured by VLBI. This sample contains Galactic...  相似文献   

Paleozoic Age of Metaterrigenous Sequences of the Maksyutov Metamorphic Complex (Southern Urals): Results of U–Pb Dating of Detrital Zircons     

Golionko  B. G.  Ryazantsev  A. V.  Degtyarev  K. E.  Kanygina  N. A.  Kuznetsov  N. B.  Sheshukov  V. S.  Dubensky  A. S.  Gareev  B. I. 《Doklady Earth Sciences》2020,493(2):578-583

Doklady Earth Sciences - The first U–Pb (LA–ICP–MS) isotope dating of detrital zircons from quartzites of two strata of the Maksyutov metamorphic complex (Southern Urals) was...  相似文献   

Geodynamic Model of the Neoproterozoic Evolution of the Yenisei Paleosubduction Zone (Western Margin of the Siberian Craton), Russia     

Kozlov  P. S.  Filippov  Yu. F.  Likhanov  I. I.  Nozhkin  A. D. 《Geotectonics》2020,54(1):54-67

Geotectonics - The article proposes a model of collisional and accretionary events of the Neoproterozoic at the western margin of the Siberian Craton based on the results of geological,...  相似文献   

Uncertainty of hydrologic simulation,and its impact on the design and the effectiveness of water conservation structures     

Vema  Vamsi Krishna  Sudheer  K. P.  Chaubey  I. 《Stochastic Environmental Research and Risk Assessment (SERRA)》2020,34(7):973-991

Stochastic Environmental Research and Risk Assessment - The uncertainties associated with the simulation models are often ignored in operational hydrology. While many methods are available for...  相似文献