Numerical Modeling of Nitrate Removal in Anoxic Groundwater during River Flooding of Riparian Zones     

Jannick Kolbjørn Jensen  Bertel Nilsson  Peter Engesgaard 《Ground water》2021,59(6):866-877

A numerical study demonstrates the effects of flooding on subsurface hydrological flowpaths and nitrate removal in anoxic groundwater in riparian zones with a top peat layer. A series of two-dimensional numerical simulations with changing conditions for flow (steady state or transient with flooding), hydrogeology, denitrification, and duration of flooding demonstrate how flowpaths, residence times, and nitrate removal are affected. In periods with no flooding groundwater flows horizontally and discharges to the river through the riverbed. During periods with flooding, shallow groundwater is forced upwards as discharge through peat layers that often have more optimal conditions for denitrification caused by the presence of highly reactive organic matter. The contrast in hydraulic conductivity between the sand aquifer and the overlying peat layer, as well as the flooding duration, have a significant role in determining the degree of nitrate removal.  相似文献   

High-frequency Faraday rotation observations of the solar corona     

Elizabeth A. Jensen 《Planetary and Space Science》2008,56(11):1562-1564

This thesis, presented on January 31, 2007 under the supervision of Professor Christopher T. Russell, discusses the solar coronal magnetic field observations that can be obtained using the phenomenon of Faraday rotation. It was defended in the Department of Earth and Space Sciences at the University of California, Los Angeles (595 Charles E. Young, Dr. East, Los Angeles, CA 90095). A resume can be found at http://acs-consulting.com/.  相似文献   

Bayesian Inversion in Hidden Markov Models with Varying Marginal Proportions     

Moja  Selamawit Serka  Asfaw  Zeytu Gashaw  Omre  Henning 《Mathematical Geosciences》2019,51(4):463-484

Mathematical Geosciences - Knowledge of the sub-surface characteristics is crucial in many engineering activities. Sub-surface soil classes must, for example, be predicted from indirect...  相似文献   

Late Pleistocene stratigraphy and sedimentary environments of the Severnaya Dvina‐Vychegda region in northwestern Russia     

Astrid Lyså  Eiliv Larsen  Jan‐Pieter Buylaert  Ola Fredin  Maria A. Jensen  Denis Kuznetsov  Andrew S. Murray  Dmitry A. Subetto  Aurelien van Welden 《Boreas: An International Journal of Quaternary Research》2014,43(4):759-779

The Late Pleistocene stratigraphy from the Severnaya Dvina‐Vychegda region of northwestern Russia is revised based on investigations of new localities, revisiting earlier localities, introduction of about 110 new OSL dates and burial depth corrections of earlier published OSL dates, in addition to six new radiocarbon dates. Most of the OSL samples studied here are from fluvial and subaquaeous sediments, which we found to be well bleached. Six chronostratigraphical units and their sedimentary environment are described, with the oldest unit consisting of pre‐Eemian glacial beds. For the first time, Early Weichselian sediments are documented from the region and a fluvial environment with some vegetation and permafrost conditions is suggested to have persisted from the end of the Eemian until at least about 92 ka ago. The period in which a Middle Weichselian White Sea Lake could have existed is constrained to 67?62 ka, but as the lake level never reached the thresholds of the drainage basin, the lake probably existed only for a short interval within this time‐span. Blocking and reversal of fluvial drainage started again around 21?20 ka ago when the Fennoscandian Ice Sheet advanced into the area, reaching its maximum 17?15 ka ago. At that time, an ice‐dammed lake reached its maximum water level, which was around 135 m above present sea level. Drainage of the lake started shortly after 15 ka ago, and the lake was emptied within 700 years. Severe periglacial conditions, with permafrost and aeolian activity, prevailed in the area until about 10.7 ka.  相似文献   

Die Red Beds     

Karl L. Henning 《International Journal of Earth Sciences》1913,4(4):228-244

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Alaska in den Jahren 1909 und 1910     

Charles L. Henning 《International Journal of Earth Sciences》1912,3(1):35-50

Ohne Zusammenfassung  相似文献   

Analysis of pumping tests of partially penetrating wells in an unconfined aquifer using inverse numerical optimization     

S. Hvilshøj  K. H. Jensen  H. C. Barlebo  B. Madsen 《Hydrogeology Journal》1999,7(4):365-379

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Meeresschutzgebiete für den Nordost-Atlantik und die ostsee im Rahmen der Oslo-Paris-und der Helsinki-Übereinkommen     

von Nordheim  Henning 《Ocean Dynamics》1999,51(10):117-124

Ocean Dynamics - Seit Jahrzehnten, besonders intensiv jedoch seit Verabschiedung der “Konvention zum Schutz der Biologischen Vielfalt” in Rio (1992), werden Meeresgebiete unter Schutz...  相似文献   

Cessation of the Norwegian drift net fishery: changes observed in Norwegian and Russian populations of Atlantic salmon   总被引：3，自引：2，他引：1  

Jensen  A. J.; Zubchenko  A. V.; Heggberget  T. G.; Hvidsten  N. A.; Johnsen  B. O.; Kuzmin  O.; Loenko  A. A.; Lund  R. A.; Martynov  V. G.; Naesje  T. F.; Sharov  A. F.; Okland  F. 《ICES Journal of Marine Science》1999,56(1):84-95

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DEM simulation of granular media—structure interface: effects of surface roughness and particle shape     

Richard P. Jensen  Peter J. Bosscher  Michael E. Plesha  Tuncer B. Edil 《国际地质力学数值与分析法杂志》1999,23(6):531-547

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