Water

21 pages, 1617 KiB

Open AccessArticle

Challenges of Providing Safe Drinking Water in African Rural Communities: A Case Study on the Oio Region, Guinea-Bissau

by Pedro Silveira, Maria Teresa Rebelo and Daniel Salvador

Water 2024, 16(24), 3621; https://doi.org/10.3390/w16243621 (registering DOI) - 16 Dec 2024

Access to safe drinking water is a fundamental human right, yet it remains a global challenge affecting nearly 2 billion people, particularly in Africa in regions such as Guinea-Bissau. This study investigated the microbiological and physicochemical quality of drinking water in four rural [...] Read more.

Access to safe drinking water is a fundamental human right, yet it remains a global challenge affecting nearly 2 billion people, particularly in Africa in regions such as Guinea-Bissau. This study investigated the microbiological and physicochemical quality of drinking water in four rural areas of the Oio region of Guinea-Bissau—Cangha N’Tchugal, Cajaque, Infaidi and Insanha—over a one-year period (October 2022–September 2023) to assess water safety and seasonal variations. During this period, eight water samples were collected and analysed from each site, split evenly between the dry and wet seasons. The results showed widespread faecal coliform contamination, with concentrations escalating during the wet season (2 to 39 CFU/100 mL), posing a health risk. Physicochemical analysis showed consistently acidic pH values (from 4.93 to 6.58) and seasonal variations in phosphate and iron concentrations, with a marked decrease in iron concentrations during the wet season. These results indicated that the water from the four sampling points was unfit for human consumption. In light of these findings, there is an urgent need for the regular monitoring of water sources used for drinking and for improved access to resources and basic sanitation in the future. Full article

(This article belongs to the Section Water Quality and Contamination)

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22 pages, 1902 KiB

Open AccessReview

Production, Toxicological Effects, and Control Technologies of Ochratoxin A Contamination: Addressing the Existing Challenges

by Yan Yang, Mingtao Li, Junxiong Zhao, Jingxuan Li, Kangwen Lao and Fuqiang Fan

Water 2024, 16(24), 3620; https://doi.org/10.3390/w16243620 (registering DOI) - 16 Dec 2024

Abstract

Ochratoxin A (OTA) is a mycotoxin commonly found in food and feed. It presents a serious threat to human and animal health while also posing a risk as a potential aquatic contaminant. Although many research efforts have been placed on OTA contamination and [...] Read more.

Ochratoxin A (OTA) is a mycotoxin commonly found in food and feed. It presents a serious threat to human and animal health while also posing a risk as a potential aquatic contaminant. Although many research efforts have been placed on OTA contamination and detoxification, systematic and in-depth studies on summarizing its primary sources, formation mechanisms, toxicological effects, and control technologies remain essential. This review systematically analyzed the sources of OTA contamination, including the main toxin-producing strains and their specific colonization environments, in which the biosynthetic pathways and key regulatory factors of OTA were outlined. On this basis, the principle, merits, disadvantages, and application potential of OTA control technologies, including the physical, chemical, and biological detoxification techniques, were comparatively evaluated. The applications of genetic engineering with an emphasis on newly identified degradative enzymes and their potential in OTA removal were carefully elucidated. Considering the stringent global OTA regulatory standards and food safety handling requirements, this review highlights the necessity of comprehensive control measure development and emphasizes the importance of rigorous technical evaluation and regulatory approval. The aim is to provide theoretical support for effective OTA control and to guide future OTA contamination management in complex environments. Full article

(This article belongs to the Special Issue Analytical Methodology, Environmental Behavior and Risk Assessment of New Organic Pollutants)

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14 pages, 5637 KiB

Open AccessArticle

Rapid Start-Up of Anammox Process with a Stepwise Strategy: System Performance, Microbial Community Succession and Mechanism Exploration

by Sha Wang, Yangxin Yin, Yueyao Gao, Fang Li and Jian Zhou

Water 2024, 16(24), 3619; https://doi.org/10.3390/w16243619 (registering DOI) - 16 Dec 2024

Viewed by 85

Abstract

Anammox has emerged as a primary alternative to conventional biological nitrogen removal because of its excellent nitrogen removal performance and minimal energy utilization. However, the slow growth and reproduction of anammox bacteria (AnAOB) leads to an overlong start-up period, which severely restricts the [...] Read more.

Anammox has emerged as a primary alternative to conventional biological nitrogen removal because of its excellent nitrogen removal performance and minimal energy utilization. However, the slow growth and reproduction of anammox bacteria (AnAOB) leads to an overlong start-up period, which severely restricts the full-scale promotion and application of anammox in wastewater treatment plants. Therefore, in this study, a sequencing batch biofilm reactor (SBBR) equipped with combined packing was used to investigate the rapid start-up of the anammox process. The result showed that the anammox reactor started successfully in only 75 days using a stepwise strategy, and the total nitrogen removal rate (TNRR) increased from 0.02 kg N m⁻³ d⁻¹ on day 1 to 0.23 kg N m⁻³ d⁻¹ on day 75. The primary AnAOB was Candidatus Kuenenia with a relative abundance of 37.20% at the end of the start-up of the anammox reactor. Denitrifying bacteria, nitrifying bacteria, and hydrolytic bacteria were also detected in the reactor. The synergistic interactions between AnAOB and these bacteria facilitated the efficient removal of pollutants. This study can offer a potential approach for the start-up of anammox in domestic wastewater treatment plants, which is conducive to achieving widespread application of anammox. Full article

(This article belongs to the Special Issue ANAMMOX Based Technology for Nitrogen Removal from Wastewater)

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18 pages, 1899 KiB

Open AccessReview

Methane Production Mechanism and Control Strategies for Sewers: A Critical Review

by Feng Hou, Shuai Liu, Wan-Xin Yin, Li-Li Gan, Hong-Tao Pang, Jia-Qiang Lv, Ying Liu, Ai-Jie Wang and Hong-Cheng Wang

Water 2024, 16(24), 3618; https://doi.org/10.3390/w16243618 (registering DOI) - 16 Dec 2024

Viewed by 192

Abstract

Methane (CH₄) emissions from urban sewer systems represent a significant contributor to greenhouse gases, driven by anaerobic decomposition processes. This review elucidates the mechanisms underlying CH₄ production in sewers, which are influenced by environmental factors such as the COD/SO₄ [...] Read more.

Methane (CH₄) emissions from urban sewer systems represent a significant contributor to greenhouse gases, driven by anaerobic decomposition processes. This review elucidates the mechanisms underlying CH₄ production in sewers, which are influenced by environmental factors such as the COD/SO₄²⁻ ratio, temperature, dissolved oxygen, pH, flow rate, and hydraulic retention time. We critically evaluated the effectiveness of empirical, mechanistic, and machine learning (ML) models in predicting CH₄ emissions, highlighting the limitations of each. This review further examines control strategies, including oxygen injection, iron salt dosing, and nitrate application, emphasizing the importance of balancing CH₄ reduction with the operational efficiency of wastewater treatment plants (WWTPs). An integrated approach combining mechanistic and data-driven models is advocated to enhance prediction accuracy and optimize CH₄ management across urban sewer systems. Full article

(This article belongs to the Section Urban Water Management)

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12 pages, 4355 KiB

Open AccessArticle

Effect of Seepage on Sand Levee Failure Due to Lateral Overtopping

by Woochul Kang, Seongyun Kim and Eunkyung Jang

Water 2024, 16(24), 3617; https://doi.org/10.3390/w16243617 (registering DOI) - 16 Dec 2024

Viewed by 119

Abstract

Recent increases in rainfall duration and intensity due to climate change have heightened the importance of levee stability. However, previous studies on levee failure, primarily caused by seepage and overtopping, have mostly examined these causes independently owing to their distinct characteristics. In this [...] Read more.

Recent increases in rainfall duration and intensity due to climate change have heightened the importance of levee stability. However, previous studies on levee failure, primarily caused by seepage and overtopping, have mostly examined these causes independently owing to their distinct characteristics. In this study, we conducted lateral overtopping failure experiments under seepage conditions that closely resembled those in experiments conducted in previous studies. Seepage was monitored using water pressure sensors and a distributed optical fiber cable that provided continuous heat for temperature monitoring in the levee. Τhe analysis of levee failure due to lateral overtopping, in the presence of seepage, was conducted using image analysis with digitization techniques and machine learning-based color segmentation techniques on the protected lowland side of the levee, targeting the same area. The results revealed that levee failure occurred more than twice as fast in experiments where seepage conditions were considered compared to the experiments where they were not. Thus, levees weakened by seepage are more vulnerable to overtopping and breaching. Consequently, employing a comprehensive approach that integrates various monitoring and analysis methods for assessing levee stability is preferable to relying on a single method alone. Full article

(This article belongs to the Special Issue Safety Monitoring of Hydraulic Structures)

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26 pages, 2256 KiB

Open AccessReview

Recent Progress on Surface Water Quality Models Utilizing Machine Learning Techniques

by Mengjie He, Qin Qian, Xinyu Liu, Jing Zhang and James Curry

Water 2024, 16(24), 3616; https://doi.org/10.3390/w16243616 (registering DOI) - 15 Dec 2024

Viewed by 644

Abstract

Surface waterbodies are heavily exposed to pollutants caused by natural disasters and human activities. Empowering sensor technologies in water quality monitoring, sufficient measurements have become available to develop machine learning (ML) models. Numerous ML models have quickly been adopted to predict water quality [...] Read more.

Surface waterbodies are heavily exposed to pollutants caused by natural disasters and human activities. Empowering sensor technologies in water quality monitoring, sufficient measurements have become available to develop machine learning (ML) models. Numerous ML models have quickly been adopted to predict water quality indicators in various surface waterbodies. This paper reviews 78 recent articles from 2022 to October 2024, categorizing water quality models utilizing ML into three groups: Point-to-Point (P2P), which estimates the current target value based on other measurements at the same time point; Sequence-to-Point (S2P), which utilizes previous time series data to predict the target value at one time point ahead; and Sequence-to-Sequence (S2S), which uses previous time series data to forecast sequential target values in the future. The ML models used in each group are classified and compared according to water quality indicators, data availability, and model performance. Widely used strategies for improving performance, including feature engineering, hyperparameter tuning, and transfer learning, are recognized and described to enhance model effectiveness. The interpretability limitations of ML applications are discussed. This review provides a perspective on emerging ML for surface water quality models. Full article

(This article belongs to the Special Issue Application of Smart Technologies in Integrated Water Quality Modeling)

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18 pages, 6768 KiB

Open AccessArticle

An Interpretable CatBoost Model Guided by Spectral Morphological Features for the Inversion of Coastal Water Quality Parameters

by Baofeng Chen, Yunzhi Chen and Hongmei Chen

Water 2024, 16(24), 3615; https://doi.org/10.3390/w16243615 (registering DOI) - 15 Dec 2024

Viewed by 359

Abstract

Chlorophyll-a (Chla) and total suspended solid (TSS) concentrations are important parameters for water quality assessment, and in recent years, machine learning has been shown to have great potential in this field. However, current water quality parameter inversion models lack interpretability and rarely consider [...] Read more.

Chlorophyll-a (Chla) and total suspended solid (TSS) concentrations are important parameters for water quality assessment, and in recent years, machine learning has been shown to have great potential in this field. However, current water quality parameter inversion models lack interpretability and rarely consider the morphological characteristics of the spectrum. To address this limitation, we used Sentinel-3 OLCI data to construct an interpretable CatBoost model guided by spectral morphological characteristics for remote sensing monitoring of Chla and TSS along the coast of Fujian. The results show that the coastal waters of Fujian Province can be divided into five clusters, and the areas of different clusters will change with the alternation of seasons. Clusters 2 and 4 are the main types of coastal waters. The CatBoost model combined with spectral feature engineering has a high accuracy in predicting Chla and TSS, among which Chla is slightly better than TSS (R² = 0.88, MSE = 8.21, MAPE = 1.10 for Chla predictions; R² = 0.77, MSE = 380.49, MAPE = 2.48 for TSS predictions). We further conducted an interpretability analysis on the model output and found that the combination of BRI and TBI indexes composed of bands such as b8, b9, and b10 and the fluctuation of spectral curves will have a significant impact on the prediction of model output. The interpretable CatBoost model based on spectral morphological features proposed in this study can provide an effective technical means of estimating the chlorophyll-a and total suspended particulate matter concentrations in the coastal areas of Fujian. Full article

(This article belongs to the Special Issue The Interrelationship Between Climate Change, Human Activities and Hydrological Processes (3rd Edition))

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12 pages, 21792 KiB

Open AccessArticle

Distribution and Affecting Factors of Aragonite Saturation in the Northern South China Sea in Summer

by Ping Han, Zhaojun Wang, Honggang Lv, Feiyong Chen, Xuewan Zhang and Jin Wang

Water 2024, 16(24), 3614; https://doi.org/10.3390/w16243614 (registering DOI) - 15 Dec 2024

Viewed by 370

Abstract

Based on the carbonate and hydrological parameters of a survey made in August–September 2011, we investigated the distribution and affecting factors of aragonite saturation (Ω_arag) in the northern South China Sea. The levels of Ω_arag were found to gradually decrease [...] Read more.

Based on the carbonate and hydrological parameters of a survey made in August–September 2011, we investigated the distribution and affecting factors of aragonite saturation (Ω_arag) in the northern South China Sea. The levels of Ω_arag were found to gradually decrease with depth in the northern South China Sea. Surface-water Ω_arag values ranged from 2.56 to 3.68, with the highest value occurring in the region of Pearl River-diluted water near the northern coast. The increase in Ω_arag due to primary production, stimulated by the Pearl River freshwater input, exceeded the decrease in Ω_arag due to the direct input of low-Ω_arag fresh water, resulting in high Ω_arag in that area. In contrast, Ω_arag levels below 2 generally appeared in subsurface water below 50 m in depth. Intense community respiration was the main reason for the low Ω_arag. By 2100, bottom-water Ω_arag levels could be lower than 1.7, and even the undersaturation of aragonite could appear, due to the oceanic absorption of atmospheric CO₂. Full article

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20 pages, 3072 KiB

Open AccessReview

Spatiotemporal Dynamics of Suspended Particulate Matter in Water Environments: A Review

by Trung Tin Huynh, Jaein Kim, Sang Deuk Lee, Michael Fettweis, Qilong Bi, Sangsik Kim, Sungyun Lee, Yun Young Choi, Huu Son Nguyen, Trong Vinh Bui and Byung Joon Lee

Water 2024, 16(24), 3613; https://doi.org/10.3390/w16243613 (registering DOI) - 15 Dec 2024

Viewed by 396

Abstract

Suspended particulate matter (SPM) is an indispensable component of water environments. Its fate and transport involve various physical and biogeochemical cycles. This paper provides a comprehensive review of SPM dynamics by integrating insights from biogeochemical processes, spatiotemporal observation techniques, and numerical modeling approaches. [...] Read more.

Suspended particulate matter (SPM) is an indispensable component of water environments. Its fate and transport involve various physical and biogeochemical cycles. This paper provides a comprehensive review of SPM dynamics by integrating insights from biogeochemical processes, spatiotemporal observation techniques, and numerical modeling approaches. It also explores methods for diagnosing SPM-mediated biogeochemical processes, such as the flocculation kinetics test and organic matter composition analysis. Advances in remote sensing, in situ monitoring, and high-resolution retrieval algorithms are discussed, highlighting their significance in detecting and quantifying SPM concentrations across varying spatial and temporal scales. Furthermore, this review examines integrated models that incorporate population balance equations on the basis of flocculation kinetics into multi-dimensional sediment transport models. The results from this study provide valuable insights into SPM dynamics, ultimately enhancing our knowledge of SPM behavior and transport in water environments. However, uncertainties remain due to limited field data on flocculation kinetics and the need for parameter optimization in numerical models. Addressing these gaps through enhanced fieldwork and model refinement will significantly improve our ability to predict and manage SPM dynamics, which is critical for sustainable aquatic ecosystem management in an era of rapid environmental change. Full article

(This article belongs to the Section Water Erosion and Sediment Transport)

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Sources, fate, and transport of flocs with heterogeneous composition. Full article ">Figure 2
Schematic diagram of the biogeochemical cycle of carbonaceous materials mediated by flocculation with heterogeneous components in water and benthic environments. Full article ">Figure 3
Schematic diagram of satellite-, aircraft-, and UAV-based remote sensing, and measurable spectral bands of satellites in operation [<a href="#B96-water-16-03613" class="html-bibr">96</a>]. Full article ">Figure 4
Basic structure for quantification of (a) total suspended matter (TSM), (b) Chlorophyll-a, and (c) bed load flux using the machine learning algorithms [<a href="#B20-water-16-03613" class="html-bibr">20</a>,<a href="#B115-water-16-03613" class="html-bibr">115</a>,<a href="#B118-water-16-03613" class="html-bibr">118</a>]. Full article ">Figure 5
Conceptual schematic of dual frequency echosounder on fluid mud detection with high-frequency (180–220 kHz) and low-frequency (15–38 kHz) ranges [<a href="#B129-water-16-03613" class="html-bibr">129</a>]. Full article ">Figure 6
Comparison of (a) single−class population balance equation, (b) two−class population balance equation, (c) three−class population balance equation, and (d) multi−class population balance equation mode [<a href="#B32-water-16-03613" class="html-bibr">32</a>,<a href="#B35-water-16-03613" class="html-bibr">35</a>,<a href="#B145-water-16-03613" class="html-bibr">145</a>,<a href="#B146-water-16-03613" class="html-bibr">146</a>]. Full article ">

18 pages, 832 KiB

Open AccessArticle

Monetizing Co-Benefits of Nature-Based Sanitation-Constructed Wetlands Using Contingent Valuation Method—Jordan as a Case Study

by Ahmed M. N. Masoud, Amani Alfarra and Sabrina Sorlini

Water 2024, 16(24), 3612; https://doi.org/10.3390/w16243612 (registering DOI) - 15 Dec 2024

Viewed by 383

Abstract

Parallel to the growing evidence about the efficiency of Nature-based Solutions (NbS) in sanitation, there is a growing need to highlight the co-benefits of these solutions compared to conventional alternatives. This study focuses on economically valuing these co-benefits, with constructed wetlands (CWs) examined [...] Read more.

Parallel to the growing evidence about the efficiency of Nature-based Solutions (NbS) in sanitation, there is a growing need to highlight the co-benefits of these solutions compared to conventional alternatives. This study focuses on economically valuing these co-benefits, with constructed wetlands (CWs) examined as a sanitation solution. The contingent valuation (CV) method has been utilized for this purpose, measuring people’s willingness to pay (WTP) and willingness to accept (WTA) CWs as a sanitation solution. Jordan has been selected as a case study due to the country’s preference for sustainable, cost-efficient solutions. By utilizing extended questionnaires at the stakeholder and community levels, this research aims to identify gaps between these groups’ perspectives on CWs. Additionally, this study investigates the main factors affecting communities’ WTP and WTA. The collected data were analyzed using descriptive statistics for the responses, followed by the CV method, and regression analysis to understand the main factors affecting WTP and WTA. The results are intended to guide decision-makers in developing programs that align with community preferences and address gaps in the acceptance of NbS-CWs. The main results found that while stakeholders have concerns about people’s WTA CWs, the community survey revealed that people prefer CWs over conventional solutions. The findings revealed that 78.9% of respondents were willing to accept (WTA) CWs to treat wastewater in their town, but only 33% WTA having CW near their households. Meanwhile, 53.2% were willing to pay (WTP) for CWs in general, while 80.7% are willing to accept (WTP) using CWs to treat greywater at the household level and 56.9% of the respondents are WTP for that. Full article

(This article belongs to the Special Issue Ecohydrological Processes, Environmental Effects, and Integrated Regulation of Wetland Ecosystems, 3rd Edition)

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16 pages, 2817 KiB

Open AccessArticle

Optimizing Chemical Oxygen Demand Prediction in Spectroscopy Through Hybrid Feature Engineering and Regression-Based Similarity Analysis

by Chenjie Jia, Zhicheng Zhou, Jiehui Li, Jiankang Ma and Xinming Ji

Water 2024, 16(24), 3611; https://doi.org/10.3390/w16243611 (registering DOI) - 15 Dec 2024

Viewed by 264

Abstract

This paper presents a hybrid feature extraction and regression-based machine learning approach for predicting COD concentrations in water samples using spectral data. The method integrates SK-Best and FA to tackle high dimensionality and information redundancy in small datasets. SK-Best identifies key absorbance features, [...] Read more.

This paper presents a hybrid feature extraction and regression-based machine learning approach for predicting COD concentrations in water samples using spectral data. The method integrates SK-Best and FA to tackle high dimensionality and information redundancy in small datasets. SK-Best identifies key absorbance features, enhancing predictive reliability, while FA reduces dimensionality and extracts valuable information for similarity prediction. The combination of SK-Best, FA, and Linear Regression achieves strong prediction performance (R² ~ 0.87, MAE = 0.23), demonstrating interpretability, flexibility, and robustness in small datasets. This approach offers a promising solution for real-time water quality monitoring and will be further optimized for broader applications. Full article

17 pages, 3261 KiB

Open AccessArticle

Characteristics of Suspended Solid Responses to Forest Thinning in Steep Small Headwater Catchments in Coniferous Forest

by Honggeun Lim, Qiwen Li, Byoungki Choi, Hyung Tae Choi and Sooyoun Nam

Water 2024, 16(24), 3610; https://doi.org/10.3390/w16243610 (registering DOI) - 15 Dec 2024

Viewed by 305

Abstract

We examined the responses of suspended solids to forest thinning in steep small headwater catchments, P_T (0.8 ha) and P_R (0.7 ha), that drain a Korean pine (Pinus koraiensis) plantation forest. Based on a paired-catchment design, the relationship between [...] Read more.

We examined the responses of suspended solids to forest thinning in steep small headwater catchments, P_T (0.8 ha) and P_R (0.7 ha), that drain a Korean pine (Pinus koraiensis) plantation forest. Based on a paired-catchment design, the relationship between total suspended solids (TSS) and the time differential of water runoff (dQ/dt) indicated a difference in the characteristics of TSS in the rising and falling stages within the initial two years after forest thinning. The relatively high initial TSS responded to the concentration-based first flush criterion in the early stage of the rainfall event concentrated in this initial period after the thinning. The rate of TSS event loads in the P_T catchment was 4.3-fold greater than that in the P_R catchment within the initial two years after forest thinning. This was induced by the low disturbance of soil surface by forest workers using chainsaws and non-heavy machinery. Three years later, the TSS event loads in the P_T catchment appeared to decrease due to trapping and settling by protective vegetation. Therefore, mitigating accelerated TSS events during forest thinning requires appropriate site-specific land preparation, particularly for improving stream water quality in forested catchments. Full article

(This article belongs to the Special Issue Non-Point Source Pollution and Water Resource Protection)

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16 pages, 6401 KiB

Open AccessArticle

Estimation of Water Interception of Winter Wheat Canopy Under Sprinkler Irrigation Using UAV Image Data

by Xueqing Zhou, Haijun Liu and Lun Li

Water 2024, 16(24), 3609; https://doi.org/10.3390/w16243609 (registering DOI) - 15 Dec 2024

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Abstract

Canopy water interception is a key parameter to study the hydrological cycle, water utilization efficiency, and energy balance in terrestrial ecosystems. Especially in sprinkler-irrigated farmlands, the canopy interception further influences field energy distribution and microclimate, then plant transpiration and photosynthesis, and finally crop [...] Read more.

Canopy water interception is a key parameter to study the hydrological cycle, water utilization efficiency, and energy balance in terrestrial ecosystems. Especially in sprinkler-irrigated farmlands, the canopy interception further influences field energy distribution and microclimate, then plant transpiration and photosynthesis, and finally crop yield and water productivity. To reduce the field damage and increase measurement accuracy under traditional canopy water interception measurement, UAVs equipped with multispectral cameras were used to extract in situ crop canopy information. Based on the correlation coefficient (r), vegetative indices that are sensitive to canopy interception were screened out and then used to develop canopy interception models using linear regression (LR), random forest (RF), and back propagation neural network (BPNN) methods, and lastly these models were evaluated by root mean square error (RMSE) and mean relative error (MRE). Results show the canopy water interception is first closely related to relative normalized difference vegetation index (R_△NDVI) with r of 0.76. The first seven indices with r from high to low are R_△NDVI, reflectance values of the blue band (Blue), reflectance values of the near-infrared band (Nir), three-band gradient difference vegetation index (TGDVI), difference vegetation index (DVI), normalized difference red edge index (NDRE), and soil-adjusted vegetation index (SAVI) were chosen to develop canopy interception models. All the developed linear regression models based on three indices (R_△NDVI, Blue, and NDRE), the RF model, and the BPNN model performed well in canopy water interception estimation (r: 0.53–0.76, RMSE: 0.18–0.27 mm, MRE: 21–27%) when the interception is less than 1.4 mm. The three methods underestimate the canopy interception by 18–32% when interception is higher than 1.4 mm, which could be due to the saturation of NDVI when leaf area index is higher than 4.0. Because linear regression is easy to perform, then the linear regression method with NDVI is recommended for canopy interception estimation of sprinkler-irrigated winter wheat. The proposed linear regression method and the R_△NDVI index can further be used to estimate the canopy water interception of other plants as well as forest canopy. Full article

(This article belongs to the Special Issue Agricultural Water-Land-Plant System Engineering)

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Map of experimental location and experimental field in this study. Full article ">Figure 2
Heat map of correlation analysis between vegetation indices and canopy water interception. Note: * indicates the correlation coefficient between the two indices is significant at 0.05 level; ** indicates the relationship is significant at 0.01 level. Full article ">Figure 3
Performance of linear regression models using unary and multiple vegetative indices. Panel (a) represents the linear model based on R△NDVI (model 7 in <a href="#water-16-03609-t003" class="html-table">Table 3</a>); (b) represents the model based on R△NDVI and Blue (model 8 in <a href="#water-16-03609-t003" class="html-table">Table 3</a>); (c) represents model based on R△NDVI, Blue, and NDRE (model 11 in <a href="#water-16-03609-t003" class="html-table">Table 3</a>). Full article ">Figure 4
The estimated and measured canopy interceptions by RF model in the model developing and calibrating processes. Full article ">Figure 5
The estimated and measured canopy interceptions by BP neural network model in the model developing and calibrating processes. Full article ">Figure 6
The relationship between normalized difference vegetation index (NDVI) and leaf area index (LAI) in winter wheat. Full article ">

16 pages, 4094 KiB

Open AccessArticle

Study of the Biogas Ebullition from Lacustrine Carbonate Enriched and Black Silt Bottom Sediments

by Evaldas Maceika, Laima Kazakevičiūtė-Jakučiūnienė, Zita Žukauskaitė, Nina Prokopčiuk, Marina Konstantinova, Vadimas Dudoitis and Nikolay Tarasiuk

Water 2024, 16(24), 3608; https://doi.org/10.3390/w16243608 (registering DOI) - 15 Dec 2024

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Abstract

The greenhouse effect, which is also promoted by naturally occurring biogas ebullition fluxes (released via bubbles), generated by the decomposition of organic matter in carbonate-enriched and black silt sediments, has been analyzed. This study is based on results obtained using passive gas collectors [...] Read more.

The greenhouse effect, which is also promoted by naturally occurring biogas ebullition fluxes (released via bubbles), generated by the decomposition of organic matter in carbonate-enriched and black silt sediments, has been analyzed. This study is based on results obtained using passive gas collectors at different parts of eutrophic Lake Juodis, located in a temperate climate zone in the vicinity of Vilnius (Lithuania). The measured annual biogas (containing about 60% of biomethane) ebullition fluxes from carbonate-enriched sediments and black silt sediments were 16.9–23.0 L/(m²∙y) and 38.5–43.2 L/(m²∙y), respectively. This indicates that the gas fluxes from carbonate sediments were almost twice as low as those from black silt sediments. Oxygen, produced by the photosynthetic activity of green algae in the near-surface water and sediments, helps to retain carbonates in the sediments by preventing their dissolution. In turn, the calcite coating on sediment particles partially preserves organic matter from decomposition, reducing the effective thickness of the sediment layer generating biogas. The characteristic vertical distribution profile of ¹³⁷Cs activity, with sharp peaks in sediments, suggests that generated biogas bubbles move to the surface of the sediments forming vertical channels by pushing sediment particles asides without noticeably mixing them vertically. This examination showed that factors such as abundance of carbonates in the sediments may result in a significant reduction in biogas generation and emissions from the lake sediments. Full article

(This article belongs to the Section Water Quality and Contamination)

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16 pages, 2554 KiB

Open AccessArticle

Revealing the Adverse Potential of Six SARS-CoV-2 Antivirals by Aliivibrio fischeri Assay: Toxicity Analysis of Single Agent Solutions and Binary Mixtures

by Viktorija Martinjak, Martina Miloloža, Marinko Markić, Lidija Furač, Matija Cvetnić, Tomislav Bolanča, Dajana Kučić Grgić and Šime Ukić

Water 2024, 16(24), 3607; https://doi.org/10.3390/w16243607 (registering DOI) - 15 Dec 2024

Viewed by 537

Abstract

The COVID-19 pandemic has intensified the development of new antiviral agents specifically intended for the SARS-CoV-2 virus, but has also increased the use of some already known antiviral agents originally intended for other viruses. Although the pandemic has ended, the SARS-CoV-2 virus is [...] Read more.

The COVID-19 pandemic has intensified the development of new antiviral agents specifically intended for the SARS-CoV-2 virus, but has also increased the use of some already known antiviral agents originally intended for other viruses. Although the pandemic has ended, the SARS-CoV-2 virus is expected to be present in the human population forever, as is the case with the influenza virus, for example. Such a scenario guarantees the continued use of SARS-CoV-2 antivirals and, accordingly, their continued release into the environment. Unfortunately, there is little or no information on the adverse potential of most of these antiviral agents. In this study, the acute toxicity of six antiviral agents used in the treatment of SARS-CoV-2 infections was determined. These are atazanavir, ribavirin, emtricitabine, nirmatrelvir, sofosbuvir and oseltamivir, sorted according to their toxicity, starting with the most toxic agent. Toxicity was determined using the marine bacterium Aliivibrio fischeri according to the ISO 11348-1:2007 standard. In addition to the toxicities of the individual antiviral solutions, the toxicities of binary antiviral mixtures were also determined. By comparing the experimentally determined toxicities of the mixtures with the values estimated by the concentration addition model and the independent action model, we analyzed the mode of joint toxic activity of these antiviral agents. Additive behavior was observed for most binary combinations. The combination of nirmatrelvir and sofosbuvir led to an antagonistic deviation from the concentration addition model, while a synergistic deviation was observed for the combinations of emtricitabine with atazanavir and with nirmatrelvir, as well as for the combinations of ribavirin with atazanavir, oseltamivir and sofosbuvir. All tested binary combinations showed a synergistic deviation from the independent action model. Full article

(This article belongs to the Special Issue The Occurrence, Fate and Removal of Emerging Contaminants in Wastewater)

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Chemical structures of: (A) atazanavir, (B) emtricitabine, (C) nirmatrelvir, (D) oseltamivir, (E) ribavirin and (F) sofosbuvir. Full article ">Figure 2
Isobolograms of binary mixtures of antivirals. Comparison of experimentally determined joint toxicity (circles) and additive behavior (solid lines). Different colors represent different binary mixtures, i.e., the mixtures containing different ratios of the individual antiviral solutions: MIX 1 (75:25; blue circle), MIX 2 (50:50, red circle) and MIX 3 (25:75, green circle). Full article ">Figure 3
Comparison between the predicted and experimentally determined toxicity values for the mixtures of (A) nirmatrelvir and sofosbuvir, and (B) oseltamivir and sofosbuvir. The cases correspond to the concentration addition model (red color) and the independent action model (blue color). The straight line is the y = x line, which represents the ideal scenario where the predicted values agree with the experimentally obtained values. Full article ">Figure 4
Correlation between toxicity and (A) the logP value, and (B) molar mass, for atazanavir, nirmatrelvir, oseltamivir and sofosbuvir (blue circles). The orange circles represent the highly hydrophilic antiviral agents emtricitabine and ribavirin, which were excluded from the regression analysis. Full article ">

17 pages, 4357 KiB

Open AccessReview

Nature-Based Solutions (NbS) for Flood Management in Malaysia

by Haziq Sarhan Bin Rosmadi, Minhaz Farid Ahmed, Mazlin Bin Mokhtar, Bijay Halder and Miklas Scholz

Water 2024, 16(24), 3606; https://doi.org/10.3390/w16243606 (registering DOI) - 15 Dec 2024

Viewed by 295

Abstract

Flash floods are a concerning social issue that affect urban areas all over the world. Flash floods can disrupt vital services, damage infrastructure, have socio-economic impacts on the earth’s surface, and significantly impact the community near the water body. Household and commercial damage, [...] Read more.

Flash floods are a concerning social issue that affect urban areas all over the world. Flash floods can disrupt vital services, damage infrastructure, have socio-economic impacts on the earth’s surface, and significantly impact the community near the water body. Household and commercial damage, physical health issues from contaminated floodwater, mental health issues including post-traumatic stress disorder, and even fatalities are some of these common effects. Additionally, it is anticipated that climate change, continuous population growth, and urbanisation will increase flood events and flood risk exposure. Nature-based solutions (NbS) for flood management that lower flood risks include sustainable, economical methods that improve biodiversity, ecosystem resilience, and community well-being. This in-depth study analyses research and literature that previous researchers conducted related to flood management around ASEAN countries, as all these countries are closely located and share similarities in climate and temperature. This survey focuses on identifying the most suitable and effective NbS to overcome the problem and appropriate non-structural measures to support it in solving the flood problem in Malaysia. NbS provide a multi-benefit approach by improving ecosystem resilience, cutting costs, and offering co-benefits, including biodiversity conservation and better water quality, in contrast to conventional methods that put infrastructure before environmental sustainability. This survey also looks at the weaknesses in the existing flood management system and provides recommendations to overcome these problems. Additionally, this survey offers practical policy suggestions to help incorporate NbS into regional and national flood control frameworks, guaranteeing that the solutions are not only socially just but also ecologically sound. Full article

(This article belongs to the Special Issue Recent Advances in Flood Risk Analysis and Management Practice)

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17 pages, 8422 KiB

Open AccessArticle

A New Procedure for Determining Monthly Reservoir Storage Zones to Ensure Reliable Hourly Hydropower Supply

by Shuangquan Liu, Jingzhen Luo, Kaixiang Fu, Huixian Li, Guoyuan Qian, Wang Xia and Jinwen Wang

Water 2024, 16(24), 3605; https://doi.org/10.3390/w16243605 (registering DOI) - 14 Dec 2024

Viewed by 400

Abstract

The uncertainty of natural inflows and market behavior challenges ensuring a reliable power balance in hydropower-dominated electricity markets. This study proposes a novel framework integrating hourly load balancing on typical days into a monthly scheduling model solved with Gurobi11.0.1 to evaluate demand-met reliability [...] Read more.

The uncertainty of natural inflows and market behavior challenges ensuring a reliable power balance in hydropower-dominated electricity markets. This study proposes a novel framework integrating hourly load balancing on typical days into a monthly scheduling model solved with Gurobi11.0.1 to evaluate demand-met reliability across storage and inflow states. By employing total storage as a system state to reduce dimensional complexity and simulating future runoff scenarios based on current inflows, the method performs multi-year statistical simulations to assess reliability over the following year. Applied to a system of 39 hydropower reservoirs in China, the case studies of present models and procedures suggest: (1) controlling reservoir storage levels during the dry season is crucial for ensuring the power demand-met rate in the following year, with May being the most critical month; (2) the power demand-met rate does not monotonically increase with higher storage levels—there is an optimal storage level that maximizes the demand-met rate; and (3) June and October offer the greatest flexibility in storage adjustment to achieve the highest demand-met reliability. Full article

(This article belongs to the Special Issue Research Status of Operation and Management of Hydropower Station)

26 pages, 14322 KiB

Open AccessArticle

Effects of War-Related Human Activities on Microalgae and Macrophytes in Freshwater Ecosystems: A Case Study of the Irpin River Basin, Ukraine

by Inna Nezbrytska, Olena Bilous, Tetyana Sereda, Natalia Ivanova, Maryna Pohorielova, Tetyana Shevchenko, Serhii Dubniak, Olena Lietytska, Vladyslav Zhezherya, Oleksandr Polishchuk, Taras Kazantsev, Mykola Prychepa, Yulia Kovalenko and Sergyi Afanasyev

Water 2024, 16(24), 3604; https://doi.org/10.3390/w16243604 (registering DOI) - 14 Dec 2024

Viewed by 507

Abstract

Throughout the world, river basins are directly or indirectly affected by human activities, reducing local and global biodiversity and preventing the ecosystem from properly functioning. Our research focused on the Irpin River basin (Ukraine), whose water bodies have experienced various impacts due to [...] Read more.

Throughout the world, river basins are directly or indirectly affected by human activities, reducing local and global biodiversity and preventing the ecosystem from properly functioning. Our research focused on the Irpin River basin (Ukraine), whose water bodies have experienced various impacts due to human activities, including the unexpected extremes caused by military operations in the catchment area: long-term flooding, disturbance of free flow, significant water level fluctuations, etc. The study hypothesized that the primary factors determining the structural and spatial distribution of quantitative indicators of microalgae and aquatic macrophytes are the result of various hydromorphological changes, that lead to changes in the physical and chemical parameters of the aquatic environment. Very high values of chlorophyll a in the water column (59–106 µg · L⁻¹), an increase in the abundance (number of cells) and biomass of algae (due to the predominance of certain groups in the transformed sections), as well as saprobic index were recorded in the sections of the Irpin River basin that underwent significant hydromorphological changes. Our results revealed a strong correlation between phytoplanktonic (in the water column) chlorophyll a levels and water temperature (r = 0.76, p < 0.001), as well as organic phosphorus and polyphosphate concentrations (r = 0.61, p < 0.01). ANOVA and Monte Carlo permutation tests in a Canonical Correspondence Analysis (CCA) showed that the abundance of different divisions of phytoplankton and phytobenthos were significantly and similarly related to several environmental variables. We observed a positive correlation between the number of cyanobacteria and the concentration of ammonium nitrogen, nitrites, and phosphorus compounds. An increase in dissolved organic matter in the water can explain the increase in the biomass of Dinoflagellata and Euglenophyta. Species richness and the cover values of the macrophytes also clearly reflected changes in vegetation activity in sections of the Irpin River caused by hydromorphological changes. The results indicated that long-term flooding had the most negative impact on macrophyte communities. At some sites, the impact was so severe that the number of macrophyte species was very low. The total number of macrophyte species showed a significant negative correlation with total suspended solids (r = −0.51, p < 0.05) and phytoplankton chlorophyll a concentration (r = −0.73, p < 0.001). Our results provide a scientific basis for predicting changes in riverine microalgal and aquatic macrophyte communities due to extreme hydrological events. Full article

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

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22 pages, 5263 KiB

Open AccessArticle

Determination of Heavy Metals and Hemato-Biochemical Profiling of Bagre marinus and Bagarius bagarius in Jhelum River

by Muneeba Shaheen, Sana Ullah, Muhammad Bilal, Ahmed Muneeb, Begum Yurdakok-Dikmen and Caterina Faggio

Water 2024, 16(24), 3603; https://doi.org/10.3390/w16243603 (registering DOI) - 14 Dec 2024

Viewed by 263

Abstract

Heavy metals enter river basins through industrial effluents, agricultural wastes, surface run-offs, and other human activities, negatively impacting aquatic and terrestrial life by bioaccumulating in the food chain. This problem is on a continuous rise in under-developed and developing countries, such as in [...] Read more.

Heavy metals enter river basins through industrial effluents, agricultural wastes, surface run-offs, and other human activities, negatively impacting aquatic and terrestrial life by bioaccumulating in the food chain. This problem is on a continuous rise in under-developed and developing countries, such as in Pakistan. Therefore, the current study was aimed to determine concentrations of heavy metals, essential trace elements, and macrominerals (Zn, Pb, Ni, Mn, Mg, Fe, Cu, Cr, Co, Cd, Ca, and As) in the water, sediments, and tissues (gills, liver, and muscles) of Bagarius bagarius and Bagre marinus in the Jhelum River, Pakistan. The hematological and biochemical profiles of these fish across two sampling sites (Jhelum Bridge Khushab, upstream, and Langarwala Pull—downstream) were also evaluated. Results showed greater bioaccumulation of heavy metals in fish downstream, correlating with higher concentrations of these metals in water and sediments downstream. In the case of B. marinus, the highest concentration observed was 16.59 mg/g (Ca), and the lowest concentration was 9.51 mg/g (Fe). In the case of B. bagarius, the highest concentration observed was 17.47 mg/g (Ca), and the lowest concentration was 7.95 mg/g (Mg). Increased activities of alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH) were observed downstream. Hematological changes included increased white blood cells (WBCs) and decreased red blood cells (RBCs), lymphocytes, hemoglobin (Hb), platelets (Plt), and hematocrit (Hct). A significant correlation was observed among heavy metals across the water, sediment, and different tissues of B. marinus and B. bagarius. Moreover, principal component analysis (PCA) for both species along both sampling sites illustrated the relationship between fish tissues and metals. The current study concluded that the fish accumulated a significantly higher concentration of heavy metals downstream, which might be linked with dumping of the domestic wastes and industrial and agricultural runoff, adversely affecting both fish and human health. Full article

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Summary of the preparation of samples for analysis. Full article ">Figure 2
Heavy metal concentrations in (A) water and (B) sediment; data presented as Mean ± SE; significant difference among sites is represented by asterisks (two-sample t-test, p < 0.05 = *, p < 0.01 = **, and p < 0.001 = ***). Heavy metal concentrations in tissues of (C) B. marinus (upstream), (D) B. marinus (downstream), (E). B. bagarius (upstream), and (F) B. bagarius (downstream); data are given as Mean ± SE and superscripted letters on bars show significance difference at p < 0.05 (ANOVA followed by LSD). Full article ">Figure 3
Level of heavy metals in the tissues of Bagre marinus and Bagarius bagarius. (A) Liver of B. marinus, (B) liver of B. bagarius, (C) gills of B. marinus, (D) gills of B. bagarius, (E) muscles of B. marinus, and (F) muscles of B. bagarius. Data presented as Mean ± SE. Significant difference among sites is represented by an asterisks (two-sample t-test, p < 0.05 = *, p < 0.01 = **, and p < 0.001 = ***). Full article ">Figure 4
Hematological profile of Bagre marinus and Bagarius Bagarius from upstream (US) and downstream (DS) of Jhelum River in Khushab District. Data represented as Mean ± SE. Significant difference among sites is represented by asterisks (two-sample t-test, p < 0.05 = *, p < 0.01 = **, and p < 0.001 = ***). Full article ">Figure 5
Serum biochemical profile of Bagre marinus and Bagarius bagarius from upstream (US) and downstream (DS) of Jhelum River in Khushab. (A) Bilirubin for B. marinus, (B) bilirubin for B. bagarius, (C) protein for B. marinus, (D) protein for B. bagarius, (E) enzymes for B. marinus, (F) enzymes for B. bagarius, (G) nitrogenous wastes for B. marinus, (H) nitrogenous wastes for B. bagarius, and (I) LDH for both species. Data presented as Mean ± SE. Significant difference among sites is represented by asterisks (two-sample t-test, p < 0.05 = *, p < 0.01 = ** and p < 0.001 = ***). Full article ">Figure 6
PCA diagrams for Bagre marinus and Bagarius bagarius along upstream and downstream sites of Jhelum River in Khushab District. (A) shows Bagre marinus at upstream, (B) shows Bagre marinus downstream, (C) shows Bagarius bagarius upstream and (D) shows Bagarius bagarius downstream. Full article ">

14 pages, 8958 KiB

Open AccessArticle

Improved Detection of Great Lakes Water Quality Anomalies Using Remote Sensing

by Karl R. Bosse, Robert A. Shuchman, Michael J. Sayers, John Lekki and Roger Tokars

Water 2024, 16(24), 3602; https://doi.org/10.3390/w16243602 (registering DOI) - 14 Dec 2024

Viewed by 251

Abstract

Due to their immense economic and recreational value, the monitoring of Great Lakes water quality is of utmost importance to the region. Historically, this has taken place through a combination of ship-based sampling, buoy measurements, and physical models. However, these approaches have spatial [...] Read more.

Due to their immense economic and recreational value, the monitoring of Great Lakes water quality is of utmost importance to the region. Historically, this has taken place through a combination of ship-based sampling, buoy measurements, and physical models. However, these approaches have spatial and temporal deficiencies which can be improved upon through satellite remote sensing. This study details a new approach for using long time series of satellite remote sensing data to identify historical and near real-time anomalies across a range of data products. Anomalies are traditionally detected as deviations from historical climatologies, typically assuming that there are no long-term trends in the historical data. However, if present, such trends could result in misclassifying ordinary events as anomalous or missing actual anomalies. The new anomaly detection method explicitly accounts for long-term trends and seasonal variability by first decomposing a 10-plus year data record of satellite remote sensing-derived Great Lakes water quality parameters into seasonal, trend, and remainder components. Anomalies were identified as differences between the observed water quality parameter from the model-derived expected value. Normalizing the anomalies to the mean and standard deviation of the full model remainders, the relative anomaly product can be used to compare deviations across parameters and regions. This approach can also be used to forecast the model into the future, allowing for the identification of anomalies in near real time. Multiple case studies are detailed, including examples of a harmful algal bloom in Lake Erie, a sediment plume in Saginaw Bay (Lake Huron), and a phytoplankton bloom in Lake Superior. This new approach would be best suited for use in a water quality dashboard, allowing users (e.g., water quality managers, the research community, and the public) to observe historical and near real-time anomalies. Full article

(This article belongs to the Special Issue Advancing the Monitoring and Modelling of Freshwater Systems with New Remote Sensing Technologies)

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Map showing the study area, consisting of all five of the Laurentian Great Lakes. Full article ">Figure 2
Workflow diagram showing the process of getting from individual VIIRS satellite images to 10-day aggregated STL decomposition products. Full article ">Figure 3
Lake-wide average seasonal time series for Lake Erie CHL (panel (A)), Lake Huron SM (panel (B)), and Lake Superior PZD (panel (C)). Each panel shows the annual seasonal patterns as light gray lines, the 11-year mean as a black line, and the 11-year standard deviation in the gray window. Full article ">Figure 4
Lake-wide average time series are shown for the three example parameters: Lake Erie CHL (panels (A–C)), Lake Huron SM (panels (D–F)), and Lake Superior PZD (panels (G–I)). The panels in the left column show the parameter value time series. The panels in the center column show the absolute anomaly (A) time series. The panels in the right column show the relative anomaly (rA) time series. Full article ">Figure 5
Western Lake Erie harmful algal bloom case study from 22 September 2015. Panel (A) shows the VIIRS true color image, with panel (B) showing the CPA-A derived CHL for the image. Panel (C) shows the expected CHL for this date based on the STL decomposition. Panels (D,E) show the absolute and relative CHL anomaly maps, respectively. Full article ">Figure 6
Saginaw Bay sediment plume case study from 21 May 2020. Panel (A) shows the VIIRS true color image, with panel (B) showing the CPA-A derived SM for the image. Panel (C) shows the expected SM for this date based on the STL decomposition. Panels (D,E) show the absolute and relative SM anomaly maps, respectively. Full article ">Figure 7
Lake Superior CHL forecast case study from 2 August 2023. Panel (A) shows the VIIRS true color image, with panel (B) showing the CPA-A derived CHL for the image. Panel (C) shows the expected CHL for this date based on the STL decomposition and forecast. Panels (D,E) show the absolute and relative CHL anomaly maps, respectively. Full article ">

17 pages, 2944 KiB

Open AccessArticle

Efficiency of Cerium Nitrate and Hydrogen Peroxide in Removing Ammonia and Nitrite from Aquaculture Wastewater and Its Impact on Microbial Community Dynamics

by Yu Qiao, Zhongyi Qu, Wenhuan Yang, Zhichao Wang, Ke Li and Weiping Li

Water 2024, 16(24), 3601; https://doi.org/10.3390/w16243601 (registering DOI) - 14 Dec 2024

Viewed by 317

Abstract

Aquaculture wastewater is rich in nutrients such as nitrogen and phosphorus. If discharged directly without treatment, it can cause eutrophication of water bodies and the proliferation of algae. This study explores the treatment of aquaculture wastewater using cerium nitrate and hydrogen peroxide. To [...] Read more.

Aquaculture wastewater is rich in nutrients such as nitrogen and phosphorus. If discharged directly without treatment, it can cause eutrophication of water bodies and the proliferation of algae. This study explores the treatment of aquaculture wastewater using cerium nitrate and hydrogen peroxide. To improve the treatment efficiency of ammonia and nitrite in aquaculture wastewater, a Box–Behnken design with three factors at three levels was used to optimize the process of treating aquaculture wastewater with cerium nitrate and hydrogen peroxide. The optimal process conditions for removing ammonia and nitrite were determined to be a Ce(NO₃)₃ dosage of 0.18 g/L, an H₂O₂ reaction concentration of 1.0%, and a reaction time of 30 min. Under the optimal reaction conditions, the degradation rate of ammonia and nitrite can reach 80% or more. Finally, high-throughput sequencing technology was used to explore the impact of cerium nitrate and hydrogen peroxide treatment on microbial community structure and metabolic pathways. The results showed that, at the phylum level, the dominant positions of Actinobacteriota, Proteobacteria, and Bacteroidota were maintained throughout the entire culture period. At the genus level, the relative abundance of the hgcI_clade genus under Actinobacteriota significantly increased, becoming the main dominant genus throughout the culture period. Under the condition of adding cerium nitrate and hydrogen peroxide, the metabolic functions of the microbial community were enhanced. The addition of cerium nitrate and hydrogen peroxide increased the abundance of key nitrogen metabolism genes such as amo, hao, and nap, thereby enhancing the potential nitrification/denitrification capabilities of microorganisms. The combination of cerium nitrate and hydrogen peroxide showed positive effects in the treatment of aquaculture wastewater, providing a new strategy for the green treatment of wastewater. Full article

(This article belongs to the Special Issue Water Quality, Wastewater Treatment and Water Recycling)

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17 pages, 6264 KiB

Open AccessArticle

Linking Water Quality Indicators in Stable Reservoir Ecosystems: Correlation Analysis and Ecohydrological Implications

by Juan Du, Xiao Yang, Peng Xu, Xiang Wan, Pan Wang, Ding Wang, Qi Yang, Qiu Wang and Amar Razzaq

Water 2024, 16(24), 3600; https://doi.org/10.3390/w16243600 (registering DOI) - 14 Dec 2024

Viewed by 372

Abstract

This research was conducted to determine the connections between dissolved oxygen (DO), chemical oxygen demand (COD), permanganate index (CODMn), five-day biochemical oxygen demand (BOD₅), and ammonia nitrogen (NH₃-H) across five reservoirs of Yunmeng County, China, from January to November [...] Read more.

This research was conducted to determine the connections between dissolved oxygen (DO), chemical oxygen demand (COD), permanganate index (CODMn), five-day biochemical oxygen demand (BOD₅), and ammonia nitrogen (NH₃-H) across five reservoirs of Yunmeng County, China, from January to November 2022. Each month, water samples were collected and subjected to analysis using standard methods. The samples were collected and analyzed using standard methods: dissolved oxygen was determined using the electrochemical probe method, COD was measured via the rapid digestion spectrophotometric method, CODMn was detected using the potassium permanganate oxidation method, BOD₅ was determined using the dilution and inoculation method, and NH₃-N was measured by using the Nessler reagent spectrophotometry method. The results confirmed strong positive correlations between COD and CODMn, with different intensities from reservoir to reservoir. More specific and demanding COD parameters were used to estimate the level of oxygen consumption; hence, a more variable correlation strength was observed between BOD₅ and the other two parameters. Thus, BOD₅ was found to be the main indicator of biodegradable organic matter and bacterial oxygen consumption. However, the results were negative, showing a decreasing trend. This means that the oxygen content was lower in the majority of reservoirs, which is attributed to the decomposition of ammonia nitrogen and the presence of organic matter. These findings significantly contribute to the development of appropriate programs for efficient water quality monitoring and the development of reservoir-specific management strategies. This study suggests that there is a need for continuous monitoring of these parameters, together with the extension of the program to additional reservoirs and water quality indicators, along with the use of advanced modeling techniques to clarify the underlying factors that connect water quality parameters in these complex reservoir ecosystems. Full article

(This article belongs to the Special Issue Ecohydrological Processes, Environmental Effects, and Integrated Regulation of Wetland Ecosystems, 3rd Edition)

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26 pages, 19626 KiB

Open AccessArticle

Hydrogeochemistry, Water Quality, and Health Risk Analysis of Phreatic Groundwater in the Urban Area of Yibin City, Southwestern China

by Xiangchuan Wu, Jinhai Yu, Shiming Yang, Yunhui Zhang, Qili Hu, Xiaojun Xu, Ying Wang, Yangshuang Wang, Huan Luo and Zhan Xie

Water 2024, 16(24), 3599; https://doi.org/10.3390/w16243599 (registering DOI) - 13 Dec 2024

Viewed by 377

Abstract

With rapid urbanization, intensified agricultural activities, and industrialization, groundwater resources are increasingly threatened by pollution. Industrial wastewater discharge and the extensive use of agricultural fertilizers in particular, have had substantial impacts on groundwater quality. This study examines 18 groundwater samples collected from the [...] Read more.

With rapid urbanization, intensified agricultural activities, and industrialization, groundwater resources are increasingly threatened by pollution. Industrial wastewater discharge and the extensive use of agricultural fertilizers in particular, have had substantial impacts on groundwater quality. This study examines 18 groundwater samples collected from the main urban area of Yibin City to assess hydrochemical characteristics, spatial distribution, source attribution, water quality, and human health risks. Statistical analysis reveals significant exceedances in TDS, NO₃⁻, Mn, and As levels in groundwater, with elevated concentrations of B as well. Isotopic analysis identifies atmospheric rainfall as the primary recharge source for groundwater in the area, with water–rock interactions and limestone dissolution playing key roles in shaping its chemical composition. Applying the Entropy-Weighted Water Quality Index (EWQI) for a comprehensive water quality assessment, the study found that 94.44% of groundwater samples were rated as “good”, indicating relatively high overall water quality. Deterministic health risk assessments indicate that 72.22% of the groundwater samples have non-carcinogenic health risks below the threshold of 1, while 66.67% have carcinogenic health risks below 1.00 × 10⁻⁴. Monte Carlo simulations produced similar results, reinforcing the reliability of the health risk assessment. Although the study area’s groundwater quality is generally good, a significant human health risk persists, underscoring the need to ensure the safety of drinking and household water for local residents. This study provides a valuable reference for the rational management and remediation of groundwater resources. Full article

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

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15 pages, 1087 KiB

Open AccessArticle

A Probabilistic Model for Predicting the Performance of a Stormwater Overflow Structure as Part of a Stormwater Treatment Plant

by Jarosław Górski, Bartosz Szeląg, Łukasz Bąk and Anna Świercz

Water 2024, 16(24), 3598; https://doi.org/10.3390/w16243598 (registering DOI) - 13 Dec 2024

Viewed by 275

Abstract

The purpose of this study was to attempt to develop a stochastic model that describes the operation of the stormwater overflow located in the stormwater sewerage system. The model built for this study makes it possible to simulate the annual volume of the [...] Read more.

The purpose of this study was to attempt to develop a stochastic model that describes the operation of the stormwater overflow located in the stormwater sewerage system. The model built for this study makes it possible to simulate the annual volume of the stormwater discharge, the maximum volume of the overflow discharge in a precipitation event, and the share of the latter in the total amount of stormwater conveyed directly, without pre-treatment, to the receiver. The dependence obtained with the linear regression method was employed to identify the occurrence of stormwater discharge. The prediction of the synthetic annual rainfall series was made using the Monte Carlo method. This was performed based on the determined log-normal distribution, the parameters of which were specified using 13-year rainfall series. Additionally, simulation of the stormwater overflow operation was performed with the use of a calibrated hydrodynamic model of the catchment. The model was developed using the Storm Water Management Model (SWMM). The results of the hydrodynamic simulations of the volume and number of discharges were within the scope of the probabilistic solution, which confirms the applicative character of the method presented in this study, intended to assess the operation of stormwater overflow. Full article

(This article belongs to the Special Issue Urban Stormwater Control, Utilization, and Treatment)

13 pages, 3151 KiB

Open AccessArticle

Analysis of the Relationship Between Groundwater Dynamics and Changes in Water and Salt in Soil Under Subsurface Pipe Salt Drainage Technology

by Xu Wang, Jingli Shen, Liqin Fan and Jinjun Cai

Water 2024, 16(24), 3597; https://doi.org/10.3390/w16243597 (registering DOI) - 13 Dec 2024

Viewed by 310

Abstract

Groundwater conditions are crucial for understanding the evolution of soil salinization. The installation of subsurface pipes significantly alters both the distribution of water and salt in the soil and the groundwater depth; these dynamics and their interrelationships warrant further investigation. To clarify the [...] Read more.

Groundwater conditions are crucial for understanding the evolution of soil salinization. The installation of subsurface pipes significantly alters both the distribution of water and salt in the soil and the groundwater depth; these dynamics and their interrelationships warrant further investigation. To clarify the relationship between groundwater dynamics and changes in water and salt in soil under subsurface pipe salt drainage conditions in the Yinchuan region of Ningxia, groundwater observation wells and soil sample monitoring points were established in Pingluo County. A combined approach of in situ monitoring and laboratory testing was employed to analyze changes in groundwater depth and salinity and their effects on water and salt in soil. The findings revealed that changes in groundwater depth and salinity exhibited clear seasonal patterns. The groundwater depth was deepest at 1.97 m in October and shallowest at 1.62 m in July. The salinity was highest at 22.28 g/L in April and lowest at 18.24 g/L in August. In summer, the groundwater was shallower and had lower salinity, while in other seasons, it was deeper with higher salinity. Soil salinity was lowest in July at 4.58 g/kg and highest in April at over 5.5 g/kg. It decreased with increasing groundwater depth, demonstrating a linear relationship. Additionally, soil salinity and groundwater salinity exhibited synchronous fluctuations, exhibiting an exponential relationship. Based on these observations, a model was developed to describe the relationship among groundwater salinity, groundwater depth, and soil salinity under subsurface pipe salt drainage conditions in the Yinbei region of Ningxia. This model was validated against measured data, yielding a correlation coefficient R² of 0.7238. These findings provide a reference for analyzing the relationship between soil salinity and groundwater in similar regions. Full article

(This article belongs to the Special Issue Geotechnical and Underground Engineering Problems Caused by Water Action)

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21 pages, 11003 KiB

Open AccessArticle

A Numerical Study on Impact of Coal Mining Activity and Mine Water Drainage on Flow and Transport Behavior in Groundwater

by Kaisar Ahmat, Hao Lu and Huiquan Liu

Water 2024, 16(24), 3596; https://doi.org/10.3390/w16243596 (registering DOI) - 13 Dec 2024

Viewed by 431

Abstract

Under the dual carbon mission, more and more coal mines will face shutting down in the future and stop treating mine water drainage, which, if it escapes, may cause severe secondary damage to the local groundwater quality. Wudong Coal Mine is a currently [...] Read more.

Under the dual carbon mission, more and more coal mines will face shutting down in the future and stop treating mine water drainage, which, if it escapes, may cause severe secondary damage to the local groundwater quality. Wudong Coal Mine is a currently active subsurface coal mine in Xinjiang, China, that shows high-salinity characteristics. To forecast and discuss future possible groundwater quality damages and potential solutions, we here introduce a model prediction study on the effects of water pollution by coal mine drainage. The study protocol first involves creating a calibrated 2D groundwater flow model by use of FEFLOW software, then designing several flow and solute transport prediction analyses under changing mine water drainage conditions, different pollution source areas and water treatment pumping wells to discuss future prominent flow and transport behavior, as well as water treatment-affecting factors. It has been shown that mine water drainage plays a critical role in maintaining the mine water solute distribution, as without mine draining, local flow and solute distribution change dramatically, altering the groundwater capture zone, and may change the plume-migrating direction from upstream to downstream. A larger pollution source could produce a higher concentration of pollutants and a larger pollution-coverage area. To reduce pollutant concentrations, mine water treatment pumping wells with higher pumping rates can be applied as a useful remedial measure to effectively prevent the pollutant plume front from reaching the important drinking and irrigation water source of the region, Urumqi River. The results of this study can give important suggestions and decision-making support for authorities focused on water treatment and environmental protection decision-making in the region. Full article

(This article belongs to the Section Hydrogeology)

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23 pages, 968 KiB

Open AccessArticle

Exploring Aquaculture Professionals’ Perceptions of Artificial Intelligence: Quantitative Insights into Mediterranean Fish Health Management

by Dimitris C. Gkikas, Vasileios P. Georgopoulos and John A. Theodorou

Water 2024, 16(24), 3595; https://doi.org/10.3390/w16243595 (registering DOI) - 13 Dec 2024

Viewed by 271

Abstract

This study aims to explore aquaculture professionals’ perspectives on, attitudes towards and understanding of Mediterranean farm fish health management, regarding Artificial Intelligence (A.I.), and to shed light on the factors that affect its adoption. A survey was distributed during a major fish health [...] Read more.

This study aims to explore aquaculture professionals’ perspectives on, attitudes towards and understanding of Mediterranean farm fish health management, regarding Artificial Intelligence (A.I.), and to shed light on the factors that affect its adoption. A survey was distributed during a major fish health management conference, representing more than 70% of Greek domestic production. A total of 73 questionnaires were collected, for which descriptive statistics and statistical analysis followed. Gender and age were shown to affect interest in A.I. and in viewing A.I. as a partner rather than a competitor. Age was additionally shown to affect trust in A.I. estimates and anticipation that A.I. will contribute to professional development. Education level shows no significant effect. Knowledge of A.I. is positively correlated with A.I. usage (r = 0.43, p < 0.05), as is interest in learning about A.I. (r = 0.64). A.I. usage is in turn positively correlated with eagerness to see its contribution (r = 0.72). Despite the fact that 64.4% characterized their knowledge as little or non-existent, 67.1% expressed interest in learning more, while 43.8% believe that A.I. will revolutionize aquaculture and 74% do not fear they will be replaced by A.I. in the future. The findings highlight the importance of targeted educational initiatives to bridge the knowledge gap and encourage trust in A.I. technologies. Full article

(This article belongs to the Special Issue Sustainable Transformation of Aquaculture in Marine Environments)

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19 pages, 18178 KiB

Open AccessArticle

Spatiotemporal Variations of Precipitation Extremes and Population Exposure in the Beijing–Tianjin–Hebei Region, China

by Hao Lin, Xi Yu, Yumei Lin and Yandong Tang

Water 2024, 16(24), 3594; https://doi.org/10.3390/w16243594 - 13 Dec 2024

Viewed by 345

Abstract

In recent years, precipitation extremes in China have increased due to global warming, posing a significant threat to human life and property. It is thus crucial to understand the changes in population exposure to precipitation extremes and the causes of these changes, since [...] Read more.

In recent years, precipitation extremes in China have increased due to global warming, posing a significant threat to human life and property. It is thus crucial to understand the changes in population exposure to precipitation extremes and the causes of these changes, since complex terrain areas are not accurately simulated by rain gauge interpolation data. Thus, we first used three satellite-based precipitation products—TRMM 3B42, CHIRPS, and CMORPH—combined with population data to analyze the spatiotemporal changes of precipitation extremes and population exposure from 1998 to 2019 in the Beijing–Tianjin–Hebei (BTH) region. In addition, the contributions of population, climate, and composite factors were quantified. The results showed that TRMM 3B42 outperformed the other two datasets in the BTH region. Over the past 22 years, the precipitation extremes in the central and northeastern regions, especially in Beijing, reached 2.5 days per decade, while the northern and southern regions showed a downward trend. The highest population exposure was mainly concentrated in central Beijing, most areas of Tianjin, and the urban centers of cities in southeastern Hebei province. Compared to the 2000s, a significant increase in exposure was observed in Beijing, Tianjin, and Zhangjiakou in the 2010s, whereas other regions showed negligible changes during this period. Climatic factors had the greatest influence on population exposure in most cities such as Qinhuangdao and Hengshui, where their climatic contribution exceeded 70%. While population change was more responsible for the increase in population exposure in the densely populated cities such as Tianjin, Handan, and Langfang, these cities contributed over 60% of the population. The interaction effect in Beijing and Tianjin was relatively obvious. The results of this study can provide a scientific basis for formulating targeted disaster risk management measures against climate change in the BTH region. Full article

(This article belongs to the Special Issue The Interrelationship Between Climate Change, Human Activities and Hydrological Processes (3rd Edition))

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8 pages, 199 KiB

Open AccessEditorial

Application of Biomass Functional Materials in the Environment

by Yiting Luo and Rongkui Su

Water 2024, 16(24), 3593; https://doi.org/10.3390/w16243593 - 13 Dec 2024

Viewed by 697

Abstract

With the intensification of global environmental issues, traditional materials science is facing unprecedented challenges [...] Full article

(This article belongs to the Special Issue Biomass Carbon Materials in Wastewater Treatment and Resource Utilization)

15 pages, 3606 KiB

Open AccessArticle

Global Water Use and Its Changing Patterns: Insights from OECD Countries

by Xiaomei Zhu, Minglei Hou and Jiahua Wei

Water 2024, 16(24), 3592; https://doi.org/10.3390/w16243592 - 13 Dec 2024

Viewed by 325

Abstract

Water resources are an important foundation for sustainable socioeconomic development. Revealing water use efficiency, the change in water use trends, and their driving mechanisms is essential for facilitating the scientific and reasonable prediction of water demand, thereby guiding the scientific planning and management [...] Read more.

Water resources are an important foundation for sustainable socioeconomic development. Revealing water use efficiency, the change in water use trends, and their driving mechanisms is essential for facilitating the scientific and reasonable prediction of water demand, thereby guiding the scientific planning and management of water resources. This study utilizes socioeconomic and water usage data from 65 countries spanning the years 1970 to 2020, employing the panel smooth transfer regression (PSTR) model to analyze the relationship between per capita total water withdrawal and per capita GDP. Additionally, Random Forest (RF) methods and empirical statistical analyses are implemented to identify the driving factors, control variables, and critical thresholds of water use trends in countries with different levels of development. The results show that: (1) there exists a nonlinear relationship between per capita total water withdrawal and per capita GDP on a global scale, with 70% of the countries exhibiting an inverted U-type trend in water usage; (2) the observed decline in per capita total water withdrawal in relation to per capita GDP is primarily driven by technological advancements and the optimization and enhancement of production structure; (3) common characteristics of OECD (Organization for Economic Cooperation and Development) countries that have reached their peak water usage include a service sector contribution to GDP exceeding 60%, urbanization levels at 70%, and per capita GDP surpassing USD 20,000. The observed changes in water use trends and the characteristic indicators associated with peak water usage, under conditions devoid of engineering interventions and resources constraints, can serve as valuable references for medium- and long-term water resources planning and water demand management in developing nations. Full article

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Water, Volume 16, Issue 24 (December-2 2024) – 79 articles

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