Hydrological change modeling: Challenges and opportunities          下载免费PDF全文

Jan Seibert  H.J. van Meerveld 《水文研究》2016,30(26):4966-4971

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South foehn studies since the ALPEX experiment     

Dr. P. Seibert 《Meteorology and Atmospheric Physics》1990,43(1-4):91-103

Summary After the ALPEX Special Observing Period in 1982, further field measurement campaigns have been carried out to study the south foehn in the Eastern Alps. In addition, foehn situations were investigated statistically on the basis of a 4-years-record of upper-air and synoptic data combined with data from a special regional network. In this paper, distribution of air masses around the Alps, flow patterns and the typical evolution of a foehn situation are illustrated by the case 8 November 1982. Several possible definitions of shallow foehn are given, yielding a share of approximately 10% of shallow foehn observations. Mainly statistical data are used to falsify the wide-spread version of the thermodynamical foehn theory attributing the warmth of the foehn to release of latent heat and postulating foehn air rising from the ground of the Po Valley. Instead of this, the foehn air originates from 2000–2500 m asl over the Po Valley, while the air near ground remains blocked. The potential temperature difference between southern and northern valleys during foehn is to be explained by the stable stratification in the south, not by the effects of precipitation. These findings are in agreement with Hann's original theory.With 10 Figures  相似文献   

The biogeochemical fate and toxicity of mercury in Controlled Experimental Ecosystems     

Gordon T. Wallace  Don L. Seibert  Susan M. Holzknecht  W.H. Thomas 《Estuarine, Coastal and Shelf Science》1982,15(2):151-182

The affinity of mercury for organic matter was the most important parameter governing its chemical speciation, transport and toxicity in Controlled Experimental Ecosystems (CEEs) of the Controlled Ecosystem Pollution Experiment (CEPEX) deployed in Saanich Inlet, B.C., Canada, Particulate, colloidal and high molecular weight dissolved forms of mercury accounted for about 90% of the total mercury present in the water column. Bioassays indicated that organic matter in the above size classes had an important influence on the toxicity of mercury to phytoplankton.Sorption of mercury to particulate organic matter in the CEEs could be described by either Freundlich or linear adsorption isotherms. An observed depth-dependent increase in mercury content of particulate matter was attributed to selective biological degradation of non-mercury-binding organic components of the particles during settling.The high affinity of mercury for settling particulate organic matter led to rapid removal of mercury from CEEs. Removal rates could be described as first order and were a function of primary production rates. Deviations of measured half-removal times from those predicted by an empirically formulated relationship between primary production and mercury half-removal times could be related successfully to the influence of other occasionally significant biological parameters such as zooplankton grazing activity.  相似文献   

Assessment of hormonal activity of UV filters in tadpoles of frog Xenopus laevis at environmental concentrations     

Kunz PY  Galicia HF  Fent K 《Marine environmental research》2004,58(2-5):431-435

Residues of UV filters used as ultraviolet absorbers in sunscreens, cosmetics and in light protection have been found in surface water and fish. Recently some of them were shown bearing estrogenic activity, however, very little is known about possible adverse effects to aquatic life. Here we investigate whether two UV filters, 4-methylbenzylidene camphor (4-MBC) and 3-benzylidene camphor (3-BC), interfere with the thyroid and sex hormone system during frog metamorphosis. Xenopus laevis tadpoles were exposed to 1, 5 and 50 μg/L of 4-MBC and 3-BC, respectively, for 35 days (NF stage 52–66). The rate of metamorphosis was not affected, and no obvious differences in body and tail length compared to controls were observed. Neither 4-MBC, nor 3-BC led to effects on the sex ratio or gross gonad morphology of X. laevis at stage 66. Our results indicate that these UV filters do not negatively affect the thyroid system and sex ratio of frogs at environmental concentrations.  相似文献   

The Pfitsch-Mörchner Basin,an example of the post-Variscan sedimentary evolution in the Tauern Window (Eastern Alps)     

Petra Veselá  Bernd Lammerer 《Swiss Journal of Geoscience》2008,101(1):73-88

A review of post-Variscan metasedimentary and metavolcanic successions in the western Tauern Window is presented. U/Pb – datations of zircons in metavolcanic rocks reveal ages between 309 and 280 Ma. Deposition of grey conglomerates and black pelites started before 309 Ma in the northernmost basin of the Tauern, the Riffler-Schönach basin. In the more central Pfitsch-Mörchner basin, the onset of conglomerate sedimentation can be dated into the time span between 293 and 280 Ma. The Pfitsch and Windtal Formations are newly defined. The basins were filled with up to 1 km of mainly continental clastics until Early Triassic. Short marine ingressions in Middle- and Late Triassic times flooded only basinal parts of the area where we suppose a more or less continuous sedimentation until the Late Jurassic. Only the Hochstegen Marble documents a nearly complete submergence in the area of the Tauern Window. In spite of the metamorphic overprint, the tentative interpretations of the sedimentary facies give a reasonable picture and allow correlations to nonmetamorphic areas in South Germany or the External Massifs of Eastern Switzerland.  相似文献   

Natural and anthropogenic forcing of Holocene lake ecosystem development at Lake Uddelermeer (The Netherlands)     

Stefan Engels  Rogier van Oostrom  Chiara Cherli  Jennifer A. J. Dungait  Boris Jansen  J. M. van Aken  Bas van Geel  Petra M. Visser 《Journal of Paleolimnology》2018,59(3):329-347

Lake Uddelermeer (The Netherlands) is characterized by turbid conditions and annual blooms of toxic cyanobacteria, which are supposed to be the result of increased agricultural activity in the twentieth century AD. We applied a combination of classic palaeoecological proxies and novel geochemical proxies to the Holocene sediment record of Lake Uddelermeer (The Netherlands) in order to reconstruct the natural variability of the lake ecosystem and to identify the drivers of the change to the turbid conditions that currently characterize this lake. We show that the lake ecosystem was characterized by a mix of aquatic macrophytes and abundant phytoplankton between 11,500 and 6000 cal year BP. A transition to a lake ecosystem with clear-water conditions and relatively high abundances of ‘isoetids’ coincides with the first signs of human impact on the landscape around Lake Uddelermeer during the Early Neolithic (ca. 6000 cal year BP). An abrupt and dramatic ecosystem shift can be seen at ca. 1030 cal year BP when increases in the abundance of algal microfossils and concentrations of sedimentary pigments indicate a transition to a turbid phytoplankton-dominated state. Finally, a strong increase in concentrations of plant and faecal biomarkers is observed around 1950 AD. Canonical Correspondence Analysis suggests that reconstructed lake ecosystem changes are best explained by environmental drivers that show long-term gradual changes (sediment age, water depth). These combined results document the long-term anthropogenic impact on the ecosystem of Lake Uddelermeer and provide evidence for pre-Industrial Era signs of eutrophication.  相似文献   

Soil temperature regime and vulnerability due to extreme soil temperatures in Croatia     

Petra Sviličić  Višnja Vučetić  Suzana Filić  Ante Smolić 《Theoretical and Applied Climatology》2016,123(1-2):247-261

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Integrating parameter uncertainty of a process-based model in assessments of climate change effects on forest productivity     

Christopher P. O. Reyer  Michael Flechsig  Petra Lasch-Born  Marcel van Oijen 《Climatic change》2016,135(3-4):395-408

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Gamma dose rate and soil gas radon concentration measured at low soil thickness (Czech Republic)     

Ivan Barnet  Petra Pacherová 《Environmental Earth Sciences》2016,75(7):620

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The assumption of uniform specific discharge: unsafe at any time?          下载免费PDF全文

R. H. Karlsen  J. Seibert  T. Grabs  H. Laudon  P. Blomkvist  K. Bishop 《水文研究》2016,30(21):3978-3988

Nearby catchments in the same landscape are often assumed to have similar specific discharge (runoff per unit catchment area). Five years of streamflow from 14 nested catchments in a 68 km² landscape was used to test this assumption, with the hypothesis that the spatial variability in specific discharge is smaller than the uncertainties in the measurement. The median spatial variability of specific discharge, defined as subcatchment deviation from the catchment outlet, was 33% at the daily scale. This declined to 24% at a monthly scale and 19% at an annual scale. These specific discharge differences are on the same order of magnitude as predicted for major land‐use conversions or a century of climate change. Spatial variability remained when considering uncertainties in specific discharge, and systematic seasonal patterns in specific discharge variation further provide confidence that these differences are more than just errors in the analysis of catchment area, rainfall variability or gauging. Assuming similar specific discharge in nearby catchments can thus lead to spurious conclusions about the effects of disturbance on hydrological and biogeochemical processes. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献