Integrated Water Resources Management under different hydrological,climatic and socio-economic conditions   总被引：2，自引：2，他引：0  

Edda Kalbus  Thomas Kalbacher  Olaf Kolditz  Elisabeth Krüger  Jörg Seegert  Gunda Röstel  Georg Teutsch  Dietrich Borchardt  Peter Krebs 《Environmental Earth Sciences》2012,65(5):1363-1366

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Simulation of DNAPL infiltration and spreading behaviour in the saturated zone at varying flow velocities and alternating subsurface geometries   总被引：3，自引：1，他引：2  

Katharina Erning  Sibylle Grandel  Andreas Dahmke  Dirk Schäfer 《Environmental Earth Sciences》2012,65(4):1119-1131

The influence of varying groundwater flow velocities on DNAPL infiltration and spreading behaviour was investigated by multiphase modelling using TMVOC and PetraSim. The multiphase models were calibrated by results of previously conducted laboratory experiments for the complete spatio-temporal range of the experiments. The small scale 2D scenario modelling was applied to qualify and quantify changes in position, architecture, geometry and dissolution of a TCE body in a fully saturated homogeneous sandy medium. The applied flow velocities ranging from 0.05 up to 40.00 m/day exhibited that the DNAPL TCE is affected even at the lowest flow velocity in its position, its size and its architecture. Additionally, several impermeable lenses with simple geometry were assumed in the model, to investigate the influence of stratified subsoil. In the experimental set-ups, the DNAPL body reacts more sensitive to the applied groundwater flow velocities than to the geometrical set-up of the scenarios. A possible consequence can be the transportation and displacement of a DNAPL pool due to natural or anthropogenic induced high groundwater flow velocities, as by Pump and Treat facilities, complicating site investigation process and planning of remediation activities.  相似文献   

Universal time from VLBI single-baseline observations during CONT08   总被引：2，自引：2，他引：0  

Tobias Nilsson  Johannes Böhm  Harald Schuh 《Journal of Geodesy》2011,85(7):415-423

The IVS Intensive sessions are single-baseline, 1-h VLBI sessions carried out everyday in order to determine Universal Time (UT1). We investigate different possibilities to improve the results of such sessions. We do this investigation by extracting 2-h single-baseline sessions from the CONT08 data set. These are analysed like normal Intensives, and the results are compared to the results of the analysis of the full CONT08 data set. We find that tropospheric asymmetry is the major error source for the single-baseline sessions. It is possible to improve the accuracy of the estimated UT1 either by using accurate a priori tropospheric gradients or by estimating gradients in the data analysis.  相似文献   

A study to discriminate local,urban and regional source contributions to the particulate matter concentrations in the city of Dresden,Germany     

T. Gnauk  K. Müller  E. Brüggemann  W. Birmili  K. Weinhold  D. van Pinxteren  G. Löschau  G. Spindler  H. Herrmann 《Journal of Atmospheric Chemistry》2011,68(3):199-231

The fractions of local traffic (LT), urban background (UBG) and regional background (RBG) of the particle pollution at a traffic-influenced kerbside in Dresden, Germany, were determined by measurements of size-segregated mass concentration, chemical composition and particle size distributions in a network of five measurement stations partly existing and partly set up for this study. Besides the kerbside station, one urban background site and three rural sites were included in the study. Using data from these different sites, the LT, UBG, and RBG contributions were calculated, following the approach of Lenschow et al. (2001). At the kerbside site, 19% of the total number concentration (Dp_St = 10–600 nm) could be attributed to the RBG, 15% to the UBG, and 66% to the LT immediately nearby. Particle mass concentrations up to Dp_aer = 420 nm RBG amounts to 68%, UBG to 21%, and LT only to 11%. Highest mass concentrations were observed at all stations in autumn and winter during easterly inflow directions. The local traffic fraction of PM₁₀ mass at the kerbside station was found to be 30% for westerly inflow, but only 7% for southeasterly inflow due to the dominating transport fraction from up to 80% of the particle mass at this inflow direction. Size-resolved investigation showed the main fractions in both the particle size ranges of Dp_aer = 0.42 to 1.2 and 0.14 to 0.42 μm at all stations. The main components sulphate, ammonium and total carbon showed higher concentrations at south-eastern/eastern inflow in autumn at all stations, while nitrate at the kerbside and urban background site was higher during westerly inflow in winter. The chemical composition at the regional background site at westerly inflow (12% nitrate, 8% sulphate, 11% total carbon) was significantly different from that at easterly inflow (3% nitrate, 15% sulphate, 22% total carbon). The prevailing part of the ionic mass was always found in the fine particle range of Dp_aer = 0.14 to 1.2 μm at all stations. For all inflow directions highest total carbon concentrations were observed at the kerbside station, especially in the ultra-fine size range of Dp_aer = 0.05 to 0.14 μm with up to 30% of the whole carbon. PAH concentrations were always higher at south-eastern/eastern inflow especially during wintertime. Trace metal components and silicon were found mainly in the coarse mode fraction at the kerbside resulting from abrasion or resuspension.  相似文献   

Sorption-desorption kinetics and toxic cell concentration in marine phytoplankton microalgae exposed to Linear Alkylbenzene Sulfonate     

Renaud F  Oberhänsli F  Teyssié JL  Miramand P  Temara A  Warnau M 《Marine pollution bulletin》2011,62(5):942-947

Linear Alkylbenzene Sulfonates (LAS) are ubiquitous surfactants. Traces can be found in coastal environments. Sorption and toxicity of C₁₂-LAS congeners were studied in controlled conditions (2-3500 μg C₁₂LAS/L) in five marine phytoplanktonic species, using standardized methods. IC₅₀ values ranged from 0.5 to 2 mg LAS/L. Sorption of ¹⁴C₁₂-6 LAS isomer was measured at environmentally relevant trace levels (4 μg/L) using liquid scintillation counting. Steady-state sorption on algae was reached within 5 h in the order dinoflagellate > diatoms > green algae. The sorption data, fitted a L-type Freundlich isotherm, indicating saturation. Desorption was rapid but a low LAS fraction was still sorbed after 24 h. Toxic cell concentration was 0.38 ± 0.09 mg/g for the studied species. LAS toxicity results from sorption on biological membranes leading to non-specific disturbance of algal growth. Results indicate that LAS concentrations in coastal environments do not represent a risk for these organisms.  相似文献   

Erosion rates and mechanisms of knickzone retreat inferred from 10Be measured across strong climate gradients on the northern and central Andes Western Escarpment     

Luca M. Abbühl  Kevin P. Norton  John D. Jansen  Fritz Schlunegger  Ala Aldahan  Göran Possnert 《地球表面变化过程与地形》2011,36(11):1464-1473

A steep escarpment edge, deep gorges and distinct knickzones in river profiles characterize the landscape on the Western Escarpment of the Andes between ~5°S and ~18°S (northern Peru to northern Chile). Strong north–south and east–west precipitation gradients are exploited in order to determine how climate affects denudation rates in three river basins spanning an otherwise relatively uniform geologic and geomorphologic setting. Late Miocene tectonics uplifted the Meseta/Altiplano plateau (~3000 m a.s.l.), which is underlain by a series of Tertiary volcanic‐volcanoclastic rocks. Streams on this plateau remain graded to the Late Miocene base level. Below the rim of the Meseta, streams have responded to this ramp uplift by incising deeply into fractured Mesozoic rocks via a series of steep, headward retreating knickzones that grade to the present‐day base level defined by the Pacific Ocean. It is found that the Tertiary units on the plateau function as cap‐rocks, which aid in the parallel retreat of the sharp escarpment edge and upper knickzone tips. ¹⁰Be‐derived catchment denudation rates of the Rio Piura (5°S), Rio Pisco (13°S) and Rio Lluta (18°S) average ~10 mm ky^?1 on the Meseta/Altiplano, irrespective of precipitation rates; whereas, downstream of the escarpment edge, denudation rates range from 10 mm ky^?1 to 250 mm ky^?1 and correlate positively with precipitation rates, but show no strong correlation with hillslope angles or channel steepness. These relationships are explained by the presence of a cap‐rock and climate‐driven fluvial incision that steepens hillslopes to near‐threshold conditions. Since escarpment retreat and the precipitation pattern were established at least in the Miocene, it is speculated that the present‐day distribution of morphology and denudation rates has probably remained largely unchanged during the past several millions of years as the knickzones have propagated headward into the plateau. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Biomass to Biofuels: Strategies for Global Industries     

Uwe Schröder 《洁净——土壤、空气、水》2011,39(11):1022-1022

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Preliminary Interlaboratory Trial for ISO/DIS 12010: Determination of Short Chain Polychlorinated Alkanes (SCCP) in Water     

Sabine Geiß  Nicole Lettmann  Aurélien Rey  Herbert Lepper  Birgit Körner  Silvio Mais  Theodor Prey  Bettina Hilger  Moana Engelke  Stephan Lebertz  Claudine Chatellier  George Sawal  Dirk Löffler  Tom Schillings 《洁净——土壤、空气、水》2011,39(6):537-542

A first preliminary interlaboratory trial was planned to prepare ISO/DIS 12010: Water quality – determination of short chain polychlorinated alkanes (SCCP) in water – method using GC/MS and electron capture negative ionisation (ECNI). The task was to determine the sum of short chain polychlorinated n‐alkanes with carbon chain lengths of C₁₀–C₁₃ and a chlorine content between 49 and 67% in water by GC‐ECNI‐MS and quantification by multiple linear regression described in ISO/DIS 12010 as the compulsory method. Distributed samples were obtained from a real water extract spiked with a target concentration of 0.4 µg/mL sum of SCCP, i.e. the environmental quality target level according to the Water Framework Directive. The interlaboratory trial included the calibration, a column chromatographic clean up, a concentration step and an integration of chromatographic unresolved humps as well as the quantification with multiple linear regression. Reproducibility standard deviations between 21.5 and 22.9% were achieved by 17 participating laboratories from four countries. The method outlined no significant difference of the results between the standard solution and a real water matrix extract. On the basis of this succeeded preliminary interlaboratory trial the final interlaboratory trial for validation of ISO 12010 was prepared in autumn 2010.  相似文献   

Artificial light at night: implications for early life stages development in four temperate freshwater fish species   总被引：1，自引：0，他引：1  

Anika Brüning  Franz Hölker  Christian Wolter 《Aquatic Sciences - Research Across Boundaries》2011,73(1):143-152

Flora and fauna have both evolved under a natural cycle of light and dark. But especially in urban areas, the night is now increasingly disturbed by artificial light. Many traits and behaviours in fish are triggered by a circadian clock, for example hatching and swim bladder inflation, which predominantly take place at dusk or night. As lighting becomes brighter and extends farther into rural areas, the distinction between day and night becomes increasingly blurred. Therefore, the loss of diurnal trigger by artificial light at night was hypothesized having deleterious effects on these traits and impact fish reproduction. To assess these effects, eggs of four native freshwater fishes, Eurasian perch Perca fluviatilis, roach Rutilus rutilus, bleak Alburnus alburnus and chub Leuciscus cephalus, were incubated under two different light conditions: a photoperiod of 14 h light:10 h darkness (LD) and continuous illumination (LL). The time to hatch and swim bladder inflation was recorded. The species showed inconsistent reactions to the light treatments. In roach and bleak, the time to 50% hatch was longer in LL, whereas continuous lighting had an accelerating effect in chub. Incubation in LL elongated the hatching period in perch and roach and, in perch, the onset of darkness seemed to trigger hatching. The swim bladder inflation was significantly promoted by continuous light in chub and bleak but was not affected in roach. In conclusion, nocturnal artificial illumination could have an effect on hatching and initial swim bladder filling by masking the day–night-change and thereby diminish the trigger effect. However, the reactions were species specific and the increase in variation indicated a lack of diurnal triggering, whilst a general deleterious effect of artificial light at night has not been identified on early life stages.  相似文献   

Preliminary results of a finite-element,multi-scale model of the Mahakam Delta (Indonesia)   总被引：1，自引：1，他引：0  

Benjamin de Brye  Sébastien Schellen  Maximiliano Sassi  Bart Vermeulen  Tuomas Kärnä  Eric Deleersnijder  Ton Hoitink 《Ocean Dynamics》2011,61(8):1107-1120

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