Impact of peatland drainage and restoration on esker groundwater resources: modeling future scenarios for management   总被引：1，自引：0，他引：1  

Pekka M. Rossi  Pertti Ala-aho  John Doherty  Bjørn Kløve 《Hydrogeology Journal》2014,22(5):1131-1145

Esker aquifers are common groundwater bodies in Europe. Management of these aquifers should take account of the sustainability of groundwater-dependent ecosystems and land use in an integrated way. An unconfined esker aquifer in northern Finland was modelled with MODFLOW to determine how groundwater resources are impacted by the surrounding peatland drainage scheme and to simulate scenarios for possible drainage restoration. The impacts of groundwater abstraction and climate change were also simulated. A calibration-constrained Monte Carlo method was used to provide information on the uncertainties associated with model predictions. The results suggest that peatland drainage in the vicinity of eskers can have a significant role in lowering the water table, even though climate variability may mask these impacts. Drainage restoration by filling the ditches might have positive impacts on the aquifer water levels. Comparison of water-table changes caused by peatland drainage with the changes brought by water abstraction and climate variability helped to quantify impacts of different land-use scenarios and facilitated discussion with the local stakeholders. Based on this study, more attention should be devoted to peatland drainage schemes in integrated groundwater management of esker aquifers.  相似文献   

Interacting Kasner-type cosmologies     

Mauricio Cataldo  Fabiola Ar��valo  Patricio Mella 《Astrophysics and Space Science》2011,333(1):287-293

It is well known that Kasner-type cosmologies provide a useful framework for analyzing the three-dimensional anisotropic expansion because of the simplification of the anisotropic dynamics. In this paper relativistic multi-fluid Kasner-type scenarios are studied. We first consider the general case of a superposition of two ideal cosmic fluids, as well as the particular cases of non-interacting and interacting ones, by introducing a phenomenological coupling function q(t). For two-fluid cosmological scenarios there exist only cosmological scaling solutions, while for three-fluid configurations there exist not only cosmological scaling ones, but also more general solutions. In the case of triply interacting cosmic fluids we can have energy transfer from two fluids to a third one, or energy transfer from one cosmic fluid to the other two. It is shown that by requiring the positivity of energy densities there always is a matter component which violates the dominant energy condition in this kind of anisotropic cosmological scenarios.  相似文献   

Highly radiative shock experiments driven by GEKKO XII     

A. Dizi��re  C. Michaut  M. Koenig  C. D. Gregory  A. Ravasio  Y. Sakawa  Y. Kuramitsu  T. Morita  T. Ide  H. Tanji  H. Takabe  P. Barroso  J.-M. Boudenne 《Astrophysics and Space Science》2011,336(1):213-218

In this paper, recent results obtained on highly radiative shocks generated in a xenon filled gas cell using the GEKKO XII laser facility are presented. Data show extremely high shock velocity (??150 km/s) never achieved before in gas. Preliminary analyses based on theoretical dimensionless numbers and numerical simulations suggest that these radiative shocks reach a new radiative regime where the radiative pressure plays a role in the dynamics and structure of the shock. A major effect observed is a strong anisotropic emission in the downstream gas. This unexpected feature is discussed and compared to available 2D radiation hydrodynamic simulations.  相似文献   

Comments on “A late Triassic 40Ar/39Ar age for the El Hammam high-REE fluorite deposit (Morocco): mineralization related to the Central Atlantic Magmatic Province?” by Cheilletz et al. (Mineralium Deposita 45:323–329, 2010)     

Mohammed Bouabdellah  David Banks  Andreas Klügel 《Mineralium Deposita》2010,45(7):729-731

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Grain size,geochemistry and organic pollutants in modern fluvial deposits in eastern Moravia (Czech Republic)     

Slavomír Nehyba  K. Hilscherová  J. Jarkovský  L. Dušek  T. Kuchovský  J. Zeman  J. Klánová  I. Holoubek 《Environmental Earth Sciences》2010,60(3):591-602

Modern fluvial deposits from both small and large rivers were studied at 14 monitoring sites over 2 years (4 successive sampling seasons) in the area of eastern Moravia (Czech Republic). Grain size, geochemistry, content of persistent organic pollutants (PAHs, PCBs, HCHs, DDTs, HCBs and PeCB) and TOC were examined with the aim to understand their mutual relations and seasonal variations in sediment character and pollutant content. Sand and silt fraction predominate and the clay content is relatively low. Differences in provenance for various river systems were recognised. Both regional and seasonal variations in terms of content of persistent organic pollutants were documented. The content of TOC and mud was shown to play an important role in the accumulation of chlorinated persistent organic pollutants PCBs, HCHs, DDTs and HCB.  相似文献   

The Measurement of Active Chlorine in the Atmosphere by Chemical Amplification     

D. Perner  T. Arnold  J. Crowley  T. Klüpfel  M. Martinez  R. Seuwen 《Journal of Atmospheric Chemistry》1999,34(1):9-20

Chemical amplification, CA, a method commonly used for the detection of peroxy radicals, HO₂ and RO₂, was found to be sensitive towards ClOx (Cl+ClO+OClO) as well. ClOx is reduced by NO to Cl atoms which react with carbon monoxide in the presence of O₂. The reaction sequence thus initiated oxidizes CO to CO₂ and NO to NO₂, with a chain length of 300 ± 60. This allows the atmospheric ClOx content to be measured under ambient conditions with a detection limit of better than 1 ppt. In parallel peroxy radicals are indicated with a chain length of 160 ± 15. Chemical amplification is not specific and does not indicate which radical chain it is seeing. Identification relies solely on plausibility. During the ARCtic Tropospheric Ozone Chemistry (ARCTOC) campaign in spring 1995 and 1996 the CA technique was used at Ny-Ålesund. ClOx at mixing ratios of up to 2 ppt were found in the boundary layer under certain conditions. The low concentrations of ClOx indicate that the arctic boundary ozone depletion is mainly driven by bromine.  相似文献