Cooling and contamination of mafic and ultramafic magmas during ascent through continental crust   总被引：1，自引：0，他引：1  

Herbert E. Huppert  R. Stephen  J. Sparks 《Earth and Planetary Science Letters》1985,74(4):371-386

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Zur Ökologie des Brachsen (Abramis brama (L.)) im Bodensee     

Dr. Herbert Von Löffler 《Aquatic Sciences - Research Across Boundaries》1984,46(1):147-162

The reactions of the bream,Abramis brama, to the ecological changes due to man-made eutrophication of Lake Constance were investigated. It could be demonstrated that the bream adapted only to a negligible amount. Likely due to its largeness, structure of the body and population composition the bream is more conservative than perch, roach and whitefish. The only reactions to the changed environment are modificated vertical and horizontal distribution and partly plancton feeding in summer.   相似文献   

Gravitational and buckling instabilities of a rheologically layered structure: implications for salt diapirism   总被引：2，自引：0，他引：2  

Alik T. Ismail-Zadeh  Herbert E. Huppert  John R. Lister 《Geophysical Journal International》2002,148(2):288-302

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Incoherent Scatter Radar Studies of Daytime Plasma Lines     

Frank T. Djuth  Herbert C. Carlson  Liwei D. Zhang 《Earth, Moon, and Planets》2018,121(1-2):13-43

First results from wideband (electron phase energies of 5–51 eV), high-resolution (0.1 eV) spectral measurements of photoelectron–enhanced plasma lines made with the 430 MHz radar at Arecibo Observatory are presented. In the F region, photoelectrons produced by solar EUV line emissions (He II and Mg IX) give rise to plasma line spectral peaks/valleys. These and other structures occur within an enhancement zone extending from electron phase energies of 14–27 eV in both the bottomside and topside ionosphere. However, photoelectron–thermal electron Coulomb energy losses can lead to a broadened spectral structure with no resolved peaks in the topside ionosphere. The plasma line energy spectra obtained in the enhancement zone exhibit a unique relation in that phase energy is dependent on pitch angle; this relation does not exist in any other part of the energy spectrum. Moreover, large fluctuations in the difference frequency between the upshifted and downshifted plasma lines are evident in the 14–27 eV energy interval. At high phase energies near 51 eV the absolute intensities of photoelectron-excited Langmuir waves are much larger than those predicted by existing theory. The new measurements call for a revision/improvement of plasma line theory in several key areas.  相似文献   

Long-term trends of physical, chemical and biological variables in the River Danube 1957–1995: A statistical approach     

Herbert Weilguni  Uwe H. Humpesch 《Aquatic Sciences - Research Across Boundaries》1999,61(3):234-259

: A 39-year series (1957 – 1995) of data on fourteen physical, chemical and biological variables from the Austrian section of the River Danube west of Vienna – Nußdorf was analysed statistically to detect long-term trends of the variables in relation to human activities (represented by time), discharge and water temperature. ¶ Principal component analysis distinguished four main components explaining 72 % of the total variance: PC1 contains total phosphorus, soluble reactive phosphorus, ammonium and potassium permanganate values, PC2 contains nitrate-N, chloride and oxygen, PC3 contains BOD5 and nitrite-N, and PC4 contains numbers of bacteria. Trends in time were most pronounced for variables in PC1, but also occurred in PC2; variables in PC3 and PC4 had no trends. Seasonal patterns were marked for variables in PC2, slightly less in PC1, and least in PC3 and PC4. Concentrations were minimal in summer and maximal in winter, inversely related to discharge (maximal in summer). Following reductions in point-source nutrient inputs to the Danube, in both Germany and Austria, mean concentrations in the river have fallen by at least half since the 1980s. Chloride and nitrate-N also show trends towards lower concentrations. The Danube is well-oxygenated, with concentrations near air saturation values.¶ A mathematical relationship between concentrations of the variables and river discharge (Q), water temperature (T) and time (t), was established to determine mean trends and predictions against a background of considerable seasonal and stochastic variability; for the single variables Q explained 0 – 20 % and T explained 2 – 58 % of the variation in the concentrations. The relationship was highest for variables in PC2 and lowest for those in PC3 and PC4, where Q and T had little or no influence.¶ Reasons for rising and falling long-term trends with time are discussed in detail. Austria now contributes only minor proportions to the nutrient load of the Danube, which is causing eutrophication of the Black Sea downstream, and water quality of the Austrian section of the river is good.¶ The advantages and problems of statistical process analysis are discussed in relation to environmental monitoring programs and the different specific requirements of compliance monitoring.  相似文献   

Impact of water temperature on nutrient concentrations in the Oder estuary in 1996–1998     

Marianna Pastuszak  Herbert Siegel  Stanisław Sitek  Monika Gerth  Gisela Tschersich  Klaus Nagel  Alfred Grelowski 《Ocean Dynamics》1999,51(4):423-439

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Climate change effects on hydrological system conditions influencing generation of storm runoff in small Alpine catchments   总被引：1，自引：0，他引：1       下载免费PDF全文

Gertraud Meißl  Herbert Formayer  Klaus Klebinder  Florian Kerl  Friedrich Schöberl  Clemens Geitner  Gerhard Markart  David Leidinger  Axel Bronstert 《水文研究》2017,31(6):1314-1330

Floods and debris flows in small Alpine torrent catchments (<10 km²) arise from a combination of critical antecedent system state conditions and mostly convective precipitation events with high precipitation intensities. Thus, climate change may influence the magnitude–frequency relationship of extreme events twofold: by a modification of the occurrence probabilities of critical hydrological system conditions and by a change of event precipitation characteristics. Three small Alpine catchments in different altitudes in Western Austria (Ruggbach, Brixenbach and Längentalbach catchment) were investigated by both field experiments and process‐based simulation. Rainfall–runoff model (HQsim) runs driven by localized climate scenarios (CNRM‐RM4.5/ARPEGE, MPI‐REMO/ECHAM5 and ICTP‐RegCM3/ECHAM5) were used in order to estimate future frequencies of stormflow triggering system state conditions. According to the differing altitudes of the study catchments, two effects of climate change on the hydrological systems can be observed. On one hand, the seasonal system state conditions of medium altitude catchments are most strongly affected by air temperature‐controlled processes such as the development of the winter snow cover as well as evapotranspiration. On the other hand, the unglaciated high‐altitude catchment is less sensitive to climate change‐induced shifts regarding days with critical antecedent soil moisture and desiccated litter layer due to its elevation‐related small proportion of sensitive areas. For the period 2071–2100, the number of days with critical antecedent soil moisture content will be significantly reduced to about 60% or even less in summer in all catchments. In contrast, the number of days with dried‐out litter layers causing hydrophobic effects will increase by up to 8%–11% of the days in the two lower altitude catchments. The intensity analyses of heavy precipitation events indicate a clear increase in rain intensities of up to 10%.  相似文献   

Phosphorus input by upwelling in the eastern Gotland Basin (Baltic Sea) in summer and its effects on filamentous cyanobacteria     

Monika Nausch  Günther Nausch  Hans Ulrich Lass  Volker Mohrholz  Klaus Nagel  Herbert Siegel  Norbert Wasmund   《Estuarine, Coastal and Shelf Science》2009,83(4):434-442

In July 2007, phosphorus input by an upwelling event along the east coast of Gotland Island and the response of filamentous cyanobacteria were studied to determine whether introduced phosphorus can intensify cyanobacterial bloom formation in the eastern Gotland Basin. Surface temperature, nutrient concentrations, phytoplankton biomass and its stoichiometry, as well as phosphate uptake rates were determined in two transects between the coasts of Gotland and Latvia and in a short grid offshore of Gotland. In the upwelling area, surface temperatures of 11–12 °C and average dissolved inorganic phosphorus (DIP) concentrations of 0.26 μM were measured. Outside the upwelling, surface temperatures were higher (15.5–16.6 °C) and DIP supplies in the upper 10 m layer were exhausted. Nitrite and nitrate concentrations (0.01–0.22 μM) were very low within and outside the upwelling region. Abundances of filamentous cyanobacteria were highly reduced in the upwelling area, accounting for only 1.4–6.0% of the total phytoplankton biomass, in contrast to 18–20% outside the upwelling. The C:P ratio of filamentous cyanobacteria varied between 32.8 and 310 in the upwelling region, most likely due to the introduction of phosphorus-depleted organisms into the upwelling water. These organisms accumulate DIP in upwelling water and have lower C:P ratios as long as they remain in DIP-rich water. Thus, diazotrophic cyanobacteria benefit from phosphorus input directly in the upwelling region. Outside the upwelling region, the C:P ratios of filamentous cyanobacteria varied widely, between 240 and 463, whereas those of particulate material in the water ranged only between 96 and 224. To reduce their C:P ratio from 300 to 35, cyanobacteria in the upwelling region had to take up 0.05 mmol m⁻³ DIP, which is about 20% of the available DIP. Thus, a larger biomass of filamentous cyanobacteria may be able to benefit from a given DIP input. As determined from the DIP uptake rates measured in upwelling cells, the time needed to reduce the C:P ratio from 300 to 35 was too long to explain the huge bloom formations that typically occur in summer. However, phosphorus uptake rates increased significantly with increasing C:P ratios, allowing phosphorus accumulation within 4–5 days, a span of time suitable for bloom formation in July and August.  相似文献   

Policing Illegal Drug Markets: Geographic Approaches to Crime Reduction by George F. Rengert,Jerry H. Ratcliffe,and Sanjoy Chakravorty     

Steve Herbert 《The Professional geographer》2007,59(2):269-270

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Editorial     

Giovanni Barla  Herbert Einstein  Kalman Kovari 《Rock Mechanics and Rock Engineering》2007,40(1):1-1

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