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Water, Volume 15, Issue 20 (October-2 2023) – 181 articles

Cover Story (view full-size image): The hinterland of the Taranto Gulf in Basilicata (Southern Italy) provides a great opportunity for the study of coarse-grained coastal systems belonging to a staircase of Quaternary terraced marine-deposits. Among gravelly successions, beach deposits abound in the stratigraphic record, offering exceptional outcrops useful for providing detailed information on their facies features. In this paper, we describe sedimentary facies, textural variations, and the depositional architecture of these deposits in order to (1) demonstrate that the area is an excellent training ground for the study of gravelly beaches in microtidal settings; (2) discuss the use of beach deposits as a proxy for even small relative sea-level variations. View this paper
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18 pages, 19128 KiB  
Article
Research on the Performance Characteristics and Unsteady Flow Mechanism of a Centrifugal Pump under Pitch Motion
by Ye Yuan, Weihong Gong, Guojun Wang and Jun Wang
Water 2023, 15(20), 3706; https://doi.org/10.3390/w15203706 - 23 Oct 2023
Cited by 2 | Viewed by 1880
Abstract
Pitch motion is the key factor affecting the performance characteristics of centrifugal pumps on board ships and exacerbates hydraulic excitation to induce the unsteady vibration of pump units. A hydraulic test platform with swing motion is established to explore the effects of pitch [...] Read more.
Pitch motion is the key factor affecting the performance characteristics of centrifugal pumps on board ships and exacerbates hydraulic excitation to induce the unsteady vibration of pump units. A hydraulic test platform with swing motion is established to explore the effects of pitch motion on a pump’s performance characteristics. An obvious hump zone exists in the head characteristic curve in the low-flow-rate condition due to the pitch motion. The pump head in the shut-off condition has a significant decrease due to the pitch motion, compared to the static state. The head decrease gradually increases as the maximum pitch angle increases or the pitch period shortens. Specifically, the head in the rated flow condition decreases by 6.3 % to reach a minimum at the maximum pitch angle of 20 degrees in a period of 5 s. Based on a multiple-reference coordinate system, a large eddy simulation with a shear-modified eddy viscosity model is employed to simulate inner flow characteristics under the influence of pitch motion. A distinct vortex flow appears near the blade suction surface and becomes increasingly turbulent as the pitch period shortens. The pitch motion intensifies the unsteady stretching and deformation of vortices. The periodic variations in fluid-induced pressure over time present parabolic features, and the amplitude in the frequency domain reaches its maximum value within a pitch period of 5 s. Full article
(This article belongs to the Section Hydraulics and Hydrodynamics)
►▼ Show Figures

Figure 1

Figure 1
<p>Centrifugal pump swing test platform.</p> Full article ">Figure 2
<p>Pump performance characteristics under static state.</p> Full article ">Figure 3
<p>Computation domain and grid system.</p> Full article ">Figure 4
<p>Comparison between simulated and tested performance characteristics: (<b>a</b>) static, (<b>b</b>) pitch motion.</p> Full article ">Figure 5
<p>Centrifugal pump pitch direction.</p> Full article ">Figure 6
<p>Comparison of performance curves for static state and different levels of pitch motion with three periods of 5 s, 10 s and 20 s under the maximum pitch angle of 5 degrees: (<b>a</b>) <math display="inline"><semantics> <mrow> <msub> <mrow> <mrow> <mi mathvariant="italic">φ</mi> <mo>/</mo> <mi mathvariant="italic">φ</mi> </mrow> </mrow> <mi mathvariant="italic">d</mi> </msub> <mo> </mo> <mo>≤</mo> <mrow> <mo> </mo> <mn>1.0</mn> </mrow> </mrow> </semantics></math>, (<b>b</b>) <math display="inline"><semantics> <mrow> <msub> <mrow> <mrow> <mi mathvariant="italic">φ</mi> <mo>/</mo> <mi mathvariant="italic">φ</mi> </mrow> </mrow> <mi mathvariant="italic">d</mi> </msub> <mo> </mo> <mo>≥</mo> <mrow> <mo> </mo> <mn>1.0</mn> </mrow> </mrow> </semantics></math>.</p> Full article ">Figure 7
<p>Comparison of performance curves for static state and different levels of pitch motion with three periods of 5 s, 10 s and 20 s under the maximum pitch angle of 10 degrees: (<b>a</b>) <math display="inline"><semantics> <mrow> <msub> <mrow> <mrow> <mi mathvariant="italic">φ</mi> <mo>/</mo> <mi mathvariant="italic">φ</mi> </mrow> </mrow> <mi mathvariant="italic">d</mi> </msub> <mo> </mo> <mo>≤</mo> <mrow> <mo> </mo> <mn>1.0</mn> </mrow> </mrow> </semantics></math>, (<b>b</b>) <math display="inline"><semantics> <mrow> <msub> <mrow> <mrow> <mi mathvariant="italic">φ</mi> <mo>/</mo> <mi mathvariant="italic">φ</mi> </mrow> </mrow> <mi mathvariant="italic">d</mi> </msub> <mo> </mo> <mo>≥</mo> <mrow> <mo> </mo> <mn>1.0</mn> </mrow> </mrow> </semantics></math>.</p> Full article ">Figure 8
<p>Comparison of performance curves for static state and different levels of pitch motion with three periods of 5 s, 10 s and 20 s under the maximum pitch angle of 15 degrees: (<b>a</b>) <math display="inline"><semantics> <mrow> <msub> <mrow> <mrow> <mi mathvariant="italic">φ</mi> <mo>/</mo> <mi mathvariant="italic">φ</mi> </mrow> </mrow> <mi mathvariant="italic">d</mi> </msub> <mo> </mo> <mo>≤</mo> <mrow> <mo> </mo> <mn>1.0</mn> </mrow> </mrow> </semantics></math>, (<b>b</b>) <math display="inline"><semantics> <mrow> <msub> <mrow> <mrow> <mi mathvariant="italic">φ</mi> <mo>/</mo> <mi mathvariant="italic">φ</mi> </mrow> </mrow> <mi mathvariant="italic">d</mi> </msub> <mo> </mo> <mo>≥</mo> <mrow> <mo> </mo> <mn>1.0</mn> </mrow> </mrow> </semantics></math>.</p> Full article ">Figure 9
<p>Comparison of performance curves for static state and different levels of pitch motion with three periods of 5 s, 10 s and 20 s under the maximum pitch angle of 20 degrees: (<b>a</b>) <math display="inline"><semantics> <mrow> <msub> <mrow> <mrow> <mi mathvariant="italic">φ</mi> <mo>/</mo> <mi mathvariant="italic">φ</mi> </mrow> </mrow> <mi mathvariant="italic">d</mi> </msub> <mo> </mo> <mo>≤</mo> <mrow> <mo> </mo> <mn>1.0</mn> </mrow> </mrow> </semantics></math>, (<b>b</b>) <math display="inline"><semantics> <mrow> <msub> <mrow> <mrow> <mi mathvariant="italic">φ</mi> <mo>/</mo> <mi mathvariant="italic">φ</mi> </mrow> </mrow> <mi mathvariant="italic">d</mi> </msub> <mo> </mo> <mo>≥</mo> <mrow> <mo> </mo> <mn>1.0</mn> </mrow> </mrow> </semantics></math>.</p> Full article ">Figure 10
<p>Comparison of performance curves for static state and different levels of pitch motion with maximum pitch angles of 5 degrees, 10 degrees, 15 degrees and 20 degrees for a pitch period of 20 s: (<b>a</b>) <math display="inline"><semantics> <mrow> <msub> <mrow> <mrow> <mi mathvariant="italic">φ</mi> <mo>/</mo> <mi mathvariant="italic">φ</mi> </mrow> </mrow> <mi mathvariant="italic">d</mi> </msub> <mo> </mo> <mo>≤</mo> <mrow> <mo> </mo> <mn>1.0</mn> </mrow> </mrow> </semantics></math>, (<b>b</b>) <math display="inline"><semantics> <mrow> <msub> <mrow> <mrow> <mi mathvariant="italic">φ</mi> <mo>/</mo> <mi mathvariant="italic">φ</mi> </mrow> </mrow> <mi mathvariant="italic">d</mi> </msub> <mo> </mo> <mo>≥</mo> <mrow> <mo> </mo> <mn>1.0</mn> </mrow> </mrow> </semantics></math>.</p> Full article ">Figure 11
<p>Comparison of performance curves for static state and different levels of pitch motion with maximum pitch angles of 5 degrees, 10 degrees, 15 degrees and 20 degrees for a pitch period of 10 s: (<b>a</b>) <math display="inline"><semantics> <mrow> <msub> <mrow> <mrow> <mi mathvariant="italic">φ</mi> <mo>/</mo> <mi mathvariant="italic">φ</mi> </mrow> </mrow> <mi mathvariant="italic">d</mi> </msub> <mo> </mo> <mo>≤</mo> <mrow> <mo> </mo> <mn>1.0</mn> </mrow> </mrow> </semantics></math>, (<b>b</b>) <math display="inline"><semantics> <mrow> <msub> <mrow> <mrow> <mi mathvariant="italic">φ</mi> <mo>/</mo> <mi mathvariant="italic">φ</mi> </mrow> </mrow> <mi mathvariant="italic">d</mi> </msub> <mo> </mo> <mo>≥</mo> <mrow> <mo> </mo> <mn>1.0</mn> </mrow> </mrow> </semantics></math>.</p> Full article ">Figure 12
<p>Comparison of performance curves for static state and different levels of pitch motion with maximum pitch angles of 5 degrees, 10 degrees, 15 degrees and 20 degrees for a pitch period of 5 s: (<b>a</b>) <math display="inline"><semantics> <mrow> <msub> <mrow> <mrow> <mi mathvariant="italic">φ</mi> <mo>/</mo> <mi mathvariant="italic">φ</mi> </mrow> </mrow> <mi mathvariant="italic">d</mi> </msub> <mo> </mo> <mo>≤</mo> <mrow> <mo> </mo> <mn>1.0</mn> </mrow> </mrow> </semantics></math>, (<b>b</b>) <math display="inline"><semantics> <mrow> <msub> <mrow> <mrow> <mi mathvariant="italic">φ</mi> <mo>/</mo> <mi mathvariant="italic">φ</mi> </mrow> </mrow> <mi mathvariant="italic">d</mi> </msub> <mo> </mo> <mo>≥</mo> <mrow> <mo> </mo> <mn>1.0</mn> </mrow> </mrow> </semantics></math>.</p> Full article ">Figure 13
<p>The <span class="html-italic">ψ</span> variation under pitch motion at <span class="html-italic">φ<sub>d</sub></span>.</p> Full article ">Figure 14
<p>Velocity distributions along the normalized meridional locations for blade passage inlet.</p> Full article ">Figure 15
<p>Velocity distributions along the normalized meridional locations for blade passage outlet.</p> Full article ">Figure 16
<p>Flow structures under different pitch motion periods: (<b>a</b>) static, (<b>b</b>) 20 s, (<b>c</b>) 10 s, (<b>d</b>) 5 s.</p> Full article ">Figure 17
<p>Unsteady flows under different pitch motion periods: (<b>a</b>) static, (<b>b</b>) 20 s, (<b>c</b>) 10 s, (<b>d</b>) 5 s.</p> Full article ">Figure 18
<p>RVS distributions under different pitch periods: (<b>a</b>) static, (<b>b</b>) 20 s, (<b>c</b>) 10 s, (<b>d</b>) 5 s.</p> Full article ">Figure 19
<p>CORF distributions under different pitch periods: (<b>a</b>) static, (<b>b</b>) 20 s, (<b>c</b>) 10 s, (<b>d</b>) 5 s.</p> Full article ">Figure 20
<p>VISD distributions under different pitch periods: (<b>a</b>) static, (<b>b</b>) 20 s, (<b>c</b>) 10 s, (<b>d</b>) 5 s.</p> Full article ">Figure 21
<p>Pressure distributions along the normalized meridional locations for blade passage inlet.</p> Full article ">Figure 22
<p>Pressure distributions along the normalized meridional locations for blade passage outlet.</p> Full article ">Figure 23
<p>Pressure gradients under different pitch periods: (<b>a</b>) static, (<b>b</b>) 20 s, (<b>c</b>) 10 s, (<b>d</b>) 5 s.</p> Full article ">Figure 24
<p>Pressure variations with time at impeller inlet.</p> Full article ">Figure 25
<p>Pressure variations with time at impeller outlet.</p> Full article ">Figure 26
<p>Pressure variations in frequency domain at impeller inlet.</p> Full article ">Figure 27
<p>Pressure variations in frequency domain at impeller outlet.</p> Full article ">
20 pages, 3356 KiB  
Article
Dynamics of the Agricultural Water Footprint and the Decoupling Associations with Agricultural Economic Growth in Hangzhou, China
by Hua Zhu, Qing Zhang, Ligang Xu, Ying Liu, Yan Wang and Shuzhan Ma
Water 2023, 15(20), 3705; https://doi.org/10.3390/w15203705 - 23 Oct 2023
Viewed by 1673
Abstract
Understanding the relationship between the agricultural water footprint (AWF) and agricultural economic growth (AEG) is of great significance for promoting sustainable agriculture and regional economic development. In this study, we used agricultural statistics data from Hangzhou from 2010 to 2021 to calculate the [...] Read more.
Understanding the relationship between the agricultural water footprint (AWF) and agricultural economic growth (AEG) is of great significance for promoting sustainable agriculture and regional economic development. In this study, we used agricultural statistics data from Hangzhou from 2010 to 2021 to calculate the AWF, predicted the decoupling relationship between the AWF and AEG, and explored the influencing factors of the decoupling relationship between the AWF and AEG. The results showed the following: (1) The AWF in Hangzhou exhibited a decreasing trend, with a reduction from 58.88 × 108 m3 in 2010 to 37.80 × 108 m3 in 2021; this was mainly related to the decline in the water footprints of grain, pork, and egg production. (2) The strong decoupling accounted for 63.64% of the decoupling between the AWF and AEG in Hangzhou during the study period. It was found that an agricultural structure adjustment was the main factor for achieving decoupling between the AWF and AEG. Under the guidance of policy, the decoupling between them could be changed by regulating the output of agricultural products with different water footprint contents per unit. (3) From 2022 to 2026, the AWF in Hangzhou is expected to decrease to 28.21 × 108 m3, while the agricultural economy is projected to increase to CNY 40.008 billion. There will continue to be a strong decoupling status between the AWF and AEG in Hangzhou. Full article
(This article belongs to the Section Water Resources Management, Policy and Governance)
►▼ Show Figures

Figure 1

Figure 1
<p>The flow chart of the methods.</p> Full article ">Figure 2
<p>The AWF in Hangzhou from 2010 to 2021.</p> Full article ">Figure 3
<p>The water footprint of crops in Hangzhou from 2010 to 2021.</p> Full article ">Figure 4
<p>The water footprints of animal products in Hangzhou from 2010 to 2021.</p> Full article ">Figure 5
<p>Percentage of the AWF in Hangzhou from 2010 to 2021.</p> Full article ">Figure 6
<p>(<b>a</b>) Autocorrelation function chart. (<b>b</b>) Partial autocorrelation function chart. (<b>c</b>) Autocorrelation coefficients of the residual model. (<b>d</b>) Partial autocorrelation coefficients of the residual model.</p> Full article ">Figure 7
<p>Forecasting of the AWF in Hangzhou from 2010 to 2026. UCL represents the upper control limit and LCL represents the lower control limit.</p> Full article ">Figure 8
<p>Agriculture economy forecast for Hangzhou from 2022 to 2026.</p> Full article ">Figure 9
<p>The mechanisms of the decoupling relationship between the AWF and AEG.</p> Full article ">Figure 10
<p>Agricultural policies issued by the government from 2011 to 2021.</p> Full article ">
13 pages, 2666 KiB  
Article
Drought Priming and Subsequent Irrigation Water Regimes Enhanced Grain Yield and Water Productivity of Wheat Crop
by Inayatullah Katohar, Rajesh Kumar Soothar, Farman Ali Chandio, Mashooque Ali Talpur, Shakeel Ahmed Soomro, Ashutus Singha, Li Bin and Muhammad Uris Mirjat
Water 2023, 15(20), 3704; https://doi.org/10.3390/w15203704 - 23 Oct 2023
Cited by 1 | Viewed by 1662
Abstract
The most important factor impacting wheat production is water stress that occurs during the reproductive growth stage. Therefore, the plant responses and water productivity as affected by drought priming were investigated during Rabi seasons 2021 and 2022. The field trials were conducted in [...] Read more.
The most important factor impacting wheat production is water stress that occurs during the reproductive growth stage. Therefore, the plant responses and water productivity as affected by drought priming were investigated during Rabi seasons 2021 and 2022. The field trials were conducted in the research field of the Department of Irrigation and Drainage, Faculty of Agricultural Engineering, Sindh Agriculture University, Tandojam. The Hamal-BNS wheat variety was subjected to differing irrigation water regime levels (40%, 50% and 60% of soil water holding capacity, SWHC) after being subjected to drought priming, irrigation water recovery (water closure period) and drought priming. There were six treatments: (1) DPP-40 (drought priming plants at 40% of SWHC), (2) DPP-50, (3) DPP-60, (4) CTP-40 (controlled treated plants at 40% of SWHC), (5) CTP-50 and (6) CTP-60. During the experiment period, soil moisture content was significantly affected by the different treatments at various growth stages of wheat. The results indicated that winter wheat pre-exposed to drought priming attained a stress imprint that improved the subsequent deficit water levels which occurred during the later plant growth stage as demonstrated by the progress of test weight, grain yield, plant level water use efficiency and irrigation water use efficiency as well as relative yield compared to CTP-50 (control treatment). Under the irrigation water regime levels during the post-anthesis period, primed wheat plants sustained grain yield and higher relative yield than wheat plants without priming due to the better irrigation water regime for drought-primed wheat plants. Similarly, primed wheat plants consumed 18.3% less irrigation water as compared to non-primed plants, which significantly increased plant level WUE and irrigation WUE and decreased dry biomass and root development of drought-primed wheat plants. Therefore, to conserve fresh water for other field crops and increase water productivity in the Sindh province, it is recommended that drought priming is used during the early growth period of wheat plants as a successful irrigation method. Full article
(This article belongs to the Special Issue How Does Agricultural Water Resources Management Adapt to Climate Change?)
►▼ Show Figures

Figure 1

Figure 1
<p>Bird’s eye view of the experimental site.</p> Full article ">Figure 2
<p>Treatments during the experimental period.</p> Full article ">Figure 3
<p>Experimental plot layout and setup for field experiment.</p> Full article ">Figure 4
<p>Mean temporal variation of soil moisture content at 0–100 cm soil depth under different treatments throughout the growing seasons.</p> Full article ">Figure 5
<p>Mean plant height of wheat crop as affected by different treatments throughout the growing season. DPP-40, DPP-50, DPP-60, CTP-40, CTP-50 and CTP-60 indicate the treatments, respectively. The values are means ± SE (<span class="html-italic">n</span> = 3). The small bars are standard error. *** Indicates significant differences among the treatments according to Duncan’s multiple range test at <span class="html-italic">p ≤</span> 0.001 level.</p> Full article ">Figure 6
<p>Mean spike length (<b>a</b>), grains per spike (<b>b</b>), and grain weight per spike (<b>c</b>) of wheat crop as affected by different treatments. DPP-40, DPP-50, DPP-60, CTP-40, CTP-50 and CTP-60 indicate the treatments, respectively. The values are means ± SE (<span class="html-italic">n</span> = 3). The small bars are standard error. Different letters indicate significant differences among the treatments according to Duncan’s multiple range test at <span class="html-italic">p ≤</span> 0.05 level.</p> Full article ">Figure 7
<p>Mean tillers square m<sup>—1</sup> (<b>a</b>), test weight (<b>b</b>), biomass (<b>c</b>), and grain yield (<b>d</b>) of wheat crop as affected by different treatments. DPP-40, DPP-50, DPP-60, CTP-40, CTP-50 and CTP-60 indicate the treatments, respectively. The values are means ± SE (<span class="html-italic">n</span> = 3). The small bars are standard error. Different letters indicate significant differences among the treatments according to Duncan’s multiple range test at <span class="html-italic">p ≤</span> 0.05 level.</p> Full article ">Figure 8
<p>Mean root development of wheat crop as affected by different treatments. The values are means ± SE (<span class="html-italic">n</span> = 3). The small bars are standard error. Different letters indicate significant differences among the treatments according to Duncan’s multiple range test at <span class="html-italic">p</span> ≤ 0.05 level.</p> Full article ">Figure 9
<p>Simple correlation analysis between wheat yield and dry root biomass. ** = Significant at <span class="html-italic">p</span> &lt; 0.01.</p> Full article ">Figure 10
<p>Mean relative yield of wheat crop as affected by different treatments. DPP-40, DPP-50, DPP-60, CTP-40 and CTP-60 indicate the treatments, respectively. The values are means ± SE (<span class="html-italic">n</span> = 3). The small bars are standard error.</p> Full article ">Figure 11
<p>Mean plant level water use efficiency (WUE) (<b>a</b>) and irrigation water use efficiency (WUE) (<b>b</b>) of wheat crop as affected by different treatments. DPP-40, DPP-50, DPP-60, CTP-40, CTP-50 and CTP-60 indicate the treatments, respectively. The values are means ± SE (<span class="html-italic">n</span> = 3). The small bars are standard error. Different letters indicate significant differences among the treatments according to Duncan’s multiple range test at <span class="html-italic">p</span> ≤ 0.05 level.</p> Full article ">
29 pages, 5940 KiB  
Article
Green Synthesis of Surface Modified Biochar for Simultaneous Removal of Steroidal Hormones and Heavy Metals from Wastewater: Optimisation by Central Composite Design
by Sefiu Olaitan Amusat, Temesgen Girma Kebede, Edward Ndumiso Nxumalo, Simiso Dube and Mathew Muzi Nindi
Water 2023, 15(20), 3703; https://doi.org/10.3390/w15203703 - 23 Oct 2023
Cited by 1 | Viewed by 2721
Abstract
The modification of pristine biochar derived from the waste of sweet prickly pear using the green modification method to produce nano-sized biochar (nanobiochar) for the removal of steroidal hormones and heavy metals from water and wastewater is reported in this study. Based on [...] Read more.
The modification of pristine biochar derived from the waste of sweet prickly pear using the green modification method to produce nano-sized biochar (nanobiochar) for the removal of steroidal hormones and heavy metals from water and wastewater is reported in this study. Based on the characterisation results using FTIR, Raman spectroscopy, and XPS, the material had (COOH), (C=O), and (OH) functional groups typical of graphitic amorphous carbon. The SEM-EDS and XRD results showed that the material was mesoporous and amorphous in nature. The BET analysis results revealed that the surface area significantly increased from 220.1 m2/g to 354.6 m2/g after the modification of the pristine biochar. Based on the TGA-DSC results, the material was thermally stable up to 550 °C. A complete factorial experimental design using Minitab 21 Statistical Software (version 18.1) was employed to optimise the experimental adsorption conditions. The F-values and p-values for the lack-of-fit of the model showed the acceptability and significance of the ANOVA model. The Freundlich adsorption isotherm was found to provide a better fit for the steroid adsorption data than the Langmuir adsorption isotherm, with moderate values of R2 ≥ 0.92 for Langmuir and R2 ≥ 0.95 for Freundlich, as well as maximum adsorption capacities of 14.53 mg/g, 10.58 mg/g, 12.50 mg/g, 5.73 mg/g, 5.63 mg/g, and 9.75 mg/g obtained for estriol, α-oestradiol, β-oestradiol, testosterone, progesterone, and bisphenol A. Freundlich R2 values were lower than Langmuir R2 values for metal adsorption, with maximum adsorption capacities of 8.58 mg/g, 4.15 mg/g, and 6.95 mg/g obtained for nickel, cadmium, and lead, respectively. The maximum percentage of removal for effluents and influents was between 84–89% and 78–86% for steroid hormones and heavy metals, respectively. The highest removal percentage between 90–95% was obtained for spiked ultrapure water for both steroid hormones and heavy metals. The material exhibited a removal percentage up to 60% after the first four cycles. Full article
(This article belongs to the Special Issue The Evolution of Sorbents Based on Natural Materials for Wastewater Pollution Control)
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Figure 1
<p>Isotherm curves for the adsorption and desorption of (<b>a</b>) B500 and (<b>b</b>) BMB500.</p> Full article ">Figure 2
<p>XRD patterns of pristine and ball-milled biochar obtained at 400, 500, and 600 °C.</p> Full article ">Figure 3
<p>FTIR spectra of (<b>a</b>) pristine and (<b>b</b>) ball-milled biochar.</p> Full article ">Figure 4
<p>SEM and mapping micrograph of B500, (<b>a</b>) SEM image at 300× magnification, (<b>b</b>) full-scan mapping of all elements, (<b>c</b>) C, (<b>d</b>) O, (<b>e</b>) K, (<b>f</b>) Ca.</p> Full article ">Figure 5
<p>SEM and mapping micrograph of BMB500 (<b>a</b>) SEM image at 300× magnification, (<b>b</b>) full-scan mapping of all elements, (<b>c</b>) C, (<b>d</b>) O, (<b>e</b>) K, (<b>f</b>) Ca.</p> Full article ">Figure 6
<p>SEM-EDS micrograph images of B500 (<b>a</b>,<b>c</b>) and BMB500 (<b>b</b>,<b>d</b>).</p> Full article ">Figure 7
<p>TGA and DSC of the BMB500.</p> Full article ">Figure 8
<p>(<b>a</b>) Full-survey scan, (<b>b</b>) carbon and (<b>c</b>) oxygen element spectra of B500.</p> Full article ">Figure 9
<p>(<b>a</b>) Full-survey scan, (<b>b</b>) carbon and (<b>c</b>) oxygen spectra of BMB500.</p> Full article ">Figure 10
<p>Raman spectra of B500 and BMB500.</p> Full article ">Figure 11
<p>Three-dimensional (3D) SRM and (2D) counterplots for interaction effects of factors for SH removal by biochar.</p> Full article ">Figure 11 Cont.
<p>Three-dimensional (3D) SRM and (2D) counterplots for interaction effects of factors for SH removal by biochar.</p> Full article ">Figure 12
<p>Three-dimensional (3D) SRM and (2D) counterplots for interaction effects of factors for HM removal by BMB500.</p> Full article ">Figure 12 Cont.
<p>Three-dimensional (3D) SRM and (2D) counterplots for interaction effects of factors for HM removal by BMB500.</p> Full article ">Figure 13
<p>Reusability of BMB500 for the efficient removal of steroidal hormones and heavy metals regenerated by ethanol.</p> Full article ">
15 pages, 8393 KiB  
Article
Visible Light-Driven Photocatalytic Degradation of Tetracycline Using p-n Heterostructured Cr2O3/ZrO2 Nanocomposite
by Xueyu Wei, Saraschandra Naraginti, Pengli Chen, Jiyuan Li, Xiaofan Yang and Buwei Li
Water 2023, 15(20), 3702; https://doi.org/10.3390/w15203702 - 23 Oct 2023
Cited by 8 | Viewed by 2285
Abstract
Antibiotic pollution beyond the safety limits poses a significant threat to the environmental sustainability and human health which necessitates the development of efficient methods for reducing antibiotics in pharmaceutical wastewater. Photocatalysis is a proven technology which has drawn considerable attention in semiconductor photocatalysts. [...] Read more.
Antibiotic pollution beyond the safety limits poses a significant threat to the environmental sustainability and human health which necessitates the development of efficient methods for reducing antibiotics in pharmaceutical wastewater. Photocatalysis is a proven technology which has drawn considerable attention in semiconductor photocatalysts. Our study aims to develop a highly efficient Cr2O3/ZrO2 photocatalyst for the degradation of tetracycline (TCL) under visible light. The synthesized catalyst was well characterized by XRD, HR-TEM-SAED, XPS, FT-IR, BET and UV-Vis-DRS methods. The effects of various parameters on photocatalytic degradation were evaluated in detail, showing that 97.1% of 50 mgL−1 tetracycline concentrations could be degraded within 120 min at pH 5 with a 0.1 gL−1 photocatalyst-loading concentration under visible light (300 W Xe lamp). The uniform distribution of spherical ZrO2 nanoparticles on the surface of the Cr2O3 nano-cubes efficiently reduced the recombination rate with an energy bandgap of 2.75 eV, which provided a faster photodegradation of tetracycline under visible light. In addition, a plausible degradation pathway and photoproducts generated during the photocatalytic degradation of TCL are proposed based on the LC-ESI/MS results, which suggested that efficient photodegradation was achieved during the visible light irradiation. Thus, our study reveals that the cost-effective Cr2O3-based photocatalyst with multi-reusability and efficient energy consumption could be an efficient photocatalyst for the rapid degradation of TCL during the wastewater treatment process. Full article
(This article belongs to the Special Issue Potential of Nanomaterials for Efficient Wastewater Treatment)
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<p>p-XRD pattern of pure Cr<sub>2</sub>O<sub>3</sub>, ZrO<sub>2</sub>, and Cr<sub>2</sub>O<sub>3</sub>-ZrO<sub>2</sub> nanocomposites.</p> Full article ">Figure 2
<p>(<b>a</b>) Tauc plot (inset: UV-vis absorption spectra) and (<b>b</b>) FT-IR spectra of pure Cr<sub>2</sub>O<sub>3</sub>, ZrO<sub>2</sub> and Cr<sub>2</sub>O<sub>3</sub>–ZrO<sub>2</sub> nanocomposites.</p> Full article ">Figure 3
<p>TEM images of (<b>a</b>) Cr<sub>2</sub>O<sub>3</sub>, (<b>b</b>) ZrO<sub>2</sub>, and (<b>c</b>) Cr<sub>2</sub>O<sub>3</sub>–ZrO<sub>2</sub>; (<b>d</b>,<b>e</b>) HR-TEM images and (<b>f</b>) SAED pattern of Cr<sub>2</sub>O<sub>3</sub>–ZrO<sub>2</sub> nanocomposites.</p> Full article ">Figure 4
<p>(<b>a</b>) XPS survey spectra of Cr<sub>2</sub>O<sub>3</sub>/ZrO<sub>2</sub> nanocomposite, and (<b>b</b>–<b>d</b>) high resolution deconvoluted XPS spectra for Cr 2p, Zr 3d, and O 1s orbitals.</p> Full article ">Figure 5
<p>BET analysis spectra of Cr<sub>2</sub>O<sub>3</sub>, ZrO<sub>2</sub>, and Cr<sub>2</sub>O<sub>3</sub>–ZrO<sub>2</sub> nanocomposites.</p> Full article ">Figure 6
<p>Influence of, (<b>a</b>) solution pH, (<b>b</b>) photocatalyst quantity, (<b>c</b>,<b>d</b>) degradation kinetics of TCL molecules under optimized experimental conditions.</p> Full article ">Figure 7
<p>Plausible photocatalytic degradation pathway of TCL by Cr<sub>2</sub>O<sub>3</sub>/ZrO<sub>2</sub>.</p> Full article ">Figure 8
<p>Radical quantification of (<b>a</b>) O<sub>2</sub><sup>•−</sup> and (<b>b</b>) OH<sup>•−</sup>; (<b>c</b>) photocatalytic efficiency of nanocomposite in the presence of different trapping agents.</p> Full article ">Figure 9
<p>Photocatalytic mechanism of Cr<sub>2</sub>O<sub>3</sub>–ZrO<sub>2</sub> nanocomposite under visible light.</p> Full article ">Figure 10
<p>(<b>a</b>) Reusability studies and (<b>b</b>) XRD analysis of Cr<sub>2</sub>O<sub>3</sub>–ZrO<sub>2</sub> nanocomposite under optimized experimental conditions.</p> Full article ">
16 pages, 7092 KiB  
Article
Evaluation of Groundwater Quality and Contamination Using the Groundwater Pollution Index (GPI), Nitrate Pollution Index (NPI), and GIS
by Hefdhallah S. Al-Aizari, Fatima Aslaou, Ali R. Al-Aizari, Abdel-Basit Al-Odayni and Abdul-Jaleel M. Al-Aizari
Water 2023, 15(20), 3701; https://doi.org/10.3390/w15203701 - 23 Oct 2023
Cited by 16 | Viewed by 3263
Abstract
Groundwater is an essential and indispensable resource, meeting dire needs for drinking and irrigation purposes. The aim of this study is to assess the suitability of groundwater quality for drinking purposes. This evaluation will be conducted using the Groundwater Pollution Index (GPI), the [...] Read more.
Groundwater is an essential and indispensable resource, meeting dire needs for drinking and irrigation purposes. The aim of this study is to assess the suitability of groundwater quality for drinking purposes. This evaluation will be conducted using the Groundwater Pollution Index (GPI), the nitrate pollution index (NPI), and the geographic information system (GIS) in Sidi Slimane, Morocco. In this study, a comprehensive collection of 20 samples was obtained from various locations for analysis and evaluation. Hadrochemical facies of this study area showed that out of 20 samples, 90% belonged to a type (Na+-K+-Cl−-SO42−), while only 10% fell into a category (Ca2+-Mg2+-Cl−-SO42−). The Groundwater Pollution Index values ranged from 0.7 to 10.8, with an average of 7.03; about 60% of the groundwater samples analyzed in this study area were classified as highly polluted and unsuitable for drinking purposes. Nitrate index values ranged from −0.9 to 10.5. Approximately 80% of the sampled sites require treatment before consumption. According to the Nitrate Pollution Index (NPI), it is essential to regularly monitor 16 well sites to prevent nitrate contamination resulting from human activities, including waste disposal in open areas and sewage infiltration. This study recommends raising farmers’ awareness of the use of slow-release natural fertilizers made from nitrogen rather than nitrogen-based fertilizers, reducing waste disposal by residents, and maintaining an appropriate sewage network to minimize sewage flow leakage. This study plays a vital role in identifying the polluted areas and highlighting the need to take appropriate measures to control the sources of pollution in this study area in order to protect water resources and ensure the provision of safe water to the local population. Full article
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<p>Location of this study samples.</p> Full article ">Figure 2
<p>Order the availability of ions of groundwater in this study area.</p> Full article ">Figure 3
<p>Hydrochemical facies.</p> Full article ">Figure 4
<p>Plots showing dominant cations (<b>a</b>) and inions (<b>b</b>) as sources of groundwater chemistry.</p> Full article ">Figure 5
<p>Relationships between (HCO<sub>3</sub><sup>−</sup> + SO<sub>4</sub><sup>2−</sup>) and (Ca<sup>2+</sup>/Mg<sup>2+</sup>). Numbers refer to the studied wells.</p> Full article ">Figure 6
<p>The ratio of Ca<sup>2+</sup>/Mg<sup>2+</sup> in groundwater of wells numbered 1–20.</p> Full article ">Figure 7
<p>Relationships between (Cl<sup>−</sup> and Na<sup>+</sup>). Numbers refer to the studied wells, defined above.</p> Full article ">Figure 8
<p>Base-ion exchange. Circles refer to well number 1–20.</p> Full article ">Figure 9
<p>Saturation index. Wells numbers (1–20) are points of wells (<b>left</b>) and top (<b>right</b>) of the <span class="html-italic">x</span>-axis.</p> Full article ">Figure 10
<p>Disruption temporal map of pollution index of groundwater.</p> Full article ">Figure 11
<p>Classification Ascendant Hierarchies. Wells (w1–w20): Group 1 (red lines, <b>right</b>) and Group 2 (blue lines, <b>left</b>).</p> Full article ">Figure 12
<p>Disruption temporal map of pollution index of nitrate.</p> Full article ">
16 pages, 3274 KiB  
Article
Provenance Indication of Rare Earth Elements in Lake Particulates from Environmentally Sensitive Regions
by Pu Zhang, Zhe Zhang, Lihua Liang, Lei Li, Chenyang Cao and R. Lawrence Edwards
Water 2023, 15(20), 3700; https://doi.org/10.3390/w15203700 - 23 Oct 2023
Viewed by 1570
Abstract
The provenance of lake particulate matter in environmentally sensitive areas is crucial to understanding regional environmental and climatic changes. This study investigated two regions in the Northeast Tibetan Plateau, China: Region I (Keluke, Tuosu, and Gahai Lakes) and Region II (Qinghai Lake and [...] Read more.
The provenance of lake particulate matter in environmentally sensitive areas is crucial to understanding regional environmental and climatic changes. This study investigated two regions in the Northeast Tibetan Plateau, China: Region I (Keluke, Tuosu, and Gahai Lakes) and Region II (Qinghai Lake and nearby rivers). The results showed that: (1) The two regions have greater differences in the enrichment of rare earth elements (REEs) and heterogeneity in spatial distribution, both of which are characterized by relative enrichment of LREE and depletion of HREE, but to different degrees; (2) the source and formation of particulate matter in two regions are consistent. Particulate matter in Region I (Keluke and Tuosu Lakes) predominantly originates from granite rocks, which undergo weathering and transportation through rivers. Region II (Qinghai Lake and nearby rivers) particulate matter is affected by chemical weathering and partial recycling of detrital material. Diagenesis had a minimal impact on the particulate REEs. (3) This study primarily provides a preliminary understanding of REEs in lake particles, assessing particle changes during the water-to-sediment process and their provenance indication. Future studies will incorporate the solid fugacity (solid speciation) of REEs in particles, contributing to a comprehensive understanding of rare earth element geochemical processes. This study provides valuable insights into REEs distribution, source, and geochemical behavior in the Tibetan Plateau, underscoring the importance of REEs in understanding provenance processes, and is indicative of provenance studies in other climate change-sensitive regions of the world. Full article
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Location of the study area. (<b>a</b>) Schematic map of the Northeast Tibetan Plateau in China. (<b>b</b>) The detailed sampling stations of Keluke Lake, Tuosu Lake, and Gahai. (<b>c</b>) The detailed sampling stations of Qinghai Lake, Qinghaigahai, Xiligou Lake, Shaliu River, Haergai River, and Buha River.</p> Full article ">Figure 2
<p>Region I: Concentrations of REEs in particulate matter from three lakes. (<b>a</b>) Keluke Lake. (<b>b</b>) Tuosu Lake and Gahai.</p> Full article ">Figure 3
<p>Region II: Concentrations of REEs in particulate matter from lakes and rivers. (<b>a</b>) Qinghai Lake and its subsidiary lakes (Qinghaigahai and Xiligou Lake). (<b>b</b>) the Shaliu, Haergai, and Buha rivers.</p> Full article ">Figure 4
<p>Standardized distribution pattern of REEs globular meteorites in lakes and rivers in two regions. (<b>a</b>) Region I: Keluke Lake. (<b>b</b>) Region I: Tuosu Lake. (<b>c</b>) Region II: Qinghai Lake and its subsidiary lakes (Qinghaigahai and Xiligou Lake). (<b>d</b>) Region II: Shaliu and Buha rivers.</p> Full article ">Figure 5
<p>Correlation between δCe and ∑REE, δCe and δEu of particulate matter in Region I (<b>a</b>,<b>b</b>) and Region II (<b>c</b>,<b>d</b>).</p> Full article ">Figure 6
<p>The function of discrimination function (DF) values for particulate matter in Region II.</p> Full article ">
12 pages, 2714 KiB  
Article
Flux Vector Splitting Method of Weakly Compressible Water Navier-Stokes Equation and Its Application
by Heng Li and Bingxiang Huang
Water 2023, 15(20), 3699; https://doi.org/10.3390/w15203699 - 23 Oct 2023
Cited by 2 | Viewed by 1298
Abstract
Water is a weakly compressible fluid medium. Due to its low compressibility, it is usually assumed that water is an incompressible fluid. However, if there are high-pressure pulse waves in water, the compressibility of the water medium needs to be considered. Typical engineering [...] Read more.
Water is a weakly compressible fluid medium. Due to its low compressibility, it is usually assumed that water is an incompressible fluid. However, if there are high-pressure pulse waves in water, the compressibility of the water medium needs to be considered. Typical engineering applications include water hammer protection and pulse fracturing, both of which involve the problem of discontinuous pulse waves. Traditional calculation and simulation often use first-order or second-order precision finite difference methods, such as the MacCormark method. However, these methods have serious numerical dissipation or numerical dispersion, which hinders the accurate evaluation of the pulse peak pressure. In view of this, starting from the weakly compressible Navier–Stokes (N-S) equation, this paper establishes the control equations in the form of flux, derives the expressions of eigenvalues, eigenvectors, and flux vectors, and gives a new flux vector splitting (FVS) formula by considering the water equation of state. On this basis, the above flux vector formula is solved using the fifth-order weighted essentially non-oscillatory (WENO) method. Finally, the proposed FVS formula is verified by combining the typical engineering examples of water hammer and pulse fracturing. Compared with the traditional methods, it is proved that the FVS formula proposed in this paper is reliable and robust. As far as we know, the original work in this paper extends the flux vector splitting method commonly used in aerodynamics to hydrodynamics, and the developed model equation and method are expected to play a positive role in the simulation field of water hammer protection, pulse fracturing, and underwater explosion. Full article
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<p>Water equation of state described by a linear model (7) which is consistent with the Tait model. Here the <span class="html-italic">y</span>-axis shows dimensional pressure which is computed by combining Equation (7) and the reference pressure <span class="html-italic">p</span><sub>ref</sub> = 1 MPa. The experimental data are from reference [<a href="#B15-water-15-03699" class="html-bibr">15</a>].</p> Full article ">Figure 2
<p>Comparison of wave speed between the present simulation and theory.</p> Full article ">Figure 3
<p>Comparison of water pressure for the water hammer case, (<b>a</b>) variation regularity of water head at the right endpoint of pipe, (<b>b</b>) variation regularity of water head at the midpoint of pipe. Here exp is the experimental data from [<a href="#B23-water-15-03699" class="html-bibr">23</a>].</p> Full article ">Figure 4
<p>Comparison of water pressure distribution, (<b>a</b>) simulation results from the MAC method, (<b>b</b>) simulation results from the FVS-WENO method.</p> Full article ">Figure 5
<p>Comparison of water pressure curves along the symmetry axis marked by the dashed line in <a href="#water-15-03699-f004" class="html-fig">Figure 4</a>.</p> Full article ">Figure 6
<p>Simulation results of water shock wave reflection in wedge-shaped structure based on the present FVS-WENO method. The red represents the high-pressure and the blue represents the low-pressure.</p> Full article ">Figure 7
<p>Experimental photos of water shock waves’ reflection in wedge-shaped structure from reference [<a href="#B28-water-15-03699" class="html-bibr">28</a>].</p> Full article ">
12 pages, 1804 KiB  
Article
Microplastics in the Syr Darya River Tributaries, Uzbekistan
by Yulia Frank, Alijon Khusanov, Mansur Yuldashov, Egor Vorobiev, Svetlana Rakhmatullina, Alexey Rednikin, Sherzodbek Tashbaev, Sarvinoz Mamatkarimova, Kristina Ruchkina, Sirojiddin Namozov, Laziz Turaev, Jobir Sobirov, Akramjon Yuldashev and Danil Vorobiev
Water 2023, 15(20), 3698; https://doi.org/10.3390/w15203698 - 23 Oct 2023
Cited by 4 | Viewed by 2474
Abstract
The objective of the study was a pre-screening of the microplastic (MP) content in surface water and benthic sediments of Kara Darya and Chirchiq rivers, the first-order tributaries of the Syr Darya River (Uzbekistan). For the first time, surface water and benthic sediment [...] Read more.
The objective of the study was a pre-screening of the microplastic (MP) content in surface water and benthic sediments of Kara Darya and Chirchiq rivers, the first-order tributaries of the Syr Darya River (Uzbekistan). For the first time, surface water and benthic sediment samples were taken from this region, and quantitative screening of MPs 0.15–5.00 mm in size was performed. A combined visual and μRaman-based methodology was used to quantify and characterize artificial polymer microparticles from the surface water and bottom sediments of two rivers. The average abundance of MPs in the Kara Darya River and Chirchiq River waters was found to be 4.28 ± 0.09 and 0.95 ± 0.36 items per m3, and that in benthic sediments attained 244 ± 28.9 and 333 ± 11.5 items per kg of dry soil, respectively. MP concentration in surface water and benthic sediments of the Kara Darya River significantly exceeded (p-value < 0.01) that in the Chirchiq River. Microfibers were most abundant; the proportion of MP fibers in the water of the Kara Darya and Chirchiq rivers amounted to 89 and 95%, respectively, and that in benthic sediments of the rivers was 86 and 84%, respectively. The dominance of microfibers may indicate the route of entry to the rivers through domestic wastewater treatment plant discharges. The polymer microparticles in the surface water and benthic sediments of the Kara Darya and Chirchiq rivers were mainly represented by polyethylenterephtalate (PET), which accounted for half of all MPs detected in the Kara Darya River. Microparticles of textile origin were particularly abundant in the Kara Darya River, where viscose and nylon fibers were also found, which suggests the leading role of synthetic textiles in the pollution. The reported data are the first experimental evidence of MP pollution of the Syr Darya tributaries, but the distribution and circulation of MPs in surface water in Central Asia requires further comprehensive studies. Full article
(This article belongs to the Special Issue Microplastics in Water Environments: Methods, Occurrence, and Sources)
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<p>Schematic map indicating the location of sampling points (★) on Kara Darya and Chirchiq rivers in the Syr Darya basin, Central Asia. Source of the background map: UNEP, 2011 [<a href="#B18-water-15-03698" class="html-bibr">18</a>].</p> Full article ">Figure 2
<p>Morphology of MP particles extracted from surface water of Kara Darya (<b>1</b>) and Chirchiq (<b>2</b>) rivers, including shape (<b>a</b>) and size range (<b>b</b>). Microphotographs (<b>c</b>) illustrate MP particles: fm—film; fi—fiber; fr—fragment; 0.5 mm scale.</p> Full article ">Figure 3
<p>Morphology of MP samples taken from benthic sediments of Kara Darya (<b>1</b>) and Chirchiq (<b>2</b>) rivers, including shape (<b>a</b>) and size range (<b>b</b>). Microphotographs (<b>c</b>) illustrate MP particles: fr—fragment; fi—fiber; 0.5 mm scale.</p> Full article ">Figure 4
<p>Polymer constituents of MPs extracted from surface water and benthic sediments of Chirchiq (<b>1</b>) and Kara Darya (<b>2</b>) rivers obtained based on µRaman data, µm scale.</p> Full article ">
17 pages, 6443 KiB  
Article
Self-Regenerating Solar Evaporation System for Simultaneous Salt Collection and Freshwater from Seawater
by Muneerah Alomar, Badriah S. Almutairi, Seham S. Alterary, Manal A. Awad, Fida Hussain, Awatif A. Hendi, Maha F. El-Tohamy and N. Al-Hoshani
Water 2023, 15(20), 3697; https://doi.org/10.3390/w15203697 - 23 Oct 2023
Cited by 1 | Viewed by 2882
Abstract
Water scarcity is a serious issue which is increasing gradually due to rapid industrialization and population explosion. Biomass-inspired photothermal materials are of great importance due to their low-cost and enhanced photothermal conversion efficiencies. Herein, a pyrolyzed honokiol biochar (HB) is successfully synthesized to [...] Read more.
Water scarcity is a serious issue which is increasing gradually due to rapid industrialization and population explosion. Biomass-inspired photothermal materials are of great importance due to their low-cost and enhanced photothermal conversion efficiencies. Herein, a pyrolyzed honokiol biochar (HB) is successfully synthesized to fabricate a self-regenerating solar evaporating system for in situ freshwater, and salt collection from seawater. The pyrolyzed biochar was innovatively printed onto a non-woven fabric (HB@NF) that exhibits excellent solar absorption (96%), and efficient stability in seawater. The self-regenerating structure is constructed in two parts: (1) HB-printed fabric as a photothermal layer for efficient solar-to-vapor conversion efficiencies (93%) under 1 kW m−2. (2) Umbrella-like centralized seawater supply via cigarette filter to achieve the Marangoni effect for in situ water evaporation and salt collection. More importantly, effective thermal management achieved efficient heat accumulation (48.5 °C) under one sun intensity (1 kWm−2), and its validation is also demonstrated in a COMSOL heat transfer simulation. Furthermore, a series of experiments on salt collection over different periods, evaporation stability under different cycles, and rejection of primary metal ions via Inductively Coupled Plasma–Optical Emission Spectrometry (ICP–OES) have been investigated. It is believed that this work will create new avenues regarding in situ freshwater and minerals recovery from seawater. Full article
(This article belongs to the Special Issue Advanced Technology for Desalination and Water Purification)
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<p>Illustration of a solar evaporation system for simultaneous salt and freshwater production.</p> Full article ">Figure 2
<p>Synthesis of honokiol biochar (HB), UV-induced printing, and device fabrication for in situ freshwater and salt collection from seawater.</p> Full article ">Figure 3
<p>(<b>a</b>) XPS spectra of honokiol biochar. (<b>b</b>–<b>d</b>) C1s, N1s and O1s spectrums. (<b>e</b>) FTIR spectrum of HB NPs. (<b>f</b>) Raman spectrum of HB NPs.</p> Full article ">Figure 4
<p>Microstructural and morphological analysis. FESEM images of (<b>a</b>–<b>d</b>) pyrolyzed honokiol biochar with different magnifications, and (<b>e</b>,<b>f</b>) UV-induced HB-printed non-woven fabric at different resolutions.</p> Full article ">Figure 5
<p>(<b>a</b>) UV–Vis spectrum of honokiol powder and honokiol biochar. (<b>b</b>,<b>c</b>) Thermal conductivity of wet HB@NF printed fabric. (<b>d</b>) Water contact test of HB@NF. (<b>e</b>,<b>f</b>) The enhanced surface temperature of UV-induced printed HB@NF fabric under different solar irradiation.</p> Full article ">Figure 6
<p>(<b>a</b>) Time-dependent IR images of HB@NF hybrid evaporator during solar evaporation showing thermal distribution for the top surface and excellent thermal insulation for the cross surface. (<b>b</b>,<b>c</b>) The mesh geometry and corresponding developed heat transfer model of the HB@NF hybrid evaporator using COMSOL Multiphysics software (version 6.1).</p> Full article ">Figure 7
<p>(<b>a</b>) Evaporation rate measurement of the four developed systems. (<b>b</b>) Evaporation rate evaluation of HB@NF hybrid solar evaporator over multiple operating cycles under 3.2 wt% NaCl condition. (<b>c</b>) Evaporation rates of HB@NF under 1, 2, 3 kWm<b><sup>−</sup></b><sup>2</sup> solar intensities. (<b>d</b>) Comparative evaporation efficiency analysis of the designed systems.</p> Full article ">Figure 8
<p>(<b>a</b>–<b>h</b>) Time-dependent salt transportation in the hybrid HB@NF under 1 kWm<b><sup>−</sup></b><sup>2</sup> solar evaporation: the salt migrates from the center towards the edge in the concentrated form. As saline keeps evaporating, salt becomes increasingly concentrated and accumulates at the edges. (<b>i</b>) Evaporation rates of HB@NF solar evaporator over various washing cycles. (<b>j</b>) Concentrations of primary salt ions in simulated water and condensed water when operated using HB@NF solar evaporator.</p> Full article ">Figure 9
<p>Small-scale prototype of freshwater collection using a glass beaker to condense vapors.</p> Full article ">
23 pages, 2596 KiB  
Article
Potentially Toxic Cyanobacteria in a Eutrophic Reservoir in Northern Colombia
by Tapia-Larios Claudia and Olivero-Verbel Jesus
Water 2023, 15(20), 3696; https://doi.org/10.3390/w15203696 - 23 Oct 2023
Cited by 2 | Viewed by 2460
Abstract
The El Guájaro reservoir, situated in northern Colombia, holds significant economic and ecological importance. It is categorized as eutrophic due to factors such as wastewater discharges, agricultural practices, and the dragging of limestone material. These factors create favorable conditions for cyanobacterial proliferation. This [...] Read more.
The El Guájaro reservoir, situated in northern Colombia, holds significant economic and ecological importance. It is categorized as eutrophic due to factors such as wastewater discharges, agricultural practices, and the dragging of limestone material. These factors create favorable conditions for cyanobacterial proliferation. This study evaluates the diversity and abundance of cyanobacteria, with special attention to the genera identified as toxin producers, and bloom formers within the reservoir. Sampling was conducted in the photic zone at seven stations during both rainy and dry seasons between 2015 and 2019. Abundance and diversity were quantified using the iNEXT program, while a beta diversity analysis assessed community differentiation in relation to environmental parameters. A total of 86 species from 12 orders and 42 genera were identified, with 44% of these species noted as potentially toxic. A significant predominance of filamentous species was identified. Pseudanabaena and Phormidium were the most frequent and abundant genera. The results reveal distinct distribution and abundance patterns influenced by seasonal fluctuations. A notable bloom, co-dominated by Microcystis and Dolichospermum, occurred during the 2019 dry season, leading to the mortality of livestock and other animals. Urgent governance measures and control strategies are imperative to mitigate the health impact of such blooms. Full article
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<p>Distribution of monitoring stations in El Guájaro reservoir, northern Colombia (2015–2019).</p> Full article ">Figure 2
<p>Abundance and richness of planktonic cyanobacteria species in the El Guájaro reservoir (Colombia) during the dry and rainy seasons from 2015 to 2019.</p> Full article ">Figure 3
<p>Alpha diversity analysis: (<b>a</b>) species richness (<sup>0</sup>D); (<b>b</b>) species in common (<sup>1</sup>D); and (<b>c</b>) dominant species (<sup>2</sup>D) of cyanobacteria found in different sampling sites of El Guájaro reservoir during the years 2015 to 2019.</p> Full article ">Figure 4
<p>Estimation of beta diversity by turnover and nestedness in the species composition of cyanobacterial communities in El Guájaro reservoir during the 2015–2019 period.</p> Full article ">Figure 5
<p>Non-parametric multidimensional scaling analysis of the cyanobacterial community in El Guájaro reservoir. (<b>a</b>) NMDS based on the effect of climatic epochs (rainfall and drought) and (<b>b</b>) NMDS based on the differences of the communities present in the years of the study (2015–2019).</p> Full article ">Figure 6
<p>NMDS non-metric multidimensional scaling analysis of the species of cyanobacteria of interest, considering the interaction with relevant environmental variables and confidence ellipses for climatic periods.</p> Full article ">
14 pages, 2224 KiB  
Article
Exploration of Applicability of Diatom Indices to Evaluate Water Ecosystem Quality in Tangwang River in Northeast China
by Hao Xue, Lei Wang, Lingsong Zhang, Yeyao Wang, Fansheng Meng and Min Xu
Water 2023, 15(20), 3695; https://doi.org/10.3390/w15203695 - 23 Oct 2023
Cited by 2 | Viewed by 1694
Abstract
The diatom index has been widely used in the evaluation of water ecological quality, but the applicability of the diatom index often varies in different study areas. The accuracy of the evaluation results depends on the applicability of the diatom index, especially when [...] Read more.
The diatom index has been widely used in the evaluation of water ecological quality, but the applicability of the diatom index often varies in different study areas. The accuracy of the evaluation results depends on the applicability of the diatom index, especially when it is not applied to the place where it is created. In order to screen out the diatom index suitable for the evaluation of the water ecological quality of Tangwang River in northeast China, and to identify the factors affecting the accuracy of the diatom index, the community structure and water environment characteristics of 24 sample sites were investigated in Tangwang River in August 2018, and 18 diatom indices were calculated. The discriminative ability of diatom indices was analyzed using the box plot method, and the factors affecting the accuracy of the diatom index were identified by combining Pearson and Spearman correlation analyses. The results show that the discriminability of the Biological Diatom Index (BDI), Specific Pollution Sensitivity Index (IPS), Idse Leclercq (IDSE), Indice Diatomique Artois Picardie (IDAP), Diatom Eutrophication Pollution Index (EPI-D), Trophic Index (Rott TI), European Economic Community Index (CEE), and Watanabe Index (WAT) was the strongest, which could reasonably distinguish the reference group from the lightly damaged group. In general, the water ecological condition of Tangwang River Basin is good in the wet season, and the water ecological quality of about 80% of the sample sites was “moderate” or better. The main factors affecting the evaluation accuracy of the diatom index in Tangwang River Basin are the correlation strength between the diatom index and habitat quality, organic pollution, and nutrients. The coverage of diatom index species had no significant effect on the accuracy of evaluation. In order to reasonably evaluate the aquatic ecological status, it is recommended to use the diatom index, which has a good correlation with the environmental factors in the study area, or to establish a new diatom index based on the diatom community and environmental factors in the study area. Full article
(This article belongs to the Special Issue Research on Watershed Ecology, Hydrology and Climate)
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<p>Sampling sites in Tangwang River.</p> Full article ">Figure 2
<p>PCA ordination diagram of the Tangwang River environmental data.</p> Full article ">Figure 3
<p>Boxplot analysis of diatom indices.</p> Full article ">Figure 4
<p>Evaluation results of the 8 diatom indexes showing the strongest discrimination ability.</p> Full article ">Figure 5
<p>Analysis of influence on accuracy of diatom indices.</p> Full article ">
15 pages, 1602 KiB  
Article
The Taxon-Specific Species Sensitivity and Aquatic Ecological Risk Assessment of Three Heavy Metals in Songhua River Water, China
by Lingsong Zhang, Fansheng Meng, Na Liu, Jiasheng Zhang and Hao Xue
Water 2023, 15(20), 3694; https://doi.org/10.3390/w15203694 - 23 Oct 2023
Cited by 2 | Viewed by 1463
Abstract
Copper (Cu), zinc (Zn), and nickel (Ni) are essential micronutrients for aquatic life, but they produce adverse effects on aquatic organisms when environmental concentrations exceed a certain threshold. The objective of this study was to analyze the taxon-specific sensitivities of aquatic life to [...] Read more.
Copper (Cu), zinc (Zn), and nickel (Ni) are essential micronutrients for aquatic life, but they produce adverse effects on aquatic organisms when environmental concentrations exceed a certain threshold. The objective of this study was to analyze the taxon-specific sensitivities of aquatic life to the three metals and assess ecological risks at exposure levels prevalent in the Songhua River, China. The results showed that sensitivities to these metals varied among different taxonomic groups, with intra-taxon sensitivities being lower than inter-taxa sensitivities, and the consistency of intra-taxon sensitivity increased from phylum to order. The maximum detected concentrations of Cu, Zn, and Ni in the Songhua River were 52.7, 166.0, and 65.3 μg/L, respectively, which met the water quality standards set by China but exceeded the chronic criteria established by the USA. A probabilistic risk assessment based on chronic toxicity data revealed that these three metals posed an intermediate to high risk to aquatic animals, with maximum risk products of 36.4% for Cu, 14.3% for Ni, and 6.2% for Zn, respectively. These results indicate that the ecological damage of heavy metals in the Songhua River cannot be ignored. Full article
(This article belongs to the Special Issue Research on Watershed Ecology, Hydrology and Climate)
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<p>Profile of sample sites along the Songhua River.</p> Full article ">Figure 2
<p>Specific species sensitivity for three metals ((<b>a</b>–<b>c</b>): phylum level, (<b>d</b>–<b>f</b>): class level, (<b>g</b>–<b>i</b>): order level).</p> Full article ">Figure 2 Cont.
<p>Specific species sensitivity for three metals ((<b>a</b>–<b>c</b>): phylum level, (<b>d</b>–<b>f</b>): class level, (<b>g</b>–<b>i</b>): order level).</p> Full article ">Figure 3
<p>Concentrations of three metals in Songhua River waters.</p> Full article ">Figure 4
<p>Joint probabilistic curve of 3 metals of Songhua River water in different water periods. Three black dotted lines organize ecological risk into 4 sections, from the lower left corner to the upper right direction: de minimis, low, intermediate, and high risk.</p> Full article ">Figure 5
<p>Comparisons among point estimates of exposure and effects for three metals. The horizontal lines represent the 10th and 90th percentiles, and the boxes represent the 25th and 75th percentiles. Median concentrations are shown as solid lines. Outliers are shown as black dots.</p> Full article ">
18 pages, 4672 KiB  
Article
Application of the Monte-Carlo Method to Assess the Operational Reliability of a Household-Constructed Wetland with Vertical Flow: A Case Study in Poland
by Karolina Migdał, Krzysztof Jóźwiakowski, Wojciech Czekała, Paulina Śliz, Jorge Manuel Rodrigues Tavares and Adelaide Almeida
Water 2023, 15(20), 3693; https://doi.org/10.3390/w15203693 - 23 Oct 2023
Cited by 1 | Viewed by 1874
Abstract
The objective of this study was to model the operation of a vertical-flow constructed wetland (VF-CW) for domestic wastewater, using Monte-Carlo simulations and selected probability distributions of various random variables. The analysis was based on collected wastewater quality data, including the values of [...] Read more.
The objective of this study was to model the operation of a vertical-flow constructed wetland (VF-CW) for domestic wastewater, using Monte-Carlo simulations and selected probability distributions of various random variables. The analysis was based on collected wastewater quality data, including the values of the pollutant indicators BOD5 (biochemical oxygen demand), CODCr (chemical oxygen demand), and TSS (total suspended solids), in the 2017–2020 period. Anderson–Darling (A–D) statistics were applied to assess the fit of the theoretical distributions to the empirical distributions of the random variables under study. The selection of the best-fitting statistical distributions was determined using the percentage deviation (PBIAS) criterion. Based on the analyses that were performed, the best-fitting statistical distributions for the pollution indicators of the raw wastewater were the generalised extreme value distribution for BOD5, the Gaussian distribution for CODCr, and the log-normal distribution for TSS. For treated effluent, the log-normal distribution was the best fit for BOD5 and CODCr; the semi-normal distribution, for TSS. The new data generated using the Monte-Carlo method allowed the reliability of the VF-CW operation to be assessed by determining the reliability indices, i.e., the average efficiency of the removal of pollutants (η), the technological efficiency index (R), the reliability index (CR), and the risk index of the negative control of the sewage treatment plant operation (Re). The obtained results indicate that only in the case of CODCr, the analysed treatment facility may fail to meet the requirements related to the reduction of organic pollutants to the required level, which is evidenced by the values of the indicators CR = 1.10, R = 0.49, and η = 0.82. In addition, the risk index of the negative operation of the facility (Re) assumes a value of 1, which indicates that during the period of its operation, the VF-CW system will not operate with the required efficiency in relation to this indicator. The novelty of this work is the implementation of the indicated mathematical simulation methods for analysing the reliability of the operation of the domestic wastewater treatment facility. Full article
(This article belongs to the Special Issue Water, Wastewater and Waste Management for Sustainable Development)
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<p>The flowchart of the methodology used in this study.</p> Full article ">Figure 2
<p>The location of Gawłówek village against the background of the Lesser Poland Voivodeship in Poland.</p> Full article ">Figure 3
<p>Schematic of the VF-CW.</p> Full article ">Figure 4
<p>The values of the pollutant indicators for raw and treated sewage and corresponding permissible levels (<b>a</b>) BOD<sub>5</sub>; (<b>b</b>) COD<sub>Cr</sub>; (<b>c</b>) TSS.</p> Full article ">Figure 4 Cont.
<p>The values of the pollutant indicators for raw and treated sewage and corresponding permissible levels (<b>a</b>) BOD<sub>5</sub>; (<b>b</b>) COD<sub>Cr</sub>; (<b>c</b>) TSS.</p> Full article ">Figure 5
<p>Q–Q plots of best-fit theoretical distributions of the random-variable distributions for indicators for raw sewage (<b>a</b>) BOD<sub>5</sub> (GEV distribution); (<b>b</b>) COD<sub>Cr</sub> (Gaussian distribution); (<b>c</b>) TSS (Log-normal distribution).</p> Full article ">Figure 6
<p>Q–Q plot of best-fit statistical distributions of indicators for treated wastewater (<b>a</b>) BOD<sub>5</sub> (Log-normal distribution); (<b>b</b>) COD<sub>Cr</sub> (Log-normal distribution); (<b>c</b>) TSS (Half-normal distribution).</p> Full article ">
14 pages, 6907 KiB  
Article
Modeling Method for Aerobic Zone of A2O Based on KPCA-PSO-SCN
by Wenxia Lu, Xueyong Tian, Yongguang Ma, Yinyan Guan, Libo Liu and Liwei Shi
Water 2023, 15(20), 3692; https://doi.org/10.3390/w15203692 - 23 Oct 2023
Viewed by 1597
Abstract
Sewage treatment plants face significant problems as a result of the annual growth in urban sewage discharge. Substandard sewage discharge can also be caused by rising sewage treatment expenses and unpredictable procedures. The most widely used sewage treatment process in urban areas is [...] Read more.
Sewage treatment plants face significant problems as a result of the annual growth in urban sewage discharge. Substandard sewage discharge can also be caused by rising sewage treatment expenses and unpredictable procedures. The most widely used sewage treatment process in urban areas is the Anaerobic–Anoxic–Oxic (A2O) sewage treatment process. Therefore, modeling the sewage treatment process and predicting the effluent quality are of great significance. A process modeling method based on Kernel Principal Component Analysis–Particle Swarm Optimization–Stochastic Configuration Network (KPCA-PSO-SCN) is proposed for the A2O aerobic wastewater treatment process. Firstly, eight auxiliary variables were determined through mechanism analysis, including Chemical Oxygen Demand (COD) and ammonia nitrogen (NH4+) and nitrate nitrogen (NO3−) of influent water, pH, temperature (T), Mixed Liquor Suspended Solid (MLSS), Dissolved Oxygen (DO) and hydraulic residence time (HRT) in the aerobic zone. Dimensionality reduction was carried out using the kernel principal component analysis method based on the Gaussian function, and the eight-dimensional data were changed to five-dimensional data, which improved the running speed and efficiency of subsequent models. Then, according to the advantages of the particle swarm optimization algorithm, such as low calculation cost and fast convergence, combined with the advantages of stochastic configuration network general approximation performance, the PSO-SCN model was established to predict the three water quality indexes of effluent COD, NH4+, and NO3− for the aerobic zone. The experimental results proved the effectiveness of the model. Compared with classic water quality prediction algorithm models such as SCN, PSO-BP, RBF, PSO-RBF, etc., the superiority of the PSO-SCN algorithm model was demonstrated. Full article
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<p>A<sup>2</sup>O aerobic zone sewage treatment process diagram.</p> Full article ">Figure 2
<p>The Matlab implementation process of KPCA algorithm.</p> Full article ">Figure 3
<p>Contribution rate chart of each principal component.</p> Full article ">Figure 4
<p>SCN Structure diagram.</p> Full article ">Figure 5
<p>PSO-SCN algorithm flow chart.</p> Full article ">Figure 6
<p>E<sub>COD</sub> concentration prediction. (<b>a</b>) Error plot; (<b>b</b>) training set RMSE; (<b>c</b>) testing set RMSE.</p> Full article ">Figure 7
<p>E<sub>NH4</sub><sup>+</sup> concentration prediction. (<b>a</b>) Error plot; (<b>b</b>) training set RMSE; (<b>c</b>) testing set RMSE.</p> Full article ">Figure 8
<p>E<sub>NO3</sub><sup>−</sup> concentration prediction. (<b>a</b>) Error plot; (<b>b</b>) training set RMSE; (<b>c</b>) testing set RMSE.</p> Full article ">
18 pages, 4822 KiB  
Article
Incipient Motion of Bed Material in a Channel with Varying Width and Vegetated Channel Walls
by Sanaz Hadian, Hossein Afzalimehr and Jueyi Sui
Water 2023, 15(20), 3691; https://doi.org/10.3390/w15203691 - 22 Oct 2023
Viewed by 1494
Abstract
This experimental study aims to investigate the characteristics of turbulent flow in channels with vegetated banks and varying channel width under the condition of the incipient motion of bed material. The natural reeds were used as emergent vegetation on the sidewalls of a [...] Read more.
This experimental study aims to investigate the characteristics of turbulent flow in channels with vegetated banks and varying channel width under the condition of the incipient motion of bed material. The natural reeds were used as emergent vegetation on the sidewalls of a laboratory flume. In total, nine experimental runs have been conducted with different experimental setups by using three different particle sizes of bed material and three different channel bed slopes. An Acoustic Doppler velocimetry (ADV) was used to acquire velocity components in three directions. The results of this study indicate that the streamwise velocities have the maximum and minimum values at the cross sections with the narrowest and widest width, respectively. When the aspect ratio is less than 5, the maximum velocity occurs below the water surface, due to presence of the secondary currents. It is found that, at all measurement points, the distribution of the Reynolds shear stress has a Z-shaped profile owing to presence of vegetation on the channel sidewalls. By extrapolating the profiles for flow velocity and Reynolds shear stress towards the surface of the channel bed, the near-bed incipient velocities and the corresponding shear stresses for the incipient motion have been determined. By increasing the channel bed slope, the estimated near-bed parameters for all particle sizes decreased, indicating the dominance of the gravity effect over the pressure gradient effect. It was also observed that the Shields method was invalid for assessing the incipient motion of bed material in the presence of vegetation on the sidewalls of a channel that has a varying width. Full article
(This article belongs to the Section Hydraulics and Hydrodynamics)
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<p>The construction steps of varying width of the experimental flume; (<b>a</b>) the PVC barriers, (<b>b</b>) The row of reeds, as the wall vegetation, (<b>c</b>) the experimental flume with variable width and vegetated walls.</p> Full article ">Figure 2
<p>Grain size distributions for three bed materials.</p> Full article ">Figure 3
<p>The locations for data acquisitions.</p> Full article ">Figure 4
<p>(<b>a</b>–<b>c</b>) Streamwise velocity distributions (experimental setup: <span class="html-italic">S</span> = 0, <span class="html-italic">d</span><sub>50</sub> = 0.56 mm).</p> Full article ">Figure 5
<p>(<b>a</b>–<b>c</b>) Streamwise velocity distributions (experimental setup: <span class="html-italic">S</span> = 0, <span class="html-italic">d</span><sub>50</sub> = 1.08 mm).</p> Full article ">Figure 6
<p>(<b>a</b>–<b>c</b>) Turbulence intensity distributions (experimental setup: <span class="html-italic">S</span> = 0, <span class="html-italic">d</span><sub>50</sub> = 0.56 mm).</p> Full article ">Figure 7
<p>(<b>a</b>–<b>c</b>) Turbulence intensity distributions (experimental setup: <span class="html-italic">S</span> = 0, <span class="html-italic">d</span><sub>50</sub> = 1.08 mm).</p> Full article ">Figure 8
<p>(<b>a</b>–<b>c</b>) Reynolds shear stress distributions (experimental setup: <span class="html-italic">S</span> = 0, <span class="html-italic">d</span><sub>50</sub> = 0.56 mm).</p> Full article ">Figure 9
<p>(<b>a</b>–<b>c</b>) Reynolds shear stress distributions (experimental setup: <span class="html-italic">S</span> = 0, <span class="html-italic">d</span><sub>50</sub> = 1.08 mm).</p> Full article ">Figure 10
<p>(<b>a</b>–<b>c</b>) Streamwise velocity distributions (experimental setup: <span class="html-italic">S</span> = 0.015, <span class="html-italic">d</span><sub>50</sub> = 0.56 mm).</p> Full article ">Figure 11
<p>(<b>a</b>–<b>c</b>) Streamwise velocity distributions (experimental setup: <span class="html-italic">S</span> = 0.015, <span class="html-italic">d</span><sub>50</sub> = 1.08 mm).</p> Full article ">Figure 12
<p>(<b>a</b>–<b>c</b>) Turbulence intensity distributions, (experimental setup: <span class="html-italic">S</span> = 0.015, <span class="html-italic">d</span><sub>50</sub> = 0.56 mm).</p> Full article ">Figure 13
<p>(<b>a</b>–<b>c</b>) Turbulence intensity distributions (experimental setup: <span class="html-italic">S</span> = 0.015, <span class="html-italic">d</span><sub>50</sub> = 1.08 mm).</p> Full article ">Figure 14
<p>(<b>a</b>–<b>c</b>) Reynolds shear stress distributions (experimental setup: <span class="html-italic">S</span> = 0.015, <span class="html-italic">d</span><sub>50</sub> = 0.56 mm).</p> Full article ">Figure 15
<p>(<b>a</b>–<b>c</b>) Reynolds shear stress distributions (experimental setup: <span class="html-italic">S</span> = 0.015, <span class="html-italic">d</span><sub>50</sub> = 1.08 mm).</p> Full article ">Figure 16
<p>The measured data of this study on the Shields diagram (circle dot symbol).</p> Full article ">
25 pages, 6725 KiB  
Review
A Review of Heavy Metal Migration and Its Influencing Factors in Karst Groundwater, Northern and Southern China
by Wanjun Zhang, Cunlin Xin and Shi Yu
Water 2023, 15(20), 3690; https://doi.org/10.3390/w15203690 - 22 Oct 2023
Cited by 6 | Viewed by 2768
Abstract
With the substantial increase in karst groundwater pollution, the pollution caused by heavy metal migration has become one of the hottest topics. The migration characteristics of heavy metals in karst groundwater are closely related to the geological environment in which they are found. [...] Read more.
With the substantial increase in karst groundwater pollution, the pollution caused by heavy metal migration has become one of the hottest topics. The migration characteristics of heavy metals in karst groundwater are closely related to the geological environment in which they are found. Therefore, this review focuses on the migration characteristics of heavy metals in karst groundwater in southern and northern China and highlights the effect of different environmental contexts such as atmosphere (precipitation), vegetation, soil, rock, and aquifers on the behavior of heavy metals. It also summarizes existing research methods on heavy metal migration in karst groundwater. Meanwhile, current advances and the future perspectives on karst groundwater heavy metal migration will be presented. It is hoped that this review may shed light on the study of heavy metal migration in karst areas. Full article
(This article belongs to the Special Issue Karst Dynamic System and Its Water Resources Environmental Effects)
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<p>Distribution of karst regions in China.</p> Full article ">Figure 2
<p>Progress of research on heavy metal migration in karst groundwater at home and abroad based on Web of Science.</p> Full article ">Figure 3
<p>Comparison of heavy metal migration characteristics in karst groundwater between southern and northern China [<a href="#B56-water-15-03690" class="html-bibr">56</a>].</p> Full article ">Figure 4
<p>Comparison of the effects of vegetation on heavy metals in southern and northern China.</p> Full article ">
14 pages, 4297 KiB  
Article
Frog Crabs (Ranina ranina) in South Penghu Marine National Park, Taiwan: A Case Study of Population Dynamics and Recreational Fishing Sustainable Development
by Chun-Han Shih
Water 2023, 15(20), 3689; https://doi.org/10.3390/w15203689 - 22 Oct 2023
Cited by 1 | Viewed by 1923
Abstract
The frog crab/red frog crab (Ranina ranina), a species of symbolic significance in the South Penghu Marine National Park, Taiwan, represents a collaboration between marine conservation and recreational fishing under Sustainable Development Goal 14 (SDG14) as defined by the United Nations. [...] Read more.
The frog crab/red frog crab (Ranina ranina), a species of symbolic significance in the South Penghu Marine National Park, Taiwan, represents a collaboration between marine conservation and recreational fishing under Sustainable Development Goal 14 (SDG14) as defined by the United Nations. From 2020 to 2021, the growth and reproduction of R. ranina were examined in the Taiwan Strait, off the coast of Taiwan. Samples were gathered from the South Penghu Marine National Park water square in Penghu County using red frog crab nets. A comparative analysis of the existing biological literature has revealed that the spawning season of R. ranina differs among populations, as evidenced by varying percentages of ovigerous females: 10–90% in Hachijojima, Japan; 86% in Molokai, Hawaii; 1–17% in the Andaman Sea, Thailand; more than 50% in Mindanao, Philippines; and 30–80% in New South Wales, Australia, and Taiwan. Additionally, analysis of the reproductive patterns, growth parameters, and spawning seasons of R. ranina can serve as a scientific foundation for the implementation of SDG14 as well as the formulation of conservation principles for resource management. This research has underscored the essential role of localized conservation strategies that cohesively resonate with broader global sustainability goals, offering a strategic framework for effective marine resource management. Full article
(This article belongs to the Special Issue Coastal Ecology and Fisheries Management)
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<p>The shadowed area shows the sampling area in the South Penghu Marine National Park water square.</p> Full article ">Figure 2
<p>Relationship between CL and CW for females (<b>left</b>) and males (<b>right</b>).</p> Full article ">Figure 3
<p>Relationship between CL and WT for females (<b>left</b>) and males (<b>right</b>).</p> Full article ">Figure 4
<p>Restructured length frequency data and seasonal growth curves for females (<b>top</b>) and males (<b>bottom</b>). Numbers indicate sample size.</p> Full article ">Figure 5
<p>Recruitment patterns for females (<b>left</b>) and males (<b>right</b>).</p> Full article ">Figure 6
<p>A logarithmic function fitting the proportion of mature female <span class="html-italic">Ranina ranina</span> to CL (7.02 cm), which corresponds to a proportion of 0.5 (50% of females are mature).</p> Full article ">Figure 7
<p>(<b>a</b>) Percentages of female maturity stages and (<b>b</b>) and mean GSIs of females and males of <span class="html-italic">R. ranina</span> from September 2020 to August 2021.</p> Full article ">Figure 8
<p>Sex ratio of males and females of <span class="html-italic">R. ranina</span> from 2020 to 2021.</p> Full article ">Figure 9
<p>Variations in spawning seasons of <span class="html-italic">R. ranina</span> across different populations, highlighted by percentages of ovigerous females: 10–90% in Hachijojima, Japan; 86% in Molokai, Hawaii; 1–17% in the Andaman Sea, Thailand; over 50% in Mindanao, Philippines; and 30–80% in New South Wales, Australia, and Taiwan.</p> Full article ">
13 pages, 818 KiB  
Article
Bibliometric Analysis of Research Trends in Water Management Aimed at Increasing the Sustainability of the Socio-Economic Development of a Region
by Zhanna Mingaleva, Olga Chernova and Inna V. Mitrofanova
Water 2023, 15(20), 3688; https://doi.org/10.3390/w15203688 - 22 Oct 2023
Cited by 3 | Viewed by 2204
Abstract
The growing negative anthropogenic impact on the environment causes scientific interest in the problems of water management. The increasing number of publications in this scientific field requires their intellectual systematization. The purpose of this study is to conduct a bibliometric review of scientific [...] Read more.
The growing negative anthropogenic impact on the environment causes scientific interest in the problems of water management. The increasing number of publications in this scientific field requires their intellectual systematization. The purpose of this study is to conduct a bibliometric review of scientific publications related to water management issues in the context of solving the problems of increasing the sustainability of the socio-economic development of a region for better understanding of current research trends. To achieve this goal, bibliometric analysis using the VOSviewer software product (Manual for VOSviewer version 1.6.17) was used. The international database Scopus was taken as the source of information. This study examined 10,208 articles on water management issues from 2012 to 2022. The basic criterion for including a publication in the selection was that the topic of the work belongs to the subject areas of economics, econometrics and finance and business, management and accounting. As a result of the analysis, it was determined that the problems of water resources management have not lost their popularity in the global research community and the research methodology is evolving towards the concept of “water–energy–food”. The centers of knowledge forming the vector of scientific research are the USA and the Netherlands; however, in recent years, the research of Chinese scientists has become increasingly important. It is concluded that the potential for the development of research in the field of water resources management in the context of solving the problems of the sustainable development of regions is associated with the search for opportunities for revealing the synergy of intersectoral interactions while taking into account their sectoral and regional specifics. Full article
(This article belongs to the Section Water Resources Management, Policy and Governance)
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<p>Annual number of publications on water management issues. Note: Compiled by the authors according to the source: <a href="https://www.sciencedirect.com" target="_blank">https://www.sciencedirect.com</a> (accessed on 11 October 2023).</p> Full article ">Figure 2
<p>Data on the annual number of publications from the top 3 countries by the number of publications. Note: Compiled by the authors according to the source: <a href="https://www.scival.com" target="_blank">https://www.scival.com</a> (accessed on 11 October 2023).</p> Full article ">Figure 3
<p>The relationship of keywords in publications on water management issues.</p> Full article ">
19 pages, 15286 KiB  
Article
Numerical Modeling and Simulation of Fractured-Vuggy Reservoirs Based on Field Outcrops
by Sanbai Li, Zhijiang Kang and Yun Zhang
Water 2023, 15(20), 3687; https://doi.org/10.3390/w15203687 - 21 Oct 2023
Cited by 2 | Viewed by 1949
Abstract
We propose a novel workflow to investigate the complex flow behaviors and remaining oil distribution related to the oil–gas–water three-phase system based on information from typical outcrops of fractured-vuggy reservoirs. A refined geological model is built to represent the size, geometry, and spatial [...] Read more.
We propose a novel workflow to investigate the complex flow behaviors and remaining oil distribution related to the oil–gas–water three-phase system based on information from typical outcrops of fractured-vuggy reservoirs. A refined geological model is built to represent the size, geometry, and spatial distribution of the karst caves and fractures extracted from the field outcrop photographs. The combination of the perpendicular bisector (PEBI) grid technique and the control-volume finite difference method is adopted for space discretization. We have validated the numerical model against experimental data. Numerical simulations were performed to explore the impacts of the permeability of karst cave and natural fractures and the position of natural water bodies upon oil production performance. Numerical results indicate that (1) the cave permeability has few impacts on the oil production, yet the fracture permeability plays a significant role in determining the oil recovery; (2) a higher permeability of the fractures will lead to a longer period of time for no-water oil production and, thus, a higher oil recovery; (3) the position of natural water body shows significant impacts on oil recovery, e.g., a short distance between the natural water body and the production well tends to form preferential passages, causing severe reduction of water flooding range; and (4) the distribution of remaining oil is controlled by spatial patterns of the fractured-vuggy system and reservoir development schemes. We found that the remaining oil is mainly distributed along the model boundaries and at the corner of the caves with single or multiple connection/s to fractures. Full article
(This article belongs to the Special Issue Fluid Dynamics Modeling in Porous Media)
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<p>Schematic of the characteristics of the fluid flow through multiscale fractures and caves within the fractured-vuggy reservoirs.</p> Full article ">Figure 2
<p>Space discretization and geometry data in the integral finite difference method [<a href="#B31-water-15-03687" class="html-bibr">31</a>].</p> Full article ">Figure 3
<p>Snapshots of the remaining oil in the cylinders with different porous volume numbers (PVs): (<b>a</b>) 0.0 PVs; (<b>b</b>) 0.25 PVs; (<b>c</b>) 0.5 PVs; and (<b>d</b>) 1.0 PVs.</p> Full article ">Figure 4
<p>Comparison of oil production rate and oil recovery between numerical and experimental results.</p> Full article ">Figure 5
<p>The workflow of modeling and discretization of a typical outcrop of fractured vuggy reservoirs: (<b>a</b>) an outcrop picture of a fractured-vuggy reservoir; (<b>b</b>) digital description of the fractures and caves; (<b>c</b>) domain discretization; and (<b>d</b>) digital extraction of the fractures and caves using computational grids.</p> Full article ">Figure 6
<p>Initial state of the studied domain: (<b>a</b>) pressure distribution and (<b>b</b>) oil saturation distribution of oil phase.</p> Full article ">Figure 7
<p>Relative permeability curve for (<b>a</b>) fractures and (<b>b</b>) filled caves.</p> Full article ">Figure 8
<p>Oil saturation distribution of (<b>a</b>) edge water and (<b>b</b>) bottom water. Note that the grey rectangle zone denotes a production well and the red arrow denotes fluid extraction from the well.</p> Full article ">Figure 9
<p>Comparison of cumulative oil production between bottom and edge water drive.</p> Full article ">Figure 10
<p>Comparison of the response of water cut between bottom and edge water drive.</p> Full article ">Figure 11
<p>Comparison of oil production rate between bottom and edge water drive.</p> Full article ">Figure 12
<p>Oil distributions with various cave permeabilities: (<b>a</b>) 100 mD, (<b>b</b>) 5 D, and (<b>c</b>) 10 D. Note that the red arrow denotes fluid extraction from the well.</p> Full article ">Figure 13
<p>Comparison of cumulative oil production between different cave permeabilities.</p> Full article ">Figure 14
<p>Comparison of water cut history between different cave permeabilities.</p> Full article ">Figure 15
<p>Comparison of oil production rate between different cave permeabilities.</p> Full article ">Figure 16
<p>Oil distributions with various fracture permeabilities: (<b>a</b>) 100 mD, (<b>b</b>) 5 D, and (<b>c</b>) 10 D. Note that the red arrow denotes fluid extraction from the well.</p> Full article ">Figure 17
<p>Comparison of cumulative oil production between different fracture permeabilities.</p> Full article ">Figure 18
<p>Comparison of water cut history between different fracture permeabilities.</p> Full article ">Figure 19
<p>Comparison of oil production rate between different fracture permeabilities.</p> Full article ">
15 pages, 4357 KiB  
Article
The Effects of Aniline-Promoted Electron Shuttle-Mediated Goethite Reduction by Shewanella oneidensis MR-1 and theDegradation of Aniline
by Mengmeng Tang, Chaoyong Wang, Zaitian Dong, Qianjin Che, Zetang Wang and Yuxuan Zhu
Water 2023, 15(20), 3686; https://doi.org/10.3390/w15203686 - 21 Oct 2023
Cited by 1 | Viewed by 1666
Abstract
The biological reduction of Fe (III) is common in underground environments. This process not only affects the biogeochemical cycle of iron but also influences the migration and transformation of pollutants. Humic substances are considered effective strategies for improving the migration and transformation of [...] Read more.
The biological reduction of Fe (III) is common in underground environments. This process not only affects the biogeochemical cycle of iron but also influences the migration and transformation of pollutants. Humic substances are considered effective strategies for improving the migration and transformation of toxic substances and enhancing the bioavailability of Fe (III). In this study, the electron shuttle anthraquinone-2-sulfonate (AQS) significantly promoted the bio-reduction of Fe (III). On this basis, different concentrations of aniline were added. The research results indicate that at an aniline concentration of 3 μM, the production of Fe (II) in the reaction system was 2.51 times higher compared to the microbial reaction group alone. Furthermore, the degradation of aniline was most effective in this group. The increased consumption of sodium lactate suggests that aniline, under the mediation of AQS, promoted the metabolism of Shewanella oneidensis MR-1 cells and facilitated the involvement of more electrons in the reduction process. After the reaction, the solid mineral Fe (II)-O content increased to 41.32%. This study provides insights into the reduction mechanism of Fe (III) in the complex environment of microorganisms, iron minerals, electron shuttles, and pollutants. It aims to offer a theoretical basis for the biodegradation of aromatic hydrocarbon pollutants. Full article
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<p>Characterizations of synthesized goethite: (<b>a</b>) XRD pattern and (<b>b</b>) SEM image.</p> Full article ">Figure 2
<p>Effect of different concentrations of AQS on Fe (II) production in the bio-reduction process of goethite. (<b>a</b>) Fe (II) content in the reaction system. Data are presented as mean ± SD (n = 3); at certain time points, the error bar is smaller than the size of the top line. (<b>b</b>) Color change of GT + MR-1 culture medium. (<b>c</b>) Color change of GT + MR-1 + 0.5 mM AQS culture medium.</p> Full article ">Figure 3
<p>Effect of different concentrations of aniline on the production of Fe (II) during AQS-mediated goethite bio-reduction. Data are presented as mean ± SD (n = 3). At certain time points, the error bar is smaller than the size of the top line.</p> Full article ">Figure 4
<p>Sodium lactate consumption and first-order kinetic fitting: (<b>a</b>) Consumption of sodium lactate during AQS-mediated Fe (III) bio-reduction. (<b>b</b>) AQS-mediated first-order kinetic fitting of sodium lactate in Fe (III) bio-reduction processes. (<b>c</b>) Impact of aniline on sodium lactate consumption during AQS-mediated Fe (III) bio-reduction. (<b>d</b>) First-order kinetic depletion of sodium lactate consumption during AQS-mediated Fe (III) bio-reduction by aniline. Data are presented as mean ± SD (n = 3). At certain time points, the error bar is smaller than the size of the top line.</p> Full article ">Figure 5
<p>(<b>a</b>) Change in aniline concentration. (<b>b</b>) First-order kinetic fitting of aniline degradation. Data are presented as mean ± SD (n = 3). At certain time points, the error bar is smaller than the size of the top line.</p> Full article ">Figure 6
<p>SEM characterization of minerals after bio-reduction of goethite: (<b>a</b>) GT + MR-1; (<b>b</b>) GT + MR-1 + 0.5 mM AQS; (<b>c</b>) GT + MR-1 + 1 μM aniline; (<b>d</b>) GT + MR-1 + 0.5 mM AQS + 3 μM aniline.</p> Full article ">Figure 7
<p>XPS characterization of minerals after bio-reduction of goethite: (<b>a</b>) GT + MR-1; (<b>b</b>) GT + 0.5 mM AQS; (<b>c</b>) GT + MR-1 + 1 μM aniline; (<b>d</b>) GT + MR-1 + 0.5 mM AQS + 3 μM aniline.</p> Full article ">Figure 8
<p>XRD patterns of minerals after bio-reduction of goethite under different conditions.</p> Full article ">
25 pages, 17413 KiB  
Article
Assessing the Susceptibility of Landslides in the Tuoding Section of the Upper Reaches of the Jinsha River, China, Using a Combination of Information Quantity Modeling and GIS
by Yunkai Ruan, Ranran Huo, Jinzi Chen, Weicheng Liu, Xin Zhou, Tanhua Wang, Mingzhi Hou and Wei Huang
Water 2023, 15(20), 3685; https://doi.org/10.3390/w15203685 - 21 Oct 2023
Cited by 1 | Viewed by 1451
Abstract
Combined with visible light remote sensing technology and InSAR technology, this study employed the fundamental principles of the frequency ratio model, information content model, and analytic hierarchy process to assess the susceptibility of the study area. Nine susceptibility assessment factors such as elevation, [...] Read more.
Combined with visible light remote sensing technology and InSAR technology, this study employed the fundamental principles of the frequency ratio model, information content model, and analytic hierarchy process to assess the susceptibility of the study area. Nine susceptibility assessment factors such as elevation, slope, aspect, water system, vegetation coverage, geological structure, stratum lithology, rainfall, and human activities were selected, and the factor correlation degree was calculated by using the relative area density value of the landslide. The frequency ratio model and information content model were selected to carry out landslide susceptibility zoning, and the accuracy of the two models was verified by the ROC curve and density method. The results indicate that the information content model performed relatively well. Therefore, the information model, combined with the analytic hierarchy process and fuzzy superposition method using the landslide point density map, was chosen to evaluate landslide susceptibility. The study area was divided into five levels of landslide hazard, ranging from low to high, using the natural discontinuity point method. The results show that the area of each hazard zoning is 197.48, 455.72, 408.21, 152.66, and 16.22 km2 from low to high, and the proportion of landslides in the corresponding area is 0.17%, 1.60%, 3.88%, 8.41%, and 16.65%, respectively. It can be seen that with the increase in the hazard level, the proportion of landslides also increases significantly, which verifies the accuracy of the hazard results. Additionally, four representative landslides in the study area were selected for analysis to understand their characteristics and underlying mechanisms. The results revealed that these landslides were notably influenced by the density of the Jinsha River and the surrounding roads. The susceptibility assessment outcomes for geological disasters align well with the current situation of landslide occurrences in the Tuoding river section, demonstrating high accuracy. This study provides a scientific foundation for effective prevention and control measures against local landslide disasters. Full article
(This article belongs to the Special Issue Effects of Groundwater and Surface Water on the Natural Geo-Hazards)
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<p>(<b>a</b>) The geographical location of the study area; (<b>b</b>) the geological map of the study area (adapted with permission from Ref. [<a href="#B3-water-15-03685" class="html-bibr">3</a>], 2022, Cen C).</p> Full article ">Figure 2
<p>Stacking-InSAR technology was utilized for landslide detection based on descending data in this study.</p> Full article ">Figure 3
<p>The three-dimensional geological model map of the study area and the distribution location of the corresponding gravity geological disasters.</p> Full article ">Figure 4
<p>Deformation features of old landslide deposits.</p> Full article ">Figure 5
<p>Field investigation of old landslide deposits. (<b>a</b>) Occurrence characteristics of bedrock level and structural plane; (<b>b</b>) a typical road crack; (<b>c</b>) a typical section of the middle and lower boundary of the upper reaches of the deposit body; (<b>d</b>) a small landslide in the direction of highway free face; (<b>e</b>) DZ landslide.</p> Full article ">Figure 6
<p>The cracks in the middle and upper reaches of the old accumulation body in the old area.</p> Full article ">Figure 7
<p>Landslide susceptibility evaluation index system in the study area.</p> Full article ">Figure 8
<p>Landslide susceptibility factor classification in Tuoding: (<b>a</b>) elevation; (<b>b</b>) slope; (<b>c</b>) aspect; (<b>d</b>) distance from river; (<b>e</b>) vegetation cover; (<b>f</b>) distance from fault; (<b>g</b>) lithology; (<b>h</b>) distance from road; and (<b>i</b>) precipitation.</p> Full article ">Figure 9
<p>Landslide susceptibility assessment evaluation map of frequency ratio method.</p> Full article ">Figure 10
<p>Landslide susceptibility assessment via information method.</p> Full article ">Figure 11
<p>ROC curves obtained for the model accuracy evaluation.</p> Full article ">Figure 12
<p>Comparison chart of density method model validation.</p> Full article ">Figure 13
<p>Landslide point density analysis diagram.</p> Full article ">Figure 14
<p>Landslide susceptibility assessment map of the study area.</p> Full article ">
21 pages, 16178 KiB  
Article
Tall Herb Fringe Vegetation on Banks of Montenegrin Rivers as a Habitat Type of European Importance
by Monika Myśliwy and Vladimir Pešić
Water 2023, 15(20), 3684; https://doi.org/10.3390/w15203684 - 21 Oct 2023
Cited by 2 | Viewed by 1830
Abstract
River valleys are known to be of high natural value; however, they are exposed to a strong human influence. Anthropogenic changes are evident in the structure and species composition of plant assemblages; therefore, vegetation is a very good indicator of the state of [...] Read more.
River valleys are known to be of high natural value; however, they are exposed to a strong human influence. Anthropogenic changes are evident in the structure and species composition of plant assemblages; therefore, vegetation is a very good indicator of the state of the environment. Convolvuletalia sepium tall herb communities are a natural component of riverside vegetation; they are protected in the EU (habitat 6430), yet have been very poorly studied, especially in SE Europe. Information regarding the geographical distribution of these communities, and their floristic composition and threats, along with effective conservation and restoration strategies, remains insufficient; therefore, this study was aimed at a comprehensive investigation of tall herbs. The paper presents results of the first detailed study of this group of communities in Montenegro. Classification of 70 vegetation samples (relevés) using the UPGMA produced six clusters corresponding to plant communities which were included in the Dorycnio recti-Rumicion conglomerati. Two of them were ranked as associations: Mentho longifolii-Pulicarietum dysentericae and Rubo sancti-Eupatorietum cannabini, the latter new to science. Others (communities of Rubus caesius, Rubus caesius-Eupatorium cannabinum, Helianthus ×laetiflorus, and Helianthus tuberosus) were left without a syntaxonomic rank. The ordination analysis with the CANOCO software confirmed the authors’ hypothesis that the variability of the vegetation patches studied was related to the land use type and river size. Relevés taken in watercourses flowing through built-up areas were dominated by invasive alien species (IAS). Vegetation samples taken in heavily flooded areas, along the Zeta, one of the largest rivers surveyed, had a simplified species composition. Studies in Montenegro should be continued. Moreover, comparative studies of the Convolvuletalia sepium communities described in the Mediterranean region are also necessary. Attention is drawn to the overly narrow interpretation of habitat 6430 in the lowlands, as it lacks a representation of Mediterranean tall herbs. Full article
(This article belongs to the Special Issue Development of New Tools and Techniques for Aquatic Monitoring and Conservation)
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<p>Location of vegetation sampling sites (indicated by red circles) along the rivers studied in Montenegro.</p> Full article ">Figure 2
<p>Numerical classification of 70 relevés from rivers of Montenegro (UPGMA and average distance). Explanations: 1–69, relevé numbers; A, <span class="html-italic">Helianthus</span> ×<span class="html-italic">laetiflorus</span> community; B, <span class="html-italic">Rubo sancti-Eupatorietum cannabini</span> Myśliwy ass. nov. hoc loco; C1, <span class="html-italic">Rubus caesius</span> community; C2, <span class="html-italic">Rubus caesius-Eupatorium cannabinum</span> community; D, <span class="html-italic">Mentho longifolii-Pulicarietum dysentericae</span> Slavnić 1958; E, <span class="html-italic">Helianthus tuberosus</span> community.</p> Full article ">Figure 3
<p>DCA ordination plot with 70 vegetation samples (colour-coded circles) and supplementary variables: land use type (red triangles) and riverbed width (red arrow) along the first two axes. The distances between samples indicate how similar or dissimilar they are in terms of species composition. The position of samples in relation to supplementary variables indicates their preference for certain environmental conditions. Explanations: 1–69, relevé numbers; brown circles, <span class="html-italic">Helianthus</span> ×<span class="html-italic">laetiflorus</span> community; dark pink circles, <span class="html-italic">Rubo sancti-Eupatorietum cannabini</span> Myśliwy ass. nov. hoc loco; green circles, <span class="html-italic">Rubus caesius</span> community; blue circles, <span class="html-italic">Rubus caesius-Eupatorium cannabinum</span> community; yellow circles, <span class="html-italic">Mentho longifolii-Pulicarietum dysentericae</span> Slavnić 1958; black circles, <span class="html-italic">Helianthus tuberosus</span> community.</p> Full article ">Figure A1
<p><span class="html-italic">Helianthus</span> ×<span class="html-italic">laetiflorus</span> community by the river Bečićka (photo: M. Myśliwy, 9 October 2010).</p> Full article ">Figure A2
<p><span class="html-italic">Helianthus</span> ×<span class="html-italic">laetiflorus</span> community in Zeta valley (photo: M. Myśliwy, 15 October 2010).</p> Full article ">Figure A3
<p><span class="html-italic">Rubo sancti-Eupatorietum cannabini</span> Myśliwy ass. nov. hoc loco by the river Orahovištica (photo: M. Myśliwy, 30 August 2012).</p> Full article ">Figure A4
<p><span class="html-italic">Rubo sancti-Eupatorietum cannabini</span> Myśliwy ass. nov. hoc loco by the river Rikavac (photo: M. Myśliwy, 27 August 2012).</p> Full article ">Figure A5
<p><span class="html-italic">Rubo sancti-Eupatorietum cannabini</span> Myśliwy ass. nov. hoc loco on the edge of the riparian forest in the Zeta valley (photo: M. Myśliwy, 13 October 2010).</p> Full article ">Figure A6
<p><span class="html-italic">Rubus caesius</span> community in Zeta valley (photo: M. Myśliwy, 12 October 2010).</p> Full article ">Figure A7
<p>Signs of flooding on riverside vegetation on the Zeta river (photo: M. Myśliwy, 12 October 2010).</p> Full article ">Figure A8
<p><span class="html-italic">Rubus caesius-Eupatorium cannabinum</span> community in Zeta valley (photo: M. Myśliwy, 12 October 2010).</p> Full article ">Figure A9
<p><span class="html-italic">Mentho longifolii-Pulicarietum dysentericae</span> Slavnić 1958 by the river Rikavac (photo: M. Myśliwy, 27 August 2012).</p> Full article ">Figure A10
<p><span class="html-italic">Mentho longifolii-Pulicarietum dysentericae</span> Slavnić 1958 by the river Rikavac (photo: M. Myśliwy, 27 August 2012).</p> Full article ">
16 pages, 2006 KiB  
Article
A Non-Stationarity Analysis of Annual Maximum Floods: A Case Study of Campaspe River Basin, Australia
by Abdullah Gokhan Yilmaz, Monzur Alam Imteaz, Abdallah Shanableh, Rami Al-Ruzouq, Serter Atabay and Khaled Haddad
Water 2023, 15(20), 3683; https://doi.org/10.3390/w15203683 - 21 Oct 2023
Cited by 1 | Viewed by 2043
Abstract
A design flood is an essential input for water infrastructure design and flood protection. A flood frequency analysis has been traditionally performed under stationarity assumption indicating that the statistical properties of historical flooding will not change over time. Climate change and variability challenges [...] Read more.
A design flood is an essential input for water infrastructure design and flood protection. A flood frequency analysis has been traditionally performed under stationarity assumption indicating that the statistical properties of historical flooding will not change over time. Climate change and variability challenges the stationarity assumption, and a flood frequency analysis without consideration of non-stationarity can result in under- or overestimation of the design floods. In this study, non-stationarity of annual maximum floods (AMFs) was investigated through a methodology consisting of trend and change point tests, and non-stationary Generalized Extreme Value (NSGEV) models, and the methodology was applied to Campaspe River Basin as a case study. Statistically significant decreasing trends in AMFs were detected for almost all stations at the 0.01 significance level in Campaspe River Basin. NSGEV models outperformed the stationary counterparts (SGEV) for some stations based on statistical methods (i.e., Akaike information criterion (AIC) and Bayesian information criterion (BIC)) and graphical approaches (i.e., probability and quantile plots). For example, at Station 406235, AIC and BIC values were found to be 334 and 339, respectively, for the SGEV model, whereas AIC and BIC values were calculated as 330 and 334, respectively, for the NSGEV 15 model with time-varying location and scale parameters. Deriving a design flood from conventional stationary models will result in uneconomical water infrastructure design and poor water resource planning and management in the study basin. Full article
(This article belongs to the Special Issue Flood Frequency Analysis and Modelling)
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<p>Location of the Campaspe River Basin and selected stations.</p> Full article ">Figure 2
<p>Trend and autocorrelation graphs for AMF at Stations 406208 and 406214.</p> Full article ">Figure 3
<p>Observed data and residual P-P and Q-Q plots of NSGEV5 for Station 406250.</p> Full article ">Figure 4
<p>Design flood estimations from SGEV and NSGEV15 for 2-, 10-, 20-, and 50-year return periods at Station 406235.</p> Full article ">Figure 5
<p>Correlation between AMF and physical covariates (SOI, TPI, SAM, and DMI).</p> Full article ">
25 pages, 8287 KiB  
Article
Single-Step Modification of Brewer’s Spent Grains Using Phosphoric Acid and Application in Cheese Whey Remediation via Liquid-Phase Adsorption
by Luiz Eduardo Nochi Castro, Larissa Resende Matheus, Rosana Rabelo Mançano, William Gustavo Sganzerla, Rafael Gabriel da Rosa, Tiago Linhares Cruz Tabosa Barroso, Vanessa Cosme Ferreira and Leda Maria Saragiotto Colpini
Water 2023, 15(20), 3682; https://doi.org/10.3390/w15203682 - 21 Oct 2023
Cited by 3 | Viewed by 1583
Abstract
Brewer’s spent grains (BSG) are a significant by-product of beer production, and its improper disposal poses environmental challenges. This study investigated the use of BSG for activated carbon production with phosphoric acid as a chemical activator and its application in cheese whey remediation [...] Read more.
Brewer’s spent grains (BSG) are a significant by-product of beer production, and its improper disposal poses environmental challenges. This study investigated the use of BSG for activated carbon production with phosphoric acid as a chemical activator and its application in cheese whey remediation through liquid-phase adsorption. The adsorbent was thoroughly characterized through using techniques such as FTIR, SEM, N2 isotherms, and surface charge distribution. The adsorbent exhibited substantial pores, a high surface area (605.1 m2 g–1), good porosity, and positive surface charges that facilitated favorable interactions with cheese whey compounds. Equilibrium was achieved in 330 min for lactose, BOD5, and COD. The maximum adsorption capacities were 12.77 g g–1 for lactose, 3940.99 mg O2 g–1 for BOD5, and 12,857.92 mg O2 g−1 for COD at 318 K. Removing these adsorbates from cheese whey effluent reduces its organic load, enabling water reuse in the manufacturing unit, depending on its intended use. The adsorption process was spontaneous and endothermic, with ΔH° ≥ 265.72 kJ mol−1. Additionally, the activated carbon produced demonstrated impressive regeneration capability with sodium hydroxide, maintaining 75% of its adsorption capacity. These results emphasize the potential of activated carbon as an effective adsorbent for cheese whey remediation, providing a sustainable solution for waste management in the dairy industry and water reuse. Full article
(This article belongs to the Special Issue Water Use in Processing Industry)
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<p>SEM micrographs: BSG (<b>a</b>) 500× magnification and (<b>b</b>) 5000× magnification; commercial activated carbon (5 mm) (<b>c</b>) 500× magnification and (<b>d</b>) 5000× magnification; ACPO<sub>4</sub> (<b>e</b>) 500× magnification and (<b>f</b>) 5000× magnification.</p> Full article ">Figure 2
<p>N<sub>2</sub> measurements: (<b>a</b>) adsorption and desorption isotherm for BSG; (<b>b</b>) adsorption and desorption isotherm for the commercial activated carbon (5 mm); (<b>c</b>) adsorption and desorption isotherm for AC<sub>PO4</sub>; (<b>d</b>) pore size distribution.</p> Full article ">Figure 3
<p>FTIR spectra for (<b>a</b>) the BSG, (<b>b</b>) the commercial activated carbon (5 mm), and (<b>c</b>) AC<sub>PO4</sub>.</p> Full article ">Figure 4
<p>Point of zero charge for the adsorbents.</p> Full article ">Figure 5
<p>Effect of acid modification in cheese whey adsorption.</p> Full article ">Figure 6
<p>Effect of AC<sub>PO4</sub> dosage in cheese whey adsorption: (<b>a</b>) lactose; (<b>b</b>) BOD<sub>5</sub>; (<b>c</b>) COD.</p> Full article ">Figure 7
<p>AFO kinetic curves of cheese whey uptake. Conditions: adsorbent dosage of 2 g L<sup>−1</sup>, temperature of 25 °C, initial pH of 6.5.</p> Full article ">Figure 8
<p>Adsorption isotherms of cheese whey on AC<sub>PO4</sub> at different temperatures: (<b>a</b>) lactose; (<b>b</b>) BOD<sub>5</sub>; (<b>c</b>) COD. Conditions: adsorbent dosage of 2 g L<sup>−1</sup>, initial pH of 6.5, and contact time of 330 min.</p> Full article ">Figure 9
<p>Proposed adsorption mechanism for the adsorption of cheese whey onto AC<sub>PO4</sub>.</p> Full article ">Figure 10
<p>Recycle test for the adsorption of cheese whey onto AC<sub>PO4</sub>: (<b>a</b>) lactose; (<b>b</b>) BOD<sub>5</sub>; (<b>c</b>) COD.</p> Full article ">
13 pages, 261 KiB  
Article
The Impact of Aquaculture Cooperation Organization Support on Fish Farmers’ Selected Good Aquaculture Practices: Based on a Survey Data of 586 Fish Farmers in China
by Wei Yan, Panfeng Chai and Changbiao Zhong
Water 2023, 15(20), 3681; https://doi.org/10.3390/w15203681 - 20 Oct 2023
Cited by 2 | Viewed by 1946
Abstract
This study delves into the significance of integrating small-scale aquaculturists. Through a unique linkage mechanism established between aquaculture cooperative societies and these small-scale practitioners, characterized by mutual risk-bearing and benefit-sharing, there is not only an incentive for the adoption of advanced aquaculture techniques [...] Read more.
This study delves into the significance of integrating small-scale aquaculturists. Through a unique linkage mechanism established between aquaculture cooperative societies and these small-scale practitioners, characterized by mutual risk-bearing and benefit-sharing, there is not only an incentive for the adoption of advanced aquaculture techniques but also an enhancement of the overall quality and safety standards of aquatic produce. Utilizing the ordered probit model, the research sheds light on the profound influence of organizational support in guiding the selection of optimal aquaculture practices. Organizational support is bifurcated into two primary dimensions: emotional support and instrumental support. The empirical results indicate that the dual facets of support provided by aquaculture cooperatives significantly bolster the propensity of aquaculturists to adopt best practices. Specifically, for each unit increase in organizational support, there are marked rises of 12.3%, 17.3%, 18.3%, and 17% in activities including seedling inspection, procurement of quality feed, management of fish diseases, and external fish inspection, respectively. Crucially, the effect of instrumental support surpasses that of emotional backing, positioning it as a more dominant factor in guiding aquaculturists toward embracing optimal practices. Full article
(This article belongs to the Section Water, Agriculture and Aquaculture)
21 pages, 4601 KiB  
Article
Prediction of the Mine Water Inflow of Coal-Bearing Rock Series Based on Well Group Pumping
by Hongtao Zhai, Jucui Wang, Yangchun Lu, Zhenxing Rao, Kai He, Shunyi Hao, Aidi Huo and Ahmed Adnan
Water 2023, 15(20), 3680; https://doi.org/10.3390/w15203680 - 20 Oct 2023
Cited by 6 | Viewed by 1984
Abstract
Previous scholarly investigations have mainly concentrated on examining water intake, particularly within the specific domain of coal mines. Nevertheless, the scholarly discourse lacks significant research on predicting water inflow in environments with complex multi-layer mineral distributions. The Yanlong mining area is a complex [...] Read more.
Previous scholarly investigations have mainly concentrated on examining water intake, particularly within the specific domain of coal mines. Nevertheless, the scholarly discourse lacks significant research on predicting water inflow in environments with complex multi-layer mineral distributions. The Yanlong mining area is a complex mine containing coal and bauxite. Forecasting the water inflow of bauxite deposits is crucial for designing mining drainage and formulating a mining plan in a coal-bearing rock series mining area. The water inflow on the roof and floor of bauxite was studied with various numerical simulation and analytical methods (such as the big well method). The hydrogeological conceptual and numerical model of the mining area was established by the MODFLOW module in Groundwater Modeling System (GMS (7.1)) software, and the measured groundwater level was identified and verified in the model. The results show that the model average values of R2, Ens, and PBIAS are 0.86, 0.81 and 2.71, respectively, indicating that the established numerical simulation model can accurately forecast water inflow into the aquifer. Taking No. XII orebody in the eastern Songshan Mining area as an example, a virtual well group consisting of 12 wells was set up, and the numerical model forecast a water inflow of 71,500 m3/d from the Taiyuan Formation aquifer in the bauxite ore roof, which was lower than the value predicted by the large well method (72,786.66 m3/d). The numerical method predicted an average water inflow of 59,000 m3/d and a maximum water inflow of 82,600 m3/d from the Majiagou Formation in the bauxite ore floor. A dependence has been established that the numerical method estimates water inflow with accuracy. Additionally, the model predicts future mining water inflow, and also provides a standard framework for estimating inflow in similar mining conditions. Full article
(This article belongs to the Special Issue Hydrological Simulation for Erosion and Infiltration)
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<p>The Yanlong mining area. (<b>a</b>) Research area; (<b>b</b>) the Yanlong karst water system and subsystem in Henan Province; (<b>c</b>) the Yanlong karst water system and subsystem; (<b>d</b>) a plane view of the simulated area.</p> Full article ">Figure 2
<p>Formation generalization and aquifer properties.</p> Full article ">Figure 3
<p>(<b>a</b>) Parameter partition map of Shanxi formation; (<b>b</b>) parameter partition map of Taiyuan group.</p> Full article ">Figure 3 Cont.
<p>(<b>a</b>) Parameter partition map of Shanxi formation; (<b>b</b>) parameter partition map of Taiyuan group.</p> Full article ">Figure 4
<p>(<b>a</b>) Fitting the graph of simulated values and observed values of SJ02; (<b>b</b>) fitting the graph of simulated values and observed values of ZK2304.</p> Full article ">Figure 5
<p>(<b>a</b>) Iso-water level map of Taiyuan Formation; (<b>b</b>) iso-water level map of Majiagou Formation.</p> Full article ">Figure 6
<p>No. XII orebody map and dredging schematic diagram.</p> Full article ">Figure 7
<p>Distribution map of virtual pumping holes and iso-water lines in Taiyuan Formation, No. XII orebody roof, Songshan Mining area.</p> Full article ">Figure 8
<p>Distribution map of virtual pumping holes and iso-water lines in Majiagou Formation, No. XII orebody floor, Songshan Mining area.</p> Full article ">
20 pages, 3651 KiB  
Article
Improvement of the Carbocatalytic Degradation of Pharmaceuticals in Water by the Use of Ultrasound Waves
by Carolina Quimbaya-Ñañez, Efraím A. Serna-Galvis, Javier Silva-Agredo, Inés García-Rubio, Ricardo A. Torres-Palma and Yenny P. Ávila-Torres
Water 2023, 15(20), 3679; https://doi.org/10.3390/w15203679 - 20 Oct 2023
Cited by 2 | Viewed by 1601
Abstract
A carbonaceous material obtained from wood wastes (SW-Mn) was initially used for the removal of pharmaceuticals in water by a carbocatalytic system. The SW-Mn material adsorbed only 41% of the diclofenac (DCF) and 3% of the valsartan (VAL). Interestingly, SW-Mn activated peroxymonosulfate (PMS) [...] Read more.
A carbonaceous material obtained from wood wastes (SW-Mn) was initially used for the removal of pharmaceuticals in water by a carbocatalytic system. The SW-Mn material adsorbed only 41% of the diclofenac (DCF) and 3% of the valsartan (VAL). Interestingly, SW-Mn activated peroxymonosulfate (PMS) and presented a significant increase in the removal rate of DCF, surpassing 90%, while VAL achieved a 24% removal rate at 20 min of treatment. The carbonaceous material was not effective in activating peroxydisulfate or hydrogen peroxide. Nevertheless, the addition of ultrasound waves at 40 kHz to the carbocatalytic system (SW-Mn +PMS) significantly enhanced VAL degradation, exhibiting a high synergy index (4.98). The routes of the degradation were determined using scavengers, and XPS and EPR analyses, evidencing the main action of singlet oxygen in both carbocatalytic and sonocarbocatalytic systems. It is important to note that radicals also participated in the sonocarbocatalytic process, albeit with a minor contribution. The reuse of SW-Mn was tested during various cycles, showing up to a 39.2% VAL degradation rate after the third consecutive reuse. Moreover, the sonocarbocatalytic system was applied to a sample of irrigation crop water spiked with VAL. The treatment induced a partial elimination of the pollutant due to some interfering effects of the matrix components. Full article
(This article belongs to the Special Issue Recent Advances in Water and Wastewater Treatment)
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<p>Elimination of the target pollutants by PMS, adsorption, and carbocatalysis, after 30 min of treatment: (<b>a</b>) DCF; and (<b>b</b>) VAL. Conditions: pollutant = 0.0306 mM; PMS = 0.5 mM; SW-Mn = 0.5 g L<sup>−</sup><sup>1</sup>; V = 350 mL; matrix = distilled water; and initial pH = 5.8.</p> Full article ">Figure 2
<p>Effect of the ultrasound frequency on the sonocarbocatalytic treatment: (<b>a</b>) 40 kHz; and (<b>b</b>) 375 kHz. Conditions: pollutant = 0.0306 mM; PMS = 0.5 mM; SW-Mn = 0.5 g L<sup>−1</sup>; V = 350 mL; matrix = distilled water; and initial pH = 5.8.</p> Full article ">Figure 3
<p>Effect of the peroxide type (H<sub>2</sub>O<sub>2</sub>, PDS, and PMS) on the elimination of VAL by sonocarbocatalysis. Conditions: pollutant = 0.0306 mM; PMS = 0.5 mM; SW-Mn = 0.5 g L<sup>−</sup><sup>1</sup>; V= 350 mL; matrix = distilled water; frequency = 40 kHz; and initial pH = 5.8.</p> Full article ">Figure 4
<p>Effect of the initial pH (3.0, 5.8, and 9.0) on the elimination of VAL by sonocarbocatalysis. Conditions: pollutant = 0.0306 mM; PMS = 0.5 mM; SW-Mn = 0.5 g L<sup>−</sup><sup>1</sup>; V = 350 mL; matrix = distilled water; frequency = 40 kHz; and initial pH = 5.8.</p> Full article ">Figure 5
<p>Identification of ROS after 30 min of treatment. VAL elimination (%) by (<b>a</b>) carbocatalysis, and (<b>b</b>) sonocarbocatalysis. Condition: pollutant = 0.0306 mM; PMS = 0.5 mM; SW-Mn = 0.5 g L<sup>−</sup><sup>1</sup>; V = 350 mL; matrix = distilled water; frequency = 40 kHz; V = 350 mL; scavengers = 3 mM; and pH initial = 5.8 at 30 min.</p> Full article ">Figure 6
<p>EPR results for the interaction of SW-Mn with PMS: (<b>a</b>) participation of singlet oxygen; (<b>b</b>) participation of hydroxyl radical and superoxide.</p> Full article ">Figure 7
<p>XPS spectra for SW-Mn before treatment and after the third cycle of treatment in sonocarbocatalysis. Red arrow represents a zoom in of the orbital Mn 2p in the SW-Mn material after the 3rd cycle of reuse.</p> Full article ">Figure 8
<p>Reuse cycles for pollutant elimination. Conditions: pollutant = 0.0306 mM; PMS = 0.5 mM; SW-Mn = 0.5 g L<sup>−1</sup>; V= 350 mL; matrix = distilled water; frequency = 40 kHz; and initial pH = 5.8.</p> Full article ">Figure 9
<p>Elimination of VAL by sonocarbocatalysis in both distilled water and irrigation water. Conditions: pollutant = 0.0306 mM; catalyst = 0.5 g L<sup>−1</sup>; PMS = 0.5 mM; density power = 62.0 W L<sup>−1</sup>; frequency = 40 kHz; V = 350 mL; pH initial of distilled water = 5.8; and pH initial of irrigation water = 7.5.</p> Full article ">Figure 10
<p>The optimized geometries and HOMO and LUMO energies for SW-Mn interacting with PMS, PDS, and H<sub>2</sub>O<sub>2</sub>, which were calculated using BIOVIA Material Studio 2017 with the universal and Compass II force fields. Red line represents the HOMO orbital energy and black line is the LUMO orbital energy. In the figure of the SW-Mn + Oxidant interactions, grey balls: carbon atoms white balls: hydrogen atoms, red balls: oxygen atoms, small yellow balls linked to the red ones: sulfur atoms; and blue-yellow and violet-blue lobules: the orbital lobules.</p> Full article ">
11 pages, 2230 KiB  
Article
Occurrence of and Factors Affecting Groundwater Fluoride in the Western Coastal Area of Hainan Island, South China
by Ruinan Liu, Xiwen Li, Xiujiu Yang and Ming Zhang
Water 2023, 15(20), 3678; https://doi.org/10.3390/w15203678 - 20 Oct 2023
Viewed by 1384
Abstract
Hainan, a well-known center of tropical agricultural production in south China, has received little attention regarding groundwater fluoride contamination. This study investigates the occurrence of fluoride in the western coastal area of Hainan Island and discusses factors affecting groundwater fluoride contamination in various [...] Read more.
Hainan, a well-known center of tropical agricultural production in south China, has received little attention regarding groundwater fluoride contamination. This study investigates the occurrence of fluoride in the western coastal area of Hainan Island and discusses factors affecting groundwater fluoride contamination in various aquifers and areas with different land-use types using hydrochemistry and multivariate statistical analysis. A total of 100 groundwater samples were collected from the western coastal area of Hainan Island. The results show that the groundwater fluoride concentration is as high as 4.18 mg/L and that F−-high (>1 mg/L) groundwater accounts for 9% of total groundwater. The proportion of F−-high fissure water is about two times that of F−-high pore water. Among the different land-use types, the proportion of F−-high groundwater from highest to lowest is as follows: bare land > cultivated land > woodland > construction land > grassland. The main factor affecting fluoride in pore water is the leaching of fluorine/aluminum-containing minerals such as phlogopite and calcite in the vadose zone, which is characterized by the co-enrichment of fluoride and aluminum in pore water. The leading cause of fluoride in fissure water is the leaching of fluorine-containing fertilizers, and continuous irrigation promotes the cation exchange of sodium, strontium, and calcium, which is characterized by the co-enrichment of fluoride with sodium and strontium in fissure water. Consequently, it is advised to minimize the excessive use of fluoride fertilizers and increase groundwater quality monitoring in order to decrease the emergence of F−-high groundwater in the western coastal area of Hainan Island. Full article
(This article belongs to the Special Issue Groundwater Chemistry and Quality in Coastal Aquifers)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Hydrogeological division and sampling sites in the western coastal area of Hainan Island.</p> Full article ">Figure 2
<p>Groundwater fluoride concentrations in various aquifers and land-use types.</p> Full article ">Figure 3
<p>Proportion of F<sup>−</sup>-high groundwater in different land-use types.</p> Full article ">Figure 4
<p>Spatial distribution of fluoride concentrations interpolated using the inverse distance weighting (IDW) method.</p> Full article ">Figure 5
<p>Factor loadings for principal component analysis of (<b>a</b>) pore water and (<b>b</b>) fissure water.</p> Full article ">Figure 6
<p>Hierarchical cluster analysis of (<b>a</b>) pore water and (<b>b</b>) fissure water.</p> Full article ">Figure 7
<p>Relationship between the concentrations of F<sup>−</sup> and Na<sup>+</sup> and Sr in fissure water.</p> Full article ">
18 pages, 9391 KiB  
Article
Numerical Simulation and Application of a Channel Heat Sink with Diamond Ribs
by Dongxu Zhang, Guoqiang Liu, Yongkang Lai, Xiaohui Lin and Weihuang Cai
Water 2023, 15(20), 3677; https://doi.org/10.3390/w15203677 - 20 Oct 2023
Cited by 1 | Viewed by 1577
Abstract
This paper presents a channel radiator with ribbed ribs and primarily investigates the fluid flow and heat-transfer characteristics of the channel radiator. A three-dimensional numerical simulation of the radiator’s pressure-drop and heat-transfer process was conducted using the finite volume method. A comparison between [...] Read more.
This paper presents a channel radiator with ribbed ribs and primarily investigates the fluid flow and heat-transfer characteristics of the channel radiator. A three-dimensional numerical simulation of the radiator’s pressure-drop and heat-transfer process was conducted using the finite volume method. A comparison between the experimental data and the simulation results demonstrates that the simulation in this paper is accurate, with a maximum error not exceeding 5%. Furthermore, the radiator was further subjected to geometric parameter studies, principally including the height ratio between the fins and the channel, the fin angle, and the spacing between the fins. The thermal resistance, Nusselt number, friction factor, and heat-transfer enhancement factor were calculated. The results indicate that if the geometric parameters are selected appropriately, the heat sink will enhance heat-transfer performance within an acceptable pressure drop. When the Reynolds number is greater than 507.5, the height ratio of 25%, the rib angle of 135°, and the rib spacing of 2.5 mm can be given priority. This heat sink is used in PCR devices, and experimental results show that the novel channel heat sink can meet the heat dissipation requirements of the TEC during the PCR process. Full article
(This article belongs to the Section Hydraulics and Hydrodynamics)
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Figure 1

Figure 1
<p>Overall schematic diagram of heat sink.</p> Full article ">Figure 2
<p>Computational domain.</p> Full article ">Figure 3
<p>Experimental device.</p> Full article ">Figure 4
<p>Experimental principle.</p> Full article ">Figure 5
<p>Computational grid of heat sink.</p> Full article ">Figure 6
<p>Grid independence verification.</p> Full article ">Figure 7
<p>Validation of numerical model.</p> Full article ">Figure 8
<p>The simulation result: (<b>a</b>) Temperature; (<b>b</b>) Pressure; (<b>c</b>) Velocity.</p> Full article ">Figure 9
<p>The characteristics of heat sink: (<b>a</b>) The apparent friction factor for each channel; (<b>b</b>) The Nusselt numbers for each channel.</p> Full article ">Figure 10
<p>The influence of α on thermal hydraulic performance for the channel: (<b>a</b>) Thermal resistance; (<b>b</b>) Nusselt numbers ratio; (<b>c</b>) Apparent friction factor ratio; (<b>d</b>) Heat-transfer enhancement factor.</p> Full article ">Figure 11
<p>The influence of β on thermal hydraulic performance for the channel: (<b>a</b>) Thermal resistance; (<b>b</b>) Nusselt numbers ratio; (<b>c</b>) Apparent friction factor ratio; (<b>d</b>) Heat-transfer enhancement factor.</p> Full article ">Figure 12
<p>The influence of s on thermal hydraulic performance for the channel: (<b>a</b>) Thermal resistance; (<b>b</b>) Nusselt numbers ratio; (<b>c</b>) Apparent friction factor ratio; (<b>d</b>) Heat-transfer enhancement factor.</p> Full article ">Figure 13
<p>Application of heat sinks.</p> Full article ">Figure 14
<p>Temperature of the heat-conducting sheet surface, T<sub>H</sub>.</p> Full article ">
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