Water Quality Research Articles

How to manage regime shifts: insights from a dryland social–ecological system

ABSTRACT Effective water resource management in the Zayandeh-Rud River Basin, a critical region in the Middle East, requires understanding system dynamics and anticipating regime shifts. This study uses system dynamics to model water consumption changes in the basin, analysing various scenarios (10% to 30% increase/decrease) in agricultural, urban, and industrial sectors. Results show that increased consumption harms water systems, while reductions, especially a 30% decrease, stabilize systems and improve water quality. Upstream reductions benefit downstream resources, highlighting the importance of integrated management. Proactive strategies can mitigate adverse impacts, ensuring a sustainable water future for the region’s inhabitants.

On the underestimation of the significance of environmental impacts in Peru: an approach using homogeneous units

ABSTRACT This study examines the reliability of the Environmental Impact Statements (EISs) in Peru, focusing on projects predicted to have high negative impacts. It highlights the discrepancy between the expected and the estimated impacts in EISs, revealing a general trend of underestimating the environmental significance of projects, particularly in areas free from industrial activities. The study critiques the application of the Gomez Orea Method, originally successful under Spanish regulations but problematic in its Peruvian applications, as evidenced by inconsistencies in the methodologies and a lack of bibliographic and regulatory support for the indicators used. The analysis covers seven EISs involving hydroelectric and mineral exploitation projects. It identifies a recurrent pattern where despite the significant potential impacts of these projects on water quality, ecosystems, and biodiversity, the impacts are predominantly classified as ‘Compatible’ or low. This underestimation results in 97.37% of impacts being categorized as low, contradicting the projects’ initial high-risk classification. Moreover, the study compares the Gomez Orea Method with the Conesa Method, a more conservative approach, finding significant methodological differences affecting impact significance estimations. The study advocates for enhanced Environmental Impact Assessment practices in Peru, suggesting the adoption of more conservative assessment methods to accurately gauge and mitigate environmental impacts.

Towards Water Systems Security and Sustainability Using Deep Learning

Wastewater treatment plants (WWTPs) face significant challenges due to varying influent conditions, multiple operational constraints, and a constant lack of reliable datasets to manage and monitor water quality and flow using automated approaches. This paper introduces a novel framework showcasing soft sensors that are aimed at enhancing the sustainability and security of wastewater quality indicators using deep learning. We develop a trustworthy soft sensor that utilizes artificial intelligence (AI) approaches to provide nitrate NO3 predictions at the WWTP, as well as context-based evaluations to estimate overall predictive uncertainty. Contextual elements are injected into the model to allow for more accurate and relevant water quality monitoring, especially in different conditions (such as rain and snow). In addition, in this paper, we present a time-series Generative Adversarial Network (GAN), namely H2OGAN to address data scarcity and to improve model training by generating synthetic data that mirrors the statistical properties of water datasets from both controlled and real-world environments. Data in turn also train against data poisoning attacks on water supply systems, rendering these systems more secure. Our results indicate the potential uses of the integration of soft sensors and H2OGAN to significantly improve the operational efficiency of WWTPs by providing robust AI-driven tools for offering secure and sustainable water monitoring solutions.

Experimental investigation of surface buoyant jet interactions with grid obstructions: implications for aquaculture

Freshwater inputs originating from terrestrial streams and gullies that discharge into quiescent, semi-enclosed coastal regions (such as estuaries, tidal inlets or lagoons), typically provide point sources of nutrients (e.g. nitrates, phosphates) and/or contaminants (e.g. pesticides, pathogens) that may have a deleterious impact on water quality. Many of these sheltered coastal regions also increasingly support aquaculture operations (e.g. finfish, shellfish, or seaweed farms), which can therefore be directly impacted by nutrient and contaminant inputs. Dynamically, these terrestrial freshwater inflows behave as surface buoyant jets or plumes within the coastal saline or brackish receiving waters, due to the salinity-induced density gradients. As such, the presence of infrastructure associated with aquaculture operations in sheltered coastal waters can provide obstruction to the propagation characteristics and residence times for these surface freshwater flows. Consequently, an improved physical understanding of the flow-structure interaction is clearly crucial to assessing the potential contamination risk of aquaculture products. The aim of the current study is therefore to explore, through scaled laboratory experiments within a channel-basin facility, the impact of physical obstruction induced by a vertical grid structure on the flow evolution of a 2D – 3D expanding, surface buoyant jet. Two grid obstructions with different solidity ratios are tested, along with surface gravity currents of different density excesses and freshwater inflows to infer the influence of different parametric conditions on the propagation, blockage and mixing characteristics of the surface current in the vicinity of the grid obstruction. Measurements of the velocity structure and thickness of the expanding surface plume are obtained by ultrasonic velocity profilers, while the density excess in the evolving plume is measured by micro-conductivity probes. Dye visualization results also show that, in the presence of the grid obstruction, the generation of shear-induced billows at the lower interface of the expanding surface current is largely blocked and a local deepening of the fresh-salt water interface in the immediate vicinity of the grid obstruction is observed. In this sense, the obstruction imposed by aquaculture infrastructure in coastal domains can have a considerable influence of the local turbulent mixing and vertical transfer of substances (e.g. nutrients and contaminants), but is likely to have relatively minimal impact in the final dispersion of the surface plume.

Source–Sink Structural Coupling Within Forest-Clustered Landscapes Drives Headstream Quality Dynamics in Mountainous Sub-Watersheds: A Case Study in Chongqing, China

Water environment quality is profoundly driven by a series of landscape characteristics. However, current knowledge is limited to the independent response of water quality to single landscape elements; this has led to poor knowledge of the potential role of structural coupling within landscapes in driving water quality changes, especially in those agroforestry-mixed mountainous watersheds with highly embedded forest-clustered landscapes and abundant headstreams. Given this fact, this study aims to evaluate whether and how the source–sink coupling structure of forest-clustered landscapes systematically drives headstream quality dynamics. We first systematically assessed the association pattern of source and sink structures within forest-clustered landscapes, and then innovatively proposed and constructed a functional framework of source–sink coupling structure of landscapes across 112 agroforestry-mixed mountainous sub-watersheds in Chongqing, China. On this basis, we further evaluated the driving pattern and predictive performance of the source–sink coupling structure of landscapes behind headstream quality dynamics. We report three findings: (1) headstream quality varied across agroforestry-mixed sub-watersheds, mapping out the source–sink structures and functions of landscapes; (2) there was significant functional coordination between source–sink structures of the forest-clustered landscapes, which significantly drove headstream quality dynamics; (3) the structural positioning and differences of the forest-clustered landscapes along the multivariate functional axes directly corresponded to and predicted headstream quality status. These findings together highlight a key logic that the response of water quality dynamics to landscapes is essentially that to the functional coupling between the source–sink structures of landscapes, rather than the simple combination of a single landscape contribution. This is the first study on the landscape–runoff association from the perspective of source–sink structural coupling, which helps to deepen understanding of the correlation mechanism between water dynamics and landscape systems, and provides a new functional dimension to the development of future landscape ecological management strategies from a local to a global scale.

River invertebrate biodiversity benefits from upstream urban woodland

In urban environments, invertebrate communities are subjected to a broad mixture of impacts, including diffuse pollution. Pollutant mixtures and habitat degradation can combine to apply stress on community diversity. Water quality is influenced by the assemblage and mosaic of catchment land cover. Amongst a wider suite of Nature-Based Solutions, the value of urban woodland is increasingly recognized as having potential to support a range of ecosystem services. Despite an increasing focus on establishing urban woodland for aquatic conservation, its actual influence is yet to be manifested. Therefore, we explored trees’ location in riparian and upstream catchment, within and outside of the urban area. We conducted a combination of systematic literature review and statistical analysis to better understand the woodland influence. Despite the wide range of bioindicators studied and broad worldwide spectrum of geo-climatic regimes covered, literature evidence for benefits were found in at least half the cases. With a focus on the overall family richness and the sensitive orders Ephemeroptera, Plecoptera and Trichoptera family richness as bioindicators, the statistical analysis comprised a national study in England covering 143 sites with substantial urban cover, totaling 4226 invertebrate community observations over 30 years. Two satellite-derived land cover maps were used to enable discrimination between urban and extra-urban woodland. The analysis supported the literature evidence that impervious land had negative effects and woodland positive effects. In the urban and upstream catchment, woodland was more important than pasture or cropland. There was some evidence of those woodland effects being more advantageous when trees are located within the urban area itself. Benefits attributable to woodland were distinctly apparent against a backdrop of improving macroinvertebrate diversity found to be synchronous with long-term reductions in urban pollution signatures. The presence of sparse land, even in small amounts, was detrimental to macroinvertebrate diversity. These areas of low vegetative cover might be detrimental due to high sediment input and legacy industrial contamination. Given the increasing accessibility of land cover data, the approach adopted in this case study is applicable elsewhere wherever macroinvertebrate community data are also available.

Effect of Solar Activity Cycles on the Dnipro Water Quality Parameters

Effect of Solar Activity Cycles on the Dnipro Water Quality Parameters

Improved water and sanitation in early life and cognition in adolescence: Evidence from four countries

Abstract Early life environmental exposures, such as drinking water quality and sanitation, can have long lasting effects on human capital accumulation. Using matched samples of over 8,000 children across Ethiopia, India, Peru, and Vietnam, this paper examines
the relationship between early life access to improved drinking water and improved sanitation and cognition at the age of fifteen. It finds that children with early life access to improved drinking water score 1.6 to 2.8 percentage points higher on math, reading,
and vocabulary tests. A similar, yet less precisely measured, pattern emerges for early life access to improved sanitation. Analysis by gender shows that the effects of early life drinking water access are stronger and more precise among girls. An examination of
pathways underlying these relationships provides preliminary evidence that learning over the life course is a leading mechanism. Quantifying these long-term cognitive benefits provides insight for directing and prioritizing resources for global efforts to
increase equitable access to improved drinking water and sanitation.

Mapping barriers to food, energy, and water systems equity in the United States

Barriers to affordable, accessible, high-quality food, energy, and water systems (FEWS) harm social equity. Connections within and across FEWS suggest that co-occurring barriers to equity can compound vulnerability. We hypothesized that barriers to FEW resources are strongly associated with geographic location, both within and across FEWS, as they rely heavily on localized sociopolitical and natural environments. This study explored the geographic relationships between FEWS barriers and social equity through a spatial analysis of census tracts within the United States. Cluster analyses showed that all FEWS barriers had a positive spatial autocorrelation (Moran's I = 0.12–0.94), with energy barriers being the most spatially clustered and affordability barriers being the least spatially clustered. In 54 % of census tracts, we observed the co-occurrence of low barriers to water quality and access. Barriers to FEWS affordability almost always co-occurred in parallel (e.g., high barriers to affordability in one system co-occurred with high barriers to affordability in another system). Finally, we developed a spatial index of the barriers to FEWS equity to determine vulnerability at the census tract scale, which had a positive spatial autocorrelation (Moran's I = 0.41). Clusters and intersections of FEWS equity barriers suggest that resources are interconnected, resulting in additional challenges for people living in these areas. The maps of barriers to equity in FEWS are useful tools that could help stakeholders (e.g., federal agencies, city planners, utilities) distribute FEWS resources fairly and begin engagement with communities about FEWS barriers in their local context.

Seasonal dynamics of bacterial community structure and function in the surf zone seawater of a recreational beach in Ostend, Belgium

AbstractDespite the importance of bacteria in surf zone water quality, detailed insights into their community composition, functions, and seasonal dynamics at recreational beaches are scarce. This study conducted year‐long, weekly monitoring of bacterial communities and environmental factors at a recreational beach in Ostend, Belgium. Using full‐length 16S rRNA gene sequencing, we correlated bacterial composition and predicted functions with environmental factors to identify potential drivers. Bacterial communities were significantly affected by seasonal variations in chlorophyll a (Chl a), net primary productivity (NPP), and seawater temperature (SWT), with minimal influence from faecal inputs due to human activities. Spring showed distinct abundances of Planktomarina, Amylibacter, and Sulfitobacter, positively correlated with Chl a and related to sulphur oxidation potential. Summer had higher abundances of Cryomorphaceae, likely enhancing chemoheterotrophy. Beginning in mid to late fall and extending into winter, bacterial communities underwent substantial changes. Fall featured a distinctive enrichment of Thioglobaceae, inversely correlated with Chl a. Winter was dominated by Methylophilaceae (OM43 clade), negatively correlated with Chl a, NPP, and SWT. Both seasons exhibited elevated levels of potentially pathogenic phenotypes and predicted functions related to methanol oxidation and methylotrophy. This study provides a baseline for understanding how surf zone bacterial communities respond to environmental changes and impact health.

Electrocoagulation as a Remedial Approach for Phosphorus Removal from Onsite Wastewater: A Review

Onsite wastewater treatment systems (OWTSs), although essential for managing domestic sewage in areas without centralized sewerage treatment plants, often release phosphorus (P) into the environment due to inadequate treatment. This unregulated P discharge exacerbates water quality degradation and jeopardizes aquatic habitats and human health. Among different treatment technologies, electrocoagulation (EC) demonstrates considerable potential for addressing this challenge by efficiently removing P from OWTSs and thus protecting water resources and ecological integrity. Through electrochemical reactions, EC destabilizes and aggregates P-bearing particles, facilitating their removal through precipitation. Compared to conventional treatment approaches, i.e., chemical and biological methods, EC offers several advantages, including high efficiency, minimal chemical usage, and adaptability to varying wastewater compositions. This review underscores the urgent need for mitigating P discharge from OWTSs and the efficacy of EC as a sustainable solution for P removal, offering insights into its mechanisms, reactor design considerations, important operational factors, performance, and potential applications in OWTSs as well as providing future research directions.

Spectroscopic Investigation of the Interaction of Silicate Ions with Lead Carbonates Under Drinking Water Conditions

The presence of lead has been identified as a critical health risk in drinking water systems serviced by Pb-bearing plumbing. Among several corrosion control strategies, the use of sodium silicates has attracted interest due to the advantages it offers compared to other approaches, such as phosphate dosage. However, the interaction of silicate ions with lead corrosion scales and other ubiquitous dissolved species such as Al ions in drinking water is not well understood. In this work, surface and bulk spectroscopic analysis of the solid scale is combined with quantitative analysis of the aqueous phase. A detailed spectroscopic probing of the transformations taking place on the solid phase enables us to develop a mechanistic framework for reports published in the last four years in the open literature, suggesting that silicates may not be an adequate corrosion control option in drinking water systems rich in solid lead carbonates. The spectroscopic data obtained demonstrate that in the presence of chlorine residual, silicates inhibit Pb(II) carbonates from oxidizing into less soluble Pb(IV) oxides thus, negatively impacting water quality. Furthermore, aluminum ions interact with silicates resulting in the formation of solid allophane phase over the lead scale surface, extending into the bulk. However, the formation of this new solid allophane phase does not protect against lead dissolution.

An innovative fuzzy multi-criteria decision making model for analyzing anthropogenic influences on urban river water quality

An innovative fuzzy multi-criteria decision making model for analyzing anthropogenic influences on urban river water quality

Analysis of Natural Water Quality in the Dniester River Basin for Economic Utilization

Analysis of Natural Water Quality in the Dniester River Basin for Economic Utilization

A novel hybrid model for long-term water quality prediction with the ‘decomposition–inputs–prediction’ hierarchical optimization framework

A novel hybrid model for long-term water quality prediction with the ‘decomposition–inputs–prediction’ hierarchical optimization framework

Discriminative characteristics of hydrochemical components and sedimentary organic matter in Korean coastal aquaculture systems during summer

Understanding the spatial distribution and sources of sedimentary organic matter (OM) in coastal environments is crucial for effective water quality management and the preservation of ecosystem health. Although extensive research has been conducted on OM dynamics, there remains a gap in understanding the ongoing biogeochemical processes in Korean coastal aquaculture zones, particularly during the summer season. To address this gap, we investigated the spatial variation of water chemical properties and isotopic composition of sedimentary OM to trace the composition, source, and reactivity of mixed OM in aquaculture systems along the Korean coast during the summer season. The isotopic approach was applied to surface sediments from five sections: western (W)-1, W-2, southern (S)-1, S-2, and eastern (E)-1. With respect to increased nutrients (mainly nitrate; 1.2 ± 0.6 mg/L) by dam-water discharge near W sections, our isotopic signatures revealed that a substantial fraction of sedimentary OM might dominantly originated from autochthonous OM source (algae; 36.5%) related to the increase of terrestrial nutrients. Simultaneously, the deposition of allochthonous OM (aquacultural feces; 44%) was predominant in the S-2 sections. The 34S-depleted patterns (approximately -7.2‰) in the S-2 section was indicative of active sulfate reduction occurring at the sedimentary boundary. Therefore, together with the precise determination of ongoing OM, our isotopic results provide valuable insights for effectively managing water-sedimentary qualities under the increase of anthropogenic contamination.

Performance of water quality simulation model for lifting drainage water joints and mixing zone determination

Limited water resources with gradual increase in water demand led to higher dependence on drainage water as one of the non-conventional water resources in Egypt. However, there was no precise approach for using such resource. The practices ranged between stopping lifting drainage water to main canals at many locations due to the water quality degradation in the drains and pure dependence on polluted drainage water by farmers. This implies the importance of applying the mathematical models that provide precise and flexible alternative for the dependence on the drainage water. This procedure could save the big investments that were used in the lifting stations while mitigating the environmental hazards. Cornell Mixing Zone Expert System (CORMIX) model is one of these mathematical simulation models. The study used surface discharge sub-model (CORMIX3) to define the mixing zone between the lifted drainage water from Mehalet Rough drain and the freshwater in Mit Yazid canal, by investigated biochemical oxygen demand (BOD) and total dissolved solids (TDS). The simulation results verified that the two investigated parameters met WQ standards for the Egyptian law 48/1982. BOD standard value was met after 448.36 m, in 723 s. TDS standard value was met after 4.46 m, in 7.8 s. This was far ahead of the first municipal station regardless low quality of these parameters in the drain. This is the first time to apply this model in the irrigation sector in Egypt, and the results were promising for defining the precise approach to reuse the drainage water in Egypt.

The dominant mechanisms of nutrient cycling in high-dam reservoirs: retention, transport or transformation?

Abstract High-dam reservoirs can significantly affect nutrient cycling processes across the globe. However, the research community now has two contradictive views (i.e. retention versus transformation) about the impact of high-dam reservoirs on nutrient cycling due to incomplete information obtained from limited field samplings. To resolve this issue, we develop a physically-based, three-dimensional water quality model to examine the spatiotemporal distributions of biogenic elements (nitrogen and phosphorus) in high-dam reservoirs with high spatial and temporal details. We apply the model to the Xiaowan Reservoir, a representative high-dam reservoir in the Lancang River Basin. By scrutinizing the spatiotemporal distributions of biogenic elements across space and over time, we find a unique ‘retention-transformation-transportation’ process of nitrogen and phosphorus in the high-dam reservoir, with dominant transformation occurring in the water zone before the dam during non-flood period while dominant retention occurring in the middle part of a reservoir during flood period. We further find that transformations of biogenic elements are enhanced only in low-temperature and low-oxygen environments. Our findings show solid scientific basis to resolve the contradictive views about nutrient cycling mechanisms in high-dam reservoirs, and provide important policy implications for the operation of high-dam reservoirs to achieve improved water quality while maintaining clean energy supply.

SentemQC - A novel and cost-efficient method for quality assurance and quality control of high-resolution frequency sensor data in fresh waters

The growing use of sensors in fresh waters for water quality measurements generates an increasingly large amount of data that requires quality assurance (QA)/quality control (QC) before the results can be exploited. Such a process is often resource-intensive and may not be consistent across users and sensors. SentemQC (QA-QC of high temporal resolution sensor data) is a cost-efficient, and open-source Python approach developed to ensure the quality of sensor data by performing data QA and QC on large volumes of high-frequency (HF) sensor data. The SentemQC method is computationally efficient and features a six-step user-friendly setup for anomaly detection. The method marks anomalies in data using five moving windows. These windows connect each data point to neighboring points, including those further away in the moving window. As a result, the method can mark not only individual outliers but also clusters of anomalies. Our analysis shows that the method is robust for detecting anomalies in HF sensor data from multiple water quality sensors measuring nitrate, turbidity, oxygen, and pH. The sensors were installed in three different freshwater ecosystems (two streams and one lake) and experimental lake mesocosms. Sensor data from the stream stations yielded anomaly percentages of 0.1%, 0.1%, and 0.2%, which were lower than the anomaly percentages of 0.5%, 0.6%, and 0.8% for the sensors in Lake and mesocosms, respectively. While the sensors in this study contained relatively few anomalies (<2%), they may represent a best-case scenario in terms of use and maintenance. SentemQC allows the user to include the individual sensor uncertainty/accuracy when performing QA-QC. However, SentemQC cannot function independently. Additional QA-QC steps are crucial, including calibration of the sensor data to correct for zero offsets and implementation of gap-filling methods prior to the use of the sensor data for determination of final real-time concentrations and load calculations.

Sustainable Resource Management in an Agro-Industrial Cluster: A Case Study

Introduction: The challenge of water supply and sustainable energy is crucial for addressing long-term clean water and energy challenges. Moreover, there has been an increase in water and air pollution resulting from the community's activities. Objective: The objective of this study is to investigate conservation strategies must be enacted to reduce dependency on clean water and energy supplies. Theoretical Framework: In this topic, the main concepts and theories that underpin the research are presented. Cost reductions, environmental sustainability, and an improved public image for understanding are context of the investigation. Method: The methodology adopted for this research comprises the case study uses a quantitative descriptive method to identify the estimated potential amount of biogas and water quality produced from tapioca and sago industrial wastewater. Data collection was carried out through the specific methods used, such as interviews, questionnaires, observations,and laboratory testing. Results and Discussion: The results obtained revealed energy generation from starch wastewater and recycled water from tapioca wastewater. The wastewater was treated in a biogas reactor as primary treatment to reduce the environmental load and produce biogas simultaneously. The wastewater recycling scheme for the tapioca industry, the quality and quantity of treated water recycled. Research Implications: Biogas production from wastewater reduces energy costs in starch industries. Recycling wastewater saves fresh water daily for starch production. Excess methane can be used for electricity generation or distributed to the community. Implementing anaerobic reactors minimizes environmental pollution. The system boosts sustainability, lowering reliance on external water and energy sources. Originality/Value: This study contributes to the literature by innovative integration of water recycling and biogas generation in starch industries. First application of CoLAR technology for energy self-sufficiency in tapioca and sago sectors. Demonstrates significant cost savings by reusing treated wastewater in production. Offers a scalable model for sustainable water and energy use in agro-industrial clusters. Contributes to reducing environmental impact through waste-to-energy conversion.