Um die anderen Arten von Veröffentlichungen zu diesem Thema anzuzeigen, folgen Sie diesem Link: Water concentration profile.
Zeitschriftenartikel zum Thema „Water concentration profile“
Geben Sie eine Quelle nach APA, MLA, Chicago, Harvard und anderen Zitierweisen an
Machen Sie sich mit Top-50 Zeitschriftenartikel für die Forschung zum Thema "Water concentration profile" bekannt.
Neben jedem Werk im Literaturverzeichnis ist die Option "Zur Bibliographie hinzufügen" verfügbar. Nutzen Sie sie, wird Ihre bibliographische Angabe des gewählten Werkes nach der nötigen Zitierweise (APA, MLA, Harvard, Chicago, Vancouver usw.) automatisch gestaltet.
Sie können auch den vollen Text der wissenschaftlichen Publikation im PDF-Format herunterladen und eine Online-Annotation der Arbeit lesen, wenn die relevanten Parameter in den Metadaten verfügbar sind.
Sehen Sie die Zeitschriftenartikel für verschiedene Spezialgebieten durch und erstellen Sie Ihre Bibliographie auf korrekte Weise.
1
Zolfaghari, Ashkan, Hassan Dehghanpour, Ebrahim Ghanbari und Doug Bearinger. „Fracture Characterization Using Flowback Salt-Concentration Transient“. SPE Journal 21, Nr. 01 (18.02.2016): 233–44. http://dx.doi.org/10.2118/168598-pa.
Der volle Inhalt der QuelleAnnotation:
Summary As observed in many shale-gas operations, salt concentration of flowback water increases with time. Usually, the shape of salt-concentration/load-recovery plots is different from one well to another. We hypothesize that the shape of the salinity profile during the flowback process provides useful information about the complexity of the fracture network. In this study, we propose a model to describe the relationship between salinity and cumulative water production. We also compare the model results and flowback-salinity data to characterize the fracture network. Flowback-salinity data are collected from three multifractured horizontal wells completed in the three shale members [Muskwa (Mu), Otter-Park (OP), and Evie (Ev)] of the Horn River Basin. The salinity profiles for the Mu and OP wells initially increase and finally reach a plateau, whereas the salinity profile for the Ev well shows a continuous increase and does not show a plateau. We hypothesize that the early water with lower salt concentration at the onset of the flowback process is mainly produced from the primary fractures with larger aperture size. Also, we believe that the fractures with smaller aperture size become more important as the flowback process progresses, and therefore, the high-salinity water produced at later times is mainly produced from secondary fractures. We also propose a model to describe the salinity-profile behaviors. The model presents the aperture-size distribution (ASD) of the fracture network. A comparative analysis of the model results and the flowback-salinity data indicates that the Ev well with a steady increase in its salinity profile has a wider ASD compared with the Mu and OP wells with a plateau in their salinity profiles. This suggests that the fracture network is more complex in Ev compared with those in Mu and OP. More-complex fracture network in Ev is also in agreement with its higher gas and lower water recovery during the flowback process as opposed to the lower gas and higher water recovery in Mu and OP. The presented model for describing the behavior of the salinity profile during the flowback process and its meaningful relationship to the fracture-network complexity provide an alternative approach for reservoir characterization. This study encourages the industry to manage the flowback operations carefully and to monitor the water chemistry.
2
Carvalho, Ramon Santos, Valéria Melo Mendonça, Gilton José Ferreira da Silva und Mário Jorge Campos dos Santos. „Patentometric Profile of Social Water“. International Journal for Innovation Education and Research 8, Nr. 6 (01.06.2020): 255–65. http://dx.doi.org/10.31686/ijier.vol8.iss6.2410.
Der volle Inhalt der QuelleAnnotation:
There are regions of the planet that are affected by climatological conditions that cause water scarcity. Thus, innovative techniques have emerged with the purpose of mitigating the reflexes caused by the natural factor: drought. These innovations arise with the objective of capturing, storing and carrying out rainwater treatment for the population. These, called social water technologies, comprise products, techniques or replicable methodologies that are developed specifically to solve the problem of water shortages. The present work aims to analyze the profile of innovations generated by social water technologies through the LATIPAT, INPI and WIPO bases. To search for patents, keywords that were relevant to the research were used and combined with Boolean operators. 907 patents were identified, the largest concentration of deposits in China, justified by the fact that the country adopts development policies that invest in R&D, differentiating itself from other countries. Among the patents analyzed there is a higher concentration of deposits related to the area of human needs and water treatment.
3
Kim, Dong-Lae, und Minoru Tomozawa. „Water concentration profile in silica glasses during surface crystallization“. Journal of Non-Crystalline Solids 279, Nr. 2-3 (Februar 2001): 179–85. http://dx.doi.org/10.1016/s0022-3093(00)00400-2.
Der volle Inhalt der Quelle
4
Begum, Abida, M. Ramaiah, Harikrishna, Irfanulla Khan und K. Veena. „Heavy Metal Pollution and Chemical Profile of Cauvery River Water“. E-Journal of Chemistry 6, Nr. 1 (2009): 47–52. http://dx.doi.org/10.1155/2009/154610.
Der volle Inhalt der QuelleAnnotation:
Analysis of water, plankton, fish and sediment reveals that the Cauvery River water in the downstream is contaminated by certain heavy metals. Water samples have high carbonate hardness. Concentrations of all elements and ions increase in the downstream. Main ions are in the following order: Na > HCO3>Mg > K > Ca> Cl > SO4. Heavy metal concentration in water was Cr >Cu ≈ Mn > Co > Ni > Pb > Zn, in fish muscles Cr > Mn > Cu > Ni > Co > Pb ≈ Zn, in phytoplanktens Co > Zn > Pb > Mn > Cr and in the sediments the heavy metal concentration was Co > Cr > Ni ≈ Cu > Mn > Zn > Pb. Although, the quality of Cauvery River may be classified as very good based on the salt and sodium for irrigation, Zn, Pb and Cr concentration exceeded the upper limit of standards. Metal concentrations in the downstream indicate an increase in the pollution load due to movement of fertilizers, agricultural ashes, industrial effluents and anthropogenic wastes. An immediate attention from the concerned authorities is required in order to protect the river from further pollution.
5
Cheng, Chen, Zhi Yao Song, Yi Gang Wang und Jin Shan Zhang. „On the Suspended Sediment Concentration Profile“. Applied Mechanics and Materials 212-213 (Oktober 2012): 20–24. http://dx.doi.org/10.4028/www.scientific.net/amm.212-213.20.
Der volle Inhalt der QuelleAnnotation:
After analyzing the surface-boundary condition of suspended sediment concentration (SSC), Cheng et al.[7] further improved the sediment diffusion coefficient which was proposed by Bose and Dey[6]. Then an improved Rouse law (IRL) was developed. This equation, which has a similar form as Rouse law, not only overcomes the zero concentration at the free surface, but also behaves generally better than Rouse law and van Rijn equation over the whole water depth in the verification analysis. In this paper, the surface-boundary condition of SSC is further analyzed. It is elucidated that IRL satisfies the surface-boundary condition more reasonably than Rouse law. In addition, a first-order approximation of IRL is developed. From this approximation, we can easily get the explicit expression of the depth-averaged SSC without any implicit integrals to be solved numerically or by the help of a chart. This is very useful in the further study of non-equilibrium suspended sediment transport (SST).
6
Srinivasan, PT, und T. Viraraghavan. „Characterisation and concentration profile of aluminium during drinking-water treatment“. Water SA 28, Nr. 1 (01.01.2002): 99. http://dx.doi.org/10.4314/wsa.v28i1.4873.
Der volle Inhalt der Quelle
7
Barabash, V., A. Osepian und P. Dalin. „Influence of water vapour on the height distribution of positive ions, effective recombination coefficient and ionisation balance in the quiet lower ionosphere“. Annales Geophysicae 32, Nr. 3 (11.03.2014): 207–22. http://dx.doi.org/10.5194/angeo-32-207-2014.
Der volle Inhalt der QuelleAnnotation:
Abstract. Mesospheric water vapour concentration effects on the ion composition and electron density in the lower ionosphere under quiet geophysical conditions were examined. Water vapour is an important compound in the mesosphere and the lower thermosphere that affects ion composition due to hydrogen radical production and consequently modifies the electron number density. Recent lower-ionosphere investigations have primarily concentrated on the geomagnetic disturbance periods. Meanwhile, studies on the electron density under quiet conditions are quite rare. The goal of this study is to contribute to a better understanding of the ionospheric parameter responses to water vapour variability in the quiet lower ionosphere. By applying a numerical D region ion chemistry model, we evaluated efficiencies for the channels forming hydrated cluster ions from the NO+ and O2+ primary ions (i.e. NO+.H2O and O2+.H2O, respectively), and the channel forming H+(H2O)n proton hydrates from water clusters at different altitudes using profiles with low and high water vapour concentrations. Profiles for positive ions, effective recombination coefficients and electrons were modelled for three particular cases using electron density measurements obtained during rocket campaigns. It was found that the water vapour concentration variations in the mesosphere affect the position of both the Cl2+ proton hydrate layer upper border, comprising the NO+(H2O)n and O2+(H2O)n hydrated cluster ions, and the Cl1+ hydrate cluster layer lower border, comprising the H+(H2O)n pure proton hydrates, as well as the numerical cluster densities. The water variations caused large changes in the effective recombination coefficient and electron density between altitudes of 75 and 87 km. However, the effective recombination coefficient, αeff, and electron number density did not respond even to large water vapour concentration variations occurring at other altitudes in the mesosphere. We determined the water vapour concentration upper limit at altitudes between 75 and 87 km, beyond which the water vapour concentration ceases to influence the numerical densities of Cl2+ and Cl1+, the effective recombination coefficient and the electron number density in the summer ionosphere. This water vapour concentration limit corresponds to values found in the H2O-1 profile that was observed in the summer mesosphere by the Upper Atmosphere Research Satellite (UARS). The electron density modelled using the H2O-1 profile agreed well with the electron density measured in the summer ionosphere when the measured profiles did not have sharp gradients. For sharp gradients in electron and positive ion number densities, a water profile that can reproduce the characteristic behaviour of the ionospheric parameters should have an inhomogeneous height distribution of water vapour.
8
Zima, P., J. Makinia, M. Swinarski und K. Czerwionka. „Effects of different hydraulic models on predicting longitudinal profiles of reactive pollutants in activated sludge reactors“. Water Science and Technology 58, Nr. 3 (01.08.2008): 555–61. http://dx.doi.org/10.2166/wst.2008.676.
Der volle Inhalt der QuelleAnnotation:
This paper presents effects of dispersion on predicting longitudinal ammonia concentration profiles in activated sludge bioreactor located at “Wschod” WWTP in Gdansk. The aim of this study was to use the one-dimensional advection-dispersion Equation (ADE) to simulate the flow conditions (based on the inert tracer concentrations in selected points) and longitudinal profile of reactive pollutant (based on the ammonia concentration profiles in selected points). The simulation results were compared with the predictions obtained using a traditional “tanks-in-series” (TIS) approach, commonly used in designing biological reactors. The use of dispersion coefficient calculated from an empirical formula resulted in substantial differences in the tracer concentration distributions in two sampling points in the bioreactor. Simulations using the one-dimensional ADE and TIS model, with the nitrification rate incorporated as the source term, revealed that the hydraulic model plays a minor role compared to the biochemical transformations in predicting the longitudinal ammonia concentration profiles.
9
Smith, R. „Multi-mode models of flow and of solute dispersion in shallow water. Part 2. Logarithmic velocity profiles“. Journal of Fluid Mechanics 286 (10.03.1995): 277–90. http://dx.doi.org/10.1017/s0022112095000735.
Der volle Inhalt der QuelleAnnotation:
A two-mode model for velocity and solute concentration in shallow-water flows is derived which allows for departures from the logarithmic velocity profile and from vertically well-mixed concentrations. The modelling is tested against exact results for a buoyancy-driven transverse flow and for a modified logarithmic velocity profile.
10
Arsenault, Guy, Alexandre D. Cvetkovic und Radovan Popovic. „Toxic Effects of Copper on Selenastrum capricornutum Measured by a Plow Cytometry-Based Method“. Water Quality Research Journal 28, Nr. 4 (01.11.1993): 757–66. http://dx.doi.org/10.2166/wqrj.1993.041.
Der volle Inhalt der QuelleAnnotation:
Abstract Adaptation of algae Selenastrum capricornutum to different copper concentrations (50,150,300 and 450 ppb) was investigated. A flow cytometry technique was used to evaluate esterase activity (staining probe: CFDA). Algal physiological stress was estimated by comparing the esterase activity profile of intoxicated samples to that of a control sample. Our results show that at high concentration (450 ppb), copper strongly reduces esterase activity, whereas it increases that activity at lower concentrations (<300 ppb). After 27 hours of incubation, the esterase activity level resumed to the normal profile for each copper concentrations. The esterase activity profile thus shows adaption processes of algae Selenastrum capricornutum to copper intoxication.
11
Warner, Ronald R., Mark C. Myers und Dennis A. Taylor. „Electron Probe Analysis of Human Skin: Determination of the Water Concentration Profile“. Journal of Investigative Dermatology 90, Nr. 2 (Februar 1988): 218–24. http://dx.doi.org/10.1111/1523-1747.ep12462252.
Der volle Inhalt der Quelle
12
Thiyagarajan, Ravi, Siddana Ravi und Prashant K. Bhattacharya. „Pervaporation of methyl–ethyl ketone and water mixture: Determination of concentration profile“. Desalination 277, Nr. 1-3 (August 2011): 178–86. http://dx.doi.org/10.1016/j.desal.2011.04.020.
Der volle Inhalt der Quelle
13
Kazmi, A. A., und H. Furumai. „A simple settling model for batch activated sludge process“. Water Science and Technology 42, Nr. 3-4 (01.08.2000): 9–16. http://dx.doi.org/10.2166/wst.2000.0352.
Der volle Inhalt der QuelleAnnotation:
A simple settling model for the batch activated sludge process was proposed that could predict sludge concentration profile as a function of time. The predicted dynamic biomass profile would be used to quantify biological reactions during settling. The model can be applied by giving easily measurable parameters such as initial MLSS concentration, sludge interface variation which characterizes the settling rate, and SVI as an index of biomass settleability. The model describes the sedimentation process of the sludge by linking three concentrations, namely the MLSS on sludge interface (XH), constant MLSS on sediment surface (XC), and the variable MLSS at the bottom (XB). It was tested for wide ranges of activated sludge concentrations (1750 mg/L-4630 mg/L) and SVI (104-265). The model was applied to express MLSS profile for a full scale SBR as well as for 1 and 2 m column settling tests. The simulated MLSS profile by linking three critical concentrations agrees well with the observed data. Mass balance applied at each time step indicated that the deviation was from −2 to +12% of the total initial mass. The stratified MLSS profile simulated from the model was applied to predict denitrification rate during settling.
14
Huong, Huynh Thi Thu, Nguyen Huu Quang, Le Van Son und Tran Trong Hieu. „Transport of oil/water partitioning components during water injection“. Petrovietnam Journal 6 (30.06.2021): 37–42. http://dx.doi.org/10.47800/pvj.2021.06-03.
Der volle Inhalt der QuelleAnnotation:
The oil/water partitioning components such as alkylphenols and aliphatic acids naturally exist in crude oil compositions at different initial concentrations of hundreds or even thousands of ppm depending on the location of the reservoir compared to the site of original rocks. During contact with sweeping injection brine, those compounds diffuse from oil phase to water phase due to oil/water partitioning behaviours. As a result, their concentration in oil contacting with water will be attenuating during water injection. Their concentration profile in water injection history contains the information related to diffusion in oil and water phase, interstitial velocity of water and oil saturation. This paper presents the research results of theoretical model and numerical model of the washed-out process of alkylphenols in the late stage of water injection. The research results have proposed approximate analytical expression for concentration of alkylphenols at the late stage of water flooding. In this regard, at the sufficient large injection volume the alkylphenol concentration attenuates exponentially and the attenuation rate depends on parameters such as partitioning coefficient, oil saturation and interstitial velocity of water and oil and diffusion coefficients. The simulation concentration results obtained from UTCHEM simulator for the 5-spot model showed a good match with analytical calculation results. The research results can be used as the basis for developing methods to assess water flooding systems as well as oil saturation. The results can also be used for study of transport of non-aqueous phase liquid (NAPL) in environmental contamination. Keywords: Residual oil saturation, waterflooding, tracer, partitioning organic compounds, enhanced oil recovery.
15
Nagaoka, H., und K. Sanda. „Simulation of turbulence and dissolved oxygen concentration profiles over biofilm using k–ɛ turbulence model“. Water Science and Technology 52, Nr. 7 (01.10.2005): 181–86. http://dx.doi.org/10.2166/wst.2005.0199.
Der volle Inhalt der QuelleAnnotation:
The objective of this study is to investigate the flow structure over biofilm experimentally and theoretically. Velocity and turbulence profiles over biofilm measured by a laser Doppler velocimetry were compared to simulated profiles using the k–ɛ turbulent model. Also, dissolved oxygen concentration profiles over biofilm are measured using a micro DO sensor. The k–ɛ turbulence model was proved to be a useful tool for the understanding of mass transfer inside and outside biofilm. Dissolved oxygen concentration profile inside and outside biofilm showed the existence of turbulent diffusion inside biofilm.
16
Puleo, Jack A., Joe Faries, Michael Davidson und Betsy Hicks. „A Conductivity Sensor for Nearbed Sediment Concentration Profiling“. Journal of Atmospheric and Oceanic Technology 27, Nr. 2 (01.02.2010): 397–408. http://dx.doi.org/10.1175/2009jtecho718.1.
Der volle Inhalt der QuelleAnnotation:
Abstract A new sensor that measures the vertical profile of nearbed sediment concentration is described. The conductivity-based sensor is composed of eight electrode pairs separated in the vertical by 2.5 × 10−3 m. Electrode pairs are sampled at 16 Hz, with higher rates achievable. Each electrode pair response is linear over the range of conductivity tested from 0.2 to 0.65 mS cm−1 that exceeds the range of conductivity values corresponding to sediment–water mixtures from clear water to the packed bed limit of 0.65 m3 m−3. A laboratory test over a planar sloping beach indicates the capability of the sensor to simultaneously quantify sediment concentration profiles from roughly 0.01 m below to 0.1 m above the at-rest bed. The data indicate that the upper few millimeters of the bed are highly mobile and that bed dilation and sediment mobility vary considerably over a swash cycle.
17
Johnsen, Gorm Krogh, Ø. G. Martinsen und S. Grimnes. „Estimation of In Vivo Water Content of the Stratum Corneum from Electrical Measurements“. Open Biomedical Engineering Journal 3, Nr. 1 (03.04.2009): 8–12. http://dx.doi.org/10.2174/1874120700903010008.
Der volle Inhalt der QuelleAnnotation:
In vivo water content in the epidermal stratum corneum can be estimated by means of low frequency susceptance measurements. In the in vitro calibration necessary to find the in vivo water content, the stratum corneum will have a uniform distribution of water across its thickness. However, in vivo stratum corneum has an increasing water concentration profile from the outermost towards the innermost parts. This paper will investigate the possibility of estimating the equilibrium water content in the in vivo stratum corneum non-invasively from electrical susceptance measurements. Given a known shape of the water concentration profile in the in vivo stratum corneum and the dependence of susceptance on the water content, it is possible to calculate the water content in vivo based on analytically derived expressions for the water concentration profile. A correspondence between in vivo and in vitro water content needed for this purpose is also established.
18
Kastl, G., I. Fisher, V. Jegatheesan, J. Chandy und K. Clarkson. „Prediction of chlorine and trihalomethanes concentration profile in bulk drinking water distribution systems from laboratory data“. Water Supply 3, Nr. 1-2 (01.03.2003): 239–46. http://dx.doi.org/10.2166/ws.2003.0110.
Der volle Inhalt der QuelleAnnotation:
Nearly all drinking water distribution systems experience a “natural” reduction of disinfection residuals. The most frequently used disinfectant is chlorine, which can decay due to reactions with organic and inorganic compounds in the water and by liquid/solids reaction with the biofilm, pipe walls and sediments. Usually levels of 0.2-0.5 mg/L of free chlorine are required at the point of consumption to maintain bacteriological safety. Higher concentrations are not desirable as they present the problems of taste and odour and increase formation of disinfection by-products. It is usually a considerable concern for the operators of drinking water distribution systems to manage chlorine residuals at the “optimum level”, considering all these issues. This paper describes how the chlorine profile in a drinking water distribution system can be modelled and optimised on the basis of readily and inexpensively available laboratory data. Methods are presented for deriving the laboratory data, fitting a chlorine decay model of bulk water to the data and applying the model, in conjunction with a simplified hydraulic model, to obtain the chlorine profile in a distribution system at steady flow conditions. Two case studies are used to demonstrate the utility of the technique. Melbourne’s Greenvale-Sydenham distribution system is unfiltered and uses chlorination as its only treatment. The chlorine model developed from laboratory data was applied to the whole system and the chlorine profile was shown to be accurately simulated. Biofilm was not found to critically affect chlorine decay. In the other case study, Sydney Water’s Nepean system was modelled from limited hydraulic data. Chlorine decay and trihalomethane (THM) formation in raw and treated water were measured in a laboratory, and a chlorine decay and THM model was derived on the basis of these data. Simulated chlorine and THM profiles agree well with the measured values available. Various applications of this modelling approach are also briefly discussed.
19
Liu, Bo, Qiong Lin Wang, Shao Wu Liu, Hui Fang Yu, Feng Wang, Yuan Bo Zhang und Shuang Zheng. „Function Component Concentration Profile-The Key Factor for the Modified Single Base Gun Propellant“. Advanced Materials Research 396-398 (November 2011): 1088–93. http://dx.doi.org/10.4028/www.scientific.net/amr.396-398.1088.
Der volle Inhalt der QuelleAnnotation:
A new generation of gun propellant, named Modified Single Base Propellant (MSBP), was successfully studied recently. The MSBP was prepared from single base propellant grain by impregnation with blasting oil, followed by deterring with deterrent in water medium. The function components in this propellant were nitroglycerine (NG) and polymer ester (NA). The concentration profiles of them were studied by Fourier Transform Infrared (FTIR) Microspectroscopy. The combustion performance of this propellant was investigated by means of closed-bomb tests and interior ballistic tests. It is found that the concentration profile of the function component is the key factor in MSBP. The static combustion performance and the characteristic of the interior ballistic are dependent on the concentration profile of function component.
20
Seibert, J., T. Grabs, S. Köhler, H. Laudon, M. Winterdahl und K. Bishop. „Linking soil- and stream-water chemistry based on a Riparian Flow-Concentration Integration Model“. Hydrology and Earth System Sciences 13, Nr. 12 (02.12.2009): 2287–97. http://dx.doi.org/10.5194/hess-13-2287-2009.
Der volle Inhalt der QuelleAnnotation:
Abstract. The riparian zone, the last few metres of soil through which water flows before entering a gaining stream, has been identified as a first order control on key aspects of stream water chemistry dynamics. We propose that the distribution of lateral flow of water across the vertical profile of soil water chemistry in the riparian zone provides a conceptual explanation of how this control functions in catchments where matrix flow predominates. This paper presents a mathematical implementation of this concept as well as the model assumptions. We also present an analytical solution, which provides a physical basis for the commonly used power-law flow-load equation. This approach quantifies the concept of riparian control on stream-water chemistry providing a basis for testing the concept of riparian control. By backward calculation of soil-water-chemistry profiles, and comparing those with observed profiles we demonstrate that the simple juxtaposition of the vertical profiles of water flux and soil water chemistry provides a plausible explanation for observed variations in stream water chemistry of several major stream components such as Total Organic Carbon (TOC), magnesium, calcium and chloride. The "static" implementation of the model structure presented here provides a basis for further development to account for seasonal influences and hydrological hysteresis in the representation of hyporheic, riparian, and hillslope processes.
21
Nekvapil, Tomáš, Ivana Borkovcová, Miriam Smutná und Zdeňka Svobodová. „Estrogenic Profile of the Svratka and Svitava Rivers in the Brno Area“. Acta Veterinaria Brno 78, Nr. 2 (2009): 313–17. http://dx.doi.org/10.2754/avb200978020313.
Der volle Inhalt der QuelleAnnotation:
Estrogens are chemical compounds considered to be endocrine disruptors. They are thought to affect the endocrine system even at low concentrations found in water (ng l-1). The aim of this work was to determine estrogenic compound levels in the rivers in the Brno area. The concentration of 17β-estradiol, ethynylestradiol, estrone and diethylstilbestrol was estimated in the water samples collected in the Svratka and Svitava rivers. Estrogens were isolated from the samples using solid-phase extraction with Oasis HLB cartridges and determined by means of reversed phase HPLC with UV detection. The detection limit of the method used was 6 ng l-1, repeatability expressed as RSD was 11%, and recovery was 87 - 103%. Estrogen values detected ranged in the interval of 6-209 ng l-1, depending on the sampling site. After treatment in the sewage water treatment plant, the water displayed markedly lower levels of estrogenic compounds. The results of the experiment demonstrate that HPLC-UV is a suitable method for determination of low concentrations of estrogens in water. The sewage water treatment plant reduces concentrations of estrogens but not sufficiently to prevent their estrogenic effect on fish.
22
VOGEL, MICHAEL J., und AMIR H. HIRSA. „Concentration measurements downstream of an insoluble monolayer front“. Journal of Fluid Mechanics 472 (30.11.2002): 283–305. http://dx.doi.org/10.1017/s0022112002002197.
Der volle Inhalt der QuelleAnnotation:
The surfactant concentration distribution on a planar uniform flow with a surface-piercing barrier was measured via the nonlinear optical technique of second-harmonic generation. The measurements were performed for an insoluble surfactant monolayer on the air/water interface. A theoretical model balancing surface elasticity and bulk shear at the interface was developed to predict the concentration profile for any insoluble monolayer. Measured equations of state, relating the surface tension to the surfactant concentration, were used in the model along with velocity data obtained using boundary-fitted digital particle image velocimetry. Theoretical concentration profiles were in agreement with experimental results. Additionally, global predictions from the model for four different insoluble surfactant systems also showed agreement with experimental measurements.
23
Carvalho, A. R., H. F. de Campos Velho, S. Stephany, R. P. Souto, J. C. Becceneri und S. Sandri. „Fuzzy ant colony optimization for estimating chlorophyll concentration profile in offshore sea water“. Inverse Problems in Science and Engineering 16, Nr. 6 (September 2008): 705–15. http://dx.doi.org/10.1080/17415970802083276.
Der volle Inhalt der Quelle
24
Priestley, Stacey C., Tavis Kleinig, Andrew J. Love, Vincent E. A. Post, Paul Shand, Martin Stute, Ilka Wallis und Daniel L. Wohling. „Palaeohydrogeology and Transport Parameters Derived from 4He and Cl Profiles in Aquitard Pore Waters in a Large Multilayer Aquifer System, Central Australia“. Geofluids 2017 (2017): 1–17. http://dx.doi.org/10.1155/2017/9839861.
Der volle Inhalt der QuelleAnnotation:
A study of chloride and 4He profiles through an aquitard that separates the Great Artesian Basin from the underlying Arckaringa Basin in central Australia is presented. The aquitard separates two aquifers with long water residence times, due to low recharge rates in the arid climate. One-dimensional solute transport models were used to determine the advective flux of groundwater across the aquitard as well as establish any major changes in past hydrological conditions recorded by variations of the pore water composition. This in situ study showed that both diffusion and slow downward advection (vz=0.7 mm/yr) control solute transport. Numerical simulations show that an increase in chloride concentration in the upper part of the profile is due to a reduction in recharge in the upper aquifer for at least 3000 years. Groundwater extraction since 2008 has likely increased chloride and 4He concentrations in the lower aquifer by pulling up water from deeper layers; however, there has been insufficient time for upward solute transport into the pore water profile by diffusion against downward advection. The transport model of 4He and chloride provides insight into how the two aquifers interact through the aquitard and how climate change is being recorded in the aquitard profile.
25
Sriboonnak, Sornsiri, Phacharapol Induvesa, Suraphong Wattanachira, Pharkphum Rakruam, Adisak Siyasukh, Chayakorn Pumas, Aunnop Wongrueng und Eakalak Khan. „Trihalomethanes in Water Supply System and Water Distribution Networks“. International Journal of Environmental Research and Public Health 18, Nr. 17 (27.08.2021): 9066. http://dx.doi.org/10.3390/ijerph18179066.
Der volle Inhalt der QuelleAnnotation:
The formation of trihalomethanes (THMs) in natural and treated water from water supply systems is an urgent research area due to the carcinogenic risk they pose. Seasonal effects and pH have captured interest as potential factors affecting THM formation in the water supply and distribution systems. We investigated THM occurrence in the water supply chain, including raw and treated water from water treatment plants (coagulation, sedimentation, sand filtration, ClO2-disinfection processes, and distribution pipelines) in the Chiang Mai municipality, particularly the educational institute area. The effects of two seasons, rainy (September–November 2019) and dry (December 2019–February 2020), acted as surrogates for the water quality profile and THM occurrence. The results showed that humic acid was the main aromatic and organic compound in all the water samples. In the raw water sample, we found a correlation between surrogate organic compounds, including SUVA and dissolved organic carbon (DOC) (R2 = 0.9878). Four species of THMs were detected, including chloroform, bromodichloromethane, dibromochloromethane, and bromoform. Chloroform was the dominant species among the THMs. The highest concentration of total THMs was 189.52 μg/L. The concentration of THMs tended to increase after chlorination when chlorine dioxide and organic compounds reacted in water. The effect of pH on the formation of TTHMs was also indicated during the study. TTHM concentrations trended lower with a pH ≤ 7 than with a pH ≥ 8 during the sampling periods. Finally, in terms of health concerns, the concentration of TTHMs was considered safe for consumption because it was below the standard (<1.0) of WHO’s Guideline Values (GVs).
26
Khudiar, Khalisa Kadim. „Effect of Magnetic Water on Some Physiological Aspects of Adult Male Rabbits“. Iraqi Journal of Veterinary Medicine 36, Nr. 0E (04.04.2012): 120–26. http://dx.doi.org/10.30539/iraqijvm.v36i0e.405.
Der volle Inhalt der QuelleAnnotation:
The present study was undertaken to search out thebeneficial effect of magnetized water on serumantioxidant, lipid profile and total protein of adult male rabbits. Twenty adult male rabbits were randomly divided into two equal groups and were treated daily for 60 days as follows:Group C:Rabbits of this group were allowed to ad libitumsupplyofdrinking water (control group),Group MG:Rabbits of this group were allowed to ad libitum supply of magnetic water.Fasting blood (for 8-12 hrs) samples were drawn by cardiac puncture technique at different times 0, 30 and 60 days of experiment for measuring the following parameters. Serum glutathione concentration (GSH), lipid profile including serum triacylglycerol (TAG), total cholesterol - (TC), high density lipoprotein - cholesterol (HDL-C), low density lipoprotein - cholesterol (LDL-C) and very low density lipoprotein cholesterol - (VLDL-C), total serum protein concentrations (TSP). The result revealed that drinking of magnetic water had beneficial effect on some physiological aspects manifested by a significant elevation in serum GSH, HDL-C and total serum proteins concentration. In addition to significant suppression in serums TC, TAG, LDL-C, and VLDL-C concentrations .In conclusion the results of this study pointed to the prevalence of magnetic water upon normal drinking water in all measures issued.
27
Seibert, J., T. Grabs, S. Köhler, H. Laudon, M. Winterdahl und K. Bishop. „Technical Note: Linking soil – and stream-water chemistry based on a riparian flow-concentration integration model“. Hydrology and Earth System Sciences Discussions 6, Nr. 4 (26.08.2009): 5603–29. http://dx.doi.org/10.5194/hessd-6-5603-2009.
Der volle Inhalt der QuelleAnnotation:
Abstract. The riparian zone, the last few meters of soil through which water flows before entering the stream, has been identified as a first order control on key aspects of stream water chemistry dynamics. We propose that the vertical distribution of lateral water flow across the profile of soil water chemistry in the riparian zone provides a conceptual explanation of how this control functions in catchments where matrix flow predominates. This paper presents a mathematical implementation of this concept as well as the model assumptions. We also present an analytical solution, which provides a physical basis for the commonly used power-law flow-load equation. This approach quantifies the concept of riparian control on stream-water chemistry providing a basis for testing the concept of riparian control. By backward calculation of soil-water-chemistry profiles and comparing those with observed profiles we demonstrate that the simple juxtaposition of water fluxes and soil water chemistry provides a plausible explanation for observed stream-water-chemistry variations of several major stream components such as Total Organic Carbon (TOC), magnesium, calcium and chloride. The "static" implementation of the model structure presented here provides a basis for further development to account for seasonal influences and hydrological hysteresis.
28
Kholodnaya, G., I. Egorov, R. Sazonov, M. Serebrennikov, A. Poloskov, D. Ponomarev und I. Zhirkov. „Study of the conditions for the effective initiation of plasma-chemical treatment of flue gas under the influence of a pulsed electron beam“. Laser and Particle Beams 38, Nr. 3 (20.08.2020): 197–203. http://dx.doi.org/10.1017/s0263034620000257.
Der volle Inhalt der QuelleAnnotation:
AbstractThis paper presents the results of comprehensive studies of the efficiency of a pulsed electron beam transmission through a mixture of gases: nitrogen (83%), carbon dioxide (14%), and oxygen (2.6%) in the presence of ash and water vapor. The studied concentrations correspond to the concentrations of nitrogen, oxygen, and carbon dioxide in flue gas. The pressure and concentration of water vapor and ash in the drift chamber varied (375, 560, and 750 Torr; humidity 15 ± 5% and 50 ± 15%). The charge dissipation of a pulsed electron beam in the gas mixture in the presence of ash and water vapor was investigated, as well as the effect of the concentration of water vapor and ash on the geometric profile of the pulsed electron beam.
29
Baigent, Stephen, Robert Unwin und Chee Chit Yeng. „Mathematical Modelling of Profiled Haemodialysis: A Simplified Approach“. Journal of Theoretical Medicine 3, Nr. 2 (2001): 143–60. http://dx.doi.org/10.1080/10273660108833070.
Der volle Inhalt der QuelleAnnotation:
For many renal patients with severe loss of kidney function dialysis treatment is the only means of preventing excessive fluid gain and the accumulation of toxic chemicals in the blood. Typically, haemodialysis patients will dialyse three times a week, with each session lasting 4-6 hours. During each session, 2-3 litres of fluid is removed along with catabolic end-products, and osmotically active solutes. In a significant number of patients, the rapid removal of water and osmotically active sodium chloride can lead to hypotension or overhydration and swelling of brain cells. Profiled haemodialysis, in which the rate of water removal and/or the dialysis machine sodium concentration are varied according to a predetermined profile, can help to prevent wide fluctuations in plasma osmolality, which cause these complications. The profiles are determined on a trial and error basis, and differ from patient to patient. Here we describe a mathematical model for a typical profiled haemodialysis session in which the variables of interest are sodium mass and body fluid volumes. The model is of minimal complexity and so could provide simple guidelines for choosing suitable profiles for individual patients. The model is tested for a series of dialysate sodium profiles to demonstrate the potential benefits of sodium profiling. Next, using the simplicity of the model, we show how to calculate the dialysate sodium profile to model a dialysis session that achieves specified targets of sodium mass removal and weight loss, while keeping the risk of intradia-lytic complications to a minimum. Finally, we investigate which of the model profiled dialysis sessions that meet a range of sodium and fluid removal targets also predict extracellular sodium concentrations and extracellular volumes that lie within “safe” limits. Our model suggests that improvements in volume control via sodium profiling need to be set against potential problems in maintaining blood concentrations and body fluid compartment volumes within “safe” limits.
30
McDonald, S., A. Lethorn, C. Loi, C. Joll, H. Driessen und A. Heitz. „Determination of odour threshold concentration ranges for some disinfectants and disinfection by-products for an Australian panel“. Water Science and Technology 60, Nr. 10 (01.11.2009): 2493–506. http://dx.doi.org/10.2166/wst.2009.662.
Der volle Inhalt der QuelleAnnotation:
Taste-and-odour complaints are a leading cause of consumer dissatisfaction with drinking water. The aim of this study was to determine odour threshold concentration ranges and descriptors, using a Western Australian odour panel, for chlorine, bromine, chlorine added to bromide ions, the four major regulated trihalomethanes (THMs), and combined THMs. An odour panel was established and trained to determine odour threshold concentration ranges for odorous compounds typically found in drinking water at 25°C, using modified flavour profile analysis (FPA) techniques. Bromine and chlorine had the same odour threshold concentration ranges and were both described as having a chlorinous odour by a majority of panellists, but the odour threshold concentration range of bromine expressed in free chlorine equivalents was lower that that of chlorine. It is likely that the free chlorine equivalent residuals measured in many parts of distribution systems in Western Australia are comprised of some portion of bromine and that bromine has the potential to cause chlorinous odours at a lower free chlorine equivalent concentration than chlorine itself. In fact, bromine is the likely cause of any chlorinous odours in Western Australian distributed waters when the free chlorine equivalent concentration is between 0.04 and 0.1 mg L−1. Odour threshold concentrations for the four individual THMs ranged from 0.06–0.16 mg L−1, and the odour threshold concentration range was 0.10 ± 0.09 mg L−1 when the four THMs were combined (in equal mass concentrations). These concentrations are below the maximum guideline value for total THM concentration in Australia so odours from these compounds may possibly be observed in distributed waters. However, while the presence of THMs may contribute to any sweet/fragrant/floral and chemical/hydrocarbon odours in local drinking waters, the THMs are unlikely to contribute to chlorinous odours.
31
Wacker, Ulrike. „An analytic study on the evolution of the vertical profile of rain water concentration“. Geophysical Research Letters 27, Nr. 9 (01.05.2000): 1275–78. http://dx.doi.org/10.1029/1999gl006088.
Der volle Inhalt der Quelle
32
Wiyoto, Wiyoto, Sukenda Sukenda, Enang Harris, Kukuh Nirmala und Daniel Djokosetiyanto. „Water Quality and Sediment Profile in Shrimp Culture with Different Sediment Redox Potential and Stocking Densities Under Laboratory Condition“. ILMU KELAUTAN: Indonesian Journal of Marine Sciences 21, Nr. 2 (02.06.2016): 65. http://dx.doi.org/10.14710/ik.ijms.21.2.65-76.
Der volle Inhalt der QuelleAnnotation:
Sediment quality has been considered as one of the prime factors influencing the environment quality that support maximum shrimp production.The aim of the study was toevaluate the effects of sediment redox potential and shrimp stocking density on the profile of some sediment and water quality parameters. Two factors randomized factorial design was applied, with stocking density (60 and 120 shrimps.m-2) as the first variable and sediment redox potential (-65 mV, -108 mV and -206 mV) as the second variable. Some significant changes in TP, total Mn, and total S concentrations in the sediment were observed after the experimentation (P<0.05). Sediment redox potential significantly affected the dissolved oxygen, TAN, NO2, NO3, and H2S concentrations in the water. Whereas shrimp stocking density affected all water quality parameters except H2S concentration. Significant interactions between redox potential and stocking densities were observed in the nitrite and alkalinity concentrations. The significant effects of both shrimp density and redox potential on the sediment and water parameters in particular those that are known to directly affect the shrimp welfare (e.g. oxygen, ammonia, nitrite and H2S) indicate that these variables are of important aspects in shrimp pond management. Furthermore, the results clearly showed that -206mV redox potential significantly reduced the dissolved oxygen concentration in the sediment-water interface and increased the generation of H2S in water column. Thereby, this redox potential level is not advisable for shrimp culture system. Keywords: redox potential, stocking density.
33
Bechmann, Henrik, Marinus K. Nielsen, Henrik Madsen und Niels Kjølstad Poulsen. „Control of sewer systems and wastewater treatment plants using pollutant concentration profiles“. Water Science and Technology 37, Nr. 12 (01.06.1998): 87–93. http://dx.doi.org/10.2166/wst.1998.0509.
Der volle Inhalt der QuelleAnnotation:
On-line measurements of pollutants in the wastewater combined with grey-box modelling are used to estimate the amount of deposits in the sewer system. The pollutant mass flow at the wastewater treatment plant is found to consist of a diurnal profile minus the deposited amount of pollutants. The diurnal profile is found to be a second order harmonic function and the pollutants deposited in the sewer are identified using first order ordinary differential equations.
34
Matoušek, Václav, Vojtěch Bareš, Jan Krupička, Tomáš Picek und Štěpán Zrostlík. „Experimental investigation of internal structure of open-channel flow with intense transport of sediment“. Journal of Hydrology and Hydromechanics 63, Nr. 4 (01.12.2015): 318–26. http://dx.doi.org/10.1515/johh-2015-0035.
Der volle Inhalt der QuelleAnnotation:
Abstract Gravity-driven open-channel flows carrying coarse sediment over an erodible granular deposit are studied. Results of laboratory experiments with artificial sediments in a rectangular tilting flume are described and analyzed. Besides integral quantities such as flow rate of mixture, transport concentration of sediment and hydraulic gradient, the experiments include measurements of the one-dimensional velocity distribution across the flow. A vertical profile of the longitudinal component of local velocity is measured across the vertical axis of symmetry of a flume cross section using three independent measuring methods. Due to strong flow stratification, the velocity profile covers regions of very different local concentrations of sediment from virtually zero concentration to the maximum concentration of bed packing. The layered character of the flow results in a velocity distribution which tends to be different in the transport layer above the bed and in the sediment-free region between the top of the transport layer and the water surface. Velocity profiles and integral flow quantities are analyzed with the aim of evaluating the layered structure of the flow and identifying interfaces in the flow with a developed transport layer above the upper plane bed.
35
Nisa, Nurfajrin, Mala Nurilmala, Tati Nurhayati und Nurlisa Butet. „The Quality of Dory Fillets based on Water Soluble Protein, Color, and Myoglobin Concentration“. Jurnal Pengolahan Hasil Perikanan Indonesia 19, Nr. 1 (22.04.2016): 44. http://dx.doi.org/10.17844/jphpi.v19i1.12543.
Der volle Inhalt der QuelleAnnotation:
<p>Fillet of dory is very easy to be find in Indonesian market with various brand and produsen.<br />Imported dory fillet is preferred by consumer so far because it has a white color compare than local<br />fillets. Color is the important parameter that used by consumers to determine the quality of filet. This<br />study was aimed to determine the quality of local and imported fillets, including protein profile using<br />SDS PAGE, color measurement, and myoglobin extractability. The results of water soluble protein profiles<br />showed dory fillet contained 13-15 bands. The redness value (a*) of local fillet (DN, DL, DM) was higher<br />compared others. However, imported fillet (DI) had the highest if redness index (a/b). Imported fillet (DI)<br />showed the lowest concentration of myoglobin compared other samples.</p>
36
López, Iago, César Álvarez, José L. Gil und José A. Revilla. „Methodology to elaborate the bathing water profile on urban beaches, according to the requirements of the European Directive 2006/7/EC: the case of Santander beaches (Spain)“. Water Science and Technology 68, Nr. 5 (01.09.2013): 1037–47. http://dx.doi.org/10.2166/wst.2013.342.
Der volle Inhalt der QuelleAnnotation:
The approval of the current Bathing Water Directive (Directive 2006/7/EC) set the necessity to define the bathing water profile. The goals established in the definition of the profile are: (i) to know the processes that determine the concentration of bacteriological indicators in the aquatic environment, (ii) to obtain relationships between the cause of pollution and its effects, and (iii) to evaluate the fulfilment of the Directive and to set the Quality Monitoring and Assessment Program, according to the bacteriological characteristics of the bathing water. In this paper an approach to elaborate the bathing water profile and its application to several bathing waters located in Santander municipality (North Spain) is shown. The methodology involves the assessment of advection, diffusion and reaction processes of bacteriological organisms in the aquatic environment by using mathematical models and the selection of an indicator to evaluate the probability to exceed the bacteriological concentrations established in Directive 2006/7/EC, which is useful for the ‘source apportionment’ assessment. In the definition of the bathing water profile we have considered the sanitation system operating under normal conditions, which includes storm water overflows, uncontrolled discharges and the discharge produced when the pumping system of the wastewater breaks. Finally, according to the bacteriological characteristics of the bathing water it is necessary to develop the Quality Monitoring and Assessment, which has been done taking into account the requirements established in Directive 2006/7/EC and the uncertainties detected in such a method regarding the number of samples to be considered.
37
Maddah, Hisham A. „FFD Analysis for the Effect of Fouling on the Permeate Flux in High-Pressure Membranes“. European Journal of Engineering Research and Science 4, Nr. 1 (08.01.2019): 12–16. http://dx.doi.org/10.24018/ejers.2019.4.1.1061.
Der volle Inhalt der QuelleAnnotation:
Porous high-pressure membranes have been widely used for both brackish water and seawater desalination. However, fouling (concentration polarization) extensively reduces permeate flux in high-pressure membranes such that reverse osmosis (RO) and/or nanofiltration (NF). In this study, we have attempted to understand the effect of membrane fouling on the permeate water flux by modeling the salt concentration profile within a membrane of interest. A parabolic (or diffusion) partial differential equation was used to describe the change in salt concentration inside the membrane. Subsequently, the PDE equation was solved numerically, under certain assumptions, by using forward finite difference (FFD) explicit method. It was found that salt accumulation occurs at the membrane feed-side surface and there was a noticeable decrease in water flux as fouling increased. For waters with an initial salt concentration of 10000 ppm (NaCl) and with an average diffusivity of , results showed that both RO/NF would have flux rates of 74.9, 67.4, 22.5, 0, –37.4, –74.9 LMH for the feed-side surface concentrations 0, 1000, 7000, 10000, 15000 and 20000 ppm, respectively, where negative flux indicates a back-flow scenario.
38
Burns, P., und E. Meiburg. „Sediment-laden fresh water above salt water: linear stability analysis“. Journal of Fluid Mechanics 691 (05.12.2011): 279–314. http://dx.doi.org/10.1017/jfm.2011.474.
Der volle Inhalt der QuelleAnnotation:
AbstractWhen a layer of particle-laden fresh water is placed above clear, saline water, both Rayleigh–Taylor and double diffusive fingering instabilities may arise. For quasi-steady base profiles, we obtain linear stability results for such situations by means of a rational spectral approximation method with adaptively chosen grid points, which is able to resolve multiple steep gradients in the base state density profile. In the absence of salinity and for a step-like concentration profile, the dominant parameter is the ratio of the particle settling velocity to the viscous velocity scale. As long as this ratio is small, particle settling has a negligible influence on the instability growth. However, when the particles settle more rapidly than the instability grows, the growth rate decreases inversely proportional to the settling velocity. This damping effect is a result of the smearing of the vorticity field, which in turn is caused by the deposition of vorticity onto the fluid elements passing through the interface between clear and particle-laden fluid. In the presence of a stably stratified salinity field, this picture changes dramatically. An important new parameter is the ratio of the particle settling velocity to the diffusive spreading velocity of the salinity, or alternatively the ratio of the unstable layer thickness to the diffusive interface thickness of the salinity profile. As long as this quantity does not exceed unity, the instability of the system and the most amplified wavenumber are primarily determined by double diffusive effects. In contrast to situations without salinity, particle settling can have a destabilizing effect and significantly increase the growth rate. Scaling laws obtained from the linear stability results are seen to be largely consistent with earlier experimental observations and theoretical arguments put forward by other authors. For unstable layer thicknesses much larger than the salinity interface thickness, the particle and salinity interfaces become increasingly decoupled, and the dominant instability mode becomes Rayleigh–Taylor-like, centred at the lower boundary of the particle-laden flow region.
39
Liang, Hao, Zafar Iqbal Khan, Kafeel Ahmad, Anam Nisar, Qaisar Mahmood, Abdol Ghaffar Ebadi und Mohsen Toughani. „Assessment of Zinc and Nickel Profile of Vegetables Grown in Soil Irrigated with Sewage Water“. Revista de Chimie 71, Nr. 4 (05.05.2020): 500–511. http://dx.doi.org/10.37358/rc.20.4.8092.
Der volle Inhalt der QuelleAnnotation:
The current investigation assessed the nickel and zinc contents of the soil, and the vegetables grown in wastewater irrigated areas. Atomic Absorption Spectrophotometer (AA-6300 Shimadzu Japan) assessed the metal profile of the samples. The mean concentrations of metals in soil samples varied from O.O85 to 1.611 mg/kg for Ni and O.453 ~ O.9O8 mg/kg for Zn. In vegetables, the maximum Ni concentration was observed in Capsicum baccatum consequent to wastewater irrigation, while its minimum concentrations were noticed in Capsicum frutescens after canal water irrigation. Sewage water irrigation resulted in the highest Zn contents in Solanum lycopersicum and the lowest Zn contents were noticed in Capsicum baccatum after canal water irrigation. The daily intake values of Ni and Zn were higher caused by sewage water irrigation as compared to the canal water irrigation in all tested vegetable samples. Health risk index (HRI) values for Ni and Zn accumulation in vegetables fell within the permissible limit in Pakistan and these were regarded as appropriate for human intake.
40
Tong, Susanna T. Y., und Pat M. Farrell. „The concentration profile of heavy metals in an urban forest“. Environmental Technology 12, Nr. 1 (Januar 1991): 79–85. http://dx.doi.org/10.1080/09593339109384984.
Der volle Inhalt der Quelle
41
Grilli, Roberto, François Darchambeau, Jérôme Chappellaz, Ange Mugisha, Jack Triest und Augusta Umutoni. „Continuous in situ measurement of dissolved methane in Lake Kivu using a membrane inlet laser spectrometer“. Geoscientific Instrumentation, Methods and Data Systems 9, Nr. 1 (20.04.2020): 141–51. http://dx.doi.org/10.5194/gi-9-141-2020.
Der volle Inhalt der QuelleAnnotation:
Abstract. We report the first high-resolution continuous profile of dissolved methane in the shallow water of Lake Kivu, Rwanda. The measurements were performed using an in situ dissolved gas sensor, called Sub-Ocean, based on a patented membrane-based extraction technique coupled with a highly sensitive optical spectrometer. The sensor was originally designed for ocean settings, but both the spectrometer and the extraction system were modified to extend the dynamical range up to 6 orders of magnitude with respect to the original prototype (from nmol L−1 to mmol L−1 detection) to fit the range of concentrations at Lake Kivu. The accuracy of the instrument was estimated to ±22 % (2σ) from the standard deviation of eight profiles at 80 m depth, corresponding to ±0.112 mbar of CH4 in water or ±160 nmol L−1 at 25 ∘C and 1 atm. The instrument was able to continuously profile the top 150 m of the water column within only 25 min. The maximum observed mixing ratio of CH4 in the gas phase concentration was 77 %, which at 150 m depth and under thermal conditions of the lake corresponds to 3.5 mmol L−1. Deeper down, dissolved CH4 concentrations were too large for the methane absorption spectrum to be correctly retrieved. Results are in good agreement with discrete in situ measurements conducted with the commercial HydroC® sensor. This fast-profiling feature is highly useful for studying the transport, production and consumption of CH4 and other dissolved gases in aquatic systems. While the sensor is well adapted for investigating most environments with a concentration of CH4 up to a few millimoles per liter, in the future the spectrometer could be replaced with a less sensitive analytical technique possibly including simultaneous detection of dissolved CO2 and total dissolved gas pressure, for exploring settings with very high concentrations of CH4 such as the bottom waters of Lake Kivu.
42
Ueda, Shinji, Kunio Kondo und Jiro Inaba. „Background Concentration of 14C in Aquatic Samples from Brackish Lake Obuchi, Rokkasho, Japan, Adjacent to Nuclear Fuel Reprocessing Facilities“. Radiocarbon 49, Nr. 1 (2007): 159–69. http://dx.doi.org/10.1017/s0033822200041989.
Der volle Inhalt der QuelleAnnotation:
The brackish Lake Obuchi in Rokkasho, Japan, is adjacent to the first Japanese commercial nuclear fuel reprocessing facilities, which are now undergoing performance testing, with commercial operation scheduled to start in 2007. Preparatory surveys were made by measuring the background levels of radiocarbon for water, aquatic biota, and sediment samples using accelerator mass spectrometry (AMS) in order to study the potential effects of 14C released by the plant to the 14C concentration in aquatic samples. Concentrations of 14C in Futamata River in 2004 ranged from 102 ± 0.5 to 109 ± 0.6 pMC (average 106 ± 0.6 pMC), while 14C concentrations in brackish water from Lake Obuchi and in seawater were 89 ± 0.5 to 104 ± 0.4 pMC (average 98 ± 0.5 pMC) and 82 ± 0.6 to 102 ± 0.4 pMC (average 93 ± 0.5 pMC), respectively. The relationship between 14C concentration and salinity showed a negative correlation (r = 0.68, P < 0.01, n = 20). 14C concentration in selected aquatic biota (i.e. fish, benthos, and seagrass) from 2003 to 2004 ranged from 105 ± 0.7 to 107 ± 0.6 pMC and in zooplankton and phytoplankton was 103 ± 2.4 to 105 ± 1.7 pMC. The depth profile of 14C in 3 core sediment samples from Lake Obuchi showed maximum concentrations from 103 ± 0.5 to 106 ± 0.5 pMC at 5–20 cm depth. The vertical profile of 14C concentration in the sediment did not follow global atmospheric 14C fallout. We confirmed that the background level of 14C concentration in aquatic samples in brackish Lake Obuchi before operation of the reprocessing plant was similar to the concentration (∼106 pMC) in the recent atmosphere.
43
Manojlovic, Predrag, Sanja Mustafic und Ben Mladenovic. „Chemical and mechanical water erosion ratio in the Mlava River basin“. Glasnik Srpskog geografskog drustva 92, Nr. 1 (2012): 27–46. http://dx.doi.org/10.2298/gsgd1201027m.
Der volle Inhalt der QuelleAnnotation:
In the hydrological year of 2001/2002, the water samples in the Mlava Basin were analyzed. On its most downstream hydrometric profile, to the Bratinac profile, the water samples were taken every 5 days for TDS an d every day for concentration suspend sediment. It was found that during the analyzed period, the transport of chemically dissolved maters was 2 times higher than the silt deposit transport.
44
Marhuenda-Egea, Frutos C., Sonsoles Piera-Velázquez, Chiquinquirá Cadenas und Eduardo Cadenas. „Reverse micelles in organic solvents: a medium for the biotechnological use of extreme halophilic enzymes at low salt concentration“. Archaea 1, Nr. 2 (2002): 105–11. http://dx.doi.org/10.1155/2002/626457.
Der volle Inhalt der QuelleAnnotation:
Alkalinep-nitrophenylphosphate phosphatase (pNPPase) from the halophilic archaeobacteriumHalobacterium salinarum(previouslyhalobium) was solubilized at low salt concentration in reverse micelles of hexadecyltrimethylammoniumbromide in cyclohexane with 1-butanol as cosurfactant. The enzyme maintained its catalytic properties under these conditions. The thermodynamic “solvation–stabilization hypothesis” has been used to explain the bell-shaped dependence ofpNPPase activity on the water content of reverse micelles, in terms of protein–solvent interactions. According to this model, the stability of the folded protein depends on a network of hydrated ions associated with acidic residues at the protein surface. At low salt concentration and low water content (the ratio of water concentration to surfactant concentration;w0), the network of hydrated ions within the reverse micelles may involve the cationic heads of the surfactant. The bell-shaped profile of the relationship between enzyme activity andw0varied depending on the concentrations of NaCl and Mn2+.
45
Maiga, Deogratius T., Bhekie B. Mamba und Titus A. M. Msagati. „Distribution profile of titanium dioxide nanoparticles in South African aquatic systems“. Water Supply 20, Nr. 2 (10.12.2019): 516–28. http://dx.doi.org/10.2166/ws.2019.185.
Der volle Inhalt der QuelleAnnotation:
Abstract This paper reports the results of a study on the analysis and characterization of titanium dioxide (TiO2) nanoparticles (NPs) in samples that were collected from selected freshwater dams in South Africa. The study employed a combination of complementary techniques to ascertain the analytical procedures and the occurrence of TiO2 NPs in water. Characterization, identification and quantification of TiO2 NPs in surface water samples from five sampled dams was performed using several techniques including scanning electron microscopy-energy dispersive X-ray (SEM-EDX), fluorescence excitation–emission matrix (FEEM) and single particle inductively coupled plasma mass spectroscopy (SP-ICP-MS). The SP-ICP-MS technique was able to simultaneously determine the size and concentration of both the dissolved and particulate titanium (Ti) in water samples. The Ti-containing NPs were found at concentrations ranging from 8.3 × 104 parts/mL to 1.4 × 105 parts/mL in the presence of 14.9 μg/L to 243 μg/L dissolved Ti. The TiO2 nanoparticles were mostly composed of small agglomerates ranging from 102.9 nm to 158.9 nm in size.
46
Pappa, F. K., G. A. Kyriakidis, C. Tsabaris, D. L. Patiris, E. G. Androulakaki, H. Kaberi, V. Zervakis, M. Kokkoris, R. Vlastou und E. Krasakopoulou. „Temporal variation of 137Cs profiles in Lemnos deep basin, North Aegean Sea, Greece“. HNPS Proceedings 23 (08.03.2019): 79. http://dx.doi.org/10.12681/hnps.1910.
Der volle Inhalt der QuelleAnnotation:
137Cs activity concentration in seawater is an efficient radio-tracing technique to separate and identify the origin of different water masses along with depth. This technique has been applied for the study of deep basins at the North Aegean Sea [1], a marine region which is continuously enriched with 137Cs originated from the Black Sea, through the Dardanelles Straits. In this work, a second sampling campaign (from 2008 to 2013) was carried out in Lemnos’s deep basin and water quantities were collected from different depths. These quantities were chemically treated at HCMR to pre-concentrate 137Cs by using the AMP precipitation method [2]. The produced samples were measured by means of γ- ray spectroscopy. The 137Cs data profile in combination with other oceanographic data (salinity and temperature), provides significant information for the water masses origin with respect to depth. More specifically, at the surface layer, Black Sea water masses (characterized by enriched concentrations of 137Cs) are observed, with 137Cs concentrations about 4 Bq/m3. At the intermediate layers, Levantine water masses (characterized by low concentrations of 137Cs) appear with 137Cs activity reduced to 2 Bq/m3, while the deep layer dense water masses exhibit intermediate 137Cs concentrations of 3 Bq/m3. The 137Cs concentration results are compared with previous measurements performed in the same basin from 1999 to 2013, where the decline of 137Cs concentrations in the surface layer is observed and similar concentrations about 3 Bq/m3(within uncertainties) in the deep layer are obtained.
47
Kurtzman, D., L. Netzer, N. Weisbrod, A. Nasser, E. R. Graber und D. Ronen. „Characterization of deep aquifer dynamics using principal component analysis of sequential multilevel data“. Hydrology and Earth System Sciences 16, Nr. 3 (08.03.2012): 761–71. http://dx.doi.org/10.5194/hess-16-761-2012.
Der volle Inhalt der QuelleAnnotation:
Abstract. Two sequential multilevel profiles were obtained in an observation well opened to a 130-m thick, unconfined, contaminated aquifer in Tel Aviv, Israel. While the general profile characteristics of major ions, trace elements, and volatile organic compounds were maintained in the two sampling campaigns conducted 295 days apart, the vertical locations of high concentration gradients were shifted between the two profiles. Principal component analysis (PCA) of the chemical variables resulted in a first principal component which was responsible for ∼60% of the variability, and was highly correlated with depth. PCA revealed three distinct depth-dependent water bodies in both multilevel profiles, which were found to have shifted vertically between the sampling events. This shift cut across a clayey bed which separated the top and intermediate water bodies in the first profile, and was located entirely within the intermediate water body in the second profile. Continuous electrical conductivity monitoring in a packed-off section of the observation well revealed an event in which a distinct water body flowed through the monitored section (v ∼ 150 m yr−1). It was concluded that the observed changes in the profiles result from dominantly lateral flow of water bodies in the aquifer rather than vertical flow. The significance of this study is twofold: (a) it demonstrates the utility of sequential multilevel observations from deep wells and the efficacy of PCA for evaluating the data; (b) the fact that distinct water bodies of 10 to 100 m vertical and horizontal dimensions flow under contaminated sites, which has implications for monitoring and remediation.
48
Ayoola, Simeon O. „Heavy metals concentration and histopathological profile of some commercial fish species at Makoko Slum Neighbourhood Environment, Lagos, Nigeria“. Aceh Journal of Animal Science 4, Nr. 1 (27.06.2019): 1–10. http://dx.doi.org/10.13170/ajas.4.1.13088.
Der volle Inhalt der QuelleAnnotation:
Potentially harmful substances such as pesticides, heavy metals, and hydro chemicals are often released into the aquatic environment. The objective of the present study was to assess the concentration of lead, copper, cadmium, chromium, and nickel in water samples from two different points (Mid-stream and downstream), also determine the levelsof Lead, Zinc, Manganese and copper in four commercially important fish species, Pseudotolithus senegalensis (croaker fish) and Ethmalosa fimbriata (bonga), Oreochromis mossambicus (Tilapia fish) and Bagrus bayad (silver catfish) from Makoko water body, Yaba, Lagos, Nigeria. Histopathological profile of the fish species selected was also examined. The results were compared to the World Health Organization (WHO) acceptable limit.The concentrations of the heavy metals were analyzed using Perkin Atomic Absorption Spectrophotometer (AAS). Pseudotholithus senegalensishad 3.01±0.02, 2.41±0.02, 3.48±0.01, 1.04±0.10 mg kg-1as the mean concentration of lead, zinc, manganese, and copper respectively, while E. fimbriatahad 1.06±0.02, 2.41±0.02, 4.14±0.01, 1.04±0.10 mg kg-1,O. mossambicushad 2.09±0.02, 3.11±0.04, 2.48±0.02, 0.62±0.01 mg kg-1and B. bayadhad 1.53±0.12, 3.61±0.05, 2.44±0.03, 0.66±0.01 mg kg-1 as the mean concentration of these metals in the tissues of these fishes. The concentrations of heavy metals were higher in the gills compared to other organs. The mean concentration of each heavy metal were varied significantly (p0.05) depending on the species of fish. In the histological analysis of the tissues, there was vacuolation of hepatocytes, inflammation, and necrosis. In the muscle, there was a mild lesion, necrosis, inflammation, and cellular degenerations. But the level of tissue and organ degeneration is more severe in the gills. The study showed that some levels of these metals were within the permissible recommended allowed limit for human consumption. It is concluded that Makoko Lagoon water body and fishes are heavily contaminated with heavy metals.
49
Li, Da, Zhonghua Yang, Zhaohua Sun, Wenxin Huai und Jianhua Liu. „Theoretical Model of Suspended Sediment Concentration in a Flow with Submerged Vegetation“. Water 10, Nr. 11 (14.11.2018): 1656. http://dx.doi.org/10.3390/w10111656.
Der volle Inhalt der QuelleAnnotation:
Vegetation in natural river interacts with river flow and sediment transport. This paper proposes a two-layer theoretical model based on diffusion theory for predicting the vertical distribution of suspended sediment concentration in a flow with submerged vegetation. The suspended sediment concentration distribution formula is derived based on the sediment and momentum diffusion coefficients through the inverse of turbulent Schmidt number ( S c t ) or the parameter η which is defined by the ratio of sediment diffusion coefficient to momentum diffusion coefficient. The predicted profile of suspended sediment concentration moderately agrees with the experimental data. Sensitivity analyses are performed to elucidate how the vertical distribution profile responds to different canopy densities, hydraulic conditions and turbulent Schmidt number. Dense vegetation renders the vertical distribution profile uneven and captures sediment particles into the vegetation layer. For a given canopy density, the vertical distribution profile is affected by the Rouse number, which determines the uniformity of the sediment on the vertical line. A high Rouse number corresponds to an uneven vertical distribution profile.
50
Piotrowski, A., S. G. Wallis, J. J. Napiórkowski und P. M. Rowiński. „Evaluation of 1-D tracer concentration profile in a small river by means of Multi-Layer Perceptron Neural Networks“. Hydrology and Earth System Sciences 11, Nr. 6 (07.12.2007): 1883–96. http://dx.doi.org/10.5194/hess-11-1883-2007.
Der volle Inhalt der QuelleAnnotation:
Abstract. The prediction of temporal concentration profiles of a transported pollutant in a river is still a subject of ongoing research efforts worldwide. The present paper is aimed at studying the possibility of using Multi-Layer Perceptron Neural Networks to evaluate the whole concentration versus time profile at several cross-sections of a river under various flow conditions, using as little information about the river system as possible. In contrast with the earlier neural networks based work on longitudinal dispersion coefficients, this new approach relies more heavily on measurements of concentration collected during tracer tests over a range of flow conditions, but fewer hydraulic and morphological data are needed. The study is based upon 26 tracer experiments performed in a small river in Edinburgh, UK (Murray Burn) at various flow rates in a 540 m long reach. The only data used in this study were concentration measurements collected at 4 cross-sections, distances between the cross-sections and the injection site, time, as well as flow rate and water velocity, obtained according to the data measured at the 1st and 2nd cross-sections. The four main features of concentration versus time profiles at a particular cross-section, namely the peak concentration, the arrival time of the peak at the cross-section, and the shapes of the rising and falling limbs of the profile are modeled, and for each of them a separately designed neural network was used. There was also a variant investigated in which the conservation of the injected mass was assured by adjusting the predicted peak concentration. The neural network methods were compared with the unit peak attenuation curve concept. In general the neural networks predicted the main features of the concentration profiles satisfactorily. The predicted peak concentrations were generally better than those obtained using the unit peak attenuation method, and the method with mass-conservation assured generally performed better than the method that did not account for mass-conservation. Predictions of peak travel time were also better using the neural networks than the unit peak attenuation method. Including more data into the neural network training set clearly improved the prediction of the shapes of the concentration profiles. Similar improvements in peak concentration were less significant and the travel time prediction appeared to be largely unaffected.