Water

15 pages, 6131 KiB

Open AccessArticle

Numerical Simulation of River Channel Change in the Suspended Sediment-Dominated Downstream Reach of the Sangu River

by Md. Majadur Rahman, Daisuke Harada and Shinji Egashira

Water 2024, 16(13), 1934; https://doi.org/10.3390/w16131934 - 8 Jul 2024

Viewed by 1248

This study aims to clarify the characteristics of the riverbed deformation, bank erosion, and channel changes in the lower Sangu River basin using a depth-averaged 2-D flow model where suspended sediment transport is dominant and its flow characteristics are influenced by active tides. [...] Read more.

This study aims to clarify the characteristics of the riverbed deformation, bank erosion, and channel changes in the lower Sangu River basin using a depth-averaged 2-D flow model where suspended sediment transport is dominant and its flow characteristics are influenced by active tides. A 45 km long area including the river mouth is computed using the 2-D model, and the results are compared with the observed channel changes. The computation results show that bed deformation and channel change are mainly caused during the ebb tide period of the spring tide particularly in an area of about 10 km from the river mouth. The detail study domain calculation results show that the flow concentration at the bend area causes the bed erosion there, and the eddy separated from the main stream causes the sediment deposition at the inner bank, while this eddy is not developed at the outer bank, resulting in the bank erosion there. Through these investigations, the characteristics and mechanisms of the morphodynamics in the lower Sangu River reach, particularly the potential of the combination of tides and floods to enhance riverbed deformations and the associated bank shifts, have been clarified. Full article

(This article belongs to the Special Issue Challenges to Interdisciplinary Application of Hydrodynamic Models)

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24 pages, 918 KiB

Open AccessReview

Systematic Review of Poultry Slaughterhouse Wastewater Treatment: Unveiling the Potential of Nanobubble Technology

by Ephraim Kaskote, Moses Basitere, Vusi Vincent Mshayisa and Marshall Sheerene Sheldon

Water 2024, 16(13), 1933; https://doi.org/10.3390/w16131933 - 8 Jul 2024

Viewed by 1226

Abstract

Aeration is crucial for the biological decomposition of organic compounds in wastewater treatment. However, it is a highly energy-intensive process in traditional activated sludge systems, accounting for 50% to 75% of a plant’s electricity consumption and making it a major cost driver for [...] Read more.

Aeration is crucial for the biological decomposition of organic compounds in wastewater treatment. However, it is a highly energy-intensive process in traditional activated sludge systems, accounting for 50% to 75% of a plant’s electricity consumption and making it a major cost driver for wastewater treatment plants. Nanobubbles (NBs), characterized by their tiny size with diameters less than 200 nm, have emerged as a potential alternative to the low efficiency of aeration and high sludge production in aeration systems. NBs proved effective in removing COD and other pollutants from wastewater. For example, when applied in flotation, aeration, and advanced oxidation, NBs achieved up to 95%, 85%, and 92.5% COD removal, respectively. Considering the recent advancements in wastewater treatment, a compelling need arises for a thorough investigation of the effectiveness and mechanisms of nanobubbles in this field. This systematic review summarizes recent advancements in understanding nanobubbles (NBs) and their unique properties that enhance physical, chemical, and biological water and wastewater treatment processes. Moreover, this study reviews various methods for generating NBs and provides an in-depth review of their applications in wastewater treatment, with a particular focus on poultry slaughterhouse wastewater (PSW) treatment. Full article

(This article belongs to the Section Wastewater Treatment and Reuse)

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19 pages, 6233 KiB

Open AccessArticle

Sampling and Analysis of Microplastics in the Coastal Environments of Sri Lanka: Estuaries of the Kelani River to Mahaoya

by P. G. Y. W. Weerasekara, D. S. M. De Silva, R. C. L. De Silva, A. A. D. Amarathunga, A. Bakir, A. R. McGoran, D. B. Sivyer and C. Reeve

Water 2024, 16(13), 1932; https://doi.org/10.3390/w16131932 - 8 Jul 2024

Viewed by 1729

Abstract

Microplastic pollution (MP) in marine environments around the globe is severe and insufficient precautions have yet to be taken for its prevention. The focus of this study was on quantifying MPs from beach sediment and seawater samples and identifying their distributions and types [...] Read more.

Microplastic pollution (MP) in marine environments around the globe is severe and insufficient precautions have yet to be taken for its prevention. The focus of this study was on quantifying MPs from beach sediment and seawater samples and identifying their distributions and types along the western coast of Sri Lanka from the Kelani River estuary to the Mahaoya estuary. Nine sites along this 42 km stretch were selected, and random sampling was employed to collect a minimum of eight sediment samples from each site between October and December 2021. Water samples were also collected, parallel to the sediments, from the ocean surface. FTIR analysis revealed that most of the MPs found were polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), and phenol formaldehyde resin. The mean abundance of MPs varied from 2.0 ± 0.6 items/L to 161.0 ± 15.7 items/L in water samples and from 3.0 ± 0.3 items/m² to 656.0 ± 34.5 items/m² in sediment samples. The MPs found were identified in different shapes as fragments (80.2%), pellets (14.9%), fibers (2.7%), and foams (2.5%). Analysis revealed that the beach sediments were contaminated with PS, phenol formaldehyde resin, PET, PP, and PE, while the surface seawater was dominated by phenol formaldehyde resin, PS, PP, and PE. Full article

(This article belongs to the Section Oceans and Coastal Zones)

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29 pages, 5638 KiB

Open AccessArticle

Green Infrastructure Microbial Community Response to Simulated Pulse Precipitation Events in the Semi-Arid Western United States

by Yvette D. Hastings, Rose M. Smith, Kyra A. Mann, Simon Brewer, Ramesh Goel, Sarah Jack Hinners and Jennifer Follstad Shah

Water 2024, 16(13), 1931; https://doi.org/10.3390/w16131931 - 7 Jul 2024

Viewed by 918

Abstract

Processes driving nutrient retention in stormwater green infrastructure (SGI) are not well quantified in water-limited biomes. We examined the role of plant diversity and physiochemistry as drivers of microbial community physiology and soil N dynamics post precipitation pulses in a semi-arid region experiencing [...] Read more.

Processes driving nutrient retention in stormwater green infrastructure (SGI) are not well quantified in water-limited biomes. We examined the role of plant diversity and physiochemistry as drivers of microbial community physiology and soil N dynamics post precipitation pulses in a semi-arid region experiencing drought. We conducted our study in bioswales receiving experimental water additions and a montane meadow intercepting natural rainfall. Pulses of water generally elevated soil moisture and pH, stimulated ecoenzyme activity (EEA), and increased the concentration of organic matter, proteins, and N pools in both bioswale and meadow soils. Microbial community growth was static, and N assimilation into biomass was limited across pulse events. Unvegetated plots had greater soil moisture than vegetated plots at the bioswale site, yet we detected no clear effect of plant diversity on microbial C:N ratios, EEAs, organic matter content, and N pools. Differences in soil N concentrations in bioswales and the meadow were most directly correlated to changes in organic matter content mediated by ecoenzyme expression and the balance of C, N, and P resources available to microbial communities. Our results add to growing evidence that SGI ecological function is largely comparable to neighboring natural vegetated systems, particularly when soil media and water availability are similar. Full article

(This article belongs to the Special Issue Soil and Water Resources Management through Nature-Based Solutions: A Multidisciplinary Approach)

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23 pages, 25329 KiB

Open AccessArticle

Benchmarking Physical Model Experiments with Numerical Simulations for the Wangjiashan Landslide-Induced Surge Waves in the Baihetan Reservoir Area

by Anchi Shi, Jie Lei, Lei Tian, Changhao Lyu, Pengchao Mao and Weiya Xu

Water 2024, 16(13), 1930; https://doi.org/10.3390/w16131930 - 7 Jul 2024

Cited by 1 | Viewed by 781

Abstract

The Baihetan Hydropower Station reservoir area began impoundment in 2021, triggering the reactivation of ancient landslides and the formation of new ones. This not only caused direct landslide disasters but also significantly increased the likelihood of secondary surge wave disasters. This study takes [...] Read more.

The Baihetan Hydropower Station reservoir area began impoundment in 2021, triggering the reactivation of ancient landslides and the formation of new ones. This not only caused direct landslide disasters but also significantly increased the likelihood of secondary surge wave disasters. This study takes the Wangjiashan (WJS) landslide in the Baihetan reservoir area as an example and conducts large-scale three-dimensional physical model experiments. Based on the results of the physical model experiments, numerical simulation is used as a comparative verification tool. The results show that the numerical simulation method effectively reproduces the formation and propagation process of the WJS landslide-induced surge waves observed in the physical experiments. At the impoundment water level of 825 m, the surge waves generated by the WJS landslide pose potential threats to the Xiangbiling (XBL) residential area. In this study, the numerical simulation based on computational fluid dynamics confirmed the actual propagation forms of the surge waves, aligning well with the results of the physical experiments at a microscopic scale. However, at a macroscopic scale, there is some discrepancy between the numerical simulation results and the physical experiment outcomes, with a maximum error of 25%, primarily stemming from the three-dimensional numerical source model. This study emphasizes the critical role of physical model experiments in understanding and mitigating surge wave disasters in China. Furthermore, physical experiments remain crucial for accurate disaster prediction and mitigation strategies. The theories and methods used in this study will provide important references for future research related to landslide disasters in reservoir areas. Full article

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15 pages, 1682 KiB

Open AccessArticle

Evaluating the Effect of Common Carp Control on Restoration of a Coastal Wetland in the Laurentian Great Lakes

by Daniel J. Moore and Nicholas E. Mandrak

Water 2024, 16(13), 1929; https://doi.org/10.3390/w16131929 - 7 Jul 2024

Viewed by 690

Abstract

Great Lakes coastal wetlands are under considerable stress from numerous anthropogenic threats, including the introduction of invasive species. Common Carp, an invasive species in North America, has been well documented as an influential wetland stressor. This study documents the impact of Common Carp [...] Read more.

Great Lakes coastal wetlands are under considerable stress from numerous anthropogenic threats, including the introduction of invasive species. Common Carp, an invasive species in North America, has been well documented as an influential wetland stressor. This study documents the impact of Common Carp reintroduction on a restored wetland fish community and abiotic and vegetation variables. Oshawa Second Marsh was restored using an exclusion berm with a fish grate and manual water-level drawdown to re-establish vegetation. Five years into restoration monitoring, Common Carp regained access to the wetland after the fish grate was vandalized. Fish community health was monitored over time using multimetric and multivariate approaches based on abiotic and vegetation variables. Improvements in fish community health were observed during restoration monitoring, but after Common Carp reintroduction, fish community health decreased and the community homogenized. Seven of the ten abiotic and vegetation variables monitored changed significantly after Common Carp reintroduction. This study highlights the impact that Common Carp has on the functional integrity of coastal wetlands and the significance of its management for restoration. Full article

(This article belongs to the Special Issue Biodiversity of Freshwater Ecosystems: Monitoring and Conservation)

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16 pages, 4018 KiB

Open AccessArticle

An Integrated Process of Struvite Precipitation/Membrane Filtration Using Flat Ceramic Membranes Is an Effective Method for the Treatment of Liquid Fraction Digestate from a Municipal Biogas Plant

by Agnieszka Urbanowska and Izabela Polowczyk

Water 2024, 16(13), 1928; https://doi.org/10.3390/w16131928 - 6 Jul 2024

Viewed by 730

Abstract

One method of processing municipal waste biogas plant digestate is to separate it into solid and liquid fractions. Since the digestate can be a potential source of water, it must undergo the appropriate treatment. Pressurised membrane processes preceded by struvite precipitation can be [...] Read more.

One method of processing municipal waste biogas plant digestate is to separate it into solid and liquid fractions. Since the digestate can be a potential source of water, it must undergo the appropriate treatment. Pressurised membrane processes preceded by struvite precipitation can be particularly useful in this regard. Experiments were conducted to determine the effectiveness of treating the digestate liquid fraction from a municipal waste biogas plant using an integrated process that combines struvite precipitation with membrane filtration, employing flat ceramic membranes with different cut-off values. The results confirm that this integrated process is effective for digestate treatment. A significantly increased improvement in the final quality of the test solution and a reduction in membrane fouling intensity were observed compared to those of these processes conducted separately. It is noteworthy that the purest solution was obtained when struvite precipitation and filtration through a flat ceramic membrane with a cut-off of 1 kDa were combined. This approach enabled the precipitation of struvite, a valuable fertiliser; the protection of the membranes from fouling; and a high degree of organic compound removal. The recovered water from the digestate (after dilution or removal of excess salts) can be used in agriculture or horticulture. Full article

(This article belongs to the Special Issue Application of Membrane Separation Technology in Water and Wastewater Treatment)

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16 pages, 2121 KiB

Open AccessArticle

Development of a Constructed Wetland for Greywater Treatment for Reuse in Arid Regions: Case Study in Rural Burkina Faso

by Ynoussa Maiga, Cheik Omar Tidiane Compaoré, Martine Diallo/Koné, Seyram Kossi Sossou, Hermann YempalaSomé, Mamady Sawadogo, Issa Nagalo, James R. Mihelcic and Aboubakar Sidiki Ouattara

Water 2024, 16(13), 1927; https://doi.org/10.3390/w16131927 - 6 Jul 2024

Viewed by 1048

Abstract

This study implemented and assessed, over a period of four weeks, a full-scale constructed wetland designed to collect and treat the greywater for a rural household located in an arid environment typical of Africa’s Sahel region. The system was constructed from local materials [...] Read more.

This study implemented and assessed, over a period of four weeks, a full-scale constructed wetland designed to collect and treat the greywater for a rural household located in an arid environment typical of Africa’s Sahel region. The system was constructed from local materials and consisted of a shower room, a receiving basin, a pre-treatment filter, and a subsurface horizontal flow wetland planted with Chrysopogon zizanioides. Results showed the overall removal of organic matter was greater than 90%, and orthophosphate and ammonium were reduced by 73% and 60%, respectively, allowing for the treated water to retain some embedded nutrients. The removal efficiency of fecal bacteria varied from 3.41 (enterococci) to 4.19 (fecal coliforms) log10 units which meets World Health Organization Guidelines for restricted irrigation. Our assessment of the full-scale household constructed wetland technology adds to the relatively low number of constructed wetland studies conducted outside a laboratory setting. Furthermore, it supports efforts to promote safe reuse of an underutilized resource at the rural household level in Sub-Saharan Africa and other arid regions in the developing world, supporting prospects for using treated greywater for agricultural reuse in regions that experience water scarcity, climate variability, and land degradation. Full article

(This article belongs to the Special Issue Water Management in Arid and Semi-arid Regions)

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Graphical abstract

14 pages, 10342 KiB

Open AccessArticle

Mesocosm Experiment to Evaluate Relations between Chlorophyll-a Concentration and Water Surface Reflectance in an Anthropogenic Reservoir

by Łukasz Pierzchała

Water 2024, 16(13), 1926; https://doi.org/10.3390/w16131926 - 5 Jul 2024

Viewed by 838

Abstract

This paper presents the results of a mesocosm experiment for the evaluation of remote sensing chlorophyll-a (chl-a) concentration estimations in an anthropogenic water reservoir. The chl-a presence in the water causes changes in the water surface reflectance spectrum, especially in the green and [...] Read more.

This paper presents the results of a mesocosm experiment for the evaluation of remote sensing chlorophyll-a (chl-a) concentration estimations in an anthropogenic water reservoir. The chl-a presence in the water causes changes in the water surface reflectance spectrum, especially in the green and red part, but many factors could affect the remote measurements of chl-a content. The in situ mesocosm method of the experiment was used for investigating the spectral reflectance of the inland water surface in a wide range of chl-a concentrations. Eight specially designed measurement boxes were placed into the water. In half of the boxes, the devices to support the development of the submerged water plant were installed. During the experiment, simultaneously, spectral data from the water surface were gathered and physical–chemical analyses of water were carried out. The obtained results confirm the usefulness of the mesocosm experiment for the remote sensing chl-a concentration algorithms being developed. The concentration of dissolved organic carbon was identified as a key factor that interfered with remote chl-a estimations in the analyzed reservoir. Full article

(This article belongs to the Special Issue Water Pollution Monitoring, Control, and Remediation)

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18 pages, 2073 KiB

Open AccessArticle

Numerical Study on the Influence of Installation Height and Operating Frequency of Biomimetic Pumps on the Incipient Motion of Riverbed Sediment

by Ertian Hua, Yabo Song, Caiju Lu, Mingwang Xiang, Tao Wang and Qizong Sun

Water 2024, 16(13), 1925; https://doi.org/10.3390/w16131925 - 5 Jul 2024

Viewed by 629

Abstract

Biomimetic pumps can effectively enhance the hydrodynamics of plain river networks, improve the water environment, and facilitate the transport of sticky bottom sediment. In this paper, a biomimetic pump equipped with an NACA0012 wing profile was used as the research subject, and a [...] Read more.

Biomimetic pumps can effectively enhance the hydrodynamics of plain river networks, improve the water environment, and facilitate the transport of sticky bottom sediment. In this paper, a biomimetic pump equipped with an NACA0012 wing profile was used as the research subject, and a commercial CFD package was employed to investigate the impact of the pump’s installation height (the vertical distance from the hydrofoil’s pivot to the riverbed) and operating frequency on the incipient motion of riverbed sediment. The results indicate that the lowest maximum near-bed velocity is obtained at an installation height of 3 times the chord length (3 c) and operating frequency of 0.5 Hz, while the highest is reached at 4 c and 5 Hz. The maximum near-bed velocity point is the furthest from the biomimetic pump when the installation height is 3 c and the operating frequency is 0.5 Hz and the closest at 4 c and 0.5 Hz. At a fixed installation height, a quadratic relationship is found between the maximum near-bed velocity and the operating frequency. At installation heights of c, 2 c, and 4 c, the effect of operating frequency on the point of action is minimal, with only a sudden change followed by stability at 3 c as the frequency increases. When the operating frequency is fixed and the installation height is increased, the maximum near-bed velocity initially decreases and then rises, being the smallest at 3 c. The distance between the point of maximum near-bed velocity and the biomimetic pump initially increases and then decreases with increasing installation height, being the farthest at 3 c. Furthermore, in this paper, we fitted mathematical expressions for the maximum near-bed velocity relative to the operating frequency under different installation heights of the biomimetic pump and calculated the threshold frequencies for the incipient motion of sediment at installation heights of c, 2 c, 3 c, and 4 c to be 1.15 Hz, 1.64 Hz, 2.85 Hz, and 1.06 Hz, respectively, providing scientific guidance for the application of biomimetic pumps in various scenarios. Full article

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12 pages, 7772 KiB

Open AccessArticle

Observations of Tide- and Wave-Driven Groundwater Dynamics in Meso-Tidal Sandy Beach

by Emilie Woussen, Damien Sous and Nadia Sénéchal

Water 2024, 16(13), 1924; https://doi.org/10.3390/w16131924 - 5 Jul 2024

Viewed by 637

Abstract

This study focuses on the non-hydrostatic groundwater dynamics of a meso-tidal sandy beach under the influence of tides and waves. A field campaign was conducted at Lacanau Beach, France, during four consecutive tide cycles in March 2022. Groundwater dynamics was monitored based on [...] Read more.

This study focuses on the non-hydrostatic groundwater dynamics of a meso-tidal sandy beach under the influence of tides and waves. A field campaign was conducted at Lacanau Beach, France, during four consecutive tide cycles in March 2022. Groundwater dynamics was monitored based on a network of buried pressure sensors. The data analysis revealed the combined influences of waves and tides on the groundwater circulation. Tidal-scale groundwater flows are predominantly seaward, primarily controlled by the head gradient resulting from a high coastal aquifer. A circulation cell develops under the swash zone and moves across the beachface following the tidal oscillations. On a daily scale per alongshore and vertical units, the observed flow is 2.5

m^{3} . m^{- 2} . {day}^{- 1}

, i.e., 912.5

m^{3} . m^{- 2} . {year}^{- 1}

. Extrapolating the present dataset, it may be expected that combined events, such as drought-induced aquifer depletion with high tides, could lead to beach-scale gradient reversal, potentially causing salinisation of the continental aquifer. Full article

(This article belongs to the Section Oceans and Coastal Zones)

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13 pages, 2012 KiB

Open AccessArticle

Distribution and Comprehensive Risk Evaluation of Cr, Cd, Fe, Zn, and Pb from Al Lith Coastal Seawater, Saudi Arabia

by Talal Alharbi, Abdelbaset S. El-Sorogy and Khaled Al-Kahtany

Water 2024, 16(13), 1923; https://doi.org/10.3390/w16131923 - 5 Jul 2024

Viewed by 709

Abstract

Seawater contamination is a global challenge due to its hazardous effects on marine organisms and human health. Twenty-three surface seawater samples were collected from the Al Lith intertidal area along the Saudi Red Sea coast to evaluate the ecological risks and document the [...] Read more.

Seawater contamination is a global challenge due to its hazardous effects on marine organisms and human health. Twenty-three surface seawater samples were collected from the Al Lith intertidal area along the Saudi Red Sea coast to evaluate the ecological risks and document the potential sources of Cr, Cd, Fe, Zn, and Pb. Contamination factor (CF), contamination degree (Cd), water quality index (WQI), and heavy metal pollution index (HPI), as well as multivariate tools were applied. The average concentrations of HMs (μg/L) had the following order: Zn (6.616) > Pb (0.284) > Cd and Cr (0.268) > Fe (0.197). CF results showed moderate contamination of seawater with Cd and low contamination of Cr, Fe, Zn, and Pb. However, 26.09% of the samples showed considerable contamination with Cd. Average Cd values revealed low contamination with HMs, while 17.39% of the samples showed moderate contamination. HPI average values indicated medium pollution of Al Lith seawater, while 13 samples reported high pollution. The higher HPI values were reported in samples characterized by higher concentrations of HMs, particularly Cd and Zn. Correlation matrix and principal component analysis suggested anthropogenic sources for Pb and Zn, mostly from industrial and agricultural effluents, landfilling, and domestic wastewater, apart from their natural sources. Full article

(This article belongs to the Special Issue Coastal Processes and Climate Change)

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28 pages, 8168 KiB

Open AccessArticle

Subsurface Hydrodynamics of the Southeastern Taoudéni Basin (West Africa) through Hydrogeochemistry and Isotopy

by Succès Malundama Kutangila, Moussa Bruno Kafando, Amadou Keita, Lawani Adjadi Mounirou, Roland Yonaba, Mahamadi Ouedraogo and Mahamadou Koita

Water 2024, 16(13), 1922; https://doi.org/10.3390/w16131922 - 5 Jul 2024

Viewed by 993

Abstract

The Taoudéni Basin, spanning 20% of Burkina Faso, holds vital aquifers for the Sahel’s water security and development. However, limited understanding of these aquifers’ hydrodynamics, including the flow patterns, mineralization processes, and renewal rates, hinders sustainable management practices in this arid region. Therefore, [...] Read more.

The Taoudéni Basin, spanning 20% of Burkina Faso, holds vital aquifers for the Sahel’s water security and development. However, limited understanding of these aquifers’ hydrodynamics, including the flow patterns, mineralization processes, and renewal rates, hinders sustainable management practices in this arid region. Therefore, this study aims to investigate the aquifer hydrodynamics, mineralization processes and groundwater renewal in the transboundary Taoudéni Basin. Through a combination of hydrogeochemical and isotopic analyses, alongside existing data, this study examines 347 physicochemical samples, 149 stable isotope samples, and 71 tritium samples collected from 2013 to 2022. The findings reveal mineralization and stable isotopes (δ¹⁸O, δ²H) spatially aligned with the groundwater flow direction, validating this and indicating potentially multiple independent aquifers. The predominant mineralization mechanisms involve silicate hydrolysis and carbonate dissolution, supplemented by minor processes like evaporitic dissolution and cation exchange. The anthropogenic influence suggests potential groundwater recharge with potential pollution in the “SAC1”, “SAC2”, “GFR”, “GGQ”, and “GKS” geological formations. The stable isotopes (δ¹⁸O, δ²H) indicate recharge occurred over 4.5 kyr B.P., while tritium (3H) analysis confirms the presence of old, mixed waters, indicating slow renewal. Overall, this study highlights the minimal recent recharge and limited renewal rates, questions tritium’s efficacy for old water detection, and emphasizes the need for sustainable management. Full article

(This article belongs to the Section Hydrogeology)

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16 pages, 2859 KiB

Open AccessArticle

Assessment of Changes in Hydrometeorological Indicators and Intra-Annual River Runoff in the Ile River Basin

by Rustam G. Abdrakhimov, Aigul N. Akzharkynova, Javier Rodrigo-Ilarri, Kh Md Nahiduzzaman, Makpal E. Dautaliyeva and María-Elena Rodrigo-Clavero

Water 2024, 16(13), 1921; https://doi.org/10.3390/w16131921 - 5 Jul 2024

Viewed by 959

Abstract

Water management strategies in the Ile River basin (Republic of Kazakhstan) have traditionally relied on historical data without fully considering the potential impacts of climate change. This gap can lead to underestimating the changes in temperature, precipitation patterns, and runoff, hindering effective water [...] Read more.

Water management strategies in the Ile River basin (Republic of Kazakhstan) have traditionally relied on historical data without fully considering the potential impacts of climate change. This gap can lead to underestimating the changes in temperature, precipitation patterns, and runoff, hindering effective water resource management. This study aimed to analyze how a changing climate is affecting the Ile River basin’s water regime. Specifically, it investigated trends in temperature, precipitation, and runoff within the basin, emphasizing the importance of incorporating these intra-annual variations when planning water management strategies and hydraulic structures. A detailed analysis of the long-term data was conducted, focusing on changes in meteorological indicators. This included average air temperatures and annual precipitation for elevations above and below 1500 m during cold and warm periods. The analysis aimed to identify and quantify trends of increase or decrease. Meteorological stations were strategically chosen to represent both arid and humid areas within the basin, accounting for the region’s significant altitude variations. The investigation revealed several key findings. Rising average annual air temperatures are leading to a larger area experiencing snowmelt and a longer warm period within the runoff formation zone. This directly impacts the water balance of the basin. Additionally, an increase in total annual precipitation, particularly during the cold season within the runoff formation zone, suggests a potential for future water resource growth, assuming that these trends persist. This study highlights the importance of considering intra-annual variations in water regimes when developing water management strategies. The observed changes in temperature and precipitation patterns within the Ile River basin necessitate adjustments to existing plans to ensure sustainable water resource management in a changing climate. Full article

(This article belongs to the Special Issue Impacts of Climate Change on Water Resources: Assessment and Modeling)

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19 pages, 3923 KiB

Open AccessReview

The Status of Research on the Root Exudates of Submerged Plants and Their Effects on Aquatic Organisms

by Yahan Shi, Xu Zhang, Min Zhao, Xiangyong Zheng, Jianya Gu, Zhiquan Wang, Chunzhen Fan and Wenwen Gu

Water 2024, 16(13), 1920; https://doi.org/10.3390/w16131920 - 5 Jul 2024

Viewed by 935

Abstract

The ecological restoration of submerged plants is one of the most widely used technologies in the remediation of eutrophic water bodies. This technology mainly removes nitrogen, phosphorus, and other nutrients in water through the absorption effects of plant roots, stems, and leaves and [...] Read more.

The ecological restoration of submerged plants is one of the most widely used technologies in the remediation of eutrophic water bodies. This technology mainly removes nitrogen, phosphorus, and other nutrients in water through the absorption effects of plant roots, stems, and leaves and the biotransformation of microorganisms attached to their surfaces. Root exudates can directly affect root-attached microorganisms and other aquatic organisms, thus significantly influencing water remediation by submerged plants. At present, there are few reviews on the root exudates of submerged plants and their effects on aquatic organisms. In this study, the composition, collection, and methods of detecting the root exudates of submerged plants are reviewed. Factors affecting the release of root exudates from submerged plants are analyzed, including abiotic (light, temperature, and nutritional status) and biotic factors (rhizosphere microorganisms). The positive or negative effects of root exudates on phytoplankton, zooplankton, and microorganisms are also discussed. The results show that plant species, growth stages, and environmental factors (light, temperature, and nutritional status) are crucial factors affecting root exudates. In addition, submerged plants can significantly influence phytoplankton, zooplankton, and microorganisms by releasing allelochemicals or other root exudates. Based on the results of this study, the influencing mechanisms of root exudates on ecological restoration processes by submerged plants are clarified. This review provides important guiding significance for applying submerged macrophytes in water restoration. Full article

(This article belongs to the Special Issue Constructed Wetlands as a Sustainable Technology for Wastewater Treatment: Current Trends and Future Potential)

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18 pages, 8263 KiB

Open AccessArticle

Inversion Method for Monitoring Daily Variations in Terrestrial Water Storage Changes in the Yellow River Basin Based on GNSS

by Wenqing Zhang and Xiaoping Lu

Water 2024, 16(13), 1919; https://doi.org/10.3390/w16131919 - 5 Jul 2024

Viewed by 697

Abstract

The uneven distribution of global navigation satellite system (GNSS) continuous stations in the Yellow River Basin, combined with the sparse distribution of GNSS continuous stations in some regions and the weak far-field load signals, poses challenges in using GNSS vertical displacement data to [...] Read more.

The uneven distribution of global navigation satellite system (GNSS) continuous stations in the Yellow River Basin, combined with the sparse distribution of GNSS continuous stations in some regions and the weak far-field load signals, poses challenges in using GNSS vertical displacement data to invert terrestrial water storage changes (TWSCs). To achieve the inversion of water reserves in the Yellow River Basin using unevenly distributed GNSS continuous station data, in this study, we employed the Tikhonov regularization method to invert the terrestrial water storage (TWS) in the Yellow River Basin using vertical displacement data from network engineering and the Crustal Movement Observation Network of China (CMONOC) GNSS continuous stations from 2011 to 2022. In addition, we applied an inverse distance weighting smoothing factor, which was designed to account for the GNSS station distribution density, to smooth the inversion results. Consequently, a gridded product of the TWS in the Yellow River Basin with a spatial resolution of 0.5 degrees on a daily scale was obtained. To validate the effectiveness of the proposed method, a correlation analysis was conducted between the inversion results and the daily TWS from the Global Land Data Assimilation System (GLDAS), yielding a correlation coefficient of 0.68, indicating a strong correlation, which verifies the effectiveness of the method proposed in this paper. Based on the inversion results, we analyzed the spatial–temporal distribution trends and patterns in the Yellow River Basin and found that the average TWS decreased at a rate of 0.027 mm/d from 2011 to 2017, and then increased at a rate of 0.010 mm/d from 2017 to 2022. The TWS decreased from the lower-middle to lower reaches, while it increased from the upper-middle to upper reaches. Furthermore, an attribution analysis of the terrestrial water storage changes in the Yellow River Basin was conducted, and the correlation coefficients between the monthly average water storage changes inverted from the results and the monthly average precipitation, evapotranspiration, and surface temperature (AvgSurfT) from the GLDAS were 0.63, −0.65, and −0.69, respectively. This indicates that precipitation, evapotranspiration, and surface temperature were significant factors affecting the TWSCs in the Yellow River Basin. Full article

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17 pages, 3236 KiB

Open AccessArticle

Flash Flood Potential Analysis and Hazard Mapping of Wadi Mujib Using GIS and Hydrological Modelling Approach

by Moayyad Shawaqfah, Yazan Ababneh, Alhaj-Saleh A. Odat, Fares AlMomani, Alaa Alomush, Fayez Abdullah and Hatem H. Almasaeid

Water 2024, 16(13), 1918; https://doi.org/10.3390/w16131918 - 5 Jul 2024

Cited by 1 | Viewed by 861

Abstract

Jordan experienced flash floods that resulted in numerous fatalities and injuries. This research focuses on identifying the Wadi Mujib’s flash flood potential zones and evaluating their potential magnitude. In this work, hydrological models were developed by integrating GIS settings with HEC-HMS software (V. [...] Read more.

Jordan experienced flash floods that resulted in numerous fatalities and injuries. This research focuses on identifying the Wadi Mujib’s flash flood potential zones and evaluating their potential magnitude. In this work, hydrological models were developed by integrating GIS settings with HEC-HMS software (V. 4.11). The hydrological model for Wadi Mujib is simulated in this research by means of the Soil Conservation Service (curve number method) while using rainfall data from 1970 to 2022. The results show that the optimum curve number values (CN) were 78.5 at normal antecedent moisture content. Additionally, in order to aid in the decision-making process for flash flood warnings, a flash flood potential index (FFPI) was also introduced based on four main physiographic parameters (slope, land use, plant cover, and soil texture) ranging from 1 to 10. The accumulative chart’s FFPI threshold, which indicates the areas with the highest potential for flash floods, was set at 95% or above. The FFPI threshold was chosen using the accumulative chart of FFPI, which shows that the FFPM threshold value is 7 and covers 13.39% of the study area. Full article

(This article belongs to the Special Issue Advances in Aquifer Systems Analysis: Flows, Interactions, Quality Status, and Remediation)

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18 pages, 4097 KiB

Open AccessArticle

Enhanced Remediation of Lead and Cadmium by the Co-System of Phosphate-Solubilizing Bacteria Immobilized on Goethite-Modified Biochar

by Gongduan Fan, Junhou Zhou, Xingfeng Cao, Wu You, Chen Lin, Jing Luo, Jianyong Zou, Kai-Qin Xu and Quanda Luo

Water 2024, 16(13), 1917; https://doi.org/10.3390/w16131917 - 5 Jul 2024

Viewed by 703

Abstract

Bioremediation has drawn widespread concern in passivating heavy metals, but the intense toxicity of heavy metals to biological cells limits the application of functional strains. Herein, goethite-modified biochar (GMB) was chosen as the carrier to immobilize phosphate-solubilizing bacteria (PSB) of strain L1 for [...] Read more.

Bioremediation has drawn widespread concern in passivating heavy metals, but the intense toxicity of heavy metals to biological cells limits the application of functional strains. Herein, goethite-modified biochar (GMB) was chosen as the carrier to immobilize phosphate-solubilizing bacteria (PSB) of strain L1 for lead and cadmium remediation. Batch experiments showed that the GMB-L1 possessed excellent adsorption performance with a maximum adsorption of 496.54 and 178.18 mg/g for Pb and Cd, respectively. Moreover, adding GMB-L1 in contaminated soil converted heavy metals (Pb and Cd) into more stable fractions and reduced TCLP-extracted heavy metal concentrations (73.24% of Pb and 57.25% of Cd). The GMB-L1 was proved to accomplish Pb and Cd remediation via the process of chemical precipitation, surface complexation, electrostatic attraction, and biomineralization, which was accompanied by the transformation of heavy metals into a more stable crystal structure, such as Pb₅(PO₄)₃OH and Cd₅(PO₄)₃OH. Therefore, the co-system of GMB and strain L1 could be regarded as a prospective option for efficiently remedying environmental heavy metal pollution. Full article

(This article belongs to the Special Issue Application of Biochar and Activated Carbon in Water Treatment)

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18 pages, 3805 KiB

Open AccessArticle

Sanitary Sewer Overflow Discharges: Estimation Based on Flow Rate Measurement in Pumping Mains

by Luís Mesquita David, António Martins, Marta Rodrigues, Anabela Oliveira, André B. Fortunato, Osvaldo Silva, Alexandre Ataíde and Ana Mendes

Water 2024, 16(13), 1916; https://doi.org/10.3390/w16131916 - 5 Jul 2024

Viewed by 753

Abstract

Modeling sanitary sewer overflow (SSO) discharges based on flows measured at pumping stations presents specific challenges distinct from modeling combined sewer overflow (CSO) discharges and is insufficiently studied. This paper presents a methodology aimed at reducing and assessing the uncertainty in SSO estimation. [...] Read more.

Modeling sanitary sewer overflow (SSO) discharges based on flows measured at pumping stations presents specific challenges distinct from modeling combined sewer overflow (CSO) discharges and is insufficiently studied. This paper presents a methodology aimed at reducing and assessing the uncertainty in SSO estimation. Four lumped models are compared: a time–area curve, linear reservoir, Clark, and simplified numerical modeling using SWMM. Clark’s model delivers the best results, with very reasonable estimates. Although the simplified SWMM model also provides good estimates, factors such as determinism in weir crest height and potential storage in the sewer network introduce additional uncertainties and errors. The attenuation of measured hydrographs at pumping mains leads to an underestimation of both the catchment area and the SSO discharges, which depends on the pump operating frequency and requires further evaluation. The maximum flow rate threshold allowed for the pumping station is a key parameter for SSO frequency and volume; its influence is evaluated in detail. This methodology can also be used to assess unknown overflows upstream of monitored weirs, as it provides estimates of total SSO discharges occurring in a catchment. The results of applying this methodology to two contrasting and paradigmatic pumping stations are discussed. Full article

(This article belongs to the Section Urban Water Management)

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16 pages, 24815 KiB

Open AccessArticle

Exploring Methane Capture Potential in Alkaline Coal Mine Drainage: Insight from the Microbial Community Structure and Function Analysis

by Yuan Li, Zhan Su, Wei Xiu, Lin Huang, Taiyu Huang and Jieming Zheng

Water 2024, 16(13), 1915; https://doi.org/10.3390/w16131915 - 4 Jul 2024

Viewed by 884

Abstract

Alkaline coal mine drainage represents one of the most critical issues in the coal industry, driven by complex hydro-biogeochemical processes. However, the interplay of hydrogeochemical and biogeochemical interactions in alkaline coal mine drainage is still poorly understood. To this end, water samples were [...] Read more.

Alkaline coal mine drainage represents one of the most critical issues in the coal industry, driven by complex hydro-biogeochemical processes. However, the interplay of hydrogeochemical and biogeochemical interactions in alkaline coal mine drainage is still poorly understood. To this end, water samples were systematically collected from alkaline coal mine drainage sites from five coal mining areas in Chongqing coal mining district, located in southwestern China. Hydrogeochemical analyses showed that the main water type of the coal mine drainage sample was HCO₃-SO₄~K-Na, which primarily originated from local meteoric water. The microbial community compositions in the studied alkaline coal drainage were critically associated with sulfate, bicarbonate, DOC, nitrate, and pH, and linked to three putative keystone genera via network analysis (Thiothrix, Methylophilaceae_MM1, and an unclassified genus from Comamonadaceae family). Functional predictions from FAPROTAX suggested a high abundance of metabolic pathways involving the oxidation of sulfide and sulfur compounds, potentially underscoring their importance in controlling sulfate enrichment in alkaline coal mine drainage. Interestingly, members of the Methylomonadaceae family (methanotrophs) and the Methylotenera genus (methylotrophs) had positive Spearman correlations with both ammonium and sulfate, potentially inferring that the enhanced activities of methanotrophs might help capture methane in the alkaline coal mine drainage. This study further enhances our comprehension of the intricate interplay between hydrogeochemical and biogeochemical interactions in alkaline coal mine drainage, contributing to the carbon budget. Full article

(This article belongs to the Section Hydrogeology)

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20 pages, 3595 KiB

Open AccessArticle

Projection of Changes in Rainfall and Drought Based on CMIP6 Scenarios on the Ca River Basin, Vietnam

by Ju-Young Shin, Pham Van Chien, Myoung-Jin Um, Hanbeen Kim and Kyungmin Sung

Water 2024, 16(13), 1914; https://doi.org/10.3390/w16131914 - 4 Jul 2024

Viewed by 844

Abstract

In this study, future precipitation and drought in the Ca river basin, Vietnam, were projected based on an ensemble of 27 CMIP6 models for four climate change scenarios. The impact of climate change on precipitation and drought was investigated. Monthly precipitation observation data [...] Read more.

In this study, future precipitation and drought in the Ca river basin, Vietnam, were projected based on an ensemble of 27 CMIP6 models for four climate change scenarios. The impact of climate change on precipitation and drought was investigated. Monthly precipitation observation data were adjusted using the bias correction method. To detect drought events, the Standard Precipitation Index (SPI) was employed. Changes in drought were assessed using SPI3, SPI6, and SPI12. Although the amount of annual total precipitation slightly increased, the drought events may become more severe. There is a high likelihood of increased drought intensity and severity in Vietnam due to climate change. The frequency of droughts is likely to change depending on the location and climate change scenario. We found that the frequency and severity of droughts may be altered depending on the window size of SPI. The short-term drought events will be more frequent and severe, and long-term drought events will become more severe in the Ca river basin. Full article

(This article belongs to the Section Water and Climate Change)

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14 pages, 3328 KiB

Open AccessArticle

Hydrochemical Characteristics and Water Quality Evaluation of Groundwater in the Luohe Formation of Binchang Mining Area, China

by Xu Wang, Kui Sun, Wanchao Ma, Jie Peng, Ruiping Liu, Jianping Chen, Kun Zhang, Shuai Gao, Cheng Li and Penghua Zhang

Water 2024, 16(13), 1913; https://doi.org/10.3390/w16131913 - 4 Jul 2024

Viewed by 696

Abstract

The groundwater of the Luohe Formation in Binchang mining area is the main source of water for industrial and agricultural use and for drinking water for residents in the area. In order to study the hydrochemical characteristics and water-quality status of Luohe Formation [...] Read more.

The groundwater of the Luohe Formation in Binchang mining area is the main source of water for industrial and agricultural use and for drinking water for residents in the area. In order to study the hydrochemical characteristics and water-quality status of Luohe Formation groundwater in the mining area, statistical analysis, Piper three-line diagram, ion ratio relationship, and other methods were used to study the hydrochemical characteristics and formation factors of the groundwater. The Nemerow index evaluation method and the fuzzy comprehensive evaluation method based on principal component analysis were used to evaluate the groundwater quality in the mining area. The results show that the groundwater is weakly acidic as a whole, and the content of SO₄²⁻ and Cl⁻ have strong variability in terms of spatial distribution. The groundwater chemical type gradually evolves from SO₄ • HCO₃ • Cl–Na, SO₄–Na and SO₄ • Cl–Na-type water in the north of the mining area to SO₄ • HCO₃ • Cl–Na • Ca, HCO₃ • SO₄–Na • Mg, and SO₄ • Cl–Na • Ca • Mg-type water in the south. The formation of the hydrochemical composition of groundwater in the study area may be related to multiple factors such as cation-alternating adsorption, carbonate and sulfate dissolution, and hydraulic exchange with the groundwater of the upper Huachi Formation. Comparing the evaluation results of the Nemerow index method and the principal component analysis method, the latter’s evaluation results can take into account the contribution of each indicator to the overall groundwater quality, and to a certain extent can weaken the control effect of a certain pollution indicator, exceeding the limit on the entire evaluation result. Therefore, the evaluation results based on the principal component analysis method are more credible. Full article

(This article belongs to the Special Issue Mine and Water)

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24 pages, 3904 KiB

Open AccessArticle

Comprehensive Safety Analysis of Ultimate Bearing Capacity Considering Hydraulic Fracture for Guxian High RCC Gravity Dam

by Mohamed Ramadan, Jinsheng Jia, Lei Zhao, Xu Li and Yangfeng Wu

Water 2024, 16(13), 1912; https://doi.org/10.3390/w16131912 - 4 Jul 2024

Viewed by 1185

Abstract

The widespread adoption of high concrete gravity dams in China and globally underscores the necessity for enhancing design processes to address potential risks, notably hydraulic fracture. This study delves into this urgency by scrutinizing common design regulations and investigating the impact of hydraulic [...] Read more.

The widespread adoption of high concrete gravity dams in China and globally underscores the necessity for enhancing design processes to address potential risks, notably hydraulic fracture. This study delves into this urgency by scrutinizing common design regulations and investigating the impact of hydraulic fracture on high concrete gravity dams. A comparative analysis of design specifications from China, the USA, and Switzerland, employing the gravity method, elucidates distinctions, focusing on the Guxian dam. In addition, evaluation of standards with higher resistance to hydraulic fracture was conducted using the Finite Element Method (FEM) with XFEM (eXtended Finite Element Method), employing initial cracks with different depths at the dam heel ranging from 0.2 to 2 m. The vulnerability of the Guxian dam’s cross-section to safety risks prompts further inquiry into the dam’s resistance to hydraulic fracture. Therefore, high-pressure water splitting risks to the ultimate bearing capacity were examined through FEM simulation and theoretical calculations. FEM simulations assessed the dam’s ultimate bearing capacity with and without automatic crack propagation combining the XFEM and overloading methods, particularly considering weak layers in the RCC (Roller-Compacted Concrete) dams. Theoretical calculations utilized a fracture mechanical evaluation model. This model derived mechanism formulas to assess the dam’s resistance to hydraulic fracture. Additionally, the investigation explored the effect of the uplift pressure on the ultimate overload coefficient. Findings indicated that the Guxian dam’s current cross-sectional area was insufficiently safe against hydraulic fracture, necessitating an increase to its cross-sectional area to 18,888.1 m². Notably, the USA’s and Switzerland’s criteria exhibited greater resistance to hydraulic fracture than the Chinese criteria, especially without considering uplift pressure. Also, the Chinese regulations tended to calculate a lower dam cross-sectional area compared with the other regulations. Numerical calculations revealed a substantial decrease in overall dam safety (up to 48%) when considering automatic crack propagation and the dam’s weak layers. The fracture mechanical evaluation model showed that the Guxian dam had the lowest resistance, with an overloading coefficient of 1.05 considering the uplift pressure. In the case of not considering the uplift pressure, the dam resistance to hydraulic fracture increased and the overloading coefficient rose to 1.27. The results highlighted the risk of hydraulic fracture in concrete dams. Hence, it is recommended that design specifications of high concrete gravity dams incorporate safety analyses of hydraulic fracture in the design process. Reducing uplift pressure plays a crucial role in enhancing the dam’s resistance to hydraulic fractures, emphasizing the need for this consideration in safety evaluations. The differences between the three design specifications were particularly pronounced for dams higher than 200 m. In contrast, dams of 50 m yielded similar results across these regulations. Full article

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18 pages, 7378 KiB

Open AccessArticle

Assessment of Soil Wind Erosion and Population Exposure Risk in Central Asia’s Terminal Lake Basins

by Wei Yu, Xiaofei Ma, Wei Yan and Yonghui Wang

Water 2024, 16(13), 1911; https://doi.org/10.3390/w16131911 - 4 Jul 2024

Viewed by 1111

Abstract

In the face of climate change and human activities, Central Asia’s (CA) terminal lake basins (TLBs) are shrinking, leading to deteriorating natural environments and serious soil wind erosion (SWE), which threatens regional socio-economic development, human health, and safety. Limited research on SWE and [...] Read more.

In the face of climate change and human activities, Central Asia’s (CA) terminal lake basins (TLBs) are shrinking, leading to deteriorating natural environments and serious soil wind erosion (SWE), which threatens regional socio-economic development, human health, and safety. Limited research on SWE and population exposure risk (PER) in these areas prompted this study, which applied the RWEQ and a PER model to assess the spatiotemporal changes in SWE and PER in TLBs in CA, including the Ili River Basin (IRB), Tarim River Basin (TRB), Syr Darya River Basin (SRB), and Amu Darya River Basin (ARB), from 2000 to 2020. We analyzed the driving factors of SWE and used the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model to simulate dust event trajectories. The findings from 2000 to 2020 show a spatial reduction trend in SWE and PER, with primary SWE areas in the Taklamakan Desert, Aral Sea Basin, and Lake Balkhash. Significant PER was observed along the Tarim River, near Lake Balkhash, and in the middle and lower reaches of the ARB and SRB. Over the past 21 years, temporal trends in SWE have occurred across basins, decreasing in the IRB, but increasing in the TRB, SRB, and ARB. Dust movement trajectories indicate that dust from the lower reaches of the SRB and ARB could affect Europe, while dust from the TRB could impact northern China and Japan. Correlations between SWE, NDVI, temperature, and precipitation revealed a negative correlation between precipitation and NDVI, suggesting an inhibitory impact of precipitation and vegetation cover on SWE. SWE also varied significantly under different LUCCs, with increases in cropland, forestland, and desert land, and decreases in grassland and wetland. These insights are vital for understanding SWE and PER in TLBs and offer theoretical support for emergency mitigation in arid regions. Full article

(This article belongs to the Special Issue Soil Erosion and Soil and Water Conservation)

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12 pages, 1501 KiB

Open AccessArticle

Bioremediation of Cd-Contaminated Soil around Bauxite with Stimulants and Microorganisms

by Luxuan Feng, Xiaofeng Chen, Jinghua Yao, Lei Xiao, Xiujuan Feng and Shengmin Wu

Water 2024, 16(13), 1910; https://doi.org/10.3390/w16131910 - 4 Jul 2024

Viewed by 755

Abstract

Heavy metal pollution in the soil around bauxite mines, especially cadmium pollution, is becoming more and more severe due to this mining becoming more frequent. Therefore, it is urgent to develop green and safe remediation technology. Biostimulants have been studied extensively, but their [...] Read more.

Heavy metal pollution in the soil around bauxite mines, especially cadmium pollution, is becoming more and more severe due to this mining becoming more frequent. Therefore, it is urgent to develop green and safe remediation technology. Biostimulants have been studied extensively, but their practical application is still challenging. In this study, the effects of humic acid (HA), glucose (GLU), and tetrasodium glutamate diacetate (GLDA), as well as their synergistic complex bacterial flora, on Cd-contaminated soil were analyzed. It has been shown that applying these three types of stimulants, individually or with complex bacterial flora, can enhance soil environment and quality. Nevertheless, the remediation efficacy of stimulants in combination with microbial communities surpasses that achieved through the use of stimulants alone. Among them, 1%GLU combined with complex bacterial flora had the best passivation effect on Cd, reducing the available Cd by 25%, followed by 0.5% GLU combined with complex bacterial flora and 0.5%HA combined with complex bacterial flora, which reduced the available Cd by 21.92% and 19.17%, respectively. The synergistic remediation method using stimulants and microorganisms can reduce the harm caused to the environment by conventional remediation methods and improve the effectiveness of soil remediation. It has broad application prospects in the field of bauxite-contaminated soil remediation. Full article

(This article belongs to the Special Issue Collaborative Monitoring and Remediation of Mine or Industrial Soils and Water)

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14 pages, 258 KiB

Open AccessArticle

Managing the Santa Cruz River: Prospects for a Future Binational Minute

by Stephen Mumme and Christopher Brown

Water 2024, 16(13), 1909; https://doi.org/10.3390/w16131909 - 3 Jul 2024

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Abstract

This paper examines the prospects for developing and implementing a binational water management agreement for the transboundary Santa Cruz River that crosses the US–Mexico boundary near the sister cities of Nogales, Sonora–Nogales, Arizona. After considering the geography, history, socio-economic context, and binational agreements [...] Read more.

This paper examines the prospects for developing and implementing a binational water management agreement for the transboundary Santa Cruz River that crosses the US–Mexico boundary near the sister cities of Nogales, Sonora–Nogales, Arizona. After considering the geography, history, socio-economic context, and binational agreements affecting utilization of the Santa Cruz River, we review the conditions influencing recent binational progress on another transboundary river, the Tijuana River. Specifically, we ask what conditions created a favorable environment in which a binational agreement for management of the Tijuana River Watershed (TRW) was developed, what specific actions by relevant policy officials took place, and how the final agreement was reached. We then compare the dynamics that unfolded in the TRW with conditions in the Santa Cruz River to identify obstacles hindering progress towards achieving an International Boundary and Water Commission (IBWC) agreement (Minute) on shared management of the Santa Cruz River in its international reach. We find that the required political conditions that favored an agreement on the Tijuana River are not yet met on the Santa Cruz, although several favorable conditions do exist. We conclude with an assessment of current prospects for advancing binational cooperation that can inform discussion of how an IBWC Minute could be drafted to address water resource management issues in the Santa Cruz River Basin. Full article

28 pages, 2685 KiB

Open AccessArticle

A Statistical Approach for the Assessment of Saturated Hydraulic Conductivity Values of Unsaturated Urban Soils Obtained by Field Infiltration Tests

by Traian Ghibus and Dragos Gaitanaru

Water 2024, 16(13), 1908; https://doi.org/10.3390/w16131908 - 3 Jul 2024

Cited by 1 | Viewed by 889

Abstract

An evaluation and interpretation of the obtained results focusing the hydraulic conductivity of anthropogenic saturated soil, k, has been performed on an urban area vadose zone. Four methods have been used to quantify the hydraulic conductivity: the tube infiltrometer (TI), the double [...] Read more.

An evaluation and interpretation of the obtained results focusing the hydraulic conductivity of anthropogenic saturated soil, k, has been performed on an urban area vadose zone. Four methods have been used to quantify the hydraulic conductivity: the tube infiltrometer (TI), the double ring infiltrometer (DRI), the minidisk infiltrometer (MDI) and the inversed auger (IA). This study comprises (a) a comparative analysis of the results obtained by each method between several trials performed at the same location and at distinct locations within the plot, (b) a comparative analysis of the results of all methods, and (c) a statistical analysis regarding the correlation between k as a dependent variable and the infiltration area A as the main independent variable. To select the k values close or corresponding to the saturation state for TI and IA methods, a domain of validity was defined. A new parameter, k* = k/A, was introduced which represents the hydraulic conductivity corresponding to an infiltration surface unit (1 cm²). An increase in this ratio with the increase in the infiltration area, within the same method or between different methods, indicates the heterogeneity of the terrain but especially the fact that the infiltration area no longer represents the main independent variable on which the hydraulic conductivity depends for the saturated state. Full article

(This article belongs to the Topic Urban Hydrogeology Research)

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20 pages, 6803 KiB

Open AccessArticle

Groundwater Contamination Source Recognition Based on a Two-Stage Inversion Framework with a Deep Learning Surrogate

by Zibo Wang and Wenxi Lu

Water 2024, 16(13), 1907; https://doi.org/10.3390/w16131907 - 3 Jul 2024

Cited by 1 | Viewed by 901

Abstract

Groundwater contamination source recognition is an important prerequisite for subsequent remediation efforts. To overcome the limitations of single inversion methods, this study proposed a two-stage inversion framework by integrating two primary inversion approaches—simulation-optimization and simulation-data assimilation—thereby enhancing inversion accuracy. In the first stage, [...] Read more.

Groundwater contamination source recognition is an important prerequisite for subsequent remediation efforts. To overcome the limitations of single inversion methods, this study proposed a two-stage inversion framework by integrating two primary inversion approaches—simulation-optimization and simulation-data assimilation—thereby enhancing inversion accuracy. In the first stage, the ensemble smoother with multiple data assimilation method (a type of simulation-data assimilation) conducted a global broad search to provide better initial values and ranges for the second stage. In the subsequent stage, a collective decision optimization algorithm (a type of simulation-optimization) was used for a refined deep search, further enhancing the final inversion accuracy. Additionally, a deep learning method, the multilayer perceptron, was utilized to establish a surrogate of the simulation model, reducing computational costs. These theories and methods were applied and validated in a hypothetical scenario for the synchronous identification of the contamination source and boundary conditions. The results demonstrated that the proposed two-stage inversion framework significantly improved search accuracy compared to single inversion methods, with a mean relative error and mean absolute error of just 4.95% and 0.1756, respectively. Moreover, the multilayer perceptron surrogate model offered greater approximation accuracy to the simulation model than the traditional shallow learning surrogate model. Specifically, the coefficient of determination, mean relative error, mean absolute error, and root mean square error were 0.9860, 9.72%, 0.1727, and 0.47, respectively, highlighting its significant advantages. The findings of this study can provide more reliable technical support for practical case applications and improve subsequent remediation efficiency. Full article

(This article belongs to the Special Issue Deep Learning-Based Methods for Groundwater Contamination Identification)

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21 pages, 12128 KiB

Open AccessArticle

Mechanism of Biological Transport and Transformation of Copper, Cadmium, and Zinc in Water by Chlorella

by Shaomin Liu, Mengyu Jiang, Jiating Wu, Xiaofeng Li and Jinglin Zhu

Water 2024, 16(13), 1906; https://doi.org/10.3390/w16131906 - 3 Jul 2024

Viewed by 922

Abstract

This study investigates the effectiveness of Chlorella vulgaris in treating copper, cadmium, and zinc in aqueous solutions; the aim of this study was to examine the effects of various factors on the adsorption capacity of Chlorella in water. This study explored the intra- [...] Read more.

This study investigates the effectiveness of Chlorella vulgaris in treating copper, cadmium, and zinc in aqueous solutions; the aim of this study was to examine the effects of various factors on the adsorption capacity of Chlorella in water. This study explored the intra- and extracellular adsorption and accumulation patterns of copper (Cu(II)), cadmium (Cd(II)), and zinc (Zn(II)), revealing their molecular response mechanisms under the most suitable conditions. The adsorption capacity of Chlorella to Cu(II), Cd(II), and Zn(II) in water was 93.63%, 73.45%, and 85.41%, respectively. The adsorption mechanism for heavy metals is governed by both intracellular and extracellular diffusion, with intracellular absorption serving as a supplement and external uptake predominating. XRD, XPS, FTIR, SEM-EDX, and TEM-EDX analyses showed that there would be the formation of precipitates such as Cu₂S, CuS₂, CdS, and ZnSO₄. The adsorption of Cu(II) involves its simultaneous reduction to Cu(I). Moreover, specific functional groups present on the cellular surface, such as amino, carboxyl, aldehyde, and ether groups, interact with heavy metal ions. In view of its efficient heavy metal adsorption capacity and biosafety, this study recommends Chlorella as a potential biosorbent for the bioremediation and environmental treatment of heavy metal contaminated water in the future. Full article

(This article belongs to the Special Issue Applications of Biotechnology in Water and Wastewater Treatment)

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17 pages, 2331 KiB

Open AccessArticle

Cadmium Removal by Adsorption on Biochars Derived from Wood Industry and Craft Beer Production Wastes

by Daiana Simón, Cristina Palet and Adrián Cristóbal

Water 2024, 16(13), 1905; https://doi.org/10.3390/w16131905 - 3 Jul 2024

Viewed by 892

Abstract

Cadmium pollution is a serious environmental issue that has an impact on both the ecosystem and human health. As a result, its removal from water is essential. Agro-industrial wastes are suggested as a sustainable adsorbent option, as they are among the most readily [...] Read more.

Cadmium pollution is a serious environmental issue that has an impact on both the ecosystem and human health. As a result, its removal from water is essential. Agro-industrial wastes are suggested as a sustainable adsorbent option, as they are among the most readily available renewable sources worldwide. Biochar is a carbonized biomass that has been shown to be a viable and novel adsorbent. This article compares the results of cadmium adsorption on biochars derived from wood industry and craft beer production wastes. Biochars were characterized before and after adsorption. Batch adsorption results of 0.18 mmol/L Cd(II) concentration solutions indicated adsorption percentages (A%) of 99.7% and 92.2% for sawdust biochar and barley biochar, respectively. For this cadmium concentration, the sawdust biochar presented an adsorption capacity (q_m) of 0.0172 mmol/L, while the barley biochar presented a value of 0.0159 mmol/L. The influence of initial Cd(II) concentration on single and multimetal solutions was studied, and a decrease in Cd(II) adsorption on sawdust biochar was observed in the presence of Ni(II) and Zn(II). The Freundlich isotherm model was found to be the best fit to the data for Cd(II) adsorption isotherms on both biochars. According to the results of this article, sawdust biochar has the best performance as an adsorbent and can be safely disposed of in building bricks at the end of its useful life. Full article

(This article belongs to the Special Issue Removal of Heavy Metals and Other Pollutants from Aqueous Solutions)

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