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141.
A Possible Photochemical Link Between Stratospheric and Near-Surface Ozone on Swiss Mountain Sites in Late Winter 总被引:2,自引:0,他引:2
Record high near-surface ozone concentrations at two elevated sites (Chaumont, 1140 m asl, and Rigi, 1030 m asl) in Switzerland were observed simultaneously with extremely low total ozone during a fair weather period in mid-February 1993. An analysis of ozone, temperature, humidity, and wind profiles suggests that the surface ozone peaks were most possibly generated within the region in a layer between about 1000 and 1500 m asl. Mean diurnal cycles of ozone concentration during the period shows a strong increase from late morning to late afternoon at Chaumont and at the same time a decrease at the high alpine site Jungfraujoch (3580 m asl). The different diurnal ozone cycles can both be explained photochemically by taking into account the large difference in NOx concentrations (about two orders of magnitude) between the sites. Photochemical processes are also indicated by the diurnal cycles of NO2 and NO concentration. As a strong photochemical activity is not expected in mid-February at 47°N, we hypothesize that the extremely low total ozone played a role. Total ozone controls the amount of UV-B radiation reaching the troposphere and thus influences photochemical processes. Using a radiation model, we calculated an increase in ozone photolysis at Chaumont and Jungfraujoch of 73% and 83%, respectively, on the day with the lowest total ozone (243 DU) compared to average February conditions (335 DU). It is suggested that total ozone changes have the potential to stimulate photochemistry sufficiently to produce the observed surface ozone peaks at Chaumont and Rigi of 61 and 64 ppbv, respectively. A fog layer just below Chaumont during these days probably also influenced photochemistry, but on a smaller spatial scale. Our empirical results on the influence of changing UV radiation on tropospheric photochemistry are in close agreement with model studies of other groups. Although this case study represents unique conditions, a distinct anticorrelation between near-surface ozone at Chaumont and total ozone also appears in other years (1992–1997) when selecting fair weather days in mid-February. However, other influences cannot be excluded. The selected days provide evidence of a significant photochemical source of ozone in the mid-latitude lower troposphere in late winter. 相似文献
142.
Study on the Chemical Character of Water Soluble Organic Compounds in Fine Atmospheric Aerosol at the Jungfraujoch 总被引:1,自引:0,他引:1
Zoltán Krivácsy András Gelencsér Gyula Kiss Ernő Mészáros Ágnes Molnár András Hoffer Tamás Mészáros Zsolt Sárvári Dóra Temesi Bálint Varga Urs Baltensperger Stephan Nyeki Ernest Weingartner 《Journal of Atmospheric Chemistry》2001,39(3):235-259
In this study the chemical nature of the bulk of water soluble organic compounds in fine atmospheric aerosol collected during summer 1998 at the Jungfraujoch, Switzerland (3580 m asl) is characterised. The mass concentration of water soluble organic substances was similar to those of major inorganic ions, and the water soluble organic matter was found to be composed of two main fractions: (i) highly polyconjugated, acidic compounds with a varying degree of hydrophobicity and (ii) slightly polyconjugated, neutral and very hydrophilic compounds. The contribution of both fractions to the total water soluble organic carbon was about 50%. Separation into individual components was impossible either by HPLC or capillary electrophoresis which indicates the presence of a high number of chemically similar but not identical species. Results obtained by ultrafiltration and HPLC-MS have shown that the molecular weights are of the order of several hundreds. Most of the protonation constants for the acidic compounds determined by capillary electrophoresis were in the range 104–107. 相似文献
143.
大别山的构造变形期次和超高压岩石折返的动力学 总被引:21,自引:2,他引:21
从构造关系上看,大别山可分为南部,中部和北部3个构造系统,大别山南部构造系统为一套(原地)构造堆叠系统(相对的),从上到下依次为:(1)未变质的震旦纪一早三叠世沉积盖层,它被造山后的侏罗-白垩纪砂-砾岩不整合覆盖;(2)弱变质的新元古代板岩;(3)高压变质岩系(宿松群),这些变质岩系大多退变质为绿片岩相;(4)含柯石英榴辉岩超高压变质单元的异地系统;(5)未经历超高压变质作用的原地(相对的)片麻岩系。北西-南东向的拉伸线理在各个地质单元均有表现。从动力学上看,上盘指向NW的剪切运动被后期的褶皱所改变,大别山中部为(混合岩)热穿窿改造系统,系经历了超高压变质作用的地体叠加了混合岩化作用的产物,它与超高压变质地体的界限为一拆离断层,而正是这个拆离断层使超高压变质地体向地表折返并经历了角闪岩相的退变质作用。大别山北部为构造堆叠系统,早期的面理和南北向的挤压线理被轴面北倾的褶皱所改造,这种褶皱对应于大别山中部同折返期的韧性变形的隆升构造。同时建立了地球运力学模型并讨论了逆冲作用和正断层的作用。 相似文献
144.
145.
The Cr(VI) reduction behaviour of five different types of grey cast iron shavings meant for construction of a permeable reactive barrier (PRB) in Thun, Switzerland, was investigated by performing batch and column experiments. Closed system batch experiments clearly demonstrated that the largest shavings also containing the largest spherical C inclusions, were best qualified for the PRB due to their fast Cr(VI) reduction rate. However, the column experiment performed with this type of material revealed that a complete and long term Cr(VI) treatment by the planned PRB was questionable due to the site-specific high groundwater flow velocities and the almost O2 and CaCO3 saturated aquifer conditions. The experimentally observed Cr(VI) breakthrough is explained as a result of a decline of reactivity provoked by a strong passivation by observed Fe hydroxides (FeOOH-polymorphs) and carbonates (calcite and aragonite).The column experiment was simulated using the reactive transport modelling code CrunchFlow. Iron cycling and intra-aqueous reactions were incorporated into a previously described reaction network in order to model the strong decline in reactivity of grey cast iron. All key parameters like aqueous species concentrations and mineralogical evolution of the column were successfully modelled. The modelling results confirmed that the observed Cr(VI) breakthrough was caused by surface passivation of the Fe shavings. Complete oxidation of the initially present mass of shavings is not predicted to occur during the expected PRB lifetime of several decades. The model seems to be robust, and it is expected that an application of the calibrated model in 2D to field sites will allow a quantitative evaluation for the performance of planned PRB’s in such environments. 相似文献
146.
Persistent scatterer interferometry analysis of the embankment failure of a red mud reservoir using ENVISAT ASAR data 总被引:1,自引:1,他引:0
On October 4, 2010, the embankment of No. 10 red mud—waste product during bauxite refining—reservoir of MAL Co. Ltd. alumina
plant collapsed. Around 700 000 cubic meter of alkaline slurry with 11–13 pH value flooded three nearby settlements. Ten people
were killed, 123 wounded, and about 350 houses were damaged or became uninhabitable in one of the biggest industrial and ecological
catastrophe in modern history of Hungary. Synthetic aperture radar interferometry (InSAR) is the only geodetic technique that
can reveal the past stability and motion history of the broken reservoir. We performed a persistent scatterer InSAR (PSI)
analysis to contribute to the better understanding of the disaster. The key question we address in this study is whether there
were signs prior to October 4th event which may have prognosticated the disaster. The PSI results could reveal if the dam
was stable in the past without prior signs of the failure or there were definite indications of deformation before the collapse
and proper monitoring of motions could have highlighted the risk and the disaster may have been prevented. This is a rare
event and its PSI study is unique and may be critical in understanding it and helping to prevent other similar occurrences. 相似文献
147.
Senecio Schefer Vladica Cvetković Bernhard Fügenschuh Alexandre Kounov Maria Ovtcharova Urs Schaltegger Stefan M. Schmid 《International Journal of Earth Sciences》2011,100(5):1181-1206
Two age groups were determined for the Cenozoic granitoids in the Dinarides of southern Serbia by high-precision single grain
U–Pb dating of thermally annealed and chemically abraded zircons: (1) Oligocene ages (Kopaonik, Drenje, Željin) ranging from
31.7 to 30.6 Ma (2) Miocene ages (Golija and Polumir) at 20.58–20.17 and 18.06–17.74 Ma, respectively. Apatite fission-track
central ages, modelling combined with zircon central ages and additionally, local structural observations constrain the subsequent
exhumation history of the magmatic rocks. They indicate rapid cooling from above 300°C to ca. 80°C between 16 and 10 Ma for
both age groups, induced by extensional exhumation of the plutons located in the footwall of core complexes. Hence, Miocene
magmatism and core-complex formation not only affected the Pannonian basin but also a part of the mountainous areas of the
internal Dinarides. Based on an extensive set of existing age data combined with our own analyses, we propose a geodynamical
model for the Balkan Peninsula: The Late Eocene to Oligocene magmatism, which affects the Adria-derived lower plate units
of the internal Dinarides, was caused by delamination of the Adriatic mantle from the overlying crust, associated with post-collisional
convergence that propagated outward into the external Dinarides. Miocene magmatism, on the other hand, is associated with
core-complex formation along the southern margin of the Pannonian basin, probably associated with the W-directed subduction
of the European lithosphere beneath the Carpathians and interfering with ongoing Dinaridic–Hellenic back-arc extension. 相似文献
148.
Nicholas Deichmann John Clinton Stephan Husen Benjamin Edwards Florian Haslinger Donat Fäh Domenico Giardini Philipp Kästli Urs Kradolfer Stefan Wiemer 《Swiss Journal of Geoscience》2011,104(3):537-547
This report of the Swiss Seismological Service summarizes the seismic activity in Switzerland and surrounding regions during
2010. During this period, 407 earthquakes and 85 quarry blasts were detected and located in the region under consideration.
With a total of only 19 events with ML ≥ 2.5, the seismic activity in the year 2010 was below the average over the previous 35 years. The two most noteworthy earthquakes
were the ML 3.4 Barrhorn event near Sankt Niklaus (VS) and the ML 3.0 event of Feldkirch, both of which produced shaking of intensity IV. 相似文献
149.
Marcel LANGENAUER Urs KRÄHENBÜHL Verena FURRER Armin WYTTENBACH 《Geostandards and Geoanalytical Research》1992,16(1):41-44
The concentrations of fluorine, chlorine, bromine and iodine of seven geochemical reference samples have been determined. Analytical techniques were neutron activation analysis for chlorine, bromine and iodine and ion-selective potentiometry for fluorine. After irradiation of the samples, these halogens were separated from the matrix elements by pyrohydrolysis in presence of vanadium (V) oxide. This extraction allows to measure the four halogens in the same sample. 相似文献
150.
R. K. Somashekar B. C. Nagaraja Kavya Urs 《Journal of the Indian Society of Remote Sensing》2008,36(1):99-104
The Western Ghats constitute one of the three biodiversity hot spots in India, which is under constant threat from various
quarters. Among the several anthropogenic causes, fire is one of the important anthropogenic factor, which plays a pivotal
role in vegetation succession and ecosystem processes. It is very important to understand the ecological changes due to fire
and other anthropogenic factors for conservation and management of biodiversity. Because of its synoptic, multi-spectral and
multi-temporal nature remote sensing data can be a good source for forest fire monitoring. In the present study, an effort
has been made to monitor the burnt areas using March 2000 and 2004 IRS LISS — III data. The study revealed that an area of
2.15 km2 and 4.46 km2 was affected by fire in 2000 and 2004 respectively. Repeated drought, followed by mass flowering and dying of bamboo accelerated
the spread of fire from ground to canopy in areas with high bamboo density. 相似文献