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81.
Martin Thullner Florian CentlerHans-Hermann Richnow Anko Fischer 《Organic Geochemistry》2012,42(12):1440-1460
Compound specific stable isotope analysis (CSIA) has been established as a viable tool for proving, characterizing and assessing degradation of organic pollutants within contaminated aquifers. The fractionation of stable isotopes during contaminant degradation leads to observable shifts in stable isotope ratios which can serve as an indicator for in situ pollutant degradation and allow for a quantitative assessment by means of the so-called Rayleigh (distillation) equation.This review highlights the recent developments of the Rayleigh equation approach for quantifying in situ degradation of organic pollutants in contaminated aquifers. The advantages and limitations of the Rayleigh equation approach are discussed and suggestions for improvements are given. Concepts are provided to estimate the uncertainty due to errors or variability of input parameters and how to deal with such uncertainty. Moreover, the applicability of the Rayleigh equation approach is evaluated regarding the heterogeneity and complexity of groundwater systems. For such systems, the review discusses the relevance of non-destructive processes, which affect the concentration (e.g., dispersive mixing) and potentially also the stable isotope ratio of contaminants (e.g., sorption, volatilization), and the resulting implications for the Rayleigh equation approach. 相似文献
82.
Nobuyoshi Miyajima Tommaso Mandolini Florian Heidelbach Caroline Bollinger 《Comptes Rendus Geoscience》2019,351(2-3):295-301
Dislocation microstructures in experimentally deformed single-crystal pyrope-rich garnet, (Mg,Fe)3(Al,Cr)3Si3O12, and polycrystalline forsterite, Mg2SiO4, were investigated by using electron channeling contrast imaging (ECCI) and transmission electron microscopy (TEM) combined with a focused ion beam (FIB)-microsampling. In the orientation-optimized ECCI method, we successfully observed individual dislocations across subgrain boundaries in a low-atomic-number mineral, pyrope-rich garnet (averaged Z-numbers, AZs ~ 10). Dislocations in a deformed forsterite (iron-free olivine) were also visible in the ECCI. In the ECCI on the single-crystal garnet, deformation bands consisting of dislocations, unusual contrasts in stripes and inhomogeneous distributions of sub-micrometer-sized pores were found. Further site-specific TEM observation on the deformation band revealed a high density of partial dislocations and stacking fault ribbons. The site-specific characterizations from ECCI to TEM, with assistance of FIB, can provide a new approach to investigate dislocation microstructures of deformed materials at high pressure and high temperature. 相似文献
83.
A multi‐method field experiment to determine local groundwater flow in a glacier forefield 下载免费PDF全文
Florian Kobierska Tobias Jonas Nena Griessinger Christian Hauck Stephan Huxol Stefano M. Bernasconi 《水文研究》2015,29(6):817-827
We implemented multiple independent field techniques to determine the direction and velocity of groundwater flow at a specific stream reach in a glacier forefield. Time‐lapse experiments were conducted using two electrical resistivity tomography (ERT) lines installed in a cross pattern. A circular array of groundwater tubes was also installed to monitor groundwater flow via discrete salt injections. Both inter‐borehole and ERT results confirmed this stream section as a losing reach and enabled quantification of the flow direction. Both techniques yielded advection velocities varying between 5.7 and 21.8 m/day. Estimates of groundwater flow direction and velocity indicated that groundwater infiltrates from the stream nearby and not from the adjacent lateral moraine. Groundwater age estimated from radon concentration measurements supported this hypothesis. Despite uncertainties inherent to each of the methods deployed, the combination of multiple field techniques allowed drawing consistent conclusions about local groundwater flow. We thus regard our multi‐method approach as a reliable way to characterize the two‐dimensional groundwater flow at sites where more invasive groundwater investigation techniques are difficult to carry out and local heterogeneities can make single measurements unreliable. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
84.
Uranyl Retention on Quartz—New Experimental Data and Blind Prediction Using an Existing Surface Complexation Model 总被引:1,自引:0,他引:1
The adsorption behaviour of uranyl onto seven different samples of quartz was studied in batch experiments. Sea-sand (0.1–0.3 mm),
Fil-Pro 12/20 (1–2 mm) and five Min-U-Sil samples with smaller particle sizes (5, 10, 15, 30 and 40 μm) were used. The uptake
curves show “pH adsorption edges” in the range of pH 4–5. A good agreement of the new data with literature data was found
when plotting surface-normalised distribution coefficients versus pH. Differences in the adsorption behaviour for pre-treated
and untreated sea-sand samples were detectable resulting in a shift of the pH edge to higher pH values after treatment. A
literature surface complexation model was applied for blind predictions of the experimental results. The simulations described
the experimental observations quite well for the Min-U-Sil samples. For the two coarser quartz samples, the calculated over-predictions
were explained by the larger-than-expected measured specific surface area and measurable amounts of associated minerals, for
Fil-Pro 12/20 and sea-sand, respectively. Dissolution of the samples was studied as a function of pH. After 5 days, the measured
Si concentrations were all higher than equilibrium quartz solubilities, but lower than those of amorphous silica. With increasing
pH, dissolved silica increased. This strongly suggests that formation of dissolved uranyl–silicato complexes have to be considered
based on measured silica concentrations. 相似文献
85.
Nicolas Deichmann John Clinton Stephan Husen Florian Haslinger Donat Fäh Domenico Giardini Philipp Kästli Urs Kradolfer Iris Marschall Stefan Wiemer 《Swiss Journal of Geoscience》2009,102(3):505-514
This report of the Swiss Seismological Service summarizes the seismic activity in Switzerland and surrounding regions during
2008. During this period, 451 earthquakes and 75 quarry blasts were detected and located in the region under consideration.
The three strongest events occurred in the Valais, near Lac des Toules (ML 3.6), and in Graubünden, near Ilanz (ML 3.7) and Paspels (ML 4.0). Although felt by the population, they were not reported to have caused any damage. However, with a total of only 15
events with ML ≥ 2.5, the seismic activity in the year 2008 was far below the average over the previous 33 years. 相似文献
86.
Renata J. Romanowicz Peter C. Young Keith J. Beven Florian Pappenberger 《Advances in water resources》2008
Operational flood forecasting requires accurate forecasts with a suitable lead time, in order to be able to issue appropriate warnings and take appropriate emergency actions. Recent improvements in both flood plain characterization and computational capabilities have made the use of distributed flood inundation models more common. However, problems remain with the application of such models. There are still uncertainties associated with the identifiability of parameters; with the computational burden of calculating distributed estimates of predictive uncertainty; and with the adaptive use of such models for operational, real-time flood inundation forecasting. Moreover, the application of distributed models is complex, costly and requires high degrees of skill. This paper presents an alternative to distributed inundation models for real-time flood forecasting that provides fast and accurate, medium to short-term forecasts. The Data Based Mechanistic (DBM) methodology exploits a State Dependent Parameter (SDP) modelling approach to derive a nonlinear dependence between the water levels measured at gauging stations along the river. The transformation of water levels depends on the relative geometry of the channel cross-sections, without the need to apply rating curve transformations to the discharge. The relationship obtained is used to transform water levels as an input to a linear, on-line, real-time and adaptive stochastic DBM model. The approach provides an estimate of the prediction uncertainties, including allowing for heterescadasticity of the multi-step-ahead forecasting errors. The approach is illustrated using an 80 km reach of the River Severn, in the UK. 相似文献
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90.
Florian Genier Jean-Luc Epard François Bussy Tomas Magna 《Swiss Journal of Geoscience》2008,101(2):431-452
Detailed field work and zircon analysis have improved the knowledge of the lithostratigraphy at the base of the Siviez-Mischabel nappe in the Mattertal (St-Niklaus-Törbel area). They confirm the existence of an overturned limb and clarify the structure of the St-Niklaus syncline. The following formations can be observed:
- Polymetamorphic gneisses; composed of paragneisses, amphibolites and micaschists (Bielen Unit, pre-Ordovician).
- Fine-grained, greyish quartzite and graywacke with kerogen-rich horizons (Törbel Formation, presumed Carboniferous).
- Green or white micaschists characterized by brown carbonate spots associated with white conglomeratic quartzites (Moosalp Formation, Early Permian).
- Massive, green or white, fine grained, microconglomeratic or conglomeratic quartzites with characteristic pink quartz pebbles (Bruneggjoch Formation, Late Permian-Early Triassic).