Artykuły w czasopismach na temat „Water column data analysis”
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Takahashi, Hisayuki, i Masayasu Tanaka. "Statistical Analysis for Comparison of the Results Obtained by Capillary Columns and Packed Columns in the Determination of Water Yield in Smoke Condensates Analyzed in Cigarettes for the 24th Asia Collaborative Study". Beiträge zur Tabakforschung International/Contributions to Tobacco Research 29, nr 2 (25.09.2020): 97–118. http://dx.doi.org/10.2478/cttr-2020-0010.
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SummaryRecently, capillary columns have been widely used in the methodology for the determination of water yields in smoke condensate, even though ISO 10362-1:1999, “Cigarettes - Determination of water in smoke condensates – Part 1: Gas chromatographic method” specifies a packed gas chromatographic column. As a result of a systematic review in 2015, ISO/TC126 decided to revise the standard to include the use of capillary columns.The goal of this study was to confirm the comparability of water yields obtained from capillary column methodology to those yields from packed columns by the statistical analysis of yield data from the 24th Asia Collaborative Study which included 86 datasets submitted by 64 laboratories. After the exclusion of outliers by Cochran’s and Grubbs’ tests, the datasets were classified by GC column type and then mean water yields, and their repeatability and reproducibility were calculated for each type of column. No significant differences were observed in water yields between capillary and packed columns. Repeatability and reproducibility of water yields using capillary column were comparable to those using packed columns as described in ISO 10362-1:1999. From these results, it was confirmed that the capillary columns are an appropriate alternative to packed columns for the gas chromatographic procedure described in ISO 10362-1:1999.
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Jasron, Jahirwan Ut, Sudjito Soeparmani, Lilis Yuliati i Djarot B. Darmadi. "Comparison of the performance of oscillating water column devices based on arrangements of water columns". Journal of Mechanical Engineering and Sciences 14, nr 3 (28.09.2020): 7082–93. http://dx.doi.org/10.15282/jmes.14.3.2020.10.0555.
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The hydrodynamic performance of oscillating water column (OWC) depends on the depth of the water, the size of the water column and its arrangement, which affects the oscillation of the water surface in the column. An experimental method was conducted by testing 4 water depths with wave periods of 1-3 s. All data recorded by the sensor is then processed and presented in graphical form. The research focused on analyzing the difference in wave power absorption capabilities of the three geometric types of OWC based on arrangements of water columns. The OWC devices designed as single water column, the double water column in a series arrangement which was perpendicular to the direction of wave propagation, and double water column in which the arrangement of columns was parallel to the direction of wave propagation. This paper discussed several factors affecting the amount of power absorbed by the device. The factors are the ratio of water depth in its relation to wavelength (kh) and the inlet openings ratio (c/h) of the devices. The test results show that if the water depth increases in the range of kh 0.7 to 0.9, then the performance of the double chamber oscillating water column (DCOWC) device is better than the single chamber oscillating water column (SCOWC) device with maximum efficiency for the parallel arrangement 22,4%, series arrangement 20.8% and single column 20.7%. However, when referring to c/h, the maximum energy absorption efficiency for a single column is 27.7%, double column series arrangement is 23.2%, and double column parallel arrangement is 29.5%. Based on the results of the analysis, DCOWC devices in parallel arrangement showed the ability to absorb better wave power in a broader range of wave frequencies. The best wave of power absorption in the three testing models occurred in the wave period T = 1.3 seconds.
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To, N. M., H. M. Brown i R. H. Goodman. "DATA ANALYSIS AND MODELING OF DISPERSANT EFFECTIVENESS IN COLD WATER". International Oil Spill Conference Proceedings 1987, nr 1 (1.04.1987): 303–6. http://dx.doi.org/10.7901/2169-3358-1987-1-303.
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ABSTRACT Tests on dispersant effectiveness in cold water have been performed, for a number of years, using nonbreaking, regular waves in the Esso wave basin. Oil concentration measurements in the water column have been used to study the kinematics of oil dispersion under regular waves. Data analysis procedures are designed to determine, based on the concentration measurements, the rate of oil dispersion in both horizontal and vertical directions into the water column. Oil dispersion rates are used in a two-dimensional, kinematic, finite difference model to simulate the diffusion and advection of oil in water. The model predicts the amount of oil that dispersed and later resurfaced from the measured concentration history. Based on the model results, a material balance of the oil is obtained. Effectiveness of the dispersant is assessed by the amount of oil remaining after each test. Results of the data analysis provide an insight into the oil dispersion mechanism and a method of improving the accuracy of the numerical model. Effectiveness of different dispersants and different application methods may be compared using this methodology.
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Landrø, M. "Attenuation of seismic water-column noise, tested on seismic data from the Grane field". GEOPHYSICS 72, nr 4 (lipiec 2007): V87—V95. http://dx.doi.org/10.1190/1.2740020.
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Seismic analysis of long-offset data is gaining increased attention for several purposes: constraining three-parameter amplitude variation with offset (AVO) methods, 4D analysis, and imaging below salt and basalt. A major challenge for exploiting long-offset seismic data is that the water-column noise mixes with and distorts the reflected seismic signal from interfaces at the target level. Traditional processing methods such as [Formula: see text] filtering often reduce this distortion problem. This article offers an alternative to conventional processing methods. The alternative exploits the difference in water depth and reservoir depth to subtract water-column noise. The proposed subtraction method works well where water depth is constant. The method was tested on a multicomponent seismic data set from the Grane field (North Sea). In this location, the water depth is fairly constant over the field. The fieldwise similarity level of water-column noise is high. A comparison of the water-column noise from various locations shows that the similarity is 10%, measured in normalized root mean squared error. The fact that the water-column noise is highly repeatable is a strong indication that the major part of it is harmonic waves that propagate in the water layer.
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Jandera, Pavel, i Tomáš Hájek. "A New Definition of the Stationary Phase Volume in Mixed-Mode Chromatographic Columns in Hydrophilic Liquid Chromatography". Molecules 26, nr 16 (9.08.2021): 4819. http://dx.doi.org/10.3390/molecules26164819.
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Polar columns used in the HILIC (Hydrophilic Interaction Liquid Chromatography) systems take up water from the mixed aqueous–organic mobile phases in excess of the water concentration in the bulk mobile phase. The adsorbed water forms a diffuse layer, which becomes a part of the HILIC stationary phase and plays dominant role in the retention of polar compounds. It is difficult to fix the exact boundary between the diffuse stationary and the bulk mobile phase, hence determining the column hold-up volume is subject to errors. Adopting a convention that presumes that the volume of the adsorbed water can be understood as the column stationary phase volume enables unambiguous determination of the volumes of the stationary and of the mobile phases in the column, which is necessary for obtaining thermodynamically correct chromatographic data in HILIC systems. The volume of the aqueous stationary phase, Vex, can be determined experimentally by frontal analysis combined with Karl Fischer titration method, yielding isotherms of water adsorbed on polar columns, which allow direct prediction of the effects of the composition of aqueous–organic mobile phase on the retention in HILIC systems, and more accurate determination of phase volumes in columns and consistent retention data for any mobile phase composition. The n phase volume ratios of 18 columns calculated according to the new phase convention strongly depend on the type of the polar column. Zwitterionic and TSK gel amide and amine columns show especially strong water adsorption.
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Korotkova, T. G., i G. I. Kasyanov. "Analysis of the rectifying separation of H2 O–D2 O mixture into light and heavy water by means of mathematical modeling". Fine Chemical Technologies 17, nr 3 (31.07.2022): 189–200. http://dx.doi.org/10.32362/2410-6593-2022-17-3-189-200.
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Objectives. To apply an analytical method for the calculation of a distillation column for the production of D2O at a two-column Kuhn installation operating under vacuum: to simulate the Kuhn installation in the Hysys software; and to compare experimental and calculated data.Methods. Analytical method for the calculation of distillation columns “from stage to stage,” from the lower theoretical separation stage (TSS) to the upper stage. This method is based on phase equilibrium at the TSS with known data of input flows and component concentrations in the column bottoms. Hysys was used as modeling software.Results. Comparison of the calculation results with Kuhn’s experimental data testified to the high calculation accuracy of the vapor–liquid phase equilibrium for the H2O–D2O mixture at the TSS. The convergence of the D2O material balance for the entire installation was 0.005%. The identification parameter was the number of the column feed plate. Simulation of the Kuhn installation in the Hysys software showed a qualitative agreement of D2O concentrations in material flows. The UNIQUAC (UNIversal QUAsiChemical) model was used to calculate activity coefficients. The found values of the number of theoretical separation stages (NTSS) in both columns, were 88 and 153 taking into account the reboiler and condenser. This is less than the experimental 295 and 400, respectively. The discrepancy can be explained by the increased phase equilibrium H2O constant in the UNIQUAC model. However, the convergence of the material balance in terms of D2O was high and amounted to 1.38·10−6 %. The absolute error of the found concentrations in material flows did not exceed 0.12 mol %.Conclusions. The results obtained indicated the possible use of the Hysys modeling software when searching for and optimizing the operating mode of the block diagram of a cascade of distillation columns with direct and recycle flows to separate a mixture of water into light and heavy water. The final results obtained with regard to the operating mode, inlet and outlet material flows (flow rate, composition, temperature, and pressure drop across the column) are recommended for use in the analytical program for the calculation of the distillation column to refine the NTSS and distribution profile of the concentrations of the H2O and D2O components along the height of the column.
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Richter, K., D. Mader, P. Westfeld i H. G. Maas. "DETERMINATION OF 3D WATER TURBIDITY PARAMETER FIELDS FROM LIDAR BATHYMETRY DATA BY VOLUMETRIC DATA ANALYSIS". International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLIII-B2-2022 (30.05.2022): 945–51. http://dx.doi.org/10.5194/isprs-archives-xliii-b2-2022-945-2022.
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Abstract. Accurate information on turbidity in water bodies is relevant to numerous limnological and oceanological issues. However, the collection of turbidity parameters using conventional in-situ measurement methods is time-consuming and cost-intensive and therefore usually limited to very small study areas. The use of airborne LiDAR bathymetry data is a promising alternative. However, existing methods for deriving turbidity parameters from airborne LiDAR bathymetry data are limited to the determination of one single turbidity parameter per water column element. The paper presents a novel approach that overcomes the existing limitations enables the determination of 3D water turbidity fields. By volumetric data analysis, the vertical turbidity stratification in the water body can be determined. For validation purposes, the approach was applied to synthetic measurement data generated in a simulation as well as a real measurement data set of a shallow coastal water.
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Wall, Carrie, Rudy Klucik, Chris Slater, Charles Anderson i Veronica Martinez. "Towards a cloud optimized data lake for archived water column sonar data". Journal of the Acoustical Society of America 153, nr 3_supplement (1.03.2023): A63. http://dx.doi.org/10.1121/10.0018170.
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Due to their value to the ocean science and fisheries management communities, NOAA National Centers for Environmental Information (NCEI), with NOAA Fisheries and University of Colorado Cooperative Institute for Research in Environmental Sciences, established a national archive for water column sonar data. There are currently 210 TB of data freely and publicly available, and that volume is growing rapidly as sonar technology advances. The spatially and temporally diverse archive is accessible through its dedicated data portal and Amazon Web Services. Throughout 2023, we will develop a cloud-optimized data lake of echosounder files representing a ∼100 TB subset of the archive holdings. The echosounder files will be translated from their complex, binary and proprietary file format into zarr files following the Earth Science Information Partners analysis-ready cloud-optimized standards. The resulting data lake will serve as the foundation for building analytical capabilities that can cost-effectively tap into the archive’s sonar holdings, especially when coupled with compute power. The zarr stores will subsequently feed into EchoFish, the archive’s AWS-hosted interactive data visualization platform to facilitate subsetting and prevent the data lake from becoming a data swamp. The progress and potential applications of this NOAA Center for Artificial Intelligence funded project will be presented.
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Malekpour, A., i B. W. Karney. "Rapid Filling Analysis of Pipelines with Undulating Profiles by the Method of Characteristics". ISRN Applied Mathematics 2011 (14.07.2011): 1–16. http://dx.doi.org/10.5402/2011/930460.
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On the premise of water hammer theory, a numerical model is proposed for simulating the filling process in an initially empty water conveyance pipeline with an undulating profile. Assuming that the pipeline remains full and ignoring air and water interactions in the already filled pipeline, the ongoing filling is simulated using the method of characteristics on an adaptive computational grid. The performance of the model is verified using previously published experimental and rigid column data. The model nicely replicates published experimental data. The model shows that the movement of the filling front into the system can be assumed as a rigid column as long as the flow away from the filling front is undisturbed elsewhere. Furthermore, applying the model to a hypothetical pipe system with an inline-partially open valve shows that the proposed model is robust enough to capture the transient events initiated within the moving column, a vital capability that the existing rigid water column models lack.
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Vetaw, Greg, Suren Jayasuriya, Brian ODonnell i Wendy Newcomb. "Estimating forward-looking sonar (FLS) image quality using water column data features". Journal of the Acoustical Society of America 154, nr 4_supplement (1.10.2023): A247. http://dx.doi.org/10.1121/10.0023441.
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Forward-looking sonar (FLS) underwater imaging systems are primarily used for measuring seafloor backscatter. These returns, however, may be occluded due to scattering from other objects in the water such as fish, bubbles, or other suspended objects, and in-band acoustic interference from sources like engines or other acoustic transmissions. The presence of non-seafloor scatterers or interference is most easily observed and estimated in the water column data, the portion of the time-series after the sonar has transmitted a ping, but before that ping has scattered off the seafloor and returned to the FLS. Analysis of the water column time-series returns can be leveraged to estimate the quality of seafloor imagery. In this study, we characterize bright scatterers that appear in the water column data using statistical tools and generate corresponding quality metrics to evaluate imagery.
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Feng, Feisheng, Suping Peng, Pingjie Fu, Wenfeng Du i Dongjing Xu. "A Study on the Seepage Flow Characteristics and Disaster-Causing Mechanism of Collapse Column". Advances in Civil Engineering 2018 (30.09.2018): 1–9. http://dx.doi.org/10.1155/2018/7841649.
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Factors such as the hydrogeological conditions, the lithological characteristics of the columns’ components, and the lithological characteristics and stress conditions of the coal seam roof and floor are interrelated and jointly affect column collapse. In this study, the disaster-causing mechanism of column collapse was studied. Based on the system theory, a collapsed column is divided into the column and the surrounding fissure zone as two subsystems for analysis. And, the permeability coefficient of the broken rock under different conditions was measured by a self-designed equipment. The variations of the permeability coefficient for rock samples with different particle diameters, different axial pressures Pa, and different seepage velocities were further studied. Through phenomena analysis and experimental data processing, it was concluded that, under the same pressure state, smaller particle diameter meant smaller permeability coefficient; with the increase of axial pressure, the permeability coefficient decreased; and the larger the water flow velocity was, the smaller the permeability coefficient became. For particle diameter Φ = 2.5–5 mm or larger, the tiny particles formed by randomly washing and breaking in the water flow blocked some of the channels. For particle diameters smaller than Φ = 2.5–5 mm, the smaller permeability coefficient was attributed to the turbulence resulting from non-Darcy flow. The study on the permeability of the fractured rock mass clarified the mechanism of water inrush from the fissure zone of the collapsed column: the collapsed column itself was impermeable, and the permeability of the fissure zone around the collapsed column was related to the lithological characteristics of the rock within the fissure zone and the sequencing of rock strata. When mining coal in areas with collapsed columns, experiments on collapsed columns and fissure zones are prerequisites. This study has a certain referential value for coal mining in this region.
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Bittler, Kimberly. "DISPERSANT PERFORMANCE: FINDING NEW RESULTS IN EXISTING DATA". International Oil Spill Conference Proceedings 2017, nr 1 (1.05.2017): 704–24. http://dx.doi.org/10.7901/2169-3358-2017.1.704.
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Abstract No. 092 Abstract: Chemical dispersants are used to mitigate oil spills in aquatic environments. Dispersants promote the breakdown of oil into smaller droplets that more readily diffuse into the water column. Federal agencies, industry, and academia have a long history of investigating dispersant performance at diverse scales and environmental conditions, including several recent publications. Several studies estimate dispersant performance as dispersion effectiveness (DE, measured as the percent of oil retained in the water column for a period of time after treatment), the concentration of oil in the dispersed in the water column, or the size of dispersed oil droplets. While many organizations have drawn qualitative conclusions from this body of work, a quantitative meta-analysis drawing together historic and recent research on the topic of dispersant effectiveness has not been conducted. This paper analyzed controlled studies measuring performance of dispersants across lab, tank, and large-scale studies. Although this paper examined only a subset of commonly tested oils, the findings strongly support that treatment with dispersants is correlated with increased effectiveness across several metrics, studies, and test methodologies. The conclusions provided by this analysis could be a critical tool for weighing the risks and benefits of using dispersants to respond to oil spills in aquatic environments.
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Zwolak, Karolina, Łukasz Marchel, Aileen Bohan, Masanao Sumiyoshi, Jaya Roperez, Artur Grządziel, Rochelle Ann Wigley i Sattiabaruth Seeboruth. "Automatic Identification of Internal Wave Characteristics Affecting Bathymetric Measurement Based on Multibeam Echosounder Water Column Data Analysis". Energies 14, nr 16 (5.08.2021): 4774. http://dx.doi.org/10.3390/en14164774.
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The accuracy of multibeam echosounder bathymetric measurement depends on the accuracy of the data of the sound speed layers within the water column. This is necessary for the correct modeling of ray bending. It is assumed that the sound speed layers are horizontal and static, according to the sound speed profile traditionally used in the depth calculation. In fact, the boundaries between varying water masses can be curved and oscillate. It is difficult to assess the parameters of these movements based on the sparse sampling of sound velocity profiles (SVP) collected through a survey; thus, alternative or augmented methods are needed to obtain information about water mass stratification for the time of a particular ping or a series of pings. The process of water column data collection and analysis is presented in this paper. The proposed method updates the sound speed profile by the automated detection of varying water mass boundaries, giving the option to adjust the SVP for each beam separately. This can increase the overall accuracy of a bathymetric survey and provide additional oceanographic data about the study area.
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Chmielewska, Iwona. "Determination of Mechanical Properties of Soils Based on CPTU Data". Architecture, Civil Engineering, Environment 16, nr 3 (1.09.2023): 55–64. http://dx.doi.org/10.2478/acee-2023-0033.
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Abstract The study aimed to interpret the results of cone penetration tests with pore pressure measurement (CPTU). Tests were performed on a section of the designed road about 200 m long. The subsoil under consideration was characterized by organic soils deposited to a depth of approximately 8 m. Due to the problematic soil and water conditions, improvement with geosynthetic encased columns (GEC) was performed. According to the Recommendations for Design and Analysis of Earth Structures using Geosynthetic Reinforcements – EBGEO, the constrained modulus Eoed and effective friction angle φ’ of soil below the GEC column base should be higher than 5 MPa (Eoed > 5 MPa) and 30° (φ’ > 30°), respectively. In this study, the Eoed and φ’ parameters were determined based on CPTU tests conducted in 12 locations. Analysis of the CPTU data showed that the constrained modulus and effective friction angle of the soil deposited below the GEC column base did not meet EBGEO requirements in most locations. It was also concluded that the minimum value of the constrained modulus required by EBGEO is too low compared with the requested value of the effective friction angle.
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Desineni, Rao, i Yan Pan. "Speeding Up Failure Analysis Using Fab and Design Data". EDFA Technical Articles 19, nr 4 (1.11.2017): 62–63. http://dx.doi.org/10.31399/asm.edfa.2017-4.p062.
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Balaban, Dario, Branislava Nikolovski, Mitar Perusic i Goran Tadic. "Experimental and modeling studies of mass transfer and hydrodynamics in a packed bed absorption column for CO2 - water system". Chemical Industry 77, nr 2 (2023): 99–109. http://dx.doi.org/10.2298/hemind230120014b.
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This paper presents research on hydrodynamics and mass transfer in a packed absorption column. Experimental data on dry column pressure drop, flooding point, and efficiency of absorption of CO2 in water is obtained on a lab-scale absorption column packed with Raschig rings. Auxiliary parts of equipment together with chemical analyses provide simple monitoring and collecting the data. All obtained data were used to test different mathematical models for a given problem, i.e. for determination of the dry column pressure drop, flooding point and the overall gas transfer unit height. For dry column pressure drop, models developed primarily for packed columns described the data the best, with the Billet model generating a 6.54 % mean error, followed by Mackowiak and Stichlmair models. In flooding point calculations, empirical models were tested and models of Lobo, Leva and Takahshi gave the best results. Mass transfer (absorption) experiments gave expected results, since absorption efficiency increased with the increase in the liquid/gas flow rate ratio, i.e. with approaching the flooding point. The Onda?s model was used to calculate partial mass transfer coefficients in liquid and gas phases based on which the height of the overall gas transfer unit was estimated and subsequently compared with the experimental data. Deviation of calculated and experimental results for the height of the overall gas transfer unit is in the expected range of 0-20 %, with mean value of 15.5 %. In conclusion, the available models for determination of the investigated hydrodynamics and mass transfer parameters in packed absorption columns gave adequate results in comparison to the experimental values.
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West, Nyree J., i David J. Scanlan. "Niche-Partitioning of ProchlorococcusPopulations in a Stratified Water Column in the Eastern North Atlantic Ocean". Applied and Environmental Microbiology 65, nr 6 (1.06.1999): 2585–91. http://dx.doi.org/10.1128/aem.65.6.2585-2591.1999.
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ABSTRACT The in situ community structure of Prochlorococcuspopulations in the eastern North Atlantic Ocean was examined by analysis of Prochlorococcus 16S rDNA sequences with three independent approaches: cloning and sequencing, hybridization to specific oligonucleotide probes, and denaturing gradient gel electrophoresis (DGGE). The hybridization of high-light (HL) and low-light (LL) Prochlorococcus genotype-specific probes to two depth profiles of PCR-amplified 16S rDNA sequences revealed that in these two stratified water columns, an obvious niche-partitioning ofProchlorococcus genotypes occurred. In each water column a shift from the HL to the LL genotype was observed, a transition correlating with the depth of the surface mixed layer (SML). Only the HL genotype was found in the SML in each water column, whereas the LL genotype was distributed below the SML. The range of in situ irradiance to which each genotype was subjected within these distinct niches was consistent with growth irradiance studies of cultured HL- and LL-adapted Prochlorococcus strains. DGGE analysis and the sequencing of Prochlorococcus 16S rDNA clones were in full agreement with the genotype-specific oligonucleotide probe hybridization data. These observations of a partitioning ofProchlorococcus genotypes in a stratified water column provide a genetic basis for the dim and brightProchlorococcus populations observed in flow cytometric signatures in several oceanic provinces.
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Horvat, Zoltan, Mirjana Horvat, Kristian Pastor, Vojislava Bursić i Nikola Puvača. "Multivariate Analysis of Water Quality Measurements on the Danube River". Water 13, nr 24 (17.12.2021): 3634. http://dx.doi.org/10.3390/w13243634.
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This study investigates the potential of using principal component analysis and other multivariate analysis techniques to evaluate water quality data gathered from natural watercourses. With this goal in mind, a comprehensive water quality data set was used for the analysis, gathered on a reach of the Danube River in 2011. The considered measurements included physical, chemical, and biological parameters. The data were collected within seven data ranges (cross-sections) of the Danube River. Each cross-section had five verticals, each of which had five sampling points distributed over the water column. The gathered water quality data was then subjected to several multivariate analysis techniques. However, the most attention was attributed to the principal component analysis since it can provide an insight into possible grouping tendencies within verticals, cross-sections, or the entire considered reach. It has been concluded that there is no stratification in any of the analyzed water columns. However, there was an unambiguous clustering of sampling points with respect to their cross-sections. Even though one can attribute these phenomena to the unsteady flow in rivers, additional considerations suggest that the position of a cross-section can have a significant impact on the measured water quality parameters. Furthermore, the presented results indicate that these measurements, combined with several multivariate analysis methods, especially the principal component analysis, may be a promising approach for investigating the water quality tendencies of alluvial rivers.
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Nitisapto, Mulyono, Azwar Maas, Benito Heru Purwanto i Putu Sudira. "Water Use Efficiency in Vertical Cropping System with Volcanic Ash Media by Using Biochar and Urban Waste Compost Fertilizer as Soil Amendement". Ilmu Pertanian (Agricultural Science) 4, nr 1 (29.05.2019): 40. http://dx.doi.org/10.22146/ipas.34304.
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Applying volcanic ash as planting media has to cope with several constrains: it quickly became sediment and hardened when exposed to water. One of the efforts to improve its physical condition is by utilizing biochar, which is one of amendment materials that can improve the soil quality. This study used vertical column container made from PVC to enable vertical plant arrangement. Volcanic ash requires additional nutrient intake from organic fertilizer such as urban waste compost. The objective of this study was to identify the proper dose combination of volcanic ash, biochar, urban waste compost fertilizer and column population per m2 to sustain the growth of curly lettuce in vertical cropping system, as well as the water use efficiency. This study was designed by using the Completely Randomized Design (CRD) Factorial with three factors. The first, second and third factors consisted of Biochar M1, M2 and M3 (25; 33; and 50 %), compost fertilizer doses of K1, K2, and K3 (25; 33; and 50 %), and column density of P1, P2 and P3 (4 columns/m2, 3 columns/m2 and 2 columns/m2), respectively. The total combination was 3 x 3 x 3 and each was repeated 3 times. Resulted data of this study consisted of growth and crops and analyzed by using the Analysis of Variance and continued with the HSD Tukey 5% Test (Honest significant deference). The water use efficiency (g/kg) can be formulated as the production of dry material per total water during the cultivation season (g/kg). Results of this study showed the highest fresh consumption result was obtained from treatment M3K3 in 556 g/column (comparison of volcanic ash, charcoal husk and compost = 25 : 25 : 50 %) and the best water-use efficiency was 2.30 g/kg.
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Schröder, Marc, Maarit Lockhoff, John M. Forsythe, Heather Q. Cronk, Thomas H. Vonder Haar i Ralf Bennartz. "The GEWEX Water Vapor Assessment: Results from Intercomparison, Trend, and Homogeneity Analysis of Total Column Water Vapor". Journal of Applied Meteorology and Climatology 55, nr 7 (lipiec 2016): 1633–49. http://dx.doi.org/10.1175/jamc-d-15-0304.1.
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AbstractThe Global Energy and Water Cycle Exchanges project (GEWEX) water vapor assessment’s (G-VAP) main objective is to analyze and explain strengths and weaknesses of satellite-based data records of water vapor through intercomparisons and comparisons with ground-based data. G-VAP results from the intercomparison of six total column water vapor (TCWV) data records are presented. Prior to the intercomparison, the data records were regridded to a common regular grid of 2° × 2° longitude–latitude. All data records cover a common period from 1988 to 2008. The intercomparison is complemented by an analysis of trend estimates, which was applied as a tool to identify issues in the data records. It was observed that the trends over global ice-free oceans are generally different among the different data records. Most of these differences are statistically significant. Distinct spatial features are evident in maps of differences in trend estimates, which largely coincide with maxima in standard deviations from the ensemble mean. The penalized maximal F test has been applied to global ice-free ocean and selected land regional anomaly time series, revealing differences in trends to be largely caused by breakpoints in the different data records. The time, magnitude, and number of breakpoints typically differ from region to region and between data records. These breakpoints often coincide with changes in observing systems used for the different data records. The TCWV data records have also been compared with data from a radiosonde archive. For example, at Lindenberg, Germany, and at Yichang, China, such breakpoints are not observed, providing further evidence for the regional imprint of changes in the observing system.
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IM, Seung Uk, Cheong Ah Lee, Changsoo Kim i Dong-guk Paeng. "A study on the prediction model of water column sound absorption coefficients considering the characteristics of the East Sea of South Korea". Journal of the Acoustical Society of America 154, nr 4_supplement (1.10.2023): A134. http://dx.doi.org/10.1121/10.0023032.
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East Sea of Korea has the deepest water depth among Korean seas, and the water column changes are distinct in space and time, resulting in a wide range of water column sound absorption coefficients. In this study, we calculate and analysis the spatiotemporal variation of water column sound absorption coefficient in the East Sea of Korea, which has unique oceanographic characteristics. Using extensive CTD data from the Korea Oceanographic Data Centre (KODC) from 1991 to 2021, we calculate the sound absorption coefficient using the widely applied Francois–Garrison model and reveal the unique absorption characteristics of the East Sea. The derived coefficients are then used to calibrate and improve past multibeam echosounder system (MBES) data, which suffered from incomplete water column information and arbitrary mean values. To facilitate the calculation and development of sound absorption coefficient, a MATLAB-based graphical user interface (GUI) was developed. The results of this study contribute to the calculation and inference of sound absorption coefficients along spatial and temporal dimensions of the water column in the East Sea and to the extraction of more accurate seafloor information from MBES data. This study developed the way for future research focusing on algorithmic advances and new methodologies for the calculation of sound absorption coefficients in the West and South Seas of Korea.
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Li, Xuemei, Zihao Meng, Kang Chen, Feifei Hu, Lu Liu, Tingbing Zhu i Deguo Yang. "Comparing diversity patterns and processes of microbial community assembly in water column and sediment in Lake Wuchang, China". PeerJ 11 (5.01.2023): e14592. http://dx.doi.org/10.7717/peerj.14592.
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The study compare the diversity patterns and processes of microbial community assembly in the water and sediment of Lake Wuchang (China) using high-throughput sequencing of 16S rRNA gene amplicons. A higher microbial α-diversity in the sediment was revealed (P < 0.01), and the most common bacterial phyla in water column were Proteobacteria, Cyanobacteria and Actinobacteria, while Proteobacteria, Acidobacteria, Chloroflexi and Nitrospirae were dominant in sediment. Functions related to phototrophy and nitrogen metabolism primarily occurred in the water column and sediment, respectively. The microbial communities in water column from different seasons were divided into three groups, while no such dispersion in sediment based on PCoA and ANOSIM. According to Pearson correlation analysis, water temperature, dissolved oxygen, water depth, total nitrogen, ammonium, and nitrite were key factors in determining microbial community structure in water column, while TN in sediment, conductivity, and organic matter were key factors in sediment. However, the stochastic processes (|βNTI| < 2) dominated community assembly in both the water column and sediment of Lake Wuchang. These data will provide a foundation for microbial development and utilization in lake water column and sediment under the circumstances of increasing tendency of lake ecological fishery in China.
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Kim, Jeong-Seok, i Bo Woo Nam. "Numerical Analysis for Hydrodynamic Performance of OWC Devices with Multiple Chambers in Waves". Journal of Ocean Engineering and Technology 36, nr 1 (28.02.2022): 21–31. http://dx.doi.org/10.26748/ksoe.2021.091.
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In recent years, various studies have been conducted on oscillating-water-column-type wave energy converters (OWC-WECs) with multiple chambers with the objective of efficiently utilizing the limited space of offshore/onshore structures. In this study, a numerical investigation based on a numerical wave tank was conducted on single, dual, and triple OWC chambers to examine the hydrodynamic performances and the energy conversion characteristics of the multiple water columns. The boundary value problem with the Laplace equation was solved by using a numerical wave tank based on a finite element method. The validity of the current numerical method was confirmed by comparing it with the measured data in the previous experimental research. We undertook a series of numerical simulations and observed that the water column motion of sloshing mode in a single chamber can be changed into the piston motion of different phases in multiple OWC chambers. Therefore, the piston motion in the multiple chambers can generate considerable airflow at a specific resonant frequency. In addition, the division of the OWC chamber results in a reduction of the time-dependent variability of the final output power from the device. As a result, the application of the multiple chambers leads to an increase of the energy conversion performance as well as a decrease of the variability of the wave energy converter.
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Razumovskii, L. V., T. N. Kushnareva, V. L. Razumovskii i A. V. Anisimova. "Long-Term Changes Reconstruction in Two Upper Volga Reservoirs Based on the Bottom Sediments Comprehensive Analysis Data". Izvestiya Rossiiskoi Akademii Nauk Seriya Geograficheskaya 87, nr 6 (1.11.2023): 885–98. http://dx.doi.org/10.31857/s2587556623060122.
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The paper presents a new research program for assessing long-term transformations occurring in reservoirs. To assess the prospects of the proposed studies, the Ivankovo and Rybinsk reservoirs were selected due to their advanced age, the power of accumulated deposits, and the degree of study. The novelty of the research consisted of the joint analysis of the results of phytoplankton complexes biomonitoring and the analysis of the diatom complexes species composition from the bottom sediments columns. At the same time, the analysis of the waters and samples chemical composition from the bottom sediments columns was carried out. The absence of redeposition processes during the formation of sediments at the sampling points was confirmed by the method of taxonomic proportions graphical analysis in diatom complexes. This determines the reliability of the diatom and chemical analysis results’ comparison of the bottom sediments. The results of the water quality assessment by two indexes are considered according to the monitoring data: the saprobity index S and the integral water quality index QI. The expected seasonal repeatability of the numerical values of S and QI is stated. Similar calculations were carried out for indicator species from diatom complexes in the bottom sediments columns samples. The processes of water quality deterioration according to the above-mentioned indexes are noted. As a result of the research conducted, the optimal location of bottom sediments column sampling points in the Rybinsk and Ivankovo reservoirs was established. During the formation of reservoirs, the lakes located on their territory were flooded. The resulting morphometric bottom relief determined those relict lakes’ locations as zones of stable sedimentation. According to the comprehensive studies results, long-term negative processes caused by anthropogenic load have been confirmed in the investigated reservoirs.
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Sen, Kalyani, Biswarup Sen i Guangyi Wang. "Diversity, Abundance, and Ecological Roles of Planktonic Fungi in Marine Environments". Journal of Fungi 8, nr 5 (8.05.2022): 491. http://dx.doi.org/10.3390/jof8050491.
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Fungi are considered terrestrial and oceans are a “fungal desert”. However, with the considerable progress made over past decades, fungi have emerged as morphologically, phylogenetically, and functionally diverse components of the marine water column. Although their communities are influenced by a plethora of environmental factors, the most influential include salinity, temperature, nutrients, and dissolved oxygen, suggesting that fungi respond to local environmental gradients. The biomass carbon of planktonic fungi exhibits spatiotemporal dynamics and can reach up to 1 μg CL−1 of seawater, rivaling bacteria on some occasions, which suggests their active and important role in the water column. In the nutrient-rich coastal water column, there is increasing evidence for their contribution to biogeochemical cycling and food web dynamics on account of their saprotrophic, parasitic, hyper-parasitic, and pathogenic attributes. Conversely, relatively little is known about their function in the open-ocean water column. Interestingly, methodological advances in sequencing and omics approach, the standardization of sequence data analysis tools, and integration of data through network analyses are enhancing our current understanding of the ecological roles of these multifarious and enigmatic members of the marine water column. This review summarizes the current knowledge of the diversity and abundance of planktonic fungi in the world’s oceans and provides an integrated and holistic view of their ecological roles.
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Nau, Amy, Vanessa Lucieer, Yoann Ladroit, Haris Kunnath i Tara Martin. "Multibeam sonar water column data simulation for improved and automated detection of gas seeps". Journal of the Acoustical Society of America 154, nr 4_supplement (1.10.2023): A92—A93. http://dx.doi.org/10.1121/10.0022905.
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Water column data (WCD) collected by multibeam echosounders (MBES) provide valuable datasets for the detection of gas bubbles. However, the presence of noise patterns, primarily caused by sidelobe interference from seafloor reverberation, limits the usability of WCD. We present a method for simulating characteristic noise patterns in WCD, particularly in Mills Cross configurations, by simulating predicted seafloor reverberation and transducer artefacts. The simulation is based on a reference pattern created from a subset of data and then applied as a correction based on the depth and seafloor backscatter of each ping within the dataset. Noise patterns can be removed by subtracting the simulated data from the original data, allowing for improved analysis of near-benthic water column features such as gas seeps. This method requires no prior knowledge of specific transducer characteristics, making it applicable to a wide range of MBES systems and acoustic targets. This method was applied to two MBES datasets collected simultaneously over a seep field in the Bay of Plenty, New Zealand, as part of the Quantitative Ocean-Column Imaging (QUOI) voyage in July 2018. We demonstrate the utility of applying a reference pattern for detecting the spatial extent of gas seep bases mapped using two different frequencies.
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French-McCay, Deborah P., Christopher Mueller, James Payne, Eric Terrill, Mark Otero, Sung Yong Kim, Melissa Carter, Walter Nordhausen, Mark Lampinen i Carter Ohlmann. "DISPERSED OIL TRANSPORT MODELING CALIBRATED BY FIELD-COLLECTED DATA MEASURING FLUORESCEIN DYE DISPERSION". International Oil Spill Conference Proceedings 2008, nr 1 (1.05.2008): 527–36. http://dx.doi.org/10.7901/2169-3358-2008-1-527.
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ABSTRACT Oil-spill fate and transport modeling may be used to evaluate water column hydrocarbon concentrations, potential exposure to organisms, and impacts of oil spills with and without dispersant use. Important inputs to transport modeling for such analyses are current velocities and turbulent dispersion coefficients. Fluorescein dye studies off San Diego, California, were used to calibrate an oil transport model by hindcasting movement and dispersion of dye. The oil spill model was then used to predict subsurface hydrocarbon concentrations and potential water column impacts if oil were to be dispersed into the water column under similar conditions. Field-collected data included surface currents calculated from high-frequency radar data (HF-Radar), near-surface currents from drifter measurements drogued at several depths (1m, 2m, 4m or 5m), dye concentrations measured by fluorescence, spreading and dye intensity measurements based on aerial photography, and water density profiles from CTD casts. As the dye plume quickly extended throughout an upper mixed layer (7–15m), the horizontal dye movements were better indicated by the drifters drogued to a depth near the middle of that layer than the HF-Radar, which measured surface (∼top 50 cm) currents (including wind drift). Diffusion rates were estimated based on dye spreading measured by aerial photography and fluorescence-depth profiles. The model used these data as inputs, modeling of wind-forced surface water turbulence and drift as a function of wind speed and direction (based on published results of fluid dynamics studies), and Stokes law for droplet rise/sinking rates, to predict oil transport and dispersion rates within the water column. Use of such diffusion rate data in an oil fate model can provide estimates of likely dispersed oil concentrations under similar conditions, which may be used to evaluate potential impacts on water column biota. However, other conditions with different patterns of current shear (due to background currents, tidal currents, and wind stress) should be examined before these results can be generalized.
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Mieruch, S., S. Noël, H. Bovensmann i J. P. Burrows. "Analysis of global water vapour trends from satellite measurements in the visible spectral range". Atmospheric Chemistry and Physics Discussions 7, nr 4 (10.08.2007): 11761–96. http://dx.doi.org/10.5194/acpd-7-11761-2007.
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Abstract. Global water vapour total column amounts have been retrieved from spectral data provided by the Global Ozone Monitoring Experiment (GOME) flying on ERS-2, which was launched in April 1995, and the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) onboard ENVISAT launched in March 2002. For this purpose the Air Mass Corrected Differential Optical Absorption Spectroscopy (AMC-DOAS) approach has been used. The combination of the data from both instruments provides us with a long-term global data set spanning more than 11 years with the potential of extension up to 2020 by GOME-2 data, on Metop. Using linear and non-linear methods from time series analysis and standard statistics the trends of H2O contents and their errors have been calculated. In this study, factors affecting the trend such as the length of the time series, the magnitude of the variability of the noise, and the autocorrelation of the noise are investigated. Special emphasis has been placed on the calculation of the statistical significance of the observed trends, which reveal significant local changes of water vapour columns distributed over the whole globe.
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Grossi, M., P. Valks, D. Loyola, B. Aberle, S. Slijkhuis, T. Wagner, S. Beirle i R. Lang. "Total column water vapour measurements from GOME-2 MetOp-A and MetOp-B". Atmospheric Measurement Techniques 8, nr 3 (5.03.2015): 1111–33. http://dx.doi.org/10.5194/amt-8-1111-2015.
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Abstract. Knowledge of the total column water vapour (TCWV) global distribution is fundamental for climate analysis and weather monitoring. In this work, we present the retrieval algorithm used to derive the operational TCWV from the GOME-2 sensors aboard EUMETSAT's MetOp-A and MetOp-B satellites and perform an extensive inter-comparison in order to evaluate their consistency and temporal stability. For the analysis, the GOME-2 data sets are generated by DLR in the framework of the EUMETSAT O3M-SAF project using the GOME Data Processor (GDP) version 4.7. The retrieval algorithm is based on a classical Differential Optical Absorption Spectroscopy (DOAS) method and combines a H2O and O2 retrieval for the computation of the trace gas vertical column density. We introduce a further enhancement in the quality of the H2O total column by optimizing the cloud screening and developing an empirical correction in order to eliminate the instrument scan angle dependencies. The overall consistency between measurements from the newer GOME-2 instrument on board of the MetOp-B platform and the GOME-2/MetOp-A data is evaluated in the overlap period (December 2012–June 2014). Furthermore, we compare GOME-2 results with independent TCWV data from the ECMWF ERA-Interim reanalysis, with SSMIS satellite measurements during the full period January 2007–June 2014 and against the combined SSM/I + MERIS satellite data set developed in the framework of the ESA DUE GlobVapour project (January 2007–December 2008). Global mean biases as small as ±0.035 g cm−2 are found between GOME-2A and all other data sets. The combined SSM/I-MERIS sample and the ECMWF ERA-Interim data set are typically drier than the GOME-2 retrievals, while on average GOME-2 data overestimate the SSMIS measurements by only 0.006 g cm−2. However, the size of these biases is seasonally dependent. Monthly average differences can be as large as 0.1 g cm−2, based on the analysis against SSMIS measurements, which include only data over ocean. The seasonal behaviour is not as evident when comparing GOME-2 TCWV to the ECMWF ERA-Interim and the SSM/I+MERIS data sets, since the different biases over land and ocean surfaces partly compensate each other. Studying two exemplary months, we estimate regional differences and identify a very good agreement between GOME-2 total columns and all three data sets, especially for land areas, although some discrepancies (bias larger than ±0.5 g cm−2) over ocean and over land areas with high humidity or a relatively large surface albedo are observed.
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Angeletti, Sabrina, Jorge O. Pierini i Patricia M. Cervellini. "Suspended sediment contribution resulting from bioturbation in intertidal sites of a SW Atlantic mesotidal estuary: data analysis and numerical modelling". Scientia Marina 82, nr 4 (16.01.2019): 245. http://dx.doi.org/10.3989/scimar.04799.07a.
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The suspended sediment contribution arising from the bioturbation activity of Neohelice granulata at intertidal sites of the Bahía Blanca estuary was analysed using several approaches, ranging from field experiments to numerical modelling. Crabs from the mudflat remove, trap and erode more sediment from their burrows per unit area than those from saltmarshes, as a consequence of the high population density and the mobility of cohesive sediments. The results obtained through the MOHID simulations showed that the sediments that were bioavailable in the intertidal of Puerto Cuatreros were maintained in the water column much longer than sediments in Villa del Mar. This longer residence time in the area could be because of the geomorphological and hydrodynamic characteristics of the internal area of the estuary, where numerous tidal channels coexist and phenomena of “retention” occur before entry into the main channel. By contrast, in Villa del Mar, located in the middle of the estuary, the sediments are affected by a greater water depth and higher tidal current speeds. In addition, the waves caused by the winds can be a determining factor in the spatio-temporal evolution of the bioavailable sediment in the water column of the study areas.
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Li, Jing, Ronghua Ma, Kun Xue, Yuchao Zhang i Steven Loiselle. "A Remote Sensing Algorithm of Column-Integrated Algal Biomass Covering Algal Bloom Conditions in a Shallow Eutrophic Lake". ISPRS International Journal of Geo-Information 7, nr 12 (30.11.2018): 466. http://dx.doi.org/10.3390/ijgi7120466.
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Column integrated algal biomass provides a robust indicator for eutrophication evaluation because it considers the vertical variability of phytoplankton. However, most remote sensing-based inversion algorithms of column algal biomass assume a homogenous distribution of phytoplankton within the water column. This study proposes a new remote sensing-based algorithm to estimate column integrated algal biomass incorporating different possible vertical profiles. The field sampling was based on five surveys in Lake Chaohu, a large eutrophic shallow lake in China. Field measurements revealed a significant variation in phytoplankton profiles in the water column during algal bloom conditions. The column integrated algal biomass retrieval algorithm developed in the present study is shown to effectively describe the vertical variation of algal biomass in shallow eutrophic water. The Baseline Normalized Difference Bloom Index (BNDBI) was adopted to estimate algal biomass integrated from the water surface to 40 cm. Then the relationship between 40 cm integrated algal biomass and the whole column algal biomass at various depths was built taking into consideration the hydrological and bathymetry data of each site. The algorithm was able to accurately estimate integrated algal biomass with R2 = 0.89, RMSE = 45.94 and URMSE = 28.58%. High accuracy was observed in the temporal consistency of satellite images (with the maximum MAPE = 7.41%). Sensitivity analysis demonstrated that the estimated algal biomass integrated from the water surface to 40 cm has the greatest influence on the estimated column integrated algal biomass. This algorithm can be used to explore the long-term variation of algal biomass to improve long-term analysis and management of eutrophic lakes.
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Liu, Dong Wu, Zhi Wei Chen, Lei Xu, Zheng Jie Zhang, Bao Yu Ju i Wen Chao Cheng. "Ion Chromatographic Determination of Cations and Anions in Tap Water". Advanced Materials Research 225-226 (kwiecień 2011): 128–31. http://dx.doi.org/10.4028/www.scientific.net/amr.225-226.128.
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Ion chromatography (IC) has been developed for the simultaneous analysis of cations and anions in the water, food, atmosphere, etc. Chromatography can yield the precise and reproducible data if the experimental condition is kept constant. In the present studies, the major cations and anions in the tap water were determined with the technique of IC. A Dionex ICS-2000 ion chromatograph with a Dionex gradient pump, eluent degassing module and conductivity detector was used. Cations were separated on a CS12 A ion-exchange column, with a CG-12 A guard column, and detected after suppression with CSRS 300 cation electrical self-regenerating suppressor. Anions were separated on an AS 11 HC ion-exchange column, with an AS 11 HC guard column, and detected after suppression with an ASRS 300 anion electrical self-regenerating suppressor. The results indicated that the technique of IC was suitable for the rapid, precise and accurate determination of major cations and anions in the tap water samples. In addition, the acceptable detection limits were obtained for all the cations and anions, and the time of analysis was significantly shortened with the technique of IC.
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Manso-Narvarte, Ivan, Anna Rubio, Gabriel Jordà, Jeffrey Carpenter, Lucas Merckelbach i Ainhoa Caballero. "Three-Dimensional Characterization of a Coastal Mode-Water Eddy from Multiplatform Observations and a Data Reconstruction Method". Remote Sensing 13, nr 4 (13.02.2021): 674. http://dx.doi.org/10.3390/rs13040674.
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Coastal mesoscale eddies are important oceanic structures partially responsible for regulating ocean-shelf exchanges. However, their description and characterization are challenging; observations are often too scarce for studying their physical properties and environmental impacts at the required spatio-temporal resolution. Therefore, models and data extrapolation methods are key tools for this purpose. Observations from high-frequency radar, one satellite and two gliders, are used here to better characterize the three-dimensional structure of a coastal mode-water eddy from a multiplatform approach in the southeastern Bay of Biscay in spring 2018. After the joint analysis of the observations, a three-dimensional data reconstruction method is applied to reconstruct the eddy current velocity field and estimate the associated water volume transport. The target eddy is detected by surface observations (high-frequency radar and satellite) for two weeks and presents similar dimensions and lifetimes as other eddies studied previously in the same location. However, this is the first time that the water column properties are also observed for this region, which depicts a mode-water eddy behavior, i.e., an uplift of the isopycnals in the near-surface and a downlift deeper in the water column. The reconstructed upper water column (1–100 m) eddy dynamics agree with the geostrophic dynamics observed by one of the gliders and result in cross-shelf inshore (offshore) volume transports between 0.04 (−0.01) and 0.15 (−0.11) Sv. The multiplatform data approach and the data reconstruction method are here highlighted as useful tools to characterize and three-dimensionally reconstruct coastal mesoscale processes in coastal areas.
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Grossi, M., P. Valks, D. Loyola, B. Aberle, S. Slijkhuis, T. Wagner, S. Beirle i R. Lang. "Total column water vapour measurements from GOME-2 MetOp-A and MetOp-B". Atmospheric Measurement Techniques Discussions 7, nr 3 (28.03.2014): 3021–73. http://dx.doi.org/10.5194/amtd-7-3021-2014.
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Abstract. The knowledge of the total column water vapour (TCWV) global distribution is fundamental for climate analysis and weather monitoring. In this work, we present the retrieval algorithm used to derive the operational TCWV from the GOME-2 sensors and perform an extensive inter-comparison and validation in order to estimate their absolute accuracy and long-term stability. We use the recently reprocessed data sets retrieved by the GOME-2 instruments aboard EUMETSAT's MetOp-A and MetOp-B satellites and generated by DLR in the framework of the O3M-SAF using the GOME Data Processor (GDP) version 4.7. The retrieval algorithm is based on a classical Differential Optical Absorption Spectroscopy (DOAS) method and combines H2O/O2 retrieval for the computation of the trace gas vertical column density. We introduce a further enhancement in the quality of the H2O column by optimizing the cloud screening and developing an empirical correction in order to eliminate the instrument scan angle dependencies. We evaluate the overall consistency between about 8 months measurements from the newer GOME-2 instrument on the MetOp-B platform with the GOME-2/MetOp-A data in the overlap period. Furthermore, we compare GOME-2 results with independent TCWV data from ECMWF and with SSMIS satellite measurements during the full period January 2007–August 2013 and we perform a validation against the combined SSM/I + MERIS satellite data set developed in the framework of the ESA DUE GlobVapour project. We find global mean biases as small as ± 0.03 g cm−2 between GOME-2A and all other data sets. The combined SSM/I-MERIS sample is typically drier than the GOME-2 retrievals (−0.005 g cm−2), while on average GOME-2 data overestimate the SSMIS measurements by only 0.028 g cm−2. However, the size of some of these biases are seasonally dependent. Monthly average differences can be as large as 0.1 g cm−2, based on the analysis against SSMIS measurements, but are not as evident in the validation with the ECMWF and the SSM/I + MERIS data. Studying two exemplary months, we estimate regional differences and identify a very good agreement between GOME-2 total columns and all three independent data sets, especially for land areas, although some discrepancies over ocean and over land areas with high humidity and a relatively large surface albedo are also present.
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Mount, Dwight L., i James W. Miles. "Gas Chromatographic Method for Determination of Fenitrothion in Technical and in Emulsifiable Concentrate and Water-Dispersible Powder Formulations: Collaborative Study". Journal of AOAC INTERNATIONAL 68, nr 3 (1.05.1985): 576–80. http://dx.doi.org/10.1093/jaoac/68.3.576.
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Abstract A variety of column packings and internal standards were evaluated to determine the most satisfactory system to use in a gas chromatograhpic (GC) method for analysis of fenitrothion, technical and formulations. Fenitrothion and the most closely related isomer, 00- dimethyl 0-(4-methyl-3-nitrophenyl) phosphorothioate, were resolved on columns packed with OV-210 and with polyphenyl ether, 6-ring (PPE-6R). A method based on the separation of fenitrothion on a PPE- 6R column with fluoranthene as internal standard was selected for use in a limited collaborative trial and later for use in a full-scale collaborative trial with 21 collaborators participating. Each collaborator was furnished matched pairs of samples of technical fenitrothion, emulsifiable concentrate, and water-dispersible powder. The coefficients of variation (CV) for the paired samples were 1.02,1.11, and 1.01, respectively, for technical fenitrothion, emulsifiable concentrates, and waterdispersible powders. Data are also presented for an alternative method in which compounds are separated on an OV-210 column with dibutyl sebacate as the internal standard. The method has been adopted official first action.
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Liu, Xinfu, Chunhua Liu i Jianjun Wu. "A Modern Approach to Analyzing the Flowing Pressures of a Two-Phase CBM and Water Column in Producing Wellbores". Geofluids 2019 (7.05.2019): 1–9. http://dx.doi.org/10.1155/2019/3093707.
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A modern methodology is presented for the system analysis of flowing pressures in order to forecast the dynamic behavior and solve the forthcoming problems that emerge in two-phase coalbed methane (CBM) wellbores. The proposed methodology involves a numerical integration technique to calculate flowing pressures and pressure drops of CBM and water flow from the bottom hole to the well head. The methodology is validated against full-scale measured data in coalfields. The relationships developed match CBM reservoir behavior and wellbore conditions along the annulus with an overall accuracy of 1.13%. The computation of flowing pressures involves a liquid holdup and kinetic energy term with flow rate increments, a compressibility factor with depth increments, and a friction factor with Reynolds number. The flowing pressures of a two-phase column fully reflect the dynamic flowing performance due to the combined action of the water level, CBM, and water flow rates. The effect of CBM and water column pressures is more obvious than that of CBM column pressures. The pressure ratios of CBM and the water column to the bottom hole decline rapidly with the increase of the dynamic water level. CBM and water flow rates can be improved with increases in CBM and water column pressure for two-phase producing wellbores. The decrease of flowing pressures and increased increment of the pressure drop for the two-phase column are beneficial to CBM desorption and result in the increased CBM and water production. It will control the falling speed of the dynamic water level above CBM and the water column and enhance CBM reservoir productivity. The increases of CBM and water column pressure from 34.6 kPa to 922 kPa and the decreases of pressure in the bottom hole from 2.252 MPa to 1.328 MPa lead to the increases of the CBM flow rate from 3327 m3/d to 6721 m3/d.
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Amorim, Felipe L. L., Julien Le Meur, Achim Wirth i Vanessa Cardin. "Tipping of the double-diffusive regime in the southern Adriatic Pit in 2017 in connection with record high-salinity values". Ocean Science 20, nr 2 (28.03.2024): 463–74. http://dx.doi.org/10.5194/os-20-463-2024.
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Abstract. In double-diffusive mixing, whenever salinity and temperature decrease with depth, the water column is either unstable or predisposed to a state called salt fingering (SF), which exhibits increased vertical mixing. Analysis of a high-frequency time series of thermohaline data measured at the EMSO-E2M3A regional facility in the southern Adriatic Pit (SAP) from 2014 to 2019 reveals that in the south Adriatic, SF is the dominant regime. The same time series shows the presence of a very saline core of the Levantine Intermediate Water that penetrated with unprecedented strength during the winter of 2016/17 at around 550 dbar and even higher-salinity water above. The effect of strong heat loss at the surface during that winter allowed deep convection to transport this high-salinity water from the intermediate to the deep layers within the pit. This resulted in an increased predisposition to SF throughout the water column. In the subsurface layer (350 to 550 dbar) the increase is from 27 % to 72 % of observations. We observe an alteration of vertical stratification throughout the water column during the winter of 2016/17 from a stratified water column to an almost homogeneous water column down to 700 dbar, with no return in the following years.
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Schneider von Deimling, J., i C. Papenberg. "Technical Note: Detection of gas bubble leakage via correlation of water column multibeam images". Ocean Science Discussions 8, nr 4 (15.07.2011): 1757–75. http://dx.doi.org/10.5194/osd-8-1757-2011.
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Abstract. Hydroacoustic detection of natural gas release from the seafloor has been conducted in the past by using singlebeam echosounders. In contrast modern multibeam swath mapping systems allow much wider coverage, higher resolution, and offer 3-D spatial correlation. However, up to the present, the extremely high data rate hampers water column backscatter investigations. More sophisticated visualization and processing techniques for water column backscatter analysis are still under development. We here present such water column backscattering data gathered with a 50 kHz prototype multibeam system. Water column backscattering data is presented in videoframes grabbed over 75 s and a "re-sorted" singlebeam presentation. Thus individual gas bubbles rising from the 24 m deep seafloor clearly emerge in the acoustic images and rise velocities can be determined. A sophisticated processing scheme is introduced to identify those rising gas bubbles in the hydroacoustic data. It applies a cross-correlation technique similar to that used in Particle Imaging Velocimetry (PIV) to the acoustic backscatter images. Tempo-spatial drift patterns of the bubbles are assessed and match very well measured and theoretical rise patterns. The application of this processing scheme to our field data gives impressive results with respect to unambiguous bubble detection and remote bubble rise velocimetry. The method can identify and exclude the main driver for misinterpretations, i.e. fish-mediated echoes. Even though image-based cross-correlation techniques are well known in the field of fluid mechanics for high resolution and non-inversive current flow field analysis, this technique was never applied in the proposed sense for an acoustic bubble detector.
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Seijo-Ellis, Giovanni, David Lindo-Atichati i Haydee Salmun. "Vertical Structure of the Water Column at the Virgin Islands Shelf Break and Trough". Journal of Marine Science and Engineering 7, nr 3 (20.03.2019): 74. http://dx.doi.org/10.3390/jmse7030074.
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The steep US Virgin Islands Shelf Break (VISB) and the Virgin Islands Trough (VIT) at the Northeastern Caribbean Sea comprise a dynamic region of the Atlantic Ocean. In situ oceanographic data collected in the region during April 2017 were used to examine the spatial variability in temperature, density, salinity, and relative Chlorophyll-a. Analysis of data from the upper 300 m of the water column, that include deep and shallow water stations in the shelf break region, shows strong stratification of the water column. Stations shallower than 800 m along the shelf break are more variable in temperature, density, and salinity than those that are deeper than 800 m along the trough. For shallow stations, the mixed layer depth deepens along-shelf from West to East while at the deep stations the opposite occurs. Salinity maxima exhibit more variability in depth and range of values in the shallow stations compared to deep stations. Six different types of water masses that contribute to the strong stratification in the region were identified in our study: Caribbean Surface Water, Subtropical Underwater, Sargasso Sea Water, Tropical Atlantic Central Water, Antarctic Intermediate Water, and North Atlantic Deep Water. The upper level Caribbean Surface Water, Subtropical Underwater, and Sargasso Sea Water are present in shallow stations, indicating potential meridional intrusions from the VIT to the VISB which may not be resolved by current ocean circulation models and are not captured in satellite data. The analysis presented here indicates that competing physical processes may be controlling the vertical structure of the water column in the region and merit further examination.
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AUDEMARD, C., L. M. RAGONE CALVO, K. T. PAYNTER, K. S. REECE i E. M. BURRESON. "Real-time PCR investigation of parasite ecology:in situdetermination of oyster parasitePerkinsus marinustransmission dynamics in lower Chesapeake Bay". Parasitology 132, nr 6 (14.02.2006): 827–42. http://dx.doi.org/10.1017/s0031182006009851.
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Perkinsus marinusis a severe pathogen of the oysterCrassostrea virginicaon the East Coast of the United States. Transmission dynamics of this parasite were investigatedin situfor 2 consecutive years (May through October) at 2 lower Chesapeake Bay sites. Compared to previous studies where seasonal infection patterns in oysters were measured, this study also provided parasite water column abundance data measured using real-time PCR. As previously observed, salinity and temperature modulated parasite transmission dynamics. Using regression analysis, parasite prevalence, oyster mortalities and parasite water column abundance were significantly positively related to salinity.Perkinsus marinusweighted prevalence in wild oysters and parasite water column abundance both were significantly related to temperature, but the responses lagged 1 month behind temperature. Parasite water column abundance was the highest during August (up to 1200 cells/l) and was significantly related toP. marinusweighted prevalence in wild oysters, and to wild oyster mortality suggesting that parasites are released in the environment via both moribund and live hosts (i.e. through feces). Incidence was not significantly related to parasite water column abundance, which seems to indicate the absence of a linear relationship or that infection acquisition is controlled by a more complex set of parameters.
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Yano, Jun-Ichi, Changhai Liu i Mitchell W. Moncrieff. "Self-Organized Criticality and Homeostasis in Atmospheric Convective Organization". Journal of the Atmospheric Sciences 69, nr 12 (1.12.2012): 3449–62. http://dx.doi.org/10.1175/jas-d-12-069.1.
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Abstract Atmospheric convection has a tendency to organize on a hierarchy of scales ranging from the mesoscale to the planetary scales, with the latter especially manifested by the Madden–Julian oscillation. The present paper examines two major competing mechanisms of self-organization in a cloud-resolving model (CRM) simulation from a phenomenological thermodynamic point of view. The first mechanism is self-organized criticality. A saturation tendency of precipitation rate with increasing column-integrated water, reminiscent of critical phenomena, indicates self-organized criticality. The second is a self-regulation mechanism that is known as homeostasis in biology. A thermodynamic argument suggests that such self-regulation maintains the column-integrated water below a threshold by increasing the precipitation rate. Previous analyses of both observational data as well as CRM experiments give mixed results. In this study, a CRM experiment over a large-scale domain with a constant sea surface temperature is analyzed. This analysis shows that the relation between the column-integrated total water and precipitation suggests self-organized criticality, whereas the one between the column-integrated water vapor and precipitation suggests homeostasis. The concurrent presence of these two mechanisms is further elaborated by detailed statistical and budget analyses. These statistics are scale invariant, reflecting a spatial scaling of precipitation processes.
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Rao, M. B., i S. Sircar. "Liquid-phase Adsorption of Bulk Ethanol–Water Mixtures by Alumina". Adsorption Science & Technology 10, nr 1-4 (marzec 1993): 93–104. http://dx.doi.org/10.1177/0263617499010001-409.
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Separation of ethanol–water liquid mixtures can be carried out by selective adsorption of water on activated alumina. The moderate selectivity and heat of adsorption of water on the alumina permits easier and less energy intensive desorption of the adsorbed water. Experimental binary surface excess isotherms, liquid-phase adsorption kinetics and column dynamics for the adsorption of bulk water–ethanol mixtures on Alcoa H152 alumina are reported. Model analyses of the data are carried out to quantify the selectivity of adsorption, adsorptive mass-transfer coefficients and the properties of the mass-transfer zones in adsorption columns.
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Mieruch, S., S. Noël, H. Bovensmann i J. P. Burrows. "Analysis of global water vapour trends from satellite measurements in the visible spectral range". Atmospheric Chemistry and Physics 8, nr 3 (6.02.2008): 491–504. http://dx.doi.org/10.5194/acp-8-491-2008.
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Abstract. Global water vapour total column amounts have been retrieved from spectral data provided by the Global Ozone Monitoring Experiment (GOME) flying on ERS-2, which was launched in April 1995, and the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) onboard ENVISAT launched in March 2002. For this purpose the Air Mass Corrected Differential Optical Absorption Spectroscopy (AMC-DOAS) approach has been used. The combination of the data from both instruments provides us with a long-term global data set spanning more than 11 years with the potential of extension up to 2020 by GOME-2 data on MetOp. Using linear and non-linear methods from time series analysis and standard statistics the trends of H2O columns and their errors have been calculated. In this study, factors affecting the trend such as the length of the time series, the magnitude of the variability of the noise, and the autocorrelation of the noise are investigated. Special emphasis has been placed on the calculation of the statistical significance of the observed trends, which reveal significant local changes from −5% per year to +5% per year. These significant trends are distributed over the whole globe. Increasing trends have been calculated for Greenland, East Europe, Siberia and Oceania, whereas decreasing trends have been observed for the northwest USA, Central America, Amazonia, Central Africa and the Arabian Peninsular.
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Borger, Christian, Steffen Beirle, Steffen Dörner, Holger Sihler i Thomas Wagner. "Total column water vapour retrieval from S-5P/TROPOMI in the visible blue spectral range". Atmospheric Measurement Techniques 13, nr 5 (28.05.2020): 2751–83. http://dx.doi.org/10.5194/amt-13-2751-2020.
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Abstract. Total column water vapour has been retrieved from TROPOMI measurements in the visible blue spectral range and compared to a variety of different reference data sets for clear-sky conditions during boreal summer and winter. The retrieval consists of the common two-step DOAS approach: first the spectral analysis is performed within a linearized scheme and then the retrieved slant column densities are converted to vertical columns using an iterative scheme for the water vapour a priori profile shape, which is based on an empirical parameterization of the water vapour scale height. Moreover, a modified albedo map was used combining the OMI LER albedo and scaled MODIS albedo map. The use of the alternative albedo is especially important over regions with very low albedo and high probability of clouds like the Amazon region. The errors of the total column water vapour (TCWV) retrieval have been theoretically estimated considering the contribution of a variety of different uncertainty sources. For observations during clear-sky conditions, over ocean surface, and at low solar zenith angles the error typically is around values of 10 %–20 %, and during cloudy-sky conditions, over land surface, and at high solar zenith angles it reaches values around 20 %–50 %. In the framework of a validation study the retrieval demonstrates that it can well capture the global water vapour distribution: the retrieved H2O vertical column densities (VCDs) show very good agreement with the reference data sets over ocean for boreal summer and winter whereby the modified albedo map substantially improves the retrieval's consistency to the reference data sets, in particular over tropical land masses. However, over land the retrieval underestimates the VCD by about 10 %, particularly during summertime. Our investigations show that this underestimation is likely caused by uncertainties within the surface albedo and the cloud input data: low-level clouds cause an underestimation, but for mid- to high-level clouds good agreement is found. In addition, our investigations indicate that these biases can probably be further reduced by the use of improved cloud input data. For the general purpose we recommend only using VCDs with cloud fraction <20 % and AMF >0.1, which represents a good compromise between spatial coverage and retrieval accuracy. The TCWV retrieval can be easily applied to further satellite sensors (e.g. GOME-2 or OMI) for creating uniform, long-term measurement data sets, which is particularly interesting for climate and trend studies of water vapour.
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Baba, J., G. B. Soda, Y. Azeh i E. Bala. "Bacteriological and Physico-Chemical Analysis of Lapai Water Supply". Bayero Journal of Pure and Applied Sciences 14, nr 2 (6.07.2022): 52–61. http://dx.doi.org/10.4314/bajopas.v14i2.6.
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Bacteriological and Physico-chemical analysis of Lapai water source was investigated. Lapai is the headquarters of Lapai Local Government Area of Niger state, Nigeria. Bacteriological quality of water samples was determined by enumeration through Total Viable Count and Coliform count using the Most Probable Number (MPN) method. The Isolates were subjected to Series of Biochemical tests for characterization and identification. The physicochemical parameters were determined according to the standard analytical methods for the examination of water and waste water and Romanian standard. Findings from this work includes the following: Maximum Total Viable Count (TVC) and Coliform count were recorded to be 2.45 x 107cfu/mg and > 1100 MPN index/100ml,while minimum TVC and Coliform count were recorded to be 1.05 x 107cfu/mg and 0MPN index/100ml in the water samples. Total bacteria count and identified from all the water sources in Lapai metropolis indicated that Escherichia coli and Klebsiella sp occurred most with five (5) and four (4) isolates respectively.The conductivity data for the raw water samples indicated that State low-cost (LN), IBB Hostel (LE) and Emir Palace (LW) analysed were 250, 120 and 580 μs/cm. The pH, conductivity, chloride, nitrate and total hardness decreases with increasing treatment time in the column for the borehole water samples. While, the pH, temperature, turbidity, conductivity, total suspended solid (TSS), total dissolved solids (TDS), and total solids (TS), BOD, COD, nitrate, phosphate, ammonia and heavy metal analysis for the surface water (stream/river) samples also decreases with increasing treatment time in the packed column. Treatment of the water using nanocellulose revealed a decrease in all the investigated parameters with increasing treatment time. Most water samples examined did not meet up with the WHO standard for portable water, and the presence of these bacteria are potential pathogens that can significantly affect microbiology water quality, resulting to great health risk.
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Han, Xiuli, Wei Wang i Xiaojian Ma. "Adsorption characteristics of methylene blue onto agricultural wastes lotus leaf in bath and column modes". Water Science and Technology 64, nr 3 (1.08.2011): 654–60. http://dx.doi.org/10.2166/wst.2011.665.
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The adsorption potential of lotus leaf to remove methylene blue (MB) from aqueous solution was investigated in batch and fixed-bed column experiments. Langmuir, Freundlich, Temkin and Koble–Corrigan isotherm models were employed to discuss the adsorption behavior. The results of analysis indicated that the equilibrium data were perfectly represented by Temkin isotherm and the Langmuir saturation adsorption capacity of lotus leaf was found to be 239.6 mg g−1 at 303 K. In fixed-bed column experiments, the effects of flow rate, influent concentration and bed height on the breakthrough characteristics of adsorption were discussed. The Thomas and the bed-depth/service time (BDST) models were applied to the column experimental data to determine the characteristic parameters of the column adsorption. The two models were found to be suitable to describe the dynamic behavior of MB adsorbed onto the lotus leaf powder column.
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Manikrishna*, K. S. G. V., Veluru Sridevi, Sri Himaja Pamu, M. Tukaram Bai i K. S. NV Prasad. "Biosorption of Malachite Green Dye from Wastewater with Henfeathers -Analysis of Various Mathematical Models Wrt Continuous Adsorption". International Journal of Innovative Technology and Exploring Engineering 10, nr 10 (30.08.2021): 15–23. http://dx.doi.org/10.35940/ijitee.j9387.08101021.
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In recent years, the remediation of hazardous organic dye-contaminated aquatic habitats has been a key research priority for environmental and chemical engineers. The goal of this research was to see how well malachite green adsorbs from waste water in a continuous column system having fixed bed. A biosorbent made from waste materials such as hen feathers has been shown to extract the water-soluble malachite green colour from waste water. The adsorption potential of malachite green dye ions in a continuous flow adsorption column is investigated in this work. The hen feathers' performance in the fixed bed column was assessed under a variety of operating circumstances, including bed height in the range 6-10cm; flow in the range 4-12ml/min, and starting concentration (10-30 mg/l). In comparison to other testing settings, the bed height (8cm), flowrate (12ml/min), and maximum input concentration (20mg/l) resulted in the highest malachite green absorption of 2.829mg/g. The column experimental data collected under various conditions was evaluated using three distinct models namely 1. Bohart-Adams model, 2 Yoon-Nelsons model, and 3 BDST model, all of which produced a decent estimation of the breakthrough curve. The findings from the Yoon-nelson and BDST models, on the other hand, were more favourable. The several characteristics of the hen feathers were studied using FTIR studies. The activated hen feather powder was a successful potential bio sorbent for the malachite green from aqueous phase.
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Zhang, Ying, Zhengqiang Li, Yu Chen, Gerrit de Leeuw, Chi Zhang, Yisong Xie i Kaitao Li. "Improved inversion of aerosol components in the atmospheric column from remote sensing data". Atmospheric Chemistry and Physics 20, nr 21 (4.11.2020): 12795–811. http://dx.doi.org/10.5194/acp-20-12795-2020.
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Abstract. Knowledge of the composition of atmospheric aerosols is important for reducing uncertainty in climate assessment. In this study, an improved algorithm is developed for the retrieval of atmospheric columnar aerosol components from optical remote sensing data. This is achieved by using the complex refractive index (CRI) of a multicomponent liquid system in the forward model and minimizing the differences with the observations. The aerosol components in this algorithm comprise five species, combining eight subcomponents including black carbon (BC), water-soluble organic matter (WSOM) and water-insoluble organic matter (WIOM), ammonium nitrate (AN), sodium chloride (SC), dust-like content (DU), and aerosol water content in the fine and coarse modes (AWf and AWc). The calculation of the CRI in the multicomponent liquid system allows for the separation of the water-soluble components (AN, WSOM and AWf) in the fine mode and SC and AWc in the coarse mode. The uncertainty in the retrieval results is analyzed based on the simulation of typical models, showing that the complex refractive index obtained from instantaneous optical–physical inversion compares well with that obtained from chemical estimation. The algorithm was used to retrieve the columnar aerosol components over China using the ground-based remote sensing measurements from the Sun–sky radiometer Observation NETwork (SONET) in the period from 2010 to 2016. The results were used to analyze the regional distribution and interannual variation. The analysis shows that the atmospheric columnar DU component is dominant in the northern region of China, whereas the AW is higher in the southern coastal region. The SC component retrieved over the desert in northwest China originates from a paleomarine source. The AN significantly decreased from 2011 to 2016, by 21.9 mg m−2, which is inseparable from China's environmental control policies.
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Marko, John R., i David R. Topham. "Analyses of Peace River Shallow Water Ice Profiling Sonar data and their implications for the roles played by frazil ice and in situ anchor ice growth in a freezing river". Cryosphere 15, nr 5 (31.05.2021): 2473–89. http://dx.doi.org/10.5194/tc-15-2473-2021.
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Abstract. Peace River SWIPS (Shallow Water Ice Profiling Sonar) data were analyzed to quantify the roles of frazil ice and riverbed anchor ice grown in situ during the initial buildup of a seasonal ice cover. Data were derived through quasi-continuous monitoring of frazil parameters throughout the water column, providing direct and indirect measures of anchor ice volume and mass growth rates. Analyses utilized water level and air and water temperature information in conjunction with acoustic volume backscattering coefficient data to track and interpret spatial and temporal changes in riverbed and water column ice. Interest focused on four frazil intervals characterized by anomalously low levels of frazil content (relative to simulations with an anchor-ice-free river ice model) as distinguished by two strikingly different types of time dependences. A simple physical model was proposed to quantitatively account for discrepancies between measured and simulated results in terms of the pronounced dominance of anchor ice as an initial source of river ice volume and mass. The distinctive differences in temporally variable water column frazil content are attributed, in this model, to corresponding differences in the stabilities of riverbed anchor ice layers against detachment and buoyancy-driven movement to the river surface. In accord with earlier observations, the stability of in situ grown riverbed ice layers appears to be inversely proportional to cooling rates. The strength of the coupling between the two studied ice species was shown to be strong enough to detect changes in the anchor ice constituent from variations in water column frazil content.
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Hayder Abd Al-kaream Muhsin. "EXPERIMENTAL STUDY OF LIQUID DISPERSION IN BUBBLE COLUMN". Diyala Journal of Engineering Sciences 1, nr 1 (1.09.2008): 56–85. http://dx.doi.org/10.24237/djes.2008.01105.
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The main object of this study is to investigate the influence of column diameter and superficial gas velocity on liquid phase dispersion coefficients (axial and radial dispersion coefficients), mixing times, gas holdup, and bubble dynamics (bubble diameter and rise velocity). The liquid phase dispersion, gas holdup, and bubble dynamics (Db and Vb0) were measured for the air-water system in bubble columns of two different diameters,15 and 30 cm. The superficial gas velocity, Ug, was varied in the range 1-10 cm/s, spanning both the homogeneous and heterogeneous flow regimes. The height of liquid in the column was kept constant at 130 cm for the two column. Axial and radial dispersion coefficients and mixing times were measured at various axial and radial locations inside the columns (Z = 25, 75, 125 cm and r/R = 0, 0.45, 0.85), bubble dynamics were measured at three axial location (Z=25, 75, 125 cm). From the experimental data it was found that, the value of the radial dispersion coefficient (Dr,L) and axial dispersion coefficient (Dax,L), gas holdup, bubble diameter and bubble rise velocity, increase with increasing superficial gas velocity. The results emphasise the significant influence of the column diameter on the hydrodynamics. Gas holdup showed a decrease with increasing column diameter, while the radial dispersion coefficient (Dr,L), axial dispersion coefficient (Dax,L), bubble diameter and bubble rise velocity increased with increasing column diameter. A statistical analysis was performed to get a general correlations for the axial liquid dispersion coefficient as a function of the mixing time and dispersion height (Hd), this correlations are: Dax,L=0.15 H2d /θ0.3 for 30 cm column diameter and Dax,L=0.11 H2d /θ0.3 for 15 cm column diameter.