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排序方式: 共有1068条查询结果,搜索用时 484 毫秒
901.
Traffic-related immissions and their impact on historic buildings: implications from a pilot study at two German cities 总被引:1,自引:1,他引:0
Michael Auras Silvia Beer Petra Bundschuh Joachim Eichhorn Martin Mach Dirk Scheuvens Michael Schorling Jonas von Schumann Rolf Snethlage Stephan Weinbruch 《Environmental Earth Sciences》2013,69(4):1135-1147
Besides the enormous improvement of air quality in Germany due to the reduction of sulphur dioxide emissions in the last decades, high immissions of nitrogen oxides and fine particulate matter are frequently observed at traffic-rich urban sites. The changed chemical composition of air pollution requires a new investigation of its impact on historic buildings constructed of natural stone. In a pilot study a multi-disciplinary approach was chosen to obtain information on the actual pollution situation of historic buildings and monuments at traffic hotspots in Germany. The study concentrated on the two German cities of Munich and Mainz of different size, traffic volume and stone inventory. Dose–response functions were calculated to demonstrate the change of impact of different pollutants over the last three decades, and for comparison of traffic hotspots and housing areas of both cities. Numeric modelling on a city-scale was used to identify the historic buildings and monuments affected by elevated traffic immissions. Because a relevant part of these pollutants is dominated by short-range transport, the differences of wind speed and deposition rates were calculated using a street-scale 3D flow and dispersion model regarding traffic volume, wind regime and adjacent buildings. Finally, particulate matter was sampled at different positions of two buildings heavily exposed to traffic emissions. Individual particles were investigated by environmental scanning electron microscopy. After classification of the particles into different chemical groups, the fraction of traffic-induced particulate matter was quantified. Summarizing the results, it must be stated that soiling by traffic-related particulate matter, deposition of nitrates deriving from exhaust emission and other diffusely emitted components bear a severe damage potential for natural building stone at least locally at traffic-rich urban sites. 相似文献
902.
Lack of relationship between Al ages of chondrules and their mineralogical and chemical compositions
Previous studies have suggested the existence of a correlation between 26Al relative crystallisation ages and mineralogical and bulk chemical compositions of ferromagnesian chondrules from the Bishunpur and Semarkona unequilibrated ordinary (0120 and 0150). However, because the precision in 26Al ages was moderate, these correlations are questionable. Here, we report mineralogical and chemical compositions of 14 ferromagnesian chondrules from Semarkona for which precise 26Al ages were previously obtained (Villeneuve et al., 2009). We find global correlation of 26Al ages neither with bulk chemical composition of chondrules, nor with the different types of ferromagnesian chondrules, i.e. PO, POP and PP. This indicates that if some kind of correlations between chemical compositions of chondrules and their ages of formation exists, they do not exist at timescales that can be measured with the 26Al-26Mg systematics but presumably at much shorter timescales. 相似文献
903.
Marc Ulrich Sarah Bureau Catherine Chauvel Christian Picard 《Geostandards and Geoanalytical Research》2012,36(1):7-20
This study reports precise and accurate data for rare earth elements (REE) measured on eight geological reference materials, five enriched in REE (BE‐N, BHVO‐2, BR, BR‐24 and RGM‐1) and three very depleted in REE (BIR‐1, UB‐N and DTS‐2). Data were acquired by quadrupole ICP‐MS after isolation of the REE using an ion‐exchange chromatography procedure. All the measured REE abundances were similar within ≈ 5% (10% for the most REE‐depleted sample DTS‐2) to the high‐quality measurements previously published in the literature. We also show that by using an internal Tm spike, the reproducibility of the data was improved to ~ 1%. Applying this technique to the analysis of ultra‐depleted rock samples (sub ng g?1), we show that significant improvements were obtained relative to the routine trace element measurement method. The chondrite‐normalised patterns were smooth instead of displaying irregularities. Although the classical method gives excellent results on REE‐rich samples, we believe that our technique improves the precision and accuracy of measurements for highly REE‐depleted rocks. 相似文献
904.
Thomas Kalbacher Jens-Olaf Delfs Haibing Shao Wenqing Wang Marc Walther Luis Samaniego Christoph Schneider Rohini Kumar Andreas Musolff Florian Centler Feng Sun Anke Hildebrandt Rudolf Liedl Dietrich Borchardt Peter Krebs Olaf Kolditz 《Environmental Earth Sciences》2012,65(5):1367-1380
Numerical modeling of interacting flow and transport processes between different hydrological compartments, such as the atmosphere/land surface/vegetation/soil/groundwater systems, is essential for understanding the comprehensive processes, especially if quantity and quality of water resources are in acute danger, like e.g. in semi-arid areas and regions with environmental contaminations. The computational models used for system and scenario analysis in the framework of an integrated water resources management are rapidly developing instruments. In particular, advances in computational mathematics have revolutionized the variety and the nature of the problems that can be addressed by environmental scientists and engineers. It is certainly true that for each hydro-compartment, there exists many excellent simulation codes, but traditionally their development has been isolated within the different disciplines. A new generation of coupled tools based on the profound scientific background is needed for integrated modeling of hydrosystems. The objective of the IWAS-ToolBox is to develop innovative methods to combine and extend existing modeling software to address coupled processes in the hydrosphere, especially for the analysis of hydrological systems in sensitive regions. This involves, e.g. the provision of models for the prediction of water availability, water quality and/or the ecological situation under changing natural and socio-economic boundary conditions such as climate change, land use or population growth in the future. 相似文献
905.
906.
AbstractThe Hai River Basin (HRB) is a heavily irrigated region encompassing the North China Plain (NCP) in northeast China. In the last decades, continuous lowering of groundwater levels had been reported in the NCP. This study used data from the Gravity Recovery and Climate Experiment (GRACE) and in situ measurements to quantify recent changes in groundwater storage from 2003 to 2012. The signal from GRACE observations highlight a sharp decline in the deep subsurface water stores (deep unsaturated zone and groundwater systems) up to a rate of 17.0 ± 4.3 mm year-1 between 2003 and 2012 over the HRB, equal to a volumetric loss of 5.5 ± 1.4 km3 year-1. This result shows good consistency with in situ observations of groundwater hydraulic heads compiled from monitoring bores, and emphasizes GRACE’s ability to monitor large-scale groundwater storage variations. Results from GRACE also provide an independent assessment of the effectiveness of water saving programmes that have been implemented by the government so far. Our study indicates that groundwater overdrawal is still prevalent and the dominant factor for the persistent loss in groundwater storage over the HRB/NCP; the current groundwater consumption pattern is far beyond the natural recharge ability in groundwater system.
Editor D. Koutsoyiannis; Associate editor T. Wagener 相似文献
907.
Agnès Bouchez Noémie Pascault Cècile Chardon Marc Bouvy Philippe Cecchi Luc Lambs Mélanie Herteman François Fromard Patrice Got Christophe Leboulanger 《Marine pollution bulletin》2013,66(1-2):39-46
Mangroves are threatened ecosystems that provide numerous ecosystem services, especially through their wide biodiversity, and their bioremediation capacity is a challenging question in tropical areas. In a mangrove in Mayotte, we studied the potential role of microbial biofilm communities in removing nutrient loads from pre-treated wastewater. Microbial community samples were collected from tree roots, sediments, water, and from a colonization device, and their structure and dynamics were compared in two areas: one exposed to sewage and the other not. The samples from the colonization devices accurately reflected the natural communities in terms of diversity. Communities in the zone exposed to sewage were characterized by more green algae and diatoms, higher bacteria densities, as well as different compositions. In the area exposed to sewage, the higher cell densities associated with specific diversity patterns highlighted adapted communities that may play a significant role in the fate of nutrients. 相似文献
908.
ABSTRACTFlood quantile estimation based on partial duration series (peak over threshold, POT) represents a noteworthy alternative to the classical annual maximum approach since it enlarges the available information spectrum. Here the POT approach is discussed with reference to its benefits in increasing the robustness of flood quantile estimations. The classical POT approach is based on a Poisson distribution for the annual number of exceedences, although this can be questionable in some cases. Therefore, the Poisson distribution is compared with two other distributions (binomial and Gumbel-Schelling). The results show that only rarely is there a difference from the Poisson distribution. In the second part we investigate the robustness of flood quantiles derived from different approaches in the sense of their temporal stability against the occurrence of extreme events. Besides the classical approach using annual maxima series (AMS) with the generalized extreme value distribution and different parameter estimation methods, two different applications of POT are tested. Both are based on monthly maxima above a threshold, but one also uses trimmed L-moments (TL-moments). It is shown how quantile estimations based on this “robust” POT approach (rPOT) become more robust than AMS-based methods, even in the case of occasional extraordinary extreme events.
Editor M.C. Acreman Associate editor A. Viglione 相似文献
909.
Alina Tudryn Piotr Tucholka Nevzat Özgûr Elisabeth Gibert Omer Elitok Zuheyr Kamaci Marc Massault André Poisson Bernard Platevoet 《Journal of Paleolimnology》2013,49(4):647-662
This work deals with changes recorded by lacustrine sediments from SW Anatolia in Turkey in the context of increasing stress on the Mediterranean environment in relation to human-climate-environmental interactions. Paleolimnological investigations were carried out on Lake Burdur (Lake District geographical subregion of Turkey), which has been subject to rapid changes in its hydrological system that caused a ~10-m water-level drop in the last 30 years. Study of a 5-m-long sediment core, taken from the recently dried out part of the lake, shows significant variation in granulometry, clay mineralogy, nitrogen and organic carbon content and its isotopic composition (?13Corg) throughout the sedimentary sequence, which represents the last 2,300 years. Chronology is based on radiocarbon dates obtained from plant fragments. The results provide a record of environmental changes, including biological productivity and erosion intensity, in relation to changes in water level and humidity of the area. The lowest previous water level, which is the same as observed today, occurred at approximately 300 BC, after which time a water-level increase led to a maximum stage between AD 200 and 1200. From AD 1200 to the present, the climate became drier accompanied by an overall lowering of water level, with periods of water-level fluctuations superimposed. The lake never dried out as is observed today at the coring site. The present drop in the lake water level is attributed to human activity rather than to climate change. This record of climate and environmental change in the Lake Burdur area appears to be stratigraphically complete. This study provides rare data for the late Holocene in Anatolia as well as information about rapid climate changes during specific periods. The influence of both the Northern hemisphere atmospheric circulation and Indian monsoon on the east Mediterranean remains unclear. Nevertheless, the North Sea—Caspian atmospheric teleconnection could be an important factor that explains local differences in climatic evolution of Anatolia during the period considered. 相似文献
910.
Wei Yang Marc Jolivet Guillaume Dupont‐Nivet Zhaojie Guo Zhicheng Zhang Chaodong Wu 《Basin Research》2013,25(2):219-240
The tectonic evolution of the Tian Shan, as for most ranges in continental Asia is dominated by north‐south compression since the Cenozoic India‐Asia collision. However, precollision governing tectonic processes remain enigmatic. An excellent record is provided by thick Palaeozoic – Cenozoic lacustrine to fluvial depositional sequences that are well preserved in the southern margin of the Junggar Basin and exposed along a foreland basin associated to the Late Cenozoic rejuvenation of the Tian Shan ranges. U/Pb (LA‐ICP‐MS) dating of detrital zircons from 14 sandstone samples from a continuous series ranging in age from latest Palaeozoic to Quaternary is used to investigate changes in sediment provenance through time and to correlate them with major tectonic phases in the range. Samples were systematically collected along two nearby sections in the foreland basin. The results show that the detrital zircons are mostly magmatic in origin, with some minor input from metamorphic zircons. The U‐Pb detrital zircon ages range widely from 127 to 2856 Ma and can be divided into four main groups: 127–197 (sub‐peak at 159 Ma), 250–379 (sub‐peak at 318 Ma), 381–538 (sub‐peak at 406 Ma) and 543–2856 Ma (sub‐peak at 912 Ma). These groups indicate that the zircons were largely derived from the Tian Shan area to the south since a Late Carboniferous basin initiation. The provenance and basin‐range pattern evolution of the southern margin of Junggar Basin can be generally divided into four stages: (1) Late Carboniferous – Early Triassic basin evolution in a half‐graben or post‐orogenic extensional context; (2) From Middle Triassic to Upper Jurassic times, the southern Junggar became a passively subsiding basin until (3) being inverted during Lower Cretaceous – Palaeogene; (4) During the Neogene, a piedmont developed along the northern margin of the North Tian Shan block and Junggar Basin became a true foreland basin. 相似文献