Spatio-temporal patterns of throughfall and solute deposition in an open tropical rain forest   总被引：4，自引：0，他引：4  

Alexander Zimmermann  Sonja Germer  Christopher Neill  Alex V. Krusche  Helmut Elsenbeer 《Journal of Hydrology》2008,360(1-4):87-102

The brief interaction of precipitation with a forest canopy can create a high spatial variability of both throughfall and solute deposition. We hypothesized that (i) the variability in natural forest systems is high but depends on system-inherent stability, (ii) the spatial variability of solute deposition shows seasonal dynamics depending on the increase in rainfall frequency, and (iii) spatial patterns persist only in the short-term. The study area in the north-western Brazilian state of Rondônia is subject to a climate with a distinct wet and dry season. We collected rain and throughfall on an event basis during the early wet season (n = 14) and peak of the wet season (n = 14) and analyzed the samples for pH and concentrations of , Na⁺, K⁺, Ca²⁺, Mg²⁺, Cl⁻, , and DOC. The coefficient of variation for throughfall based on both sampling intervals was 29%, which is at the lower end of values reported from other tropical forest sites, but which is higher than in most temperate forests. Coefficients of variation of solute deposition ranged from 29% to 52%. This heterogeneity of solute deposition is neither particularly high nor particularly low compared with a range of tropical and temperate forest ecosystems. We observed an increase in solute deposition variability with the progressing wet season, which was explained by a negative correlation between heterogeneity of solute deposition and antecedent dry period. The temporal stability of throughfall patterns was low during the early wet season, but gained in stability as the wet season progressed. We suggest that rapid plant growth at the beginning of the rainy season is responsible for the lower stability, whereas less vegetative activity during the later rainy season might favor the higher persistence of “hot” and “cold” spots of throughfall quantities. The relatively high stability of throughfall patterns during later stages of the wet season may influence processes at the forest floor and in the soil. Solute deposition patterns showed less clear trends but all patterns displayed a short-term stability only. The weak stability of those patterns is apt to impede the formation of solute deposition-induced biochemical microhabitats in the soil.  相似文献   

Pressure-dependent Production Efficiency of an Enhanced Geothermal System (EGS): Stimulation Results and Implications for Hydraulic Fracture Treatments     

Günter Zimmermann  Torsten Tischner  Björn Legarth  Ernst Huenges 《Pure and Applied Geophysics》2009,166(5-7):1089-1106

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Microseismicity induced during fluid-injection: A case study from the geothermal site at Groß Schönebeck,North German Basin   总被引：1，自引：1，他引：0  

Grzegorz Kwiatek  Marco Bohnhoff  Georg Dresen  Ali Schulze  Thomas Schulte  Günter Zimmermann  Ernst Huenges 《Acta Geophysica》2010,58(6):995-1020

The technical feasibility of geothermal power production in a low enthalpy environment will be investigated in the geothermal site at Groß Schönebeck, North German Basin, where a borehole doublet was completed in 2007. In order to complete the Enhanced Geothermal System, three massive hydraulic stimulations were performed. A seismic network was deployed including a single 3-component downhole seismic sensor at only 500 m distance to the injection point. Injection rates reached up to 9 m³/min and the maximum injection well-head pressure was as high as ～60 MPa. A total of 80 very small (?1.8 < M _W < ?1.0) induced seismic events were detected. The hypocenters were determined for 29 events. The events show a strong spatial and temporal clustering and a maximum seismicity rate of 22 events per day. Spectral parameters were estimated from the downhole seismometer and related to those from other types of induced seismicity. The majority of events occurred towards the end of stimulation phases indicating a similar behavior as observed at similar treatments in crystalline environments but in our case at a smaller level of seismic activity and at lower magnitudes.  相似文献   

Backshore coarsening processes triggered by wave‐induced sand transport: the critical role of storm events     

Keiko Udo  Akira Mano 《地球表面变化过程与地形》2010,35(11):1269-1280

Spatial backshore processes were investigated through field observations of topography and median sand grain size at a sandy beach facing the Pacific Ocean in Japan. A comparison of the backshore profile and cross‐shore distribution of the median sand grain size in 1999 and 2004 revealed an unusual sedimentary process in which sand was coarsened in a depositional area in the 5‐year period, although sediment is generally coarsened in erosional areas. In support of these observations, monthly spatial field analyses carried out in 2004 demonstrated a remarkable backshore coarsening process triggered by sedimentation in the seaward part of the backshore during a storm event. In order to elucidate mechanisms involved in the backshore coarsening process, thresholds of movable sand grain size under wave and wind actions (a uniform parameter for both these cases) in the onshore and offshore directions were estimated using wave, tide, and wind data. The cross‐shore distributions of the estimated thresholds provided reasonable values and demonstrated a coarsening mechanism involving the intermediate zone around the shoreline under alternating wave and wind actions as a result of which coarse sand was transported toward the seaward part of the backshore by large waves during storms and then toward the landward part by strong onshore winds. The 5‐year backshore coarsening is most certainly explained by repetition of short‐term coarsening mechanisms caused by wave‐induced sand transport occurring from the nearshore to the intermediate zone. Copyright © 2010 John Wiley & Sons, Ltd  相似文献   

A new towed marine vector magnetometer: methods and results from a Central Pacific cruise   总被引：1，自引：0，他引：1  

Martin Engels  Udo Barckhausen  Jeffrey S. Gee 《Geophysical Journal International》2008,172(1):115-129

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Der Einfluss der Strömung auf die Zusammensetzung der Lebensgemeinschaften im Experiment     

P. Zimmermann 《Aquatic Sciences - Research Across Boundaries》1962,24(2):408-411

Ohne Zusammenfassung  相似文献   

A method to reconstruct flood scenarios using field interviews and hydrodynamic modelling: application to the 2017 Suleja and Tafa,Nigeria flood     

Malgwi  Mark Bawa  Ramirez  Jorge Alberto  Zischg  Andreas  Zimmermann  Markus  Schürmann  Stefan  Keiler  Margreth 《Natural Hazards》2021,108(2):1781-1805

Natural Hazards - The scarcity of model input and calibration data has limited efforts in reconstructing scenarios of past floods in many regions globally. Recently, the number of studies that use...  相似文献   

Nitric oxide emissions from soils: a case study with temperate soils from Saxony, Germany   总被引：1，自引：1，他引：0  

Cornelius Oertel  Kurt Herklotz  J?rg Matschullat  Frank Zimmermann 《Environmental Earth Sciences》2012,66(8):2343-2351

Nitrogen oxides (NO _x ) are involved in acid rain and ozone formation, as well as destruction. NO _x are climate-relevant trace gases in the atmosphere. Atmospheric NO _x originate from anthropogenic emissions (mainly combustion processes). NO from natural processes derives from thunderstorms and soil microbial processes. They may play a crucial role in soil?Catmosphere feedback processes. This study aims to investigate NO _x -emissions from soils under different land use, geographical and meteorological conditions. NO _x -emissions were quantified in both field and laboratory experiments with a closed static chamber. Disturbed soil samples have been used for laboratory experiments. A climate chamber was used to regulate soil temperature of the samples. Field experiments showed that NO-soil emissions strongly depend on soil temperature. NO-emissions from a soil under meadow showed significant daily variations, unlike soil below spruce forest. Peak emission values were 18???g NO?CN?m^?2?h^?1 above meadow and 1.3???g NO?CN?m^?2?h^?1 under forest canopy. In addition, NO-emissions of meadow and forest soil were studied in a climate chamber, enhanced by an additional experiment with agricultural soil. These experiments revealed strong exponential correlations of NO-emissions and soil temperature. Maximum values reached above 400???g NO?CN?m^?2?h^?1 from agricultural soils at soil temperatures above 50°C. This study shows that soil NO-emissions strongly depend on temperature, vegetation type and geographical position. Consequently, NO-emissions may have a positive feedback effect on climate change.  相似文献   

Seafloor spreading anomalies and crustal ages of the Clarion-Clipperton Zone     

Udo Barckhausen  Meike Bagge  Douglas S. Wilson 《Marine Geophysical Researches》2013,34(2):79-88

The Clarion-Clipperton Zone (CCZ) of the central Pacific is one of the few regions in the world’s oceans that are still lacking full coverage of reliable identifications of seafloor spreading anomalies. This is mainly due to the geometry of the magnetic lineations’ strike direction sub-parallel to the Earth’s magnetic field vector near the equator resulting in low amplitude magnetic anomalies, and the remoteness of the region which has hindered systematic surveying in the past. Following recently granted research licenses for manganese nodules in the CCZ by the International Seabed Authority, new magnetic data acquired with modern instrumentation became available which combined with older underway data make the identification of seafloor spreading anomalies possible for large parts of the CCZ and adjacent areas. The spreading rates deduced from the seafloor spreading patterns show a sharp increase at the end of Chron 21 (47.5 Ma) which corresponds to the age of the bend in the Hawaii-Emperor seamount chain and an associated plate tectonic reorganisation in the Central Pacific. An accurate map of crustal ages for the central-eastern Pacific based on our anomaly picks may provide a basis for improved plate tectonic reconstructions of the region.  相似文献   

Volatile Organic Compounds in Various Marine Organisms From the Southern North Sea     

Patrick Roose  Udo A. Th. Brinkman 《Marine pollution bulletin》2000,40(12):1167-1177

The concentration levels of 12 priority volatile organic compounds (VOCs) were determined in two species of vertebrates and four species of invertebrates from sampling stations in the southern North Sea, using a modified Tekmar LSC 2000 purge and trap system coupled to gas chromatograph–mass spectrometer (GC–MS). In general, concentration levels of VOCs found in this study were of the same order of magnitude as those previously reported in the literature. The concentrations of the chlorinated hydrocarbons (CHCs), with the exception of chloroform, tended to be lower than those of the monocyclic aromatic hydrocarbons (MAHs). The experimental data were statistically evaluated using both cluster analysis and principal component analysis (PCA). From the results of cluster analysis and PCA, no specific groups could be distinguished on the basis of geographical, temporal or biological parameters. However, based on the cluster analysis and the PCA, the VOCs could be divided into three groups, C₂-substituted benzenes, CHCs and benzene plus toluene. This division could be related to different types of sources. Finally, it was shown that organisms can be used to monitor the presence of VOCs in the marine environment and the observed concentrations levels were compared with proposed safety levels.  相似文献