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  • 1
    Language: English
    In: Urban Water Journal, 07 February 2017, Vol.14(2), pp.143-159
    Description: Hydrology plays a key role in mitigating environmental impacts with Stormwater Management (SWM). Site-level Low Impact Development (LID) is a promising approach but impeded by a lack of experience, performance metrics and comprehensive analysis. This study investigated the hydrologic performance...
    Keywords: Stormwater Runoff ; Urban Hydrology ; Design ; Rainfall-Runoff Analysis ; Environmental Impact ; Source Control ; Engineering
    ISSN: 1573-062X
    E-ISSN: 1744-9006
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  • 2
    In: Wiley Interdisciplinary Reviews: Water, November 2017, Vol.4(6), pp.n/a-n/a
    Description: We review the state‐of‐the‐art of cross‐disciplinary knowledge on phosphorus (P) cycling in temperate forest ecosystems, focused at studies from hydrology, biology, biogeochemistry, soil‐, and geosciences. Changes in soil P stocks during long‐term ecosystem development are addressed briefly; the general ranges of specific P pools and P fluxes within the ecosystem and the presumed underlying processes are covered more in depth. Wherever possible, we differentiate between coniferous and deciduous forests. As the most important P pools, mineral soil, forest floor, vegetation, and microbial biomass are described in terms of pool size, molecular composition, and turnover. Litterfall, soil water seepage, atmospheric deposition, and biotic uptake as the most studied P fluxes in the forest ecosystem are discussed in detail, spotlighting biogeochemical processes relevant for mobilization and retention of P in the rooting zone. Through a meta‐analysis of available literature, we build a dataset that allows the quantification of major P‐cycle components in temperate forests in terms of range and distribution, highlighting similarities and differences between coniferous and deciduous forests. The two forest types are notably distinct in their distribution of P within compartments of the plant biomass and forest floor. The possibility to construct closed local P balances is often hindered by missing information on fluxes of dissolved and particulate P across the ecosystem boundary, be it in the atmosphere, soil, or on the surface. These fluxes are irregular in space and time and feature large overall mass fluxes but comparatively small P fluxes, making the latter one difficult to quantify. 2017, 4:e1243. doi: 10.1002/wat2.1243 This article is categorized under: A schematic respresentation of the Phosphorus cycle in temperate forests. Pools and fluxes are scaled to their average size. See the full paper for more detailed information and data sources.
    Keywords: Phosphorus Cycle ; Phosphorus ; Phosphorus Cycle ; Compartments ; Phosphorus ; Uptake ; Biogeochemistry ; Biomass ; Plant Biomass ; Environmental Changes ; Soil Water ; Pools ; Soil Water ; Distribution ; Composition ; Forests ; Phosphorus Cycle ; Biogeochemistry ; Biogeochemistry ; Biomass ; Biology ; Phosphorus ; Forests ; Microorganisms ; Ecosystems ; Moisture Content ; Forest Floor ; Forest Ecosystems ; Forests ; Stocks ; Hydrology ; Forests ; Rooting ; Pools ; Seepage ; Components ; Hydrology ; Deciduous Forests ; Forest Floor ; Fluxes ; Atmospheric Pollutant Deposition ; Soils ; Hydrology ; Seepage ; Biomass ; Hydrology ; Forest Biomass;
    ISSN: 2049-1948
    E-ISSN: 2049-1948
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  • 3
    Language: English
    In: Nanoscale Research Letters, 2014, Vol.9(1), pp.1-7
    Description: Byline: Ruth F Balderas-Valadez (6), Markus Weiler (7,8), Vivechana Agarwal (6), Claudia Pacholski (7) Keywords: Porous silicon; Hydrogel; Self-assembly; Sensor Abstract: Abstract The optical response of porous silicon (pSi) films, covered with a quasi-hexagonal array of hydrogel microspheres, to immersion in ethanol/water mixtures was investigated. For this study, pSi monolayers were fabricated by electrochemical etching, stabilized by thermal oxidation, and decorated with hydrogel microspheres using spin coating. Reflectance spectra of pSi samples with and without deposited hydrogel microspheres were taken at normal incidence. The employed hydrogel microspheres, composed of poly-N-isopropylacrylamide (polyNIPAM), are stimuli-responsive and change their size as well as their refractive index upon exposure to alcohol/water mixtures. Hence, distinct differences in the interference pattern of bare pSi films and pSi layers covered with polyNIPAM spheres could be observed upon their immersion in the respective solutions using reflective interferometric Fourier transform spectroscopy (RIFTS). Here, the amount of reflected light (fast Fourier transform (FFT) amplitude), which corresponds to the refractive index contrast and light scattering at the pSi film interfaces, showed distinct differences for the two fabricated samples. Whereas the FFT amplitude of the bare porous silicon film followed the changes in the refractive index of the surrounding medium, the FFT amplitude of the pSi/polyNIPAM structure depended on the swelling/shrinking of the attached hydrogel spheres and exhibited a minimum in ethanol-water mixtures with 20 wt% ethanol. At this value, the polyNIPAM microgel is collapsed to its minimum size. In contrast, the effective optical thickness, which reflects the effective refractive index of the porous layer, was not influenced by the attached hydrogel spheres. PACS 81.05.Rm 81.16.Dn 83.80Kn 42.79.Pw Author Affiliation: (6) CIICAp, UAEM, Av., Universidad 1001 Col. Chamilpa, Cuernavaca, Morelos, 62210, Mexico (7) Department of New Materials and Biosystems, Max Planck Institute for Intelligent Systems, Heisenbergstr. 3, Stuttgart, 70569, Germany (8) Department of Biophysical Chemistry, University of Heidelberg, Im Neuenheimer Feld 253, Heidelberg, 69120, Germany Article History: Registration Date: 12/05/2014 Received Date: 12/05/2014 Accepted Date: 29/07/2014 Online Date: 22/08/2014 Article note: Electronic supplementary material The online version of this article (doi: 10.1186/1556-276X-9-425) contains supplementary material, which is available to authorized users.
    Keywords: Porous silicon ; Hydrogel ; Self-assembly ; Sensor
    ISSN: 1931-7573
    E-ISSN: 1556-276X
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  • 4
    Language: English
    In: Advances in Water Resources, July 2012, Vol.43, pp.67-75
    Description: ► Spatial variability of flow velocities and dispersion in shallow waters. ► Heated water can serve as a conservative artificial tracer in shallow waters. ► Thermal images allow 2-dimensional assessment of transport parameters. The two-dimensional distribution of flow velocities in shallow waters is one of the governing factors for solute transport processes. Thus, a direct and simple experimental method to spatially assess mean flow velocity and dispersion could improve the prediction of solute transport. In an experimentally constructed wetland we identified these variables on the basis of highly resolved spatial datasets obtained by a novel tracer approach: we observed slug injections of heated water with hand-held thermographic systems. Adding NaCl to the heated water reduced density differences between the heated and natural water. Determined flow velocities and dispersion changed according to the variation of the wetland shape. The introduced method allows to easily determining basic flow characteristics and when applied to other wetlands or shallow surface waters with complex structures, it may be the first step for a better process understanding.
    Keywords: Solute Transport ; Dispersion ; Wetlands ; Tracer ; Thermography ; Engineering
    ISSN: 0309-1708
    E-ISSN: 1872-9657
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  • 5
    Language: English
    In: Environmental science & technology, 05 July 2016, Vol.50(13), pp.7074-81
    Description: Recently, laser-based water stable isotope spectrometers have become popular as they enable previously impossible approaches of environmental observations. Consequently, they have been subjected to increasingly heterogeneous atmospheric conditions. However, there is still a severe lack of data on the impact of nonstandardized gas matrices on analyzer performances. Against this background, we investigated the influence of changing proportions of N2, O2, and CO2 in the carrier gas on the isotope measurements of a typical laser-based water stable isotope analyzer (Picarro L2120-i). We combined environmentally relevant mixtures of N2, O2, and CO2 with referenced, flash-evaporated water and found that isotope readings of the same water were altered by up to +14.57‰ for δ(18)O and -35.9‰ for δ(2)H. All tested relationships between carrier gas changes and respective isotope readings were strongly linearly correlated (R(2) 〉 0.99). Furthermore, an analyzer-measured variable allowed for reliable postcorrection of the biased isotope readings, which we additionally tested on field data. Our findings are of importance for environmental data obtained by analyzers based on the same technology. They are relevant for assays where inconsistent gas matrices or a mismatch in this regard between unknown and reference analyses cannot be excluded, which is in particular common when investigating the soil-vegetation-atmosphere continuum.
    Keywords: Oxygen Isotopes ; Water
    ISSN: 0013936X
    E-ISSN: 1520-5851
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  • 6
    Language: English
    In: Advances in Water Resources, April 2013, Vol.54, pp.149-160
    Description: ► We present a new approach to simulate time variant recharge areas of karst systems. ► A model that includes system variability and variable recharge areas is developed. ► System dynamics and recharge area are considered separately during the calibration. ► Only when a variable recharge area is included, the model can be used for prediction. A specific characteristic of karst systems is the occurrence of time variant recharge areas. In our study we present a new type of hydrological karst model and a new calibration approach both considering this specific characteristic. The new model type considers the spatial variability of karst system properties by distribution functions, and is compared to a simple reservoir model. Both models are applied to a karst system in Southern Spain where objective functions applied on hydrodynamic and hydrochemical information helped to determine model parameters playing a role for hydrodynamic response. Thereafter, the recharge area is determined separately for individual hydrological years and for the entire time series by calibrating the model to match the water balance. We show that hydrochemical information is crucial to find a reasonable set of parameters for both models. Considering different hydrological years, we find that the recharge area is changing significantly (from 28 to 53 km ). The newly developed model is able to reproduce this variation and provide acceptable simulation results for the entire time series of available data. The classic reservoir model shows inferior performance concerning hydrodynamics and fails to reproduce the water balance because it does not consider variations of recharge area. Our calibration approach allows identifying a variable recharge area and our new model is able to reproduce its variability. Hence we obtain a more realistic system representation, which can be of high significance when models are used for prediction, i.e. beyond the conditions they were calibrated, e.g. for land-use or climate change scenarios.
    Keywords: Karst Aquifer ; Numerical Modelling ; Calibration ; Hydrochemistry ; Variable Recharge Area ; Engineering
    ISSN: 0309-1708
    E-ISSN: 1872-9657
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  • 7
    Language: English
    In: Water Quality Research Journal, 02/2009, Vol.44(1), pp.16-25
    Description: Interception loss plays an important role in controlling the water balance of a watershed, especially where urban development has taken place. The aim of this study was to illustrate the importance of urban trees as a form of 'green infrastructure' where they reduce stormwater runoff and rainwater intensity. In addition, trees cause a delay in precipitation reaching the ground. Interception loss was studied in the North Shore of British Columbia. We applied a unique methodology for measuring throughfall under six different urban trees using a system of long polyvinyl chloride pipes hung beneath the canopy capturing the throughfall and draining it to a rain gauge attached to a data logger. Different tree species (Douglas-fi r [Pseudotsuga menziesii] and western red cedar [Thuja plicata]) in variable landscape sites (streets, parks, and natural forested areas) and elevations were selected to ensure that the system adequately captured the throughfall variability. Interception and throughfall were monitored over a one year cycle for which the results of seven discrete storm events for coniferous trees from the District of North Vancouver during 2007 to 2008 are presented. Cumulative gross precipitation for seven selected events was 377 mm. Average canopy interception during these events for Douglas-fi r and western red cedar were 49.1 and 60.9%, where it corresponded to average net loss of 20.4 and 32.3 mm, respectively. The interception loss varied depending on canopy structure, climatic conditions, and rainfall characteristics.
    Keywords: Engineering ; Environmental Sciences;
    ISSN: 1201-3080
    E-ISSN: 2408-9443
    Source: CrossRef
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  • 8
    Language: English
    In: Powder Technology, 2010, Vol.203(2), pp.248-253
    Description: Micron and submicron particles tend to form agglomerates due to adhesive and cohesive forces. The disintegration of these dry powder agglomerates often represents a major task in powder technology. One model describing the mechanical stability of granulates is given by the planar fracture model of Rumpf. In the present work, a new model is introduced intended for applications where a complete disintegration of dry powder agglomerates is required (e.g. for pharmaceutical aerosol generation). Therefore, the breakup of every single connection inside an agglomerate is considered and the dispersion strength of model agglomerates is calculated and discussed. In order to balance the stability of agglomerates predicted from the model with the stress which is required for powder dispersion, mechanisms of deagglomeration in fluids are discussed. Furthermore it could be shown from an example of a dry powder disperser, that a step-wise disintegration is most likely which can also be described by the model. In addition to the planar fracture model of RUMPF, a new model is introduced intended for applications where a complete disintegration of dry powder agglomerates is required.
    Keywords: Powder Dispersion ; Deagglomeration ; Tensile Strength ; Surface Energy ; Aerosols ; Spray Drying ; Engineering
    ISSN: 0032-5910
    E-ISSN: 1873-328X
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  • 9
    In: Wiley Interdisciplinary Reviews: Water, September 2017, Vol.4(5), pp.n/a-n/a
    Description: Modeling snow redistribution by wind and avalanches in hydrological studies in alpine catchments is important, as the spatial variability of the snow cover has an impact on timing and magnitude of the snowmelt runoff. Disregarding snow redistribution in models can lead to the formation of ‘snow towers,’ i.e., multi‐year accumulation of snow at high elevations and an incorrect water balance. The reviewed approaches to deal with snow redistribution in hydrological models were first broadly grouped by the represented physical processes: (1) the correction of the precipitation input data to account mainly for preferential deposition, (2) the description of all wind‐driven processes based on wind field data, (3) the description of gravitational transports and/or wind‐driven processes based on topographic information, and (4) the statistical description of the variability of the snow water equivalent () to account for all types of snow redistribution. The review further assessed the implementation of these approaches in physically based and bucket‐type hydrological models. Generally, snow redistribution consideration has improved the simulation of snow patterns and and consequently the prediction of discharge in mountain catchments worldwide. Snow redistribution approaches still have some limitations and a large gap exists between the knowledge and processes in highly detailed physically based snow models and the widely used bucket‐type hydrological models used for water resources and climate change studies. There is a real need to bridge this gap using the knowledge earned by snow redistribution modeling with established physically based models to develop more conceptual approaches for the application in bucket‐type models. 2017, 4:e1232. doi: 10.1002/wat2.1232 This article is categorized under: An accurate representation of snow redistribution by wind and avalanches in hydrological models is important: (i) to accurately simulate runoff as the snow cover variability has an impact on timing and magnitude of snowmelt runoff; and (ii) to avoid the formation of snow towers, i.e. multi‐year accumulation of snow at high elevations.
    Keywords: Snow-Water Equivalent ; Models ; Avalanches ; Spatial Variations ; Runoff ; Water Balance ; Landslides ; Snowmelt ; Water Balance ; Snow Avalanches ; Simulation ; Runoff ; Runoff ; Variability ; Computer Simulation ; Catchment Areas ; Climate Change ; Water Resources ; Towers ; Snowmelt ; Bridges ; Water Resources ; Resources ; Gravitation ; Reviews ; Water Resources ; Simulation ; Catchments ; Water Balance ; Climate Change ; Catchments ; Avalanches ; Snow Cover ; Models ; Gravity ; Modelling ; Runoff ; Wind ; Climate Change ; Hydrology ; Spatial Discrimination ; Hydrologic Data ; Water Balance ; Water Resources ; Wind ; Data Processing ; Snow ; Snow Cover ; Modelling ; Alpine Environments ; Rainfall ; Catchment Area ; Climate Models ; Climate ; Variability ; Hydrologic Models ; Climatic Changes ; Hydrology ; Precipitation;
    ISSN: 2049-1948
    E-ISSN: 2049-1948
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  • 10
    Language: English
    In: Journal of Materials Research, 11/2010, Vol.25(11), pp.2125-2134
    Keywords: Engineering ; Physics;
    ISSN: 0884-2914
    E-ISSN: 2044-5326
    Source: CrossRef
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