Artykuły w czasopismach na temat „Residence time and flushing”
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1
Mayer, B., T. Stacke, I. Stottmeister i T. Pohlmann. "Sunda Shelf Seas: flushing rates and residence times". Ocean Science Discussions 12, nr 3 (22.05.2015): 863–95. http://dx.doi.org/10.5194/osd-12-863-2015.
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Abstract. The region of the Sunda Shelf has an average depth of approx. 48 m and is subject to many physical and biogeochemical processes with a strong impact from human activities. For the investigation of marine environmental water properties and quality, it is helpful to have an idea about exchange rates of water masses in the different parts of this region. Four numerical models, the global hydrodynamical model MPI-OM, the global hydrological model MPI-HM, the regional hydrodynamical model HAMSOM and a Lagrangian tracer model have been utilized to estimate the flushing rates and residence times in different seas on the Sunda Shelf. Using decadal averaged monthly transports, the commonly used flushing rate formula gives rates for the different months of approximately 40 to 70 days for the entire Sunda Shelf. For most parts of it (Malacca Strait, southern South China Sea, Java Sea), the results are similar, while for the Gulf of Thailand, the flushing rates amount to 80 to 170 days. The tracer model provides quite different but very detailed 3-D pictures with residence times of below 30 days to more than two years, depending on the location within the region, on the starting layer and on the season.
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Hasanloo, Davood, i Amir Etemad-Shahidi. "On the estimation of transport timescales – case study: the Dez reservoir". Journal of Hydroinformatics 13, nr 2 (29.04.2010): 217–28. http://dx.doi.org/10.2166/hydro.2010.161.
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The purpose of this study is to demonstrate an application of a hydroinformatics methodology for analysis of transport timescales in a large reservoir. Therefore, a laterally averaged two-dimensional numerical model was used to estimate the transit time, flushing times and combination of these two timescales by modeling about 230 scenarios in the Dez reservoir. The model was calibrated using temperature profiles and then executed for a period of two years (2002–2004). A possible characterization of the flushing time as e-folding time was investigated and the results revealed that the e-folding time, which is simpler to estimate, can be used in place of the flushing time in the Dez reservoir. The effects of the location of the outlet on each of these timescales were also investigated. Results indicated that the mean residence and flushing times have their smallest value when the outlet is set in the middle of the Dez dam. The mean flushing times were also less sensitive to thermal structures of the Dez reservoir than the transit times. Finally, the temporal patterns of these timescales were elucidated. It was found that no single transport timescale can be used for all conditions.
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Monsen, Nancy E., James E. Cloern, Lisa V. Lucas i Stephen G. Monismith. "A comment on the use of flushing time, residence time, and age as transport time scales". Limnology and Oceanography 47, nr 5 (wrzesień 2002): 1545–53. http://dx.doi.org/10.4319/lo.2002.47.5.1545.
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Cornett, R. J., i L. Chant. "Pu Residence Times in Freshwaters and Accumulation in Shield Lake Sediments". Canadian Journal of Fisheries and Aquatic Sciences 45, nr 3 (1.03.1988): 407–15. http://dx.doi.org/10.1139/f88-049.
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Activity balances for 239,240Pu in seven oligotrophic lakes were constructed from measurements of 239,240Pu inputs and measurements of 239,240Pu accumulated in the lake sediments. 239,240Pu eroded from the catchment was a significant input to lakes with rapid hydrologic flushing rates. From 28 to 100% of the 239,240Pu input to the lakes accumulated in the lake sediments. The fraction of 239,240Pu inputs accumulated in the lake sediments was inversely correlated with the hydrologic flushing rate of the lake. 239,240Pu concentrations in the sediments were simulated using a single reservoir input–output model. Partial residence times for 239,240Pu transfer from the water to the sediments ranged from 0.09 to 2.7 yr and were shorter in lakes with more rapid flushing. Partial residence times of 239,240Pu in these small shield lakes were very similar to the residence times of 239,240Pu in the Laurentian Great Lakes and to those of 137Cs and 210Pb in other small oligotrophic lakes.
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John, Sebin, K. R. Muraleedharan, C. Revichandran, S. Abdul Azeez, G. Seena i Pierre W. Cazenave. "What Controls the Flushing Efficiency and Particle Transport Pathways in a Tropical Estuary? Cochin Estuary, Southwest Coast of India". Water 12, nr 3 (23.03.2020): 908. http://dx.doi.org/10.3390/w12030908.
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Estuaries with poor flushing and longer residence time retain effluents and pollutants, ultimately resulting in eutrophication, a decline in biodiversity and, finally, deterioration of water quality. Cochin Estuary (CE), southwest coast of India, is under the threat of nutrient enrichment by the anthropogenic interventions and terrestrial inputs through land runoff. The present study used the FVCOM hydrodynamic model coupled with the Lagrangian particle module (passive) to estimate the residence time and to delineate site-specific transport pathways in the CE. The back and forth movements and residence time of particles was elucidated by using metrics such as path length, net displacement and tortuosity. Spatio-temporal patterns of the particle distribution in the CE showed a similar trend during monsoon and post-monsoon with an average residence time of 25 and 30 days, respectively. During the low river discharge period (pre-monsoon), flood-ebb velocities resulted in a minimum net transport of the water and longer residence time of 90 days compared to that of the high discharge period (monsoon). During the pre-monsoon, particle released at the southern upstream (station 15) traversed a path length of 350 km in 90 days before being flushed out through the Fortkochi inlet, where the axial distance was only 35 km. This indicates that the retention capacity of pollutants within the system is very high and can adversely affect the water quality of the ecosystem. However, path length (120 km) and residence time (7.5 days) of CE were considerably reduced during the high discharge period. Thus the reduced path length and the lower residence time can effectively transport the pollutants reaching the system, which will ultimately restore the healthy ecosystem. This is a pioneer attempt to estimate the flushing characteristics and residence time of the CE by integrating the hydrodynamics and Lagrangian particle tracking module of FVCOM. This information is vital for the sustainable management of sensitive ecosystems.
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Organ, A. J. "Analysis of the gas turbine rotary regenerator". Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 211, nr 2 (1.02.1997): 97–111. http://dx.doi.org/10.1243/0954407971526263.
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Recent solution of the ‘Hausen’ regenerator and conjugate heat transfer problems invites a fresh look at the Ritz rotary regenerator. The approach deals readily with the reflux phase (‘hold-up’, flushing or ‘residence time’) and with the effects of friction (re-heating and pressure drop). There is no necessity to assume constant Stanton number, Nst, and friction factor, Cf. With accurate temperature and flow solutions available, recovery ratios in terms of operating parameters are a fait accompli. Optimization for specified duty becomes possible.
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Kim, Jin Ho, Won Chan Lee, Sok Jin Hong, Jung Hyun Park, Chung Sook Kim, Woo Sung Jung i Dong-Myung Kim. "A Study on Temporal-Spatial Water Exchange Characteristics in Gamak Bay using a Method for Calculating Residence Time and Flushing Time". Journal of Environmental Science International 25, nr 8 (30.08.2016): 1087–95. http://dx.doi.org/10.5322/jesi.2016.25.8.1087.
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Murphy, Enda, Mathieu Deiber i Sylvain Perrin. "SHEAR-DRIVEN FLUSHING OF MICRO-TIDAL MARINAS". Coastal Engineering Proceedings 1, nr 33 (15.12.2012): 59. http://dx.doi.org/10.9753/icce.v33.currents.59.
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Flushing or residence times are typically used as a first step in assessing water quality in marinas, harbours and coastal basins. Recent publications have offered guidance in relation to optimal marina basin and entrance geometries to help achieve rapid renewal. However, these guidelines have been developed for the particular case where water exchange is strongly tide-driven and are not widely applicable, particularly in micro-tidal regions. Where water renewal rates are dominated by shear-driven circulation and lateral transfer of momentum at the interface between the marina and the adjacent water body (i.e. a mixing layer), there is a strong analogy to groyne fields and other cases involving flows containing quasi-stagnant peripheral areas (dead zones). A series of numerical hydrodynamic models, developed in the TELEMAC system, were used to investigate the potential for the dead zone model of water exchange to provide a
better means to guide optimization of basin and entrance geometry under such conditions. Real-world marina case
studies were used to identify any constraints affecting the practical implementation of such an approach. The numerical model results demonstrate particular conditions under which the dead zone model of water exchange can be used effectively to optimize marina basin and entrance geometry.
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Chen, Yucheng, Jian-nan Fu, Yi Wang, Jian Ding, Xiaoying Lian, Weizhi Wei i Xiao Chen. "Microbial Risks in Household UF Purifiers and Disinfection Strategy with Electrolysis". E3S Web of Conferences 143 (2020): 02028. http://dx.doi.org/10.1051/e3sconf/202014302028.
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The research studied microbial deterioration in household ultrafiltration membrane (UF) purifiers with residence time and anti-bacterial strategy with electrolysis. The pilot test was conducted on a household drinking water purifier. A 72-h stagnation test and a 60-min anti-bacterial test with electrolysis were subsequently done. There were some findings in this study: (1) The level of HPC exceeded the hygienic standard when the stagnation time was more than 3 h. (2) The lag phase of bacterial growth was no more than 12 h in filters. (3) With the method of electrolysis, microbial contamination induced by water stagnation can be controlled in the acceptable range, which was more efficient than the method of flushing with tap water.
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Zhang, J., N. Sinha, M. Ross i A. E. Tejada-Martínez. "Computational fluid dynamics analysis of the hydraulic (filtration) efficiency of a residential swimming pool". Journal of Water and Health 16, nr 5 (26.06.2018): 750–61. http://dx.doi.org/10.2166/wh.2018.110.
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Abstract Hydraulic or filtration efficiency of residential swimming pools, quantified in terms of residence time characteristics, is critical to disinfection and thus important to public health. In this study, a three-dimensional computational fluid dynamics model together with Eulerian and Lagrangian-based techniques are used for investigating the residence time characteristics of a passive tracer and particles in the water, representative of chemicals and pathogens, respectively. The flow pattern in the pool is found to be characterized by dead zone regions where water constituents may be retained for extended periods of times, thereby potentially decreasing the pool hydraulic efficiency. Two return-jet configurations are studied in order to understand the effect of return-jet location and intensity on the hydraulic efficiency of the pool. A two-jet configuration is found to perform on par with a three-jet configuration in removing dissolved constituents but the former is more efficient than the latter in removing or flushing particles. The latter result suggests that return-jet location and associated flow circulation pattern have an important impact on hydraulic efficiency. Thus return-jet configuration should be incorporated as a key parameter in the design of swimming pools complementing current design standards.
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Shore, Jennifer A. "Impact of the Monthly Variability of the Trent River on the Hydrodynamical Conditions of the Bay of Quinte, Ontario: A Case Study 2016–2019". Water 12, nr 10 (25.09.2020): 2683. http://dx.doi.org/10.3390/w12102683.
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The spatial and temporal (monthly) variability of river discharge has a significant effect on circulation and transport pathways within shallow embayments whose dynamics are largely controlled by wind and riverine inputs. This study illustrates the effects of the monthly variation in Trent River discharge on simulated particle transport and settling destination in the Bay of Quinte, Lake Ontario for the years 2016–2019. Observations of Lagrangian surface drifter data were used to derive Trent River discharge forcing for a three-dimensional hydrodynamic numerical model of the Bay of Quinte. Peak monthly flushing was up to three times as much as the lowest monthly flushing in any year, with the Trent River responsible for up to 95% of the flushing in low runoff years. Particle transport simulations showed that particles could be trapped along shorelines, which extended residence times, and Trent River releases suggest that researchers should look for delayed peaks in Total Phosphorous (TP) load measurements in observations between Trenton and Belleville as particles move downstream. Particles with constant settling velocities originating from the Trent River did not move downstream past Big Bay, and particles from the Napanee River were the primary source for Longreach.
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Dissanayake, Janith, i Mooyoung Han. "Effect of Inlet/Outlet Configuration on Water Quality in a Rainwater Harvesting Tank". Water 12, nr 7 (12.07.2020): 1970. http://dx.doi.org/10.3390/w12071970.
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Rainwater harvesting (RWH) has attracted global attention as a solution for the urban water crisis; however, the water quality can be impacted by particulate matter and soluble contaminants. Therefore, the inlet and outlet configurations of the storage tank should be designed to minimize bottom sediment resuspension and prevent the transport of soluble contaminants. Thus, this study investigated the effects of the inlet and outlet configurations of a rainwater storage tank on particle resuspension and residence time distribution for an instantaneous input of a conservative tracer. It was observed that J type inlets can reduce sediment resuspension by more than 50% while detaining and mixing a conservative pollutant, thus preventing the concentration from reaching the outlet as a plug flow. Although inlet height did not have a significant influence on the quality of water at the outlet, parameters such as inflow velocity and outlet height exerted a considerable influence on sludge resuspension and residence time distribution. The experiments also highlighted the importance of regulating the initial water level of the storage tank and regular flushing of bottom sediment to maintain the stored water quality.
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Defne, Zafer, i Neil K. Ganju. "Quantifying the Residence Time and Flushing Characteristics of a Shallow, Back-Barrier Estuary: Application of Hydrodynamic and Particle Tracking Models". Estuaries and Coasts 38, nr 5 (23.09.2014): 1719–34. http://dx.doi.org/10.1007/s12237-014-9885-3.
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Kawata, Akiyoshi, Akira Okada, Yasuhiro Okamoto i Haruya Kurihara. "Influence of Nozzle Jet Flushing on Wire Breakage in 1st-Cut Wire EDM from Start Hole". Key Engineering Materials 749 (sierpień 2017): 130–35. http://dx.doi.org/10.4028/www.scientific.net/kem.749.130.
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In wire EDM process, it is important to smoothly exclude debris and bubbles generated in the working gap for keeping stable performance. Much debris stagnation in the gap would cause frequent occurrence of discharge concentration and secondary discharge, which results in unstable machining performance, such as frequent wire breakage, low removal rate, and low shape accuracy. Therefore, a jet flushing of working fluid using upper and lower jet nozzles has been conventionally applied for excluding the debris and bubbles from the machined kerf. Nevertheless, it is well known that the wire often breaks when the machined kerf length is a few mm from the start hole in 1st-cut wire EDM. The influence of machined kerf length on the flow field, the debris exclusion, and the wire behavier caused with hydrodyanamic force by the jet flushing should be made clear.In this study, variations of flow field in the kerf, the debris accumulation state and the wire deflection caused jet flushing with machined length were analytically investigated by CFD (computational fluid dynamics) and structural analysis when 1st-cut wire EDM was done from a small start hole. Moreover, the effects of machined kerf length on the wire deflection and wire breakage were discussed. Wire breakage frequency experiments showed that wire tended to frequently break at a certain machined kerf length, where the wire deflection rapidly increased and the debris particle residence time in the gap became long.
15
Olding, Daniel D., Johan A. Hellebust i Marianne SV Douglas. "Phytoplankton community composition in relation to water quality and water-body morphometry in urban lakes, reservoirs, and ponds". Canadian Journal of Fisheries and Aquatic Sciences 57, nr 10 (1.10.2000): 2163–74. http://dx.doi.org/10.1139/f00-176.
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Distinct differences in observed summer phytoplankton communities in relation to maximum depth suggest that constraints posed by water-body morphometry may modify the trophic control of phytoplankton-community composition and structure in urban water bodies. In deep urban sites (Zmax [Formula: see text] 5 m), phytoplankton communities tended to be predictably related to trophic status (i.e., increases in trophy were associated with increased cyanobacterial dominance, a decreased proportion of Chrysophyceae-Synurophyceae and grazable-size algae, and a decrease in community richness), although exceptions existed, owing to factors such as human intervention, age of the water body, and flushing rates. In contrast, in shallow urban water bodies (Zmax < 5 m), trophic status was a poor predictor of phytoplankton communities. Across meso- to hyper-eutrophic conditions, shallow urban sites were rarely dominated by cyanobacteria and, when they were, the species composition differed from nutrient-rich deep urban sites. The key requirement for cyanobacterial dominance in shallow urban sites appears to be sufficiently long water residence times, viz., greater than 8-14 days. Further study should describe how the relationship between water body residence time and species-generation time may limit the development of specific nuisance algal species, aiding in the management and rehabilitation of urban water bodies.
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Schmalenberg, Mira, Stephanie Kreis, Lena K. Weick, Christian Haas, Fabian Sallamon i Norbert Kockmann. "Continuous Cooling Crystallization in a Coiled Flow Inverter Crystallizer Technology—Design, Characterization, and Hurdles". Processes 9, nr 9 (29.08.2021): 1537. http://dx.doi.org/10.3390/pr9091537.
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Continuous small-scale production is currently of utmost interest for fine chemicals and pharmaceuticals. For this purpose, equipment and process concepts in consideration of the hurdles for solids handling are required to transfer conventional batch processing to continuous operation. Based on empirical equations, pressure loss constraints, and an expandable modular system, a coiled flow inverter (CFI) crystallizer with an inner diameter of 1.6 mm was designed. It was characterized concerning its residence time behavior, tested for operation with seed crystals or an ultrasonic seed crystal unit, and evaluated for different purging mechanisms for stable operation. The residence time behavior in the CFI corresponds to ideal plug flow behavior. Crystal growth using seed crystals was demonstrated in the CFI for two amino acids. For fewer seed crystals, higher crystal growth rates were determined, while at the same time, secondary nucleation was observed. Feasibility for the interconnection of a sonicated seeding crystal unit could be shown. However, the hurdles are also identified and discussed. Prophylactic flushing combined with a photosensor for distinguishing between solvent and suspension phase can lead to stable and resource-efficient operation. The small-scale CFI technology was investigated in detail, and the limits and opportunities of the technology are presented here.
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Miller, Ronald L., i Benjamin F. McPherson. "Estimating estuarine flushing and residence times in Charlotte Harbor, Florida. via salt balance and a box model". Limnology and Oceanography 36, nr 3 (maj 1991): 602–12. http://dx.doi.org/10.4319/lo.1991.36.3.0602.
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Carlsson, Bengt, i Håkan Sanner. "Modelling Influence of River Regulation on Runoff to the Gulf of Bothnia". Hydrology Research 27, nr 5 (1.10.1996): 337–50. http://dx.doi.org/10.2166/nh.1996.0014.
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Runoff from a land area of approximately 490,000 km2 enters the Gulf of Bothnia. This runoff is of essential importance for the flushing of the Gulf. A change in the volume of runoff effects the residence time. There are many natural as well as man made changes in the runoff, both in the form of long-term changes over many years and those occurring within one year. The most significant man made changes come from hydropower regulation. This report describes the effect on runoff from the development of the hydropower plants in Sweden and Finland by means of comparing recorded regulated runoff and simulated natural runoff. A recent time period, 1980-91, and a time period before regulation, 1925-36, were simulated. The monthly magnitudes of the redistributed flows were found to be on average 1,700 m3/s. The maximum redistributed monthly flow in May – June reached 5,000-6,000 m3/s.
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de Haro Martí, Mario Emanuel, William Howard Neibling, Lide Chen i Mireille Chahine. "On-Farm Testing of a Zeolite Filter to Capture Ammonia and Odors from a Dairy Manure Flushing System". Transactions of the ASABE 63, nr 3 (2020): 597–607. http://dx.doi.org/10.13031/trans.13556.
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Highlights A zeolite filter achieved 92% reduction in ammonia emissions from a dairy flushed manure pit. The reduction in odor concentration was 45% at a minimum filter residence time of 0.9 seconds. The on-farm filter and air collection structure over a manure pit demonstrated the applicability of the project. Abstract. The concentration of large numbers of animals in relatively small areas, high production output per animal unit, and concentration of animal excretions and air emissions are some of the characteristics of modern animal agriculture. Ammonia (NH3) and odors are among the most noticeable as well as locally and regionally problematic emissions generated by concentrated animal feeding operation (CAFO) dairy production systems. Zeolites are defined as aluminosilicates with open three-dimensional framework structures composed of corner-sharing TO4 tetrahedra, where T is Al or Si. Zeolites are able to lose or gain water reversibly and to exchange and retain cations, including NH3 and ammonium. This study demonstrated the design and performance of a zeolite filter treating the airstream from a flushed manure pit installed on-farm at a commercial dairy. Clinoptilolite zeolite mined in Idaho was used as the filter medium. The capacity of the filter to reduce NH3 emissions was tested at three, six, and 59 days of filter operation. Reduction of odor emissions was tested at six days of operation. NH3 emissions were reduced by 92% (p < 0.001) at three days of operation and by 42% (p = 0.13) at 59 days of operation. The ammonia concentration in the pre-treatment airstream from a dairy manure collection pit was relatively high at 5.287 ±0.04 mg NH3-N m-3 (p < 0.001). The odor concentration reduction was 45% (p = 0.001) at six days of operation with the minimum empty bed residence time of 0.9 s. Total trial running time was 59 days. The roof-like pit cover structure used for air collection and the zeolite filter were proven to be capable of operating in the harsh on-farm environment and to be adaptable to changing operating conditions within the dairy. Keywords: Air filtration, Ammonia, Clinoptilolite, Dairy, Manure, Odor, Zeolite
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Ljubenkov, Igor. "Hydrodynamic modeling of stratified estuary: case study of the Jadro River (Croatia)". Journal of Hydrology and Hydromechanics 63, nr 1 (1.03.2015): 29–37. http://dx.doi.org/10.1515/johh-2015-0001.
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Abstract The Jadro River with total length of 4.3 km and average annual discharge of 7.9 m3 s-1 is a relatively small river on the east coast of the Adriatic Sea, close to Split. Field campaign measurements were made to estimate salt intrusion in the Jadro estuary in July 2012. This measurement confirmed the stratified character of the estuary where fresh water flows in a thin layer over denser sea water. Furthermore, a numerical model was set up for simulating unsteady stratified flow without mixing between the layers. The model is applied for the Jadro River and field measurements are used for calibration. In addition, the steady state of stratification within the estuary is analyzed by a box model which assumes mixing between layers. Results of the numerical and the box models were compared. The flushing time estimated with the box model is approximately 1.5 day for summer steady conditions. Numerical analysis however shows that the residence time is much larger owing to flow unsteadiness
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Radbourne, Alan D., David B. Ryves, Genevieve Madgwick i N. John Anderson. "The Influence of Climate Change on the Restoration Trajectory of a Nutrient-Rich Deep Lake". Ecosystems 23, nr 4 (20.09.2019): 859–72. http://dx.doi.org/10.1007/s10021-019-00442-1.
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Abstract Nutrient reduction in impacted lowland freshwater systems is ecologically and culturally important. Gaining a greater insight into how lakes respond to lowering nutrient loads and how climate-driven physical limnology affects present and future cycling of available nutrients is important for ecosystem resource management. This study examines the nutrient decline in a hypereutrophic freshwater lake (Rostherne Mere, Cheshire, UK) 25 years after sewage effluent diversion, a uniquely long-term analysis of a recovering nutrient-rich deep lake. Using nutrient, phytoplankton, climate and catchment hydrological monitoring, the contemporary lake system is compared to previous studies from 1990 to 2002. Nutrient change since point source load diversion showed annual average and maximum phosphorus (P) concentrations decreased significantly for the first 10 years (1992: ~ 600 µg P L−1; 2002: ~ 200 µg P L−1), but have since stabilised due to a substantial legacy sediment P internal load. Dissolved inorganic nitrogen (DIN) concentrations have not substantially changed since diversion, resulting in the alteration of the DIN/SRP ratio from a system characterised by N limitation (N:P ~ 5), to one predominantly P limited (N:P > 20). Nutrient changes over this time are shown to drive ecological change, especially in the cyanobacterial and algal communities. Furthermore, very high-resolution monitoring of lake inflow and outflow (every 5 min during 2016) shows that water residence time at this lake is significantly shorter than previously estimated (~ 0.8 years compared to previous estimates of ~ 1.6–2.4 years). Together with long-term data demonstrating that the stratification period at Rostherne Mere has increased by 40 days over the last ~ 50 years (due to later autumnal mixing), we show that a rapid rate of epilimnetic flushing together with a long stratification period substantially reduces the available epilimnetic P during the summer cyanobacterial bloom. This is of growing importance for many such lakes, given widespread climate-driven lengthening of stratification and a national trend of decreasing summer rainfall (decreasing seasonal flushing) but more intense summer storm events (resulting in short-term flushing events).
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Duvert, C., M. K. Stewart, D. I. Cendón i M. Raiber. "Time-series of tritium, stable isotopes and chloride reveal short-term variations in groundwater contribution to a stream". Hydrology and Earth System Sciences Discussions 12, nr 8 (18.08.2015): 8035–89. http://dx.doi.org/10.5194/hessd-12-8035-2015.
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Abstract. A major limitation to the accurate assessment of streamwater transit time (TT) stems from the use of stable isotopes or chloride as hydrological tracers, because these tracers are blind to older contributions. Also, while catchment processes are highly non-stationary, the importance of temporal dynamics in older water TT has often been overlooked. In this study we used lumped convolution models to examine time-series of tritium, stable isotopes and chloride in rainfall, streamwater and groundwater of a catchment located in subtropical Australia. Our objectives were to assess the different contributions to streamflow and their variations over time, and to understand the relationships between streamwater TT and groundwater residence time. Stable isotopes and chloride provided consistent estimates of TT in the upstream part of the catchment. A young component to streamflow was identified that was partitioned into quickflow (mean TT ≈ 2 weeks) and discharge from the fractured igneous rocks forming the headwaters (mean TT ≈ 0.3 years). The use of tritium was beneficial for determining an older contribution to streamflow in the downstream area. The best fits were obtained for a mean TT of 16–25 years for this older groundwater component. This was significantly lower than the residence time calculated for the alluvial aquifer feeding the stream downstream (≈ 76–102 years), outlining the fact that water exiting the catchment and water stored in it had distinctive age distributions. When simulations were run separately on each tritium streamwater sample, the TT of old water fraction varied substantially over time, with values averaging 17 ± 6 years at low flow and 38 ± 15 years after major recharge events. This was interpreted as the flushing out of deeper, older waters shortly after recharge by the resulting pressure wave propagation. Overall, this study shows the usefulness of collecting tritium data in streamwater to document short-term variations in the older component of the TT distribution. Our results also shed light on the complex relationships between stored water and water in transit, which are highly nonlinear and remain poorly understood.
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Sachoemar, Suhendar I., i Andri Purwanda. "ANALISIS MODEL SEBARAN BAHAN PENCEMAR Dl PERAIRAN SELAT NGUAN, BATAM". Jurnal Teknologi Lingkungan 10, nr 1 (14.12.2016): 90. http://dx.doi.org/10.29122/jtl.v10i1.1508.
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Analysis of the pollutant transport model was conducted to understand themagtitude, their pattern and spreading speed of the pollutant at Nguan narrowchannel of Batam. The RMA2 (Resource Management Associates) analysis wasemployed to solve those phenomena. The target analysis of the pollutant issuspended particulate matter (sediment), a rnost dominant pollutant matter withinthis area. The result shows that the spreading pollutant was strongly associatedwith the monsoonal system, current speed, tidal system and the pollutant source.The southward direction of sediment transport was inluenced by the northwestmonsoon and the tidal flood. While the northward direction was affected by thethe southeast monsoon and the ebb tide. The current speed was identified asmain factor causing the flushing out magnitude of the water mass at the channel, inwhich the flushing out in the northwest monsoon was faster than that in the southeastmonsoon. As consequence, the water resident time was to be short, the pollutantwas easily to be cleaned out and as the result, the water quality within the channelwas to be excellent.
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Lucas, Lisa V., i Eric Deleersnijder. "Timescale Methods for Simplifying, Understanding and Modeling Biophysical and Water Quality Processes in Coastal Aquatic Ecosystems: A Review". Water 12, nr 10 (29.09.2020): 2717. http://dx.doi.org/10.3390/w12102717.
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In this article, we describe the use of diagnostic timescales as simple tools for illuminating how aquatic ecosystems work, with a focus on coastal systems such as estuaries, lagoons, tidal rivers, reefs, deltas, gulfs, and continental shelves. Intending this as a tutorial as well as a review, we discuss relevant fundamental concepts (e.g., Lagrangian and Eulerian perspectives and methods, parcels, particles, and tracers), and describe many of the most commonly used diagnostic timescales and definitions. Citing field-based, model-based, and simple algebraic methods, we describe how physical timescales (e.g., residence time, flushing time, age, transit time) and biogeochemical timescales (e.g., for growth, decay, uptake, turnover, or consumption) are estimated and implemented (sometimes together) to illuminate coupled physical-biogeochemical systems. Multiple application examples are then provided to demonstrate how timescales have proven useful in simplifying, understanding, and modeling complex coastal aquatic systems. We discuss timescales from the perspective of “holism”, the degree of process richness incorporated into them, and the value of clarity in defining timescales used and in describing how they were estimated. Our objective is to provide context, new applications and methodological ideas and, for those new to timescale methods, a starting place for implementing them in their own work.
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Cuevas Madrid, Homero, Alfonso Lugo Vázquez, Laura Peralta Soriano, Josué Morlán Mejía, Gloria Vilaclara Fatjó, María del Rosario Sánchez Rodríguez, Marco Antonio Escobar Oliva i Javier Carmona Jiménez. "Identification of Key Factors Affecting the Trophic State of Four Tropical Small Water Bodies". Water 12, nr 5 (20.05.2020): 1454. http://dx.doi.org/10.3390/w12051454.
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Due to their dimensions, small and shallow water bodies are more sensitive to changes in nutrient load, water flow, and human management. The four water bodies studied are small (area <0.01 km2), constantly supplied by a non-anthropogenic source of nutrients, and these water bodies present different trophic states: mesotrophic, eutrophic, and hyper-eutrophic. The objective of this study was to identify the key environmental factors that created differences in the trophic state of these adjacent shallow urban lakes by modeling chlorophyll-a (Chl a) through the application of the Partial Least Squares Regression (PLSR). The models (n = 36) explain 45.8–60.6% (R2), and predicts 39–52.9% (Q2) of the variance. Environmental variables were identified in the water bodies as critical factors of trophic state determination, water residence time (WRT), ions (e.g., Ca2+), and minerals as hydroxyapatite (HAP). These variables were related to processes that could improve trophic conditions, such as flushing and phosphorous precipitation. Conversely, N-NH3 concentration was associated with nutrient recycling, and found to be able to promote eutrophication.
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Li, Hui Xing, Wei Wang, Bei Ni Li i Wei Xiao. "Research and Analysis on Energy Efficiency of Typical Residential Building in Super Cold Area". Advanced Materials Research 608-609 (grudzień 2012): 1705–8. http://dx.doi.org/10.4028/www.scientific.net/amr.608-609.1705.
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The purpose of the paper is to research and analysis energy-efficient technology suited the residential building and energy consumption level of building, master the application of energy saving technology in building, thus provide the basis for energy saving and integrated application of adaptability in different buildings. The basic materials of residence in Shenyang were collected by the form of survey analysis, at the same time, evaluation and analysis of the energy consumption data. Through the investigation and building self assessment index analysis of the heat consumption, to achieve the requirements of the energy saving 65%.Building is obviously relevant to climate, and 90% of electricity consumption for appliances and lighting. There is a lot of energy waste with 40% of the building water consumption for flushing. Through to the analysis of the residential energy consumption, the key to energy saving of residential building are the thermal performance of the building itself, make full use of natural light and other measures, and improve the energy consumption of the system in the building and equipment efficiency.
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Duvert, C., M. K. Stewart, D. I. Cendón i M. Raiber. "Time series of tritium, stable isotopes and chloride reveal short-term variations in groundwater contribution to a stream". Hydrology and Earth System Sciences 20, nr 1 (18.01.2016): 257–77. http://dx.doi.org/10.5194/hess-20-257-2016.
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Abstract. A major limitation to the assessment of catchment transit time (TT) stems from the use of stable isotopes or chloride as hydrological tracers, because these tracers are blind to older contributions. Yet, accurately capturing the TT of the old water fraction is essential, as is the assessment of its temporal variations under non-stationary catchment dynamics. In this study we used lumped convolution models to examine time series of tritium, stable isotopes and chloride in rainfall, streamwater and groundwater of a catchment located in subtropical Australia. Our objectives were to determine the different contributions to streamflow and their variations over time, and to understand the relationship between catchment TT and groundwater residence time. Stable isotopes and chloride provided consistent estimates of TT in the upstream part of the catchment. A young component to streamflow was identified that was partitioned into quickflow (mean TT ≈ 2 weeks) and discharge from the fractured igneous rocks forming the headwaters (mean TT ≈ 0.3 years). The use of tritium was beneficial for determining an older contribution to streamflow in the downstream area. The best fits between measured and modelled tritium activities were obtained for a mean TT of 16–25 years for this older groundwater component. This was significantly lower than the residence time calculated for groundwater in the alluvial aquifer feeding the stream downstream ( ≈ 76–102 years), emphasising the fact that water exiting the catchment and water stored in it had distinctive age distributions. When simulations were run separately on each tritium streamwater sample, the TT of old water fraction varied substantially over time, with values averaging 17 ± 6 years at low flow and 38 ± 15 years after major recharge events. This counterintuitive result was interpreted as the flushing out of deeper, older waters shortly after recharge by the resulting pressure wave propagation. Overall, this study shows the usefulness of collecting tritium data in streamwater to document short-term variations in the older component of the TT distribution. Our results also shed light on the complex relationships between stored water and water in transit, which are highly non-linear and remain poorly understood.
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Cerralbo, Pablo, Marta F.-Pedrera Balsells, Marc Mestres, Margarita Fernandez, Manuel Espino, Manel Grifoll i Agustin Sanchez-Arcilla. "Use of a hydrodynamic model for the management of water renovation in a coastal system". Ocean Science 15, nr 2 (4.03.2019): 215–26. http://dx.doi.org/10.5194/os-15-215-2019.
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Abstract. In this contribution we investigate the hydrodynamic response in Alfacs Bay (Ebro Delta, NW Mediterranean Sea) to different anthropogenic modifications in freshwater flows and inner bay–open sea connections. The fresh water coming from rice field irrigation contains nutrients and pesticides and therefore affects in multiple ways the productivity and water quality of the bay. The application of a nested oceanographic circulation modelling suite within the bay provides objective information to solve water quality problems that are becoming more acute due to temperature and phytoplankton concentration peaks during the summer period when seawater may exceed 28 ∘C, leading to high rates of mussel mortality and therefore a significant impact on the local economy. The effects of different management “solutions” (like a connection channel between the inner bay and open sea) are hydrodynamically modelled in order to diminish residence times (e-flushing time) and water temperatures. The modelling system, based on the Regional Ocean Modeling System (ROMS), consists of a set of nested domains using data from CMEMS-IBI for the initial and open boundary conditions (coarser domain). One full year (2014) of simulation is used to validate the results, showing low errors with sea surface temperature (SST) and good agreement with surface currents. Finally, a set of twin numerical experiments during the summer period (when the water temperature reaches 28 ∘C) is used to analyse the effects of proposed nature-based interventions. Although these actions modify water temperature in the water column, the decrease in SST is not enough to avoid high temperatures during some days and prevent eventual mussel mortality during summer in the shallowest regions. However, the proposed management actions reveal their effectiveness in diminishing water residence times along the entire bay, thus preventing the inner areas from having poor water renewal and the corresponding ecological problems.
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Abdelrhman, Mohamed A. "Simplified modeling of flushing and residence times in 42 embayments in New England, USA, with special attention to Greenwich Bay, Rhode Island". Estuarine, Coastal and Shelf Science 62, nr 1-2 (styczeń 2005): 339–51. http://dx.doi.org/10.1016/j.ecss.2004.09.021.
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MORUF, Rasheed Olatunji, Gabriel Femi OKUNADE i Owoyemi Wahab ELEGBELEYE. "Bivalve Mariculture in Two – Way Interaction with Phytoplankton: A Review of Feeding Mechanism and Nutrient Recycling". Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca. Animal Science and Biotechnologies 77, nr 2 (18.11.2020): 1. http://dx.doi.org/10.15835/buasvmcn-asb:2020.0010.
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Bivalve mariculture is a type of molluscan farming done in open seawater on racks, rafts or longlines where naturally occurring phytoplankton serves as a key food item, introduced into the enclosures with the normal circulation of seawater. Increasingly, the reverse trophic interaction is being recognized; dissolved inorganic and organic waste compounds released by metabolically active bivalves can supply phytoplankton with nutrient and energy requirements for their growth. This two-way interaction can be viewed as a type of community symbiosis developed over long evolutionary timescales. The extent to which this affects overall nutrient budgets and thus primary production is related to the system flushing rate and residence time. Here we reviewed the feeding mechanism and nutrient recycling activities of bivalve and also emphasized the role of phytoplankton as a key nutritional live feed in sustainable bivalve mariculture. Bivalves influence nutrient dynamics through direct excretion and indirectly through microbial mediated remineralisation of their organic deposits in the sediments. The quantitative knowledge of bivalve - phytoplankton trophic interactions in coastal waters will inform bivalve mariculture development to effectively serve the needs of both seafood production and ecosystem restoration.
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Burger, Joanna, i Michael Gochfeld. "Human Distance and Birds: Tolerance and Response Distances of Resident and Migrant Species in India". Environmental Conservation 18, nr 2 (1991): 158–65. http://dx.doi.org/10.1017/s0376892900021743.
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In this report we describe a method of examining the tolerance of birds to humans, namely by measuring the distance to which birds will allow a person to approach them before flying off (flush distance). We studied the tolerance of Indian birds to approaching people by recording the flush distance for 925 individuals of 138 species of residents (birds breeding in India) and migrants (birds that are not known to breed in India). Over 20% of the variance in flush distance was accounted for by the number of people situated within 50 m, the distance to the closest person, the bird's migratory status, the number of people approaching, the time of day, and the bird's total body-length (including tail).For migratory species, 43% of the variability in flush distance was accounted for by distance to the closest other person, time of day, number of people originally within 50 m, number of people approaching, flock size, and species size. For resident species, only 18% of the variance was accounted for by distance to the closest other person, number of people within 50 m, and number of people approaching. Migrants were thus more responsive to the effect of humans, and their response was also influenced by their own size (body length) and flock size. Migratory species were less tolerant of people, flushing sooner than residents, and being more sensitive to the number of approaching people.We suggest that resident birds in North India have become habituated to the non-violent protective behaviour of the Hindu people towards birds, whereas migrants from farther north are more wary. Alternatively migrants, being less familiar than residents with the local predators and hiding places, may be more wary than residents on their home territory. Enhanced wariness results in more time spent alert or fleeing, with resultant greater energy-demand and decreased time for feeding.
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Nhongo, Kuitakwashe, Zvikomborero Hoko i Jameson Kugara. "Investigating disinfectant by-products in Harare potable water supply, Zimbabwe". Journal of Water, Sanitation and Hygiene for Development 8, nr 3 (6.06.2018): 415–28. http://dx.doi.org/10.2166/washdev.2018.104.
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Abstract Formation of disinfectant by-products was investigated in the Harare water supply system from February to April 2015. Sampling sites were selected from the lake, Morton Jaffray Water Treatment Works and critical points in the distribution system. The spatial variations of trihalomethanes and selected water quality parameters were investigated for 15 sampling points in 5 sampling campaigns to assess suitability for drinking. All trihalomethane species were measured, namely chloroform, bromodichloromethane, dibromochloromethane and bromoform. Only chloroform and bromodichloromethane were detected. The study confirmed that there is trihalomethanes formation in the Harare water distribution system and that it is affected by the residence time and presence of organic matter in the system. However, the levels of trihalomethanes are generally within the levels suggested by the World Health Organization. Only bromodichloromethane presents a risk for long-term exposure as it had levels that exceeded the limit for long-term exposure suggested by the United States Environmental Protection Agency. Bromodichloromethane, turbidity and free residual chlorine levels were not suitable for drinking in some of the zones. Boosting of chlorine residuals is necessary especially in areas with free chlorine less than 0.2 mg/L. Injection of ammonia, periodic cleaning of storage reservoirs, and flushing of lines will reduce trihalomethanes formation.
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Huguet, Jean-Rémy, Isabelle Brenon i Thibault Coulombier. "Characterisation of the Water Renewal in a Macro-Tidal Marina Using Several Transport Timescales". Water 11, nr 10 (30.09.2019): 2050. http://dx.doi.org/10.3390/w11102050.
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In this paper, we investigate the water renewal of a highly populated marina, located in the south-west of France, and subjected to a macro-tidal regime. With the use of a 3D-numerical model (TELEMAC-3D), three water transport timescales were studied and compared to provide a fully detailed description of the physical processes occurring in the marina. Integrated Flushing times (IFT) were computed through a Eulerian way while a Lagrangian method allowed to estimate Residence Times (RT) and Exposure Times (ET). From these timescales, the return-flow (the fraction of water that re-enters the marina at flood after leaving the domain at ebb) was quantified via the Return-flow Factor (RFF) and the Return Coefficient (RC) parameters. The intrinsic information contained in these parameters is thoroughly analysed, and their relevance is discussed. A wide range of weather-marine conditions was tested to provide the most exhaustive information about the processes occurring in the marina. The results highlight the significant influence of the tide and the wind as well as the smaller influence of the Floating Structures (FS) on the renewal. Besides, this study provides the first investigation of the water exchange processes of La Rochelle marina. It offers some content that interest researchers and environmental managers in the monitoring of pollutants as well as biological/ecological applications.
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Avvedimento, Stefania, Sara Todeschini, Carlo Giudicianni, Armando Di Nardo, Tom Walski i Enrico Creaco. "Flowing Blow-Offs: A Solution to Maintain Adequate Disinfectant Residuals of Dead-End Nodes in WDNs". Proceedings 48, nr 1 (12.11.2019): 20. http://dx.doi.org/10.3390/ecws-4-06443.
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Flushing plans within a water distribution network (WDN) provide a tool for improving disinfectant residuals and removing stagnant water. The problem of low disinfectant residuals occurs in areas of a WDN such as dead-end nodes, in which low flow conditions and long residence times lead to excessive decay of the disinfectant upstream from users. Here, a methodology is presented to maintain adequate disinfectant residuals in WDNs that have numerous dead-end nodes. The slight increase in nodal outflows at these sites, which can be obtained through the opening of a blow-off at the hydrant site, can help in tackling this problem. The methodology is based on the combined use of optimization and of flow routing/water quality modelling. The concentration of disinfectant at the source(s) and the values of nodal emitter coefficients at the critical dead-end nodes are the decisional variables to be optimized. Two objective functions are considered in the optimization, namely the total volume of water delivered in the network and the total mass of disinfectant injected into the network. The effectiveness of the methodology is proven on a real WDN, yielding an insight into the economic feasibility of the solution.
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Masi, F., R. Bresciani, A. Rizzo, A. Edathoot, N. Patwardhan, D. Panse i G. Langergraber. "Green walls for greywater treatment and recycling in dense urban areas: a case-study in Pune". Journal of Water, Sanitation and Hygiene for Development 6, nr 2 (31.05.2016): 342–47. http://dx.doi.org/10.2166/washdev.2016.019.
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This paper describes a pilot installation of a green wall treating greywater from an office building in Pune, Maharashtra State (NaWaTech project). The pilot installation is located at the main entrance of the state agency responsible for water supply and sanitation. The experimental analysis is in two phases. First phase analysed the results from green walls filled only with LECA® (lightweight expanded clay aggregate). Since results from the first phase were not satisfactory, a second phase was developed. In the second phase, LECA plus sand and LECA plus coconut fibres were tested as porous media in order to increase residence times and consequently green wall treatment performance. The expected improvements in treatment efficiency have been confirmed by the wider range of observed removal rates between Phase I (chemical oxygen demand, COD, 16–20%) and Phase II (i.e. COD removal in the order of 14–86% and 7–80% for LECA-coconut and LECA-sand, respectively), denoting higher treatment potentialities for the new configurations. The obtained effluent quality was fulfilling the Indian law specifications for reuse in irrigation for all the analysed samples, while only the last samples collected during Phase II were showing an appropriate quality for reuse by flushing toilets.
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Chaichana, Saisiri, Tim Jickells i Martin Johnson. "Interannual variability in the summer dissolved organic matter inventory of the North Sea: implications for the continental shelf pump". Biogeosciences 16, nr 5 (18.03.2019): 1073–96. http://dx.doi.org/10.5194/bg-16-1073-2019.
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Abstract. We present the distribution and C:N stoichiometry of dissolved organic matter (DOM) in the North Sea in two summers (August 2011 and August 2012), with supporting data from the intervening winter (January 2012). These data demonstrate local variability superimposed on a general pattern of decreasing DOM with increasing distance from land, suggesting concentrations of DOM are controlled on large spatial scales by mixing between the open North Atlantic and either riverine sources or high DOM productivity in nearshore coastal waters driven by riverine nutrient discharge. Given the large size and long residence time of water in the North Sea, we find concentrations are commonly modified from simple conservative mixing between two endmembers. We observe differences in dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) concentrations and land–ocean gradients between the two summers, leading to an estimated 10–20 Tg difference in the DOC inventory between the two years, which is of the same order of magnitude as the annual uptake of atmospheric CO2 by the North Sea system, and thus significant for the carbon budget of the North Sea. This difference is not consistent with additional terrestrial loading and is more likely to be due to balancing of mixing and in situ production and loss processes across the North Sea. Differences were particularly pronounced in the bottom layer of the seasonally stratifying northern North Sea, with higher DOC and C:N ratio in 2011 than in 2012. Using other data, we consider the extent to which these differences in the concentrations and C:N ratio of DOM could be due to changes in the biogeochemistry or physical circulation in the two years, or a combination of both. The evidence we have is consistent with a flushing event in winter 2011/12 exchanging DOM-rich, high C:N shelf waters, which may have accumulated over more than 1 year, with deep North Atlantic waters with lower DOC and marginally higher DON. We discuss the implications of these observations for the shelf sea carbon pump and the export of carbon-rich organic matter off the shelf and hypothesise that intermittent flushing of temperate shelf systems may be a key mechanism in the maintenance of the continental shelf pump, via the accumulation and subsequent export of carbon-rich DOM.
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Vansteenberge, Stef, Niels J. de Winter, Matthias Sinnesael, Sophie Verheyden, Steven Goderis, Stijn J. M. Van Malderen, Frank Vanhaecke i Philippe Claeys. "Reconstructing seasonality through stable-isotope and trace-element analyses of the Proserpine stalagmite, Han-sur-Lesse cave, Belgium: indications for climate-driven changes during the last 400 years". Climate of the Past 16, nr 1 (16.01.2020): 141–60. http://dx.doi.org/10.5194/cp-16-141-2020.
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Abstract. Fast-growing speleothems allow for the reconstruction of palaeoclimate down to a seasonal scale. Additionally, annual lamination in some of these speleothems yields highly accurate age models for these palaeoclimate records, making these speleothems valuable archives for terrestrial climate. In this study, an annually laminated stalagmite from the Han-sur-Lesse cave (Belgium) is used to study the expression of the seasonal cycle in northwestern Europe during the Little Ice Age. More specifically, two historical 12-year-long growth periods (ca. 1593–1605 CE and 1635–1646 CE) and one modern growth period (1960–2010 CE) are analysed on a sub-annual scale for their stable-isotope ratios (δ13C and δ18O) and trace-element (Mg, Sr, Ba, Zn, Y, Pb, U) contents. Seasonal variability in these proxies is confirmed with frequency analysis. Zn, Y and Pb show distinct annual peaks in all three investigated periods related to annual flushing of the soil during winter. A strong seasonal in-phase relationship between Mg, Sr and Ba in the modern growth period reflects a substantial influence of enhanced prior calcite precipitation (PCP). In particular, PCP occurs during summers when recharge of the epikarst is low. This is also evidenced by earlier observations of increased δ13C values during summer. In the 17th century intervals, there is a distinct antiphase relationship between Mg, Sr and Ba, suggesting that processes other than PCP, i.e. varying degrees of incongruent dissolution of dolomite, eventually related to changes in soil activity and/or land-use change are more dominant. The processes controlling seasonal variations in Mg, Sr and Ba in the speleothem appear to change between the 17th century and 1960–2010 CE. The Zn, Y, Pb, and U concentration profiles; stable-isotope ratios; and morphology of the speleothem laminae all point towards increased seasonal amplitude in cave hydrology. Higher seasonal peaks in soil-derived elements (e.g. Zn and Y) and lower concentrations of host-rock-derived elements (e.g. Mg, Sr, Ba) point towards lower residence times in the epikarst and higher flushing rates during the 17th century. These observations reflect an increase in water excess above the cave and recharge of the epikarst, due to a combination of lower summer temperatures and increased winter precipitation during the 17th century. This study indicates that the transfer function controlling Mg, Sr and Ba seasonal variability varies over time. Which process is dominant – either PCP, soil activity or dolomite dissolution – is clearly climate driven and can itself be used as a palaeoenvironment proxy.
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Hurlimann, Anna, i Sara Dolnicar. "Acceptance of water alternatives in Australia – 2009". Water Science and Technology 61, nr 8 (1.04.2010): 2137–42. http://dx.doi.org/10.2166/wst.2010.007.
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In a nationally representative study with a sample size of 1495, Australian residents were asked about their attitudes to recycled and desalinated water. Specifically, they were asked to state how likely they would be to use these sources of water for 14 purposes. Recycled water was found to have a higher stated likelihood of being used for watering gardens (compared to desalinated water). No significant differences in likelihood of use were found for toilet flushing, car washing and cleaning. For all other uses (including drinking), desalinated water had higher likelihood of use ratings. Respondents were also asked about their intention to relocate under four different water scenarios. This is a topic not studied before in the Australian context. Results indicate that respondents' stated likelihood to relocate was highest when there was insufficient water to meet their needs, followed by when recycled water was introduced into their supply, then the introduction of desalinated water. The scenario where residents had to rely on self-purified rain water from a tank had the lowest level of relocation intention. The results indicate that the increased provision of rainwater tanks may be the most publically acceptable water alternative for Australians at this point in time.
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Steward, D. R., W. J. de Lange, X. Yang, S. L. Vasak i T. N. Olsthoorn. "Groundwater ecohydrology: GIScience tools to forecast change and sustainability of global ecosystems, studies in Africa, Europe and North America". Hydrology and Earth System Sciences Discussions 6, nr 2 (31.03.2009): 2795–844. http://dx.doi.org/10.5194/hessd-6-2795-2009.
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Abstract. This study examines the interface between groundwater hydrology and ecology, and addresses a scientific grand challenge to develop a comprehensive, systematic understanding of continental water dynamics by linking the hydrosphere and biosphere. There exists a current lack of data interoperability between groundwater modeling tools due to differences in numerical techniques – Analytic Element Method (AEM), Finite Difference Method (FDM), and Finite Element Method (FEM) – which lend themselves well to either vector or raster data, and legacy input/output file formats that are not well suited across models. Nonetheless, investigative computational tools are all founded in the same conceptualization of hydrologic properties associated with mass, flux, pathways and residence time. A consistent framework is developed using modern Geographic Information Science (GIScience) methods to organize and archive important information from international datasets and previous groundwater ecohydrology studies organized around aquifer and water point, line, polygon and raster features. Case studies illustrate the efficacy of this platform to address existing data interoperability issues for representative groundwater ecohydrology problems of global significance including the impact of human-induced forcings, change in species, and forcings by natural processes on groundwater ecohydrology. In North America, we study the relationships between groundwater pumping in the Ogallala Aquifer and changes in riparian habitat and phreatophyte species composition. In Europe, we study the impacts of changes in forest species composition on groundwater recharge and baseflow to biologically diverse fens and wetlands in the Veluwe sand hill region of The Netherlands. In Africa, we study the wetlands of the Okavango Delta in Botswana that forms an oasis in the midst of the Kalahari Desert and the role of groundwater in flushing salts from this freshwater ecosystem. In each study, we document the current state of knowledge, identify pertinent datasets and previous studies, develop new conceptual and computer models, and summarize findings. This computational platform provides a framework to study sustainability, to forecast the impacts of changes in forcings, and to provide a scientific underpinning that informs management and public policy debate.
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COHN, P. D., J. A. GLEASON, E. RUDOWSKI, S. M. TSAI, C. A. GENESE i J. A. FAGLIANO. "Community outbreak of legionellosis and an environmental investigation into a community water system". Epidemiology and Infection 143, nr 6 (1.08.2014): 1322–31. http://dx.doi.org/10.1017/s0950268814001964.
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SUMMARYDuring two legionellosis outbreak investigations, one at a geriatric centre and the other in high-rise housing for seniors, it was observed that additional cases of legionellosis occurred in nearby smaller residential settings. This apparent geographical cluster of legionellosis occurred in the same general area of a community water storage tank. No potential airborne sources in or near the area could be identified, but a community water system storage tank that was centrally located among case residences spurred an investigation of water-quality factors in the identified investigation area. Conditions conducive forLegionellagrowth, particularly low chlorine residuals, were found. The rate of legionellosis among residents aged ⩾50 years in the investigation areas (61·0 and 64·1/100 000) was eight times higher than in the rest of the service area (9·0/100 000) and almost 20 times higher than the statewide annual average incidence rate (3·2/100 000). A water mains flushing programme in the area was launched by the water utility, and water samples taken before and during flushing foundL. pneumophila.
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Wu, Xing, Burcu Akinci i Cliff I. Davidson. "Modeling Graywater in Residences: Using Shower Effluent in the Toilet Reservoir". Journal of Green Building 2, nr 2 (1.05.2007): 109–20. http://dx.doi.org/10.3992/jgb.2.2.109.
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Use of municipal water in residences can be decreased substantially by allowing “graywater” effluent from showering and other activities to fill the toilet reservoir. This paper considers a system developed in Germany for treatment and storage of shower wastewater for use in flushing the toilet. Based on literature data for distributions of shower duration and water flow rate, the volume of municipal water saved using the German system has been estimated for several usage scenarios. Results show significant savings of water that depend on the size of the treatment and storage tanks used in the graywater system as well as the number of toilet flushes per day. For example, a scenario with four residents each flushing nine times per day with 80 liter treatment and storage tanks shows a 50% chance that the savings in municipal water use for the toilet will exceed 73%. Because the timing of showers and toilet flushes is assumed to follow a uniform distribution throughout the day, the calculated tank sizes may be underestimates.
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Wang, Jingpeng, Youming Xiong, Baocheng Wu, Zongyu Lu, Xiaoxiao Li i Zheng Zhang. "Study on Reasonable Amount of Flushing Fluid and Flushing Time". Energies 13, nr 17 (31.08.2020): 4483. http://dx.doi.org/10.3390/en13174483.
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Oil-based drilling fluid has many advantages, such as stable performance, strong anti-pollution ability, and strong inhibition, and it has been widely used in the world. However, at present, there is no unified evaluation standard for the effect of flushing fluid under this condition, and most of them are based on the flushing effect evaluation of water-based drilling fluid. However, there are few studies on wetting reversal phenomenon, reasonable dosage, and flushing time between oil-based drilling fluid and flushing fluid on the two-phase interface. Therefore, it is necessary to establish a comprehensive evaluation method for the effect of flushing fluid under oil-based drilling fluid, and explore the relationship between the amount of flushing fluid and flushing efficiency, so as to determine the reasonable range of flushing fluid consumption. In this paper, using the existing experimental instruments, a type A oil-based flushing fluid commonly used in oil fields was selected for the experiment, and on the basis of the high-temperature and high-pressure filtration meter, a flushing fluid evaluation device was developed. Based on the principle of equal shear rate, the flushing displacement and flushing time were determined, and then the flushing effect was evaluated. In order to comprehensively consider the influencing factors of the well wall flushing effect, five experimental factors, including different core, flushing displacement, flushing time, flushing fluid type, and surfactant concentration, were selected to formulate the flushing experiment scheme. The contrast method was used to test the cementation strength of core and cement slurry under different conditions, and the microscopic morphology of the interface was observed and analyzed to explore the reasons for the change of cementation strength between core and cement slurry due to the existence of oil-based drilling fluid. The conclusion obtained has very important practical significance to guide the field practice.
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Suire, Colby G., Nathalie Brouard, Brian Blaugrund i Paul J. Simmons. "Isolation of the Stromal/Vascular Fraction of Murine Bone Marrow Dramatically Enhances MSC Yield, Allows Isolation of Marrow Endothelial Cells and Reveals Multiple Subpopulations of Stromal Cells." Blood 116, nr 21 (19.11.2010): 3861. http://dx.doi.org/10.1182/blood.v116.21.3861.3861.
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Abstract Abstract 3861 The bone marrow is the organ of residence of a population of multipotent progenitor cells most commonly referred to as mesenchymal stem cells (MSC) based upon their multilineage differentiation potential into bone, cartilage and adipose tissue. The capacity for MSC to contribute to tissue repair demonstrated by numerous previous reports has engendered considerable interest in their application to a broad range of cellular therapies. It follows that a robust reproducible methodology for obtaining high yields of MSC from preclinical animal models, such as rodents, would greatly facilitate the development of these various MSC-based cellular therapies. The plastic-adherent, clonogenic progenitors termed colony forming unit-fibroblast (CFU-F) originally identified by Freidenstein and colleagues that initiate MSC cultures are a rare population in the marrow of all mammalian species so far examined. This is particularly so in the case of the mouse where reported incidences of CFU-F are typically in the range of 1/200,000 bone marrow BM cells. The low incidence of CFU-F significantly complicates the isolation of homogeneous populations of MSC from mouse BM, a common problem being contamination with hematopoietic cells. Seeking to develop an improved methodology to harvest MSC from mouse using methods based on plastic adherent bone marrow, we took advantage of burgeoning evidence demonstrating the perivascular location of MSC not only in the bone marrow, but also in multiple tissues. We hypothesized that a potential reason for the low yield of mMSC from mBM is the flushing of the marrow used to remove single cells suspensions and the consequent destruction of the marrow vasculature, which may adversely affect recovery of MSC physically associated with the abluminal surface of blood vessels. Herein, we describe a simple methodology based on preparation of intact marrow plugs that yields distinct populations of both stromal and endothelial cells. BM plugs are subjected to 3 sequential rounds of digestion in collagenase/dispase and each fraction assayed for content of CFU-F. The recovery of CFU-F obtained by pooling the product of each digestion (1643+199) reproducibly exceeds that obtained using the standard BM flushing technique (13.3+1.9) by at least 2 orders of magnitude (P=<0.001; N = 8) with an accompanying 196-fold enrichment of CFU-F frequency. Purified BM stromal cell populations devoid of hematopoietic contamination are readily obtained by FACS at P0 and these demonstrate robust multilineage differentiation into bone, adipose and chondrogenic progeny using standard in vitro bioassays. A detailed immunophenotypic analysis of the P0 cultures demonstrated the existence of multiple stromal cell subpopulations many of the markers analyzed, including Sca-1, CD90, CD105, CD146 and PDGFRa, which was progressively lost with serial passaging. Discrete subpopulations of stromal cells identified at P0, in many cases had phenotypically identical counterparts in the BM cell suspensions prepared by serial digestion and we are in the process of quantitatively analyzing the evolution of selected phenotypes in vitro to provide clues as to the identity of the founder population of stromal cells that gives rise to ‘MSC' in vitro. Finally, the phenotypic analysis of P0 cultures also revealed a discrete population of CD105BrightPDGFRaNeg cells representing a mean of 26.7% of hematopoietic lineage-negative cells. Upon isolation and serial propagation, the cells maintain expression of all of the vascular endothelial markers examined including CD31, CD105, VCAM-1, CD144 and MECA32 and also demonstrate inducible expression of E-selectin upon treatment with TNF-a. In conclusion, we describe a simple and robust methodology that, for the first time, allows the simultaneous isolation of both the stromal and vascular components of mouse BM. Secondly, the yield of ‘MSC' afforded by this technique far exceeds that reported in any previous study. Thirdly, this technique reveals a level of stromal cell heterogeneity not apparent in previous analyses of mouse BM-derived MSC that more realistically reflects the likely complexity of stromal cell populations in vivo and represents a platform for the eventual prospective isolation of specific subpopulations. These studies will greatly enhance experimental strategies designed to analyze not only MSC identity but also the function of the vascular hematopoietic niche. Disclosures: No relevant conflicts of interest to declare.
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Nauman, E. Bruce. "Residence Time Theory". Industrial & Engineering Chemistry Research 47, nr 10 (maj 2008): 3752–66. http://dx.doi.org/10.1021/ie071635a.
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Smith, H. J. "GEOLOGY: Residence Time". Science 306, nr 5700 (19.11.2004): 1263b. http://dx.doi.org/10.1126/science.306.5700.1263b.
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Meerkov, S. M., i T. Runolfsson. "Residence time control". IEEE Transactions on Automatic Control 33, nr 4 (kwiecień 1988): 323–32. http://dx.doi.org/10.1109/9.192186.
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Delhez, Éric J. M., Benjamin de Brye, Anouk de Brauwere i Éric Deleersnijder. "Residence time vs influence time". Journal of Marine Systems 132 (kwiecień 2014): 185–95. http://dx.doi.org/10.1016/j.jmarsys.2013.12.005.
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Yu, Liming, Na Li, Xiaogang Liu, Qiliang Yang i Jun Long. "Influence of flushing pressure, flushing frequency and flushing time on the service life of a labyrinth-channel emitter". Biosystems Engineering 172 (sierpień 2018): 154–64. http://dx.doi.org/10.1016/j.biosystemseng.2018.06.010.
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Muthiya, A., T. Tazkiaturrizki i R. Ratnaningsih. "The application of grey water recycling at Gayanti City Apartment, South Jakarta". MATEC Web of Conferences 197 (2018): 13005. http://dx.doi.org/10.1051/matecconf/201819713005.
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This planning is aim to design the plumbing system at Gayanti City Apartment with a separate system or grey water recycling system so that the efficiency cost of the recycling system will be known. Clean water system from PAM JAYA DKI and recycle water system from grey water that distributed to Waste Water Treatment Plant (WWTP) to be treated and reused for flushing closet and watering plants are designed for this apartment. The amount of the clean water needed is 116.6 m3/day and the amount of the recycle water needed is 18.64 m3/day. Water supply system that applied to this apartment is roof tank system. Calculation of water consumption's fluctuations to determine the capacity of reservoirs and pumps are using Four Winds Apartment, Bellagio Apartment, Thamrin Residences Apartment, and Karet Kuningan Apartment as a comparison with the same criteria as the designed apartment. The capacity of the clean ground water tank is 123.5 m3and the recycle ground water tank is 12 m3. Transfer pumps work for 12 hour/day (1 time pause) and the capacity of clean roof water tank is 31.5 m3and the recycled one is 6.7 m3. Based on the chosen alternative in design, Gayanti City Apartment is using the first water supply system alternative that needs 18 stand pipes of clean water and 18 stands pipes of recycle water with 4 PRVs mounted on each stand pipes and booster pump installed for the top 6 floors. The amount of clean water needed is 116.6 m3/day and recycle water is 18.64 m3/day. Waste water produced is equal to 93.28 m3which 80% of it is the grey water that will be treated in Waste Water Treatment Plant into recycle water. Total amount of clean and recycled water investment and reservoir constructions is Rp. 1,637,227,201,- and percentage of clean water that can be saved from the application of recycling system is 18% with total efficiency cost Rp 233,932/day or Rp 7,017,960/month.
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Khakzad, Hamid, i Valery Ivanovich Elfimov. "Estimate of time required for environmentally friendly flushing in Dez dam reservoir". Water Practice and Technology 10, nr 1 (1.03.2015): 73–85. http://dx.doi.org/10.2166/wpt.2015.010.
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Environmentally friendly flushing aims to send only the concentrations of the sediment that the environment can withstand. In this study, the time required for environmentally friendly flushing in Dez dam reservoir was estimated. For this purpose, the relationship between the concentration, duration, and scale of the severity of ill-effect for fish was considered. A study was conducted on Dez dam reservoir in Iran, where the average historical outflow from the dam, and the volume of sediment flushing was evaluated. According to this study, the dam is facing a serious sedimentation problem. Its dead volume is presumed to be quite full in the coming 10 years. Performing flushing operations through the three irrigation gates of the dam has received much more attention in recent years as compared to the past. The results from this study help us to determine the appropriate hydraulic conditions to decrease the negative environmental effects of Dez dam flushing operations on the downstream ecosystem.