Nitrate reduction potential of a fractured Middle Triassic carbonate aquifer in Southwest Germany     

Osenbr&#;ck  Karsten  Blendinger  Eva  Leven  Carsten  R&#;gner  Hermann  Finkel  Michael  Jakus  Natalia  Schulz  Hartmut  Grathwohl  Peter 《Hydrogeology Journal》2022,30(1):163-180

Hydrogeology Journal - Nitrate reduction constitutes an important natural mechanism to mitigate the widespread and persistent nitrate contamination of groundwater resources. In fractured aquifers,...  相似文献   

The role of external forcing in prolonged trends in Australian rainfall     

Carsten S. Frederiksen  Simon Grainger 《Climate Dynamics》2015,45(9-10):2455-2468

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The Forgotten Nutrient——The Role of Nitrogen in Permafrost Soils of Northern China     

Elisabeth RAMM  Chunyan LIU  Xianwei WANG  Hongyu YUE  Wei ZHANG  Yuepeng PAN  Michael SCHLOTER  Silvia GSCHWENDTNER  Carsten W. MUELLER  Bin HU  Heinz RENNENBERG  Michael DANNENMANN 《大气科学进展》2020,37(8):793-799

正1.Introduction:permafrost carbon and nitrogen feedback to climate change Permafrost refers to any ground, including soils, sediments and rocks, with a temperature at or below the freezing point of water (0℃) for two or more consecutive years (Biskaborn et al., 2019). Permafrost soils of the Northern Hemisphere store vast amounts of both organic carbon (C) and nitrogen (N)(Tarnocai et al., 2009; Harden et al., 2012; Mueller et al.,  相似文献   

Optimizing the Environmental Performance of In Situ Thermal Remediation Technologies Using Life Cycle Assessment   总被引：3，自引：0，他引：3  

Gitte Lemming  Steffen G. Nielsen  Klaus Weber  Gorm Heron  Ralph S. Baker  Jacqueline A. Falkenberg  Mads Terkelsen  Carsten B. Jensen  Poul L. Bjerg 《Ground Water Monitoring & Remediation》2013,33(3):38-51

In situ thermal remediation technologies provide efficient and reliable cleanup of contaminated soil and groundwater, but at a high cost of environmental impacts and resource depletion due to the large amounts of energy and materials consumed. This study provides a detailed investigation of four in situ thermal remediation technologies (steam enhanced extraction, thermal conduction heating, electrical resistance heating, and radio frequency heating) in order to (1) compare the life‐cycle environmental impacts and resource consumption associated with each thermal technology, and (2) identify options to reduce these adverse effects. The study identifies a number of options for environmental optimization of in situ thermal remediation. In general, environmental optimization can be achieved by increasing the percentage of heating supplied in off peak electricity demand periods as this reduces the pressure on coal‐based electricity and thereby reduces the environmental impacts due to electricity production by up to 10%. Furthermore, reducing the amount of concrete in the vapor cap by using a concrete sandwich construction can potentially reduce the environmental impacts due to the vapor cap by up to 75%. Moreover, a number of technology‐specific improvements were identified, for instance by the substitution of stainless steel types in wells, heaters, and liners used in thermal conduction heating, thus reducing the nickel consumption by 45%. The combined effect of introducing all the suggested improvements is a 10 to 21% decrease in environmental impacts and an 8 to 20% decrease in resource depletion depending on the thermal remediation technology considered. The energy consumption was found to be the main contributor to most types of environmental impacts; this will, however, depend on the electricity production mix in the studied region. The combined improvement potential is therefore to a large extent controlled by the reduction/improvement of energy consumption.  相似文献   

Investigation of the geochemical impact of CO2 on shallow groundwater: design and implementation of a CO2 injection test in Northeast Germany     

Anita Peter  Hendrik Lamert  Matthias Beyer  G?tz Hornbruch  Ben Heinrich  Alexandra Schulz  Helmut Geistlinger  Ben Schreiber  Peter Dietrich  Ulrike Werban  Carsten Vogt  Hans-Hermann Richnow  Jochen Gro?mann  Andreas Dahmke 《Environmental Earth Sciences》2012,67(2):335-349

A small scale and temporally limited CO₂ injection test was performed in a shallow aquifer to investigate the geochemical impact of CO₂ upon such aquifers and to apply and verify different monitoring methods. Detailed site investigation coupled with multiphase simulations were necessary to design the injection experiment and to set up the monitoring network, before CO₂ was injected over a ten-day period at three injection wells, at a depth of 18?m below surface level into a quaternary sand aquifer located close to the town of Wittstock in Northeast Germany. Monitoring methods comprised groundwater sampling and standard analyses, as well as trace element analyses and isotope analyses; geoelectrical borehole monitoring; passive samplers to analyse temporally integrated for cations and multi-parameter probes that can measure continuously for dissolved CO₂, pH and electrical conductivity. Due to CO₂ injection, total inorganic carbon concentrations increased and pH decreased down to a level of 5.1. Associated reactions comprised the release of major cations and trace elements. Geoelectrical monitoring, as well as isotope analyses and multi-parameter probes proved to be suitable methods for monitoring injected CO₂ and/or the alteration of groundwater.  相似文献   

Variability of seasonal-mean fields arising from intraseasonal variability. Part 3: Application to SH winter and summer circulations     

Carsten S. Frederiksen  Xiaogu Zheng 《Climate Dynamics》2007,28(7-8):849-866

A study has been made, using the National Centers for Environmental Prediction and National Center for Atmospheric Research re-analysis 500 hPa geopotential height data, to determine how intraseasonal variability influences, or can generate, coherent patterns of interannual variability in the extratropical summer and winter Southern Hemisphere atmospheric circulation. In addition, by separating this intraseasonal component of interannual variability, we also consider how slowly varying external forcings and slowly varying (interannual and longer) internal dynamics might influence the interannual variability of the Southern Hemisphere circulation. This slow component of interannual variation is more likely to be potentially predictable. How sea surface temperatures are related to the slow components is also considered. The four dominant intraseasonal modes of interannual variability have horizontal structures similar to those seen in both well-known intraseasonal dynamical modes and statistical modes of intraseasonal variability. In particular, they reflect intraseasonal variability in the high latitudes associated with the Southern Annular Mode, and wavenumber 4 (summer) and wavenumber 3 (winter) patterns associated with south Pacific regions of persistent anomalies and blocking, and possibly variability related to the Madden-Julian Oscillation (MJO). The four dominant slow components of interannual variability, in both seasons, are related to high latitude variability associated with the Southern Annular Mode, El Nino Southern Oscillation (ENSO) variability, and South Pacific Wave variability associated with Indian Ocean SSTs. In both seasons, there are strong linear trends in the first slow mode of high latitude variability and these are shown to be related to similar trends in the Indian Ocean. Once these are taken into account there is no significant sea surface temperature forcing of these high latitude modes. The second and third ENSO related slow modes, in each season, have high correlations with tropical sea surface temperature variability in the Pacific and Indian Oceans, both contemporaneously and at one season lag. The fourth slow mode has a characteristic South Pacific wave structure of either a wavenumber 4 (summer) or wavenumber 3 (winter) pattern, with strongest loadings in the South Pacific sector, and an association simultaneously with a dipole SST temperature gradient in the subtropical Indian Ocean.  相似文献   

Assessment of the atmospheric nitrogen and sulphur inputs into the North Sea using a Lagrangian model     

O. Hertel  C. Ambelas Skjøth  L.M. Frohn  E. Vignati  J. Frydendall  G. de Leeuw  Uwe Schwarz  Stefan Reis 《Physics and Chemistry of the Earth》2002,27(35):1507-1515

The atmospheric chemistry and deposition model has been applied for calculation of nitrogen and sulphur depositions to the entire North Sea area for the year 1999. The total atmospheric nitrogen and sulphur depositions to the North Sea area were determined to 709 kton (kt) N and 551 kt S, respectively. Since the North Sea area was calculated to be 747,988 km², this is equivalent to an average deposition of 0.9 ton N km^?2 and 0.7 ton S km^?2, respectively. The depositions decrease strongly from the south end (about 2–3 kt N km^?2) to the north end (about 0.2 kt N km^?2) of the North Sea, due to increasing distance to the large source areas in the northern part of the European continent. The territorial waters of Belgium, the Netherlands and Germany receive about 50% higher deposition densities than the average value for the entire North Sea area. For the remaining territorial waters of the North Sea the depositions follow more or less the fraction of the area. The results furthermore show that about 60% of the total nitrogen deposition is related to emissions from combustion sources (nitrogen oxides) and about 40% from emissions related to agricultural activities (ammonia).  相似文献   

Tracking deepwater oxygen recovery using sedimentary chironomid assemblages: Peninsula Lake revisited     

Jeziorski  Adam  Nelligan  Clare  Corrigan  Dara  Meyer-Jacob  Carsten  Paterson  Andrew M.  Smol  John P. 《Journal of Paleolimnology》2021,66(4):371-387

Journal of Paleolimnology - Peninsula Lake, Ontario, Canada, is a Precambrian Shield lake that has experienced many environmental stressors since European settlement of the watershed in the...  相似文献   

Lu-Hf garnet geochronology of eclogites from the Balma Unit (Pennine Alps): implications for Alpine paleotectonic reconstructions     

Daniel Herwartz  Carsten Münker  Erik E. Scherer  Thorsten J. Nagel  Jan Pleuger  Nikolaus Froitzheim 《Swiss Journal of Geoscience》2008,101(1):173-189

Three samples of eclogite from the Balma Unit, an ophiolite sheet on top of the Monte Rosa Nappe in the Pennine Alps, were investigated in terms of their P-T evolution, geochemistry, and Lu-Hf geochronology. The paleogeographic origin of this unit is controversial (North Penninic vs. South Penninic). It has been interpreted as a piece of Late Cretaceous oceanic crust, on the basis of ca. 93 Ma U-Pb SHRIMP ages of synmagmatic zircon cores in an eclogite. Trace element and isotope data suggest a mid ocean ridge (MOR) rather than an intraplate or OIB setting for the protoliths of the eclogites. Electron microprobe analyses of representative garnets show typical prograde zoning profiles. Estimated peak metamorphic temperatures of 550–600 Cº most likely did not exceed the closure temperature of the Lu-Hf system. Hence, Lu-Hf ages most likely reflect garnet growth in the studied samples. To minimize inclusion effects on age determinations, a selective digestion procedure for garnet was applied, in which zircon and rutile inclusions are not dissolved. The ages obtained for three samples, 42.3 ± 0.6 Ma (MSWD: 0.47), 42 ± 1 Ma (MSWD: 3.0) and 45.5 ± 0.3 Ma (MSWD: 0.33), are younger than all Lu-Hf ages reported so far for South Penninic Units. Metamorphic zircon domains of the 42.3 Ma sample (PIS1) were previously dated by U-Pb SHRIMP at 40.4 ± 0.7 Ma, indicating that the growth of metamorphic zircon post-dated the onset of garnet growth.These new data put important constraints on the paleogeographic reconstruction of the Alps. The MORB character of the rocks, together with their previously published protolith age, imply that oceanic spreading was still taking place in the Late Cretaceous. This supports a North Penninic origin for our samples because plate tectonic models predict Cretaceous spreading in the North Penninic but not in the South Penninic Ocean. If the Balma Unit is indeed North Penninic, the new Lu-Hf data, in combination with published geochronological data, require that two independent subduction zones consumed the South and North Penninic oceans.  相似文献   

Extracting central places from the link structure in Wikipedia          下载免费PDF全文

Carsten Keßler 《Transactions in GIS》2017,21(3):488-502

Explicit information about places is captured in an increasing number of geospatial datasets. This article presents evidence that relationships between places can also be captured implicitly. It demonstrates that the hierarchy of central places in Germany is reflected in the link structure of the German language edition of Wikipedia. The official upper and middle centers declared, based on German spatial laws, are used as a reference dataset. The characteristics of the link structure around their Wikipedia pages, which link to each other or mention each other, and how often, are used to develop a bottom‐up method for extracting central places from Wikipedia. The method relies solely on the structure and number of links and mentions between the corresponding Wikipedia pages; no spatial information is used in the extraction process. The output of this method shows significant overlap with the official central place structure, especially for the upper centers. The results indicate that real‐world relationships are in fact reflected in the link structure on the web in the case of Wikipedia.  相似文献