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101.
ABSTRACTWe present a new model extension for the Water balance Simulation Model, WaSiM, which features (i) snow interception and (ii) modified meteorological conditions under coniferous forest canopies, complementing recently developed model extensions for particular mountain hydrological processes. Two study areas in Austria and Germany are considered in this study. To supplement and constrain the modelling experiments with on-site observations, a network of terrestrial time-lapse cameras was set up in one of these catchments. The spatiotemporal patterns of snow depth inside the forest and at the adjacent open field sites were recorded along with snow interception dynamics. Comparison of observed and modelled snow cover and canopy interception indicates that the new version of WaSiM reliably reconstructs the variability of snow accumulation for both the forest and the open field. The Nash-Sutcliffe efficiency computed for selected runoff events in spring increases from ?0.68 to 0.71 and 0.21 to 0.87, respectively. 相似文献
102.
Shear velocity u* is an important parameter in geophysical flows, in particular with respect to sediment transport dynamics. In this study, we investigate the feasibility of applying five standard methods [the logarithmic mean velocity profile, the Reynolds stress profile, the turbulent kinetic energy (TKE) profile, the wall similarity and spectral methods] that were initially developed to estimate shear velocity in smooth bed flow to turbulent flow over a loose bed of coarse gravel (D50 = 1·5 cm) under sub‐threshold conditions. The analysis is based on quasi‐instantaneous three‐dimensional (3D) full depth velocity profiles with high spatial and temporal resolution that were measured with an Acoustic Doppler Velocity Profiler (ADVP) in an open channel. The results of the analysis confirm the importance of detailed velocity profile measurements for the determination of shear velocity in rough‐bed flows. Results from all methods fall into a range of ± 20% variability and no systematic trend between methods was observed. Local and temporal variation in the loose bed roughness may contribute to the variability of the logarithmic profile method results. Estimates obtained from the TKE and Reynolds stress methods reasonably agree. Most results from the wall similarity method are within 10% of those obtained by the TKE and Reynolds stress methods. The spectral method was difficult to use since the spectral energy of the vertical velocity component strongly increased with distance from the bed in the inner layer. This made the choice of the reference level problematic. Mean shear stress for all experiments follows a quadratic relationship with the mean velocity in the flow. The wall similarity method appears to be a promising tool for estimating shear velocity under rough‐bed flow conditions and in field studies where other methods may be difficult to apply. This method allows for the determination of u* from a single point measurement at one level in the intermediate range (0·3 < h < 0·6). Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
103.
Zeolites have been used for a long time for purification and catalytical purposes. Recently, first products appeared on the market using zeolites also for improving the indoor air quality so far volatile organic compounds (VOC) are concerned. However, porous compounds like zeolites can be found also in plaster material. Therefore, it was manifest to evaluate the capability of plaster with regard to air cleaning. In this article, the contribution of plaster compounds toward adsorption and catalytical decomposition of VOCs is evaluated using α‐pinene, chlorobenzene, 2‐ethoxyethylacetate, and pentanal as target substances under standard conditions (23°C, 50% r.H.). These compounds were chosen because of their VOC typical physicochemical properties like molecular dimensions, density, boiling point, vapor pressure, and octanol–water distribution coefficient (logkow). Hydrated lime and metakaolin were found out to have good adsorption properties under these circumstances. Also natural zeolites showed good results especially on pentanal. By investigations in environmental chambers the reduction potential of test plasters on chlorobenzene and 2‐ethoxyethylacetate concentrations could be shown. Application of coatings had no or only temporary influence on the performance of the plaster. Additional tests in small chambers demonstrated the possibility to improve the properties of plasters with help of FAU‐ or MFI‐type zeolites but the experiments also showed that α‐pinene and pentanal undergo chemical reactions. Further effort should be made on investigations also toward other compounds, especially more volatile ones like formaldehyde. Also additional building materials like insulation material or boards should be taken into account. 相似文献
104.
Hydrothermal alteration and mineralization at the Wunugetu porphyry Cu–Mo deposit, China, include four stages, i.e., the early stage characterized by quartz, K-feldspar and minor mineralization, followed by a molybdenum mineralization stage associated with potassic alteration, copper mineralization associated with sericitization, and the last Pb–Zn mineralization stage associated with carbonation. Hydrothermal quartz contains three types of fluid inclusions, namely aqueous (W-type), daughter mineral-bearing (S-type) and CO2-rich (C-type) inclusion, with the latter two types absent in the late stage. Fluid inclusions in the early stage display homogenization temperatures above 510°C, with salinities up to 75.8 wt.% NaCl equivalent. The presence of S-type inclusions containing anhydrite and hematite daughter minerals and C-type inclusions indicates an oxidizing, CO2-bearing environment. Fluid inclusions in the Mo- and Cu-mineralization stages yield homogenization temperatures of 342–508°C and 241–336°C, and salinities of 8.6–49.4 and 6.3–35.7 wt.% NaCl equivalent, respectively. The presence of chalcopyrite instead of hematite and anhydrite daughter minerals in S-type inclusions indicates a decreasing of oxygen fugacity. In the late stage, fluid inclusions yield homogenization temperatures of 115–234°C and salinities lower than 12.4 wt.% NaCl equivalent. It is concluded that the early stage fluids were CO2 bearing, magmatic in origin, and characterized by high temperature, high salinity, and high oxygen fugacity. Phase separation occurred during the Mo- and Cu-mineralization stages, resulting in CO2 release, oxygen fugacity decrease and rapid precipitation of sulfides. The late-stage fluids were meteoric in origin and characterized by low temperature, low salinity, and CO2 poor. 相似文献
105.
ZHAO Wenjin WANG Nianzhong ZHU Min Ulrich MANN Ulrich HERTEN Andreas LüCKE 《《地质学报》英文版》2011,85(2):340-353
Carbon isotope (δ13Corg) analyses of non-marine clastic rocks and neritic carbonates and black shales spanning the Silurian/Devonian transition are compared from two richly fossiliferous sequences in Qujing of East Yunnan and Zoige of Sichuan, South China. The two sections, Xishancun and Putonggou sections in South China, reveal positive δ13Corg shifts happening in the Upper Pridoli and Lower Devonian and reaching peak values as heavy as ?25.2‰ (Xishancun) and ?19.9‰ (Putonggou) in the lowermost Lochkovian following the first occurrence of the thelodont Parathelodus and the conodont Icriodus woschmidti woschmidti (only in Putonggou Section and together with Protathyris-Lanceomyonia brachiopod fauna). These results replicate a globally known positive shift in δ13Corg from the uppermost Silurian to the lowermost Devonian. The δ13Corg variations across the Silurian/Devonian Boundary (SDB) at the two sections in South China exhibit a shift in carbon isotopic composition similar to the detailed SDB curves from the borehole Klonk-1 drilled at top of the Klonk Global Standard Stratotype-Section and Point (GSSP) in the Prague Basin, Czech Republic. In addition, four microvertebrate assemblages, including the Liaojiaoshan, Xishancun, Yanglugou and Xiaputonggou assemblages, are recognized from the Silurian/Devonian transition exposed in the Xishancun and Putonggou sections, respectively. The results from both carbon isotope stratigraphy and microvertebrate assemblage sequences suggest that the SDB in South China is located at the base of the Xishancun Formation (between sample QX-20 and sample QX-21) in the Xishancun Section and the lower part of the Xiaputonggou Formation (between sample ZP-09 and sample ZP-10) in the Putonggou Section. The isotopic trend for organic carbon together with the changes of microvertebrate remains across the SDB can offer an approach to a potential correlation of the SDB from different sedimentary facies, which help to correlate the marine with non-marine deposits. 相似文献
106.
Modeling isotopic signatures in systems affected by diffusion, advection, and a reaction which modifies the isotopic abundance of a given species, is a discipline in its infancy. Traditionally, much emphasis has been placed on kinetic isotope effects during biochemical reactions, while isotope effects caused by isotope specific diffusion coefficients have been neglected. A recent study by Donahue et al. (2008) suggested that transport related isotope effects may be of similar magnitude as microbially mediated isotope effects. Although it was later shown that the assumed differences in the isotope specific diffusion coefficients were probably overstated by one or two orders of magnitude (Bourg, 2008), this study raises several important issues: (1) Is it possible to directly calculate isotopic enrichment factors from measured concentration data without modeling the respective system? (2) Do changes in porosity and advection velocity modulate the influence of isotope specific diffusion coefficients on the fractionation factor α? (3) If one has no a priori knowledge whether diffusion coefficients are isotope specific or not, what is the nature and magnitude of the error introduced by either assumption? Here we argue (A) That the direct substitution of measured data into a differential equation is problematic and cannot be used as a replacement for a reaction-transport model; (B) That the transport related fractionation scales linearly with the difference between the respective diffusion coefficients of a given isotope system, but depends in a complex non-linear way on the interplay between advection velocity, and downcore changes of temperature and porosity. Last but not least, we argue that the influence of isotope specific diffusion coefficients on microbially mediated sulfate reduction in typical marine sediments is considerably smaller than the error associated with the determination of the fractionation factor. 相似文献
107.
Jonathan O. Sharp Juan S. Lezama-Pacheco Pilar Junier Kai-Uwe Ulrich Satya Chinni Camille Margot-Roquier Bradley M. Tebo John R. Bargar 《Geochimica et cosmochimica acta》2011,75(21):6497-6510
It has generally been assumed that the bioreduction of hexavalent uranium in groundwater systems will result in the precipitation of immobile uraninite (UO2). In order to explore the form and stability of uranium immobilized under these conditions, we introduced lactate (15 mM for 3 months) into flow-through columns containing sediments derived from a former uranium-processing site at Old Rifle, CO. This resulted in metal-reducing conditions as evidenced by concurrent uranium uptake and iron release. Despite initial augmentation with Shewanella oneidensis, bacteria belonging to the phylum Firmicutes dominated the biostimulated columns. The immobilization of uranium (∼1 mmol U per kg sediment) enabled analysis by X-ray absorption spectroscopy (XAS). Tetravalent uranium associated with these sediments did not have spectroscopic signatures representative of U-U shells or crystalline UO2. Analysis by microfocused XAS revealed concentrated micrometer regions of solid U(IV) that had spectroscopic signatures consistent with bulk analyses and a poor proximal correlation (μm scale resolution) between U and Fe. A plausible explanation, supported by biogeochemical conditions and spectral interpretations, is uranium association with phosphoryl moieties found in biomass; hence implicating direct enzymatic uranium reduction. After the immobilization phase, two months of in situ exposure to oxic influent did not result in substantial uranium remobilization. Ex situ flow-through experiments demonstrated more rapid uranium mobilization than observed in column oxidation studies and indicated that sediment-associated U(IV) is more mobile than biogenic UO2. This work suggests that in situ uranium bioimmobilization studies and subsurface modeling parameters should be expanded to account for non-uraninite U(IV) species associated with biomass. 相似文献
108.
The existence of the Cretaceous-Tertiary (K/T) boundary in the non-marine succession is expected at Jiayin in the Heilongjiang River area, China. Zircons from a tuff sample from the Baishantou Member of Wuyun Formation in Jiayin were analyzed by the laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U-Pb dating and fission-track dating methods. Ages of 64.1±0.7 Ma (U-Pb) and 61.7±1.8 Ma (fission-track dating) were obtained, which allow re-evaluation of a previously reported late Maastrichian age for the tuff layer that was in conflict with the paleontological evidence. These results confirm the Danian age of the section in agreement with the paleontological evidence. 相似文献
109.
Risk-targeted seismic design maps for mainland France 总被引:3,自引:2,他引:1
In this article, the recently proposed approach known as ‘risk targeting’ for the development of national seismic design maps is investigated for mainland France. Risk targeting leads to ground-motion maps that, if used for design purposes, would lead to a uniform level of risk nationally. The Eurocode 8 design loads currently in force for France are used as the basis of this study. Because risk targeting requires various choices on, for example, the level of acceptable risk to be made a priori and these choices are not solely engineering decisions but involve input from decision makers we undertake sensitivity tests to study their influence. It is found that, in contrast to applications of this methodology for US cities, risk targeting does not lead to large modifications with respect to the national seismic hazard map nor to changes in the relative ranking of cities with respect to their design ground motions. This is because the hazard curves for French cities are almost parallel. In addition, we find that using a target annual collapse probability of about 10?5 for seismically designed buildings and a probability of collapse when subjected to the design PGA of 10?5 leads to reasonable results. This is again in contrast to US studies that have adopted much higher values for both these probabilities. 相似文献
110.
Andreas Ertl Gerald Giester Ulrich Schüssler Helene Brätz Martin Okrusch Ekkehart Tillmanns Hermann Bank 《Mineralogy and Petrology》2013,107(2):265-279
Cu- and Mn-bearing tourmalines from Brazil and Mozambique were characterised chemically (EMPA and LA-ICP-MS) and by X-ray single-crystal structure refinement. All these samples are rich in Al, Li and F (fluor-elbaite) and contain significant amounts of CuO (up to ~1.8 wt%) and MnO (up to ~3.5 wt%). Structurally investigated samples show a pronounced positive correlation between the <Y-O> distances and the (Li + Mn2+ + Cu + Fe2+) content (apfu) at this site with R 2 = 0.90. An excellent negative correlation exists between the <Y-O> distances and the Al2O3 content (R 2 = 0.94). The samples at each locality generally show a strong negative correlation between the X-site vacancies and the (MnO + FeO) content. The Mn content in these tourmalines depends on the availability of Mn, on the formation temperature, as well as on stereochemical constraints. Because of a very weak correlation between MnO and CuO we believe that the Cu content in tourmaline is essentially dependent on the availability of Cu and on stereochemical constraints. 相似文献