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Accurate forecasting of dissolved oxygen (DO) levels is vital for river ecosystem health. A novel methodology, MVMD-TSA-GPR, combines Multivariate Variational Mode Decomposition (MVMD), the Tunicate Swarm Algorithm (TSA), and Gaussian Process Regression (GPR) to improve DO level predictions. This study also incorporated Generalized Additive Model and Regression Bagged Ensemble (RBE) for 1- and 3-month forecasts using monthly data (1974–2023) from 16 water quality parameters across five Mississippi River basin sites. Key predictors identified through cross-correlation include lagged values and parameters like water temperature, discharge, pH, total phosphorus, potassium, and sulfate, which significantly influence DO levels. The MVMD-TSA-GPR model outperformed others, especially at site 5, showing substantial improvements in accuracy with decreased RMSE values across various scenarios. Model ranking via the Taylor Diagram indicated MVMD-TSA-GPR had the highest performance, followed by MVMD-TSA-RBE and others. Notably, the GPR model's RMSE at site 3 decreased from 2.11 to 1.01 (109% reduction) for the 1-month forecast, while at site 4 for the 3-month forecast, it dropped from 1.85 to 1.04 (106% reduction). The results revealed that the MVMD-TSA-GPR model demonstrated the highest performance for DO (t + 1), achieving R = 0.90, PBIAS = 0.73%, and WI = 0.804, as well as for DO (t + 3), with R = 0.88, PBIAS = 0.54%, and WI = 0.779, at the Lower Mississippi site during the test phase. Additionally, the MVMD-TSA-RBE model excelled for DO (t + 1) in the Missouri River at the Hermann site, achieving R = 0.91, PBIAS = 0.86%, and WI = 0.805 during the test phase. These results underscore the effectiveness of the MVMD-TSA hybrid approach. Interpretative analysis using SHapley Additive exPlanations (SHAP) revealed water temperature, pH, and potassium as key factors affecting DO levels. The speed and accuracy of MVMD-TSA-GPR make it a promising tool for monitoring river water quality. [ABSTRACT FROM AUTHOR]

Groundwater, widely used for supplying drinking water to populations, is a vital resource that must be managed sustainably, which requires a thorough understanding of its diverse physico-chemical and bacteriological characteristics. This study, based on a 27-year extraction from the Sise-Eaux database (1993–2020), focused on the island of Corsica (72,000 km2), which is diverse in terms of altitude and slopes and features a strong lithological contrast between crystalline Corsica and metamorphic and sedimentary Corsica. Following logarithmic conditioning of the data (662 water catchments, 2830 samples, and 15 parameters) and distinguishing between spatial and spatiotemporal variances, a principal component analysis was conducted to achieve dimensionality reduction and to identify the processes driving water diversity. In addition, the spatial structure of the parameters was studied. The analysis notably distinguishes a seasonal determinism for bacterial contamination (rain, runoff, bacterial transport, and contamination of catchments) and a more strictly spatial determinism (geographic, lithological, and land use factors). The behavior of each parameter allowed for their classification into seven distinct groups based on their average coordinates on the factorial axes, accounting for 95% of the dataset's total variance. Several strategies can be considered for the inventory and mapping of groundwater, namely, (1) establishing quality parameter distribution maps, (2) dimensionality reduction through principal component analysis followed by two sub-options: (2a) mapping factorial axes or (2b) establishing a typology of parameters based on their behavior and mapping a representative for each group. The advantages and disadvantages of each of these strategies are discussed. [ABSTRACT FROM AUTHOR]

Socio-economic activities along the Citarum River basin in Indonesia can induce ecological disturbances in the structure of the benthic macroinvertebrate community. This research aims to (1) identify the environmental factors responsible (2) describe the ecological disturbances using biological measurements; (3) and to develop local biocriteria using a multi-metric conceptual approach. An inventory of benthic macroinvertebrates was carried out at eight stations over a sampling period of 3 months, along with water quality monitoring. The results confirm the change in the structure of benthic macroinvertebrate communities, explained by seven environmental parameters: dissolved oxygen (DO), ambient habitat quality, turbidity, nutrient enrichment, conductivity, temperature, and embeddedness percentage. The changes were then assessed using six biological measurements. Only four have been shown to be capable as alternatives to existing biocriteria. Their implementation enabled the development of local biocriteria compatible with the multimetric concept known as the cumulative biotic index (CBI). [ABSTRACT FROM AUTHOR]

The design of a representative surface water quality monitoring network is vital for accurately capturing the dynamics of water bodies and variability in pollution across a catchment. The representativeness of a surface water monitoring network refers to how well it reflects the characteristics of all monitored surface water bodies. In this study, using a micro-watershed–based approach, a Geographic Information System (GIS) tool (Surface Water Quality Monitoring Point Locations ANalysis (SWQM_PLAN)) has been developed to optimize the design of surface water quality monitoring networks. In the first stage of the two-stage study, a digital elevation model and minimum watershed area size were taken as input parameters and micro-watersheds with defined upstream–downstream relations were created. In the second stage, input parameters including land use data, pollution sources, and micro-watershed data, along with specific criteria, were used to identify the basins and determine the optimal locations for surface water monitoring stations. The developed GIS tool was then applied to evaluate the existing surface water monitoring network in the Gediz River Basin, designed by the Republic of Türkiye, Ministry of Agriculture and Forestry. The tool assessed the effectiveness if the existing monitoring network in terms of assessing agricultural pollution and provided potential revision suggestions to enhance the effectiveness of implemented pollution reduction measures. [ABSTRACT FROM AUTHOR]

Hydrobiogeochemical processes governing water quantity and quality are highly variable in space and time. Focusing on thirty river locations in Québec, Canada, three water quality hotness indices were used to classify watersheds as contaminant transport hotspots. Concentration and load data for suspended solids (SS), total nitrogen (TN), and total phosphorous (TP) were used to identify transport hotspots, and results were compared across hotness indices with different data requirements. The role of hydroclimatic and physiographic characteristics on the occurrence and temporal persistence of transport hotspots was examined. Results show that the identification of transport hotspots was dependent on both the type of data and the hotness index used. Relationships between temporal and spatial predictors, however, were generally consistent. Annual transport hotspot occurrence was found to be related to temporal characteristics such as the number of dry days, potential evapotranspiration, and snow water equivalent, while hotspot temporal persistence was correlated to landcover characteristics. Stark differences in the identification of SS, TN, and TP transport hotspots were attributed to differences in mobilization processes and provided insights into dominant water and nutrient flowpaths in the studied watersheds. This study highlighted the importance of comparing contaminant dynamics across watersheds even when high-frequency water quality data or discharge data are not available. Characterizing hotspot occurrence and persistence, among hotness indices and water quality parameters, could be useful for watershed managers when identifying problematic watersheds, exploring legacy effects, and establishing a prioritization framework for areas that would benefit from enhanced routine monitoring or targeted mitigation strategies. [ABSTRACT FROM AUTHOR]

Integral estimate of the environmental conditions of water bodies in the Russian part of the Ural River basin is presented. The estimate is based on the data of long-term state water quality monitoring, statistical data, remote sensing data, the results of special researches, and data of the authors' field studies of water bodies and drainage areas, as well as laboratory studies of water samples. The collected materials were used to characterize the current environmental conditions of water objects and the spatial heterogeneity in the economic development of the drainage area. All available data were used to compile a catalog of water bodies ranked by the level of the load on them. For water bodies experiencing the largest load and characterized by significant violations of water quality standards, a system of measures is proposed for improving their environmental conditions. The choice of the measures is based on the analysis of the Russian and foreign experience in water protection activities, including nature-based restoration technologies of water bodies. The proposals have a comprehensive character and are based on a basin-scale approach. [ABSTRACT FROM AUTHOR]

Changes in land use and landscape patterns significantly influence watershed water quality by affecting non-point source (NPS) pollution processes. Understanding the characteristics of water quality and the relationships between landscape patterns and water quality is crucial to informing land-use planning aimed at ensuring water security. In this study, we employed landscape index methods, correlation analysis, and redundancy analysis based on monitored water quality data and land-use types relative to the Yanshan River Basin, Guilin, China. The results show the following features: (1) Water quality in the small watershed exceeded the values of class III during the study period, and total nitrogen (TN) was the main pollutant, with a pollution load ratio reaching 67.9%. (2) Water quality was significantly impacted by the landscape patterns of the small watershed river. The monitored concentrations of TN, ammonia nitrogen (NH4+-N), nitrate nitrogen (NO3−-N), and total phosphorus (TP) were negatively correlated with the proportion of forest area, and the concentrations of NH4+-N and TP were positively correlated with the proportions of building, orchard, and cultivated land areas. Moreover, the influences of landscape patterns during the wet seasons on water quality were stronger than those during the dry seasons. (3) The total interpretation rates of the landscape indices for the water quality indices in the dry and wet seasons were 96.7% and 94.4%, respectively. Moreover, the largest patch and aggregation indices of the building area were the most effective variables in explaining the water quality indices, with contribution rates of 30.8% and 23.2% in the dry seasons and 34.3% and 23.8% in the wet seasons, respectively. By analyzing these relationships, in this study, we obtained insights into how different landscape patterns contribute to variations in water quality. The findings contribute to sustainable land-use planning strategies that aim to mitigate the impacts of land-use changes on water resources. [ABSTRACT FROM AUTHOR]

Aquatic ecosystems globally have been invaded by molluscs. Tarebia granifera is a highly successful invader, often becoming the dominant aquatic invertebrate species in an invaded ecosystem. Resultingly, it has been suggested that T. granifera may have severe negative impacts on these invaded ecosystems. Limited information is available regarding the population structures and densities of T. granifera, particularly in invaded countries such as South Africa, and information on this could assist in developing management and control strategies for this invasive species. The present study aimed to assess the current distribution, densities, and population structures of T. granifera in invaded habitats on the Limpopo and Phongolo River systems in South Africa. This was accomplished by collecting aquatic molluscs from sites across these systems. Water quality parameters were measured at each site and water samples were collected for chemical nutrient analyses. The density of snails was determined for each site and the population size and structure as well as birth rate was calculated for T. granifera. Tarebia granifera was found to be the dominant molluscan species in habitats where it was present and all size classes from newborn to mature adults were found throughout at some of the highest densities globally. Worryingly, native molluscan species, were often absent or in much lower densities than reported in literature at sites where T. granifera was present, suggesting a negative effect on the native molluscan density and diversity. Contrary to most previous studies, there were no significant correlations between T. granifera and the selected water quality parameters. Higher densities and newborn recruitment of T. granifera were observed in the spring than in autumn, likely in response to shifts in environmental conditions. This study provides crucial insights into the population structure, densities, and impacts of T. granifera in invaded habitats, particularly for relatively newly invaded regions such as southern Africa. [ABSTRACT FROM AUTHOR]

The Ganol River, a vital water source for Meghalaya, India, faces significant environmental degradation due to human activities, primarily the improper disposal of domestic and commercial wastes. This study aims to assess the current water quality of the Ganol River through hydro‐chemical analysis, multivariate statistical methods, and Water Quality Index (WQI) analysis. Over a span of 6 years (2014–2020), monthly water samples were collected from ten source points or stations along the river. The findings revealed that some environmental variables had mean values below the standard limit, while others, notably dissolved oxygen (DO) and turbidity, had higher values. The Pearson correlation coefficients was used to establish the closeness or relationship within and between physico‐chemical characteristics, with some displaying strong positive connections and others showing moderate to negative correlations. The study identified several key environmental contaminants, including conductivity, BOD, COD, TSS, D.O, chloride, TDS, sulphate, hardness, calcium, magnesium, potassium, fecal coliform, and total coliform, based on their highest factor loading values. Such contaminants are significantly impacting aquatic life and the overall ecosystem of the Ganol River. Moreover, the Water Quality Index (WQI) assessment indicated a continuous decline annually in the water quality of the Ganol River. This decline poses a severe threat to the river's sustainability and the well‐being of the communities relying on it for various purposes. [ABSTRACT FROM AUTHOR]

Considering the growing importance of sustainable development and value engineering in various fields, especially in water quality management, superior attention has been paid to reducing costs in water quality monitoring systems. One of the methods, which reduces environmental and economic costs in water quality monitoring networks, is to decrease the number of Water Quality Monitoring Stations (WQMS). In the present study, the optimization of the WQMS in the Mond River basin located in the south of the Fars province in Iran was studied. Three algorithms, including Tabu Search (TS), Particle Swarm Optimization (PSO), and Ant Colony Optimization (ACO), were applied to the existing WQMS to determine the optimal number of stations with the maximum number of station combinations for different applications. Then, we compared the performance of these three algorithms. The results presented that the number of existing WQMS can be reduced from 16 to 12 for irrigation and 16 to 11 for drinking purposes. As a result, the number of stations suggested for the Mond River basin was selected 12 out of 16 monitoring stations for both water usages. The results are consistent with previous studies that investigated the application of the Genetic Algorithm (GA) and Dynamic Programming Approach (DPA) for the optimization of WQMS in the Mond River. [ABSTRACT FROM AUTHOR]

The physical integrity of the Ngerengere River and its three tributaries drains within Morogoro Municipality were evaluated by assessing the variations in land-use–land cover (LULC) in the river's buffer zone, the discharge, and the contamination of river water and sediment from nutrients and heavy metals. Integrated geospatial techniques were used to classify the LULC in the river's buffer zone. In contrast, the velocity area method and monitoring data from the Wami-Ruvu Basin were used for the discharge measurements. Furthermore, atomic absorption spectrophotometry was used during the laboratory analysis to determine the level of nutrients and heavy metals in the water and river sediment across the 13 sampling locations. The LULC assessment in the river's buffer during the sampling year of 2023 showed that bare land and built-up areas dominate the river's buffer, with a coverage of 28% and 38% of the area distribution. The higher discharge across the sampling stations was in the upstream reaches at 3.73 m3/s and 2.36 m3/s at the confluences. The highest concentrations of heavy metals in the water for the dry and wet seasons were 0.09 ± 0.01, 0.25 ± 0.01, 0.03 ± 0.02, 0.73 ± 0.04, 4.07 ± 0.08, and 3.07 ± 0.04 mg/L, respectively, for Pb, Cr, Cd, Cu, Zn, and Ni. The order of magnitude of the heavy metal concentration in the sediments was Zn > Ni > Cr > Cu > Cd > Pb, while the highest NO2−, NO3−, NH3, and PO43− in the water and sediment were 2.05 ± 0.01, 0.394 ± 0.527, 0.66 ± 0.05, and 0.63 ± 0.01 mg/L, and 2.64 ± 0.03, 0.63 ± 0.01, 2.36 ± 0.01, and 48.16 ± 0.01 mg/kg, respectively, across all sampling seasons. This study highlights the significant impact of urbanization on river integrity, revealing elevated levels of heavy metal contamination in both water and sediment, the variability of discharge, and alterations in the LULC in the rivers' buffer. This study recommends the continuous monitoring of the river water quality and quantity of the urban rivers, and the overall land-use plans for conserving river ecosystems. [ABSTRACT FROM AUTHOR]

Accurately estimating nutrient loads is crucial for effective management and monitoring of aquatic ecosystems. This study evaluated the uncertainty in different sampling frequencies and calculation methods for estimating total nitrogen (TN) and total phosphorus (TP) loads in the Yiluo River watershed, a tributary of the Yellow River in China. Using daily TN and TP concentration data from 2019 to 2020, we conducted a bootstrapping analysis to evaluate the accuracy of nine different load estimation methods at different sampling frequencies. Our results showed that Method 3 (M_3, constant concentration interpolation) and Method 7 (M_7, flow-weighted concentration method), when used with a biweekly sampling frequency, had the lowest Standard Deviation of the Percentage errors (STD) (7.70% and 8.60% for TN, 12.0% and 18.8% for TP, respectively) and Mean Relative Error (MRE) values (0.078% and −1.60% for TN, 0.305% and 2.33% for TP, respectively) on an annual scale. For monthly TN and TP load estimates, M_7 can control the MRE within ±20% at a biweekly sampling frequency. Furthermore, the uncertainty in TN and TP load estimates was generally larger during the summer months (June–September), emphasizing the important role of storm events in nutrient export. Extreme events (<10% of the time) contributed approximately 50% of the annual nutrient loads. The findings of this study provide a scientific basis for optimizing water quality monitoring schemes and management strategies in agricultural watersheds. [ABSTRACT FROM AUTHOR]

The fish Erythroculter erythropterus has been introduced to the Nakdong River. It is a top carnivore (growing to up to 1.5 m long) but is inedible. The population of Erythroculter erythropterus tends to increase in areas where mainstream flow is slowed by weirs, likely due to the creation of more favorable habitat conditions. Erythroculter erythropterus dominates the fish community, reducing the number of endemic and commercial fish. The South Korean government sought to eliminate the species, but the spread was too rapid, resulting in top-down biological disturbance. The species distributions and movement patterns of Erythroculter erythropterus are not well known and no management strategy is available. Here, we determined the distribution and migration patterns of Erythroculter erythropterus in the tributaries and mainstream of the Nakdong River and analyzed how the water chemistry and physical habitat affected these variables. We used a submersible ultrasonic receiver to collect signals from transmitters attached to fish and analyzed the migration pattern. Massive aggregations of this species were evident at depth. Erythroculter erythropterus dominated all study sites but was significantly (p < 0.05) more common in the mainstream (relative abundance [RA] = 12.2%) than in tributaries (RA = 1.45%). Water quality parameters significantly regulated the population; total organic carbon was the highest one (R2 = 0.71). The transmitters revealed massive congregations in the deepest water (− 17 m) during winter hibernation, which sheds light on how the fish can best be removed. [ABSTRACT FROM AUTHOR]

In this paper, we analyse the uncertainty and parameter sensitivity of a conceptual water quality model, based on a travel time distribution (TTD) approach, simulating electrical conductivity (EC) in the Duck River, Northwest Tasmania, Australia for a 2‐year period. Dynamic TTDs of stream water were estimated using the StorAge Selection (SAS) approach, which was coupled with two alternate methods to model stream water EC: (1) a solute‐balance approach and (2) a water age‐based approach. Uncertainty analysis using the Differential Evaluation Adoptive Metropolis (DREAM) algorithm showed that: 1. parameter uncertainty was a small contribution to the overall uncertainty; 2. most uncertainty was related to input data uncertainty and model structure; 3. slightly lower total error was obtained in the water age‐based model than the solute‐balance model; 4. using time‐variant SAS functions reduced the model uncertainty markedly, which likely reflects the effect of dynamic hydrological conditions over the year affecting the relative importance of different flow pathways over time. Model parameter sensitivity analysis using the Variogram Analysis of Response Surfaces (VARS‐TOOL) framework found that parameters directly related to the EC concentration were most sensitive. In the solute‐balance model, the rainfall concentration Crain and in the age‐based model, the parameter controlling the rate of change of EC with age (λ) were the most sensitive parameter. Model parameters controlling the age mixes of both evapotranspiration and streamflow water fluxes (i.e., the SAS function parameters) were influential for the solute‐balance model. Little change in parameter sensitivity over time was found for the age‐based concentration relationship; however, the parameter sensitivity was quite dynamic over time for the solute‐balance approach. The overarching outcomes provide water quality modellers, engineers and managers greater insight into catchment functioning and its dependence on hydrological conditions. [ABSTRACT FROM AUTHOR]

Biomonitoring with bioindicators such as river macroinvertebrates is fundamental for assessing the status of freshwater ecosystems. In Japan, water quality and biomonitoring surveys are conducted separately, leading to a lack of nationwide information on their relationships and the biological status of water quality monitoring (WQM) sites. To understand the biological status of WQM sites across Japan, we developed a multiple linear regression model to estimate the average score per taxon (ASPT) using river macroinvertebrate data surveyed at a total of 237 "aligned" sites based on the co-occurrence of biomonitoring and WQM sites. The resulting regression model with eight predictors, such as biological oxygen demand, the proportion of urban areas in the catchment, could predict ASPT with reasonable accuracy (e.g., an error of ±1 for 96% of the aligned data). Using this model, we estimated ASPT values at 2925 WQM sites in rivers nationwide, categorizing them into four levels of river environment quality: "very good" (29% of WQM sites), "good" (50%), "fairly good" (14%), and "not good" (8%). Furthermore, we observed statistically significant correlations (p < 0.05; 0.4 ≤ r ≤ 0.7) between ASPT and all eight macroinvertebrate metrics examined, such as mayfly and stonefly richness, providing ecological implications of changes in ASPT. [ABSTRACT FROM AUTHOR]

Apocorophium lacustre – a species of benthic amphipod native to American and European estuaries along the North Atlantic Ocean – has rapidly expanded outside of its native range and is now established in the Illinois, Upper Mississippi, and Ohio river systems, USA. A. lacustre is considered high risk for colonization and disruption of the Laurentian Great Lakes’ benthic communities. To further our understanding of factors influencing A. lacustre distribution and its threat to the Great Lakes, zoobenthic and habitat data were collected from colonization samplers (i.e., rock bags) deployed at 370 sites along the Illinois Waterway. A. lacustre was found in the lower six pools of the Illinois Waterway and was the most abundant amphipod collected in those pools. Our results parallel other studies in that A. lacustre was not observed upstream of Dresden Island Pool, but A. lacustre was found ~11 km farther upstream of any previous records. Generalized linear mixed effects modeling indicated that parameters pertaining to food availability, water quality, and impoundment influenced A. lacustre abundance. Model averaging identified five statistically significant variables: A. lacustre abundance was negatively associated with turbidity, fluorescent dissolved organic matter, and vegetation density and positively associated with temperature and downstream distance (i.e., closer to the next downstream dam). Our findings of what factors influence A. lacustre abundance should be of broad interest to risk assessment and invasion forecasting in other regions where A. lacustre have been or may be introduced. [ABSTRACT FROM AUTHOR]

The Supraśl River is a stable water ecosystem in North-Eastern Poland. This is indicated by the flow rate over many years, as well as the water quality monitored for years. Despite this, there are periods of oxygen deficiency in the water, causing massive fish kills. Our research shows that climate change resulting in an increase in the frequency of hydro-meteorological extremes may contribute to negative processes taking place in aquatic ecosystems. On the example of Supraśl Water System (SWS), we present an analysis of the phenomenon of suspension caused by the underground inflow, supplying the surface waters with a significant load of organic matter. The accelerated decomposition of peat formations in the Supraśl River catchment after heavy rains makes it easier for organic matter to penetrate into the aquatic ecosystem. Intensive flushing of valley and river bed sediments during summer floods has a particularly negative impact on the ecosystem of inland waters. If there are organic sediments on the bottom, their re-suspension is very dangerous. Then there is the immediate demand for oxygen, which can lead to deoxygenation of the water. Although this is a natural process, alarm and monitoring procedures should be established and countermeasures sought to respond in time and prevent mass fish kills. [ABSTRACT FROM AUTHOR]

In this study, the composition and structure of the macrobenthic community in the Ulungu River Basin was investigated and the water quality status of the basin was evaluated. In May and August 2022, and October 2023, the macrobenthic and water environmental factors at 11 sample sites in the basin were investigated, and the water quality of the basin was evaluated by the Shannon–Wiener index, FBI, and BMWP index. A total of 6101 macrobenthic organisms were collected; these organisms belonged to 3 phyla, 7 classes, 14 orders, 57 families, and 117 genera. Arthropod species accounted for the largest number of species (87.9%). A total of nine dominant species were found: Micronecta sp., Eukiefferiella sp., Baetis sp., Polypedilum sp., Saetheria sp., Ephemerella sp., Limnodrilus sp., Ephemera sp., and Hydropsyche sp. At the temporal level, the average density and biomass of macrobenthos were in the order of August > October > May; at the spatial level, the average density was greater in the tributaries than in the main stream, and the average biomass was greater in the main stream than in the tributaries. The mean values of the Shannon—Wiener index and Margalef richness index were as follows: August > October > May at the temporal level; the mean values of the Pielou evenness index were as follows: May > October > August at the temporal level. At the spatial level, the overall mean value of each diversity index indicated that the tributaries had larger diversity indices than the main stream. The water quality evaluation results revealed that the overall water quality level of the Ulungu River Basin ranges from light pollution to poor quality. Human interference activities greatly impact the water quality of the basin. To restore the ecology of the basin, it is necessary to strengthen the management and control of pollution sources. [ABSTRACT FROM AUTHOR]

Remote sensing technology plays a crucial role in the rapid and wide-scale monitoring of water quality, which is of great significance for water pollution prevention and control. In this study, the downstream and nearshore areas of the Huaihe River Basin were selected as the study area. By utilizing spectral information from standard solution measurements in the laboratory and in situ water quality data matched with satellite spatiotemporal data, inversion models for total phosphorus (TP) and ammonia nitrogen (NH3-N) water quality parameters were developed. The validation results using field measurements demonstrated that the inversion models performed well, with coefficients of determination (R2) of 0.7302 and 0.8024 and root mean square errors of 0.02614 mg/L and 0.0368 mg/L for total phosphorus and ammonia nitrogen, respectively. By applying the models to Sentinel-2 satellite images from 2022, the temporal and spatial distribution characteristics of total phosphorus and ammonia nitrogen concentrations in the study area were obtained. The ammonia nitrogen concentration ranged from 0.05 to 0.30 mg/L, while the total phosphorus concentration ranged from 0.10 to 0.40 mg/L. Overall, the distribution appeared to be stable. The southern region of the Guan River estuary showed slightly higher water quality parameter concentrations compared to the northern region, while the North Jiangsu Irrigation Main Canal estuary was affected by the dilution of river water, resulting in lower concentrations in the estuarine area. [ABSTRACT FROM AUTHOR]

The Betwa River Basin (BRB), a sub-basin of the River Yamuna, is the oldest flowing water system in Central India. The water quality of the rivers are under stress, hence regular monitoring and appraisal is required to know the health of the rivers. Factor analysis and principal component analysis (FA/PCA) multivariate statistical techniques were used to extract three and four varimax factors that explained 96.408 and 100.00 percent of the total variance in water quality, respectively. Cluster analysis (CA) categorizes observed items into distinct quality categories based on correlations between stations and years. Point industrial/sewage effluents, diffuse pollution as runoff from arable land, erosion, and natural source pollution contribute to the pollution of the BRB. As a result, water quality is threatened or impaired, and conditions often departed from natural or desirable levels at Rajghat, Garrauli, Mohana, and Shahijina stations. According to the Canadian Council of Ministers of the Environment Water Quality Index (CCME-WQI), the surface water quality at the Rajghat and Mohana stations corresponds to fair ecological status. However, the surface water quality of the Garrauli and Shahijina stations has a marginal water quality as per CCME-WQI. From 1985 to 2018, the Shahijina had the most considerable load of nutrients and organic matter, as determined by the CCME-WQI and by comparing the water quality data. A thorough examination had revealed a fluctuating trend in the BRB pollution, particularly at all stations. Results indicate that between 1985 and 2018, the only defense mechanism of the river was the auto purification mechanism, which is strongly influenced by the drought, point pollution source, and extreme meteorological events that probably cause these fluctuations. [ABSTRACT FROM AUTHOR]

A robust understanding of the interactions between global and local anthropogenic stressors is crucial for ecosystem management in the Anthropocene. Manipulative experiments in the laboratory or in the field can be used to build knowledge about the physiological and ecological effects of stressors, but predicting the combined landscape‐scale effects of global stressors such as climate change, and local stressors such as land‐use change requires a different approach.Here we used water quality and hydrology process‐based models of entire river catchments in combination with a large biomonitoring dataset to predict the responses of macroinvertebrate communities under different climate change and land‐use change scenarios. Using the River Thames in the U.K. as a model system, we predicted changes in water quality (temperature, flow, phosphorus [P], nitrogen, dissolved oxygen [DO]) and subsequent changes in macroinvertebrate communities for two climate change scenarios, individually and in combination with intensified agriculture and reduced P pollution (representing improved wastewater treatment).Our models predicted that water‐quality changes associated with climate change may not influence total species richness, but that community composition will shift towards more pollution‐tolerant and common taxa based on responses of community indices and taxon‐specific responses. We also found that the negative impacts of climate change on water quality (e.g., increased P concentration, decreased DO concentration) accumulate through the catchment, but that local land‐use practices influencing P dynamics can modify this trend. Furthermore, although the intensified agriculture scenario was predicted to have minimal impacts on macroinvertebrate communities (a result potentially related to shifting baselines as the Thames is already heavily polluted), we found that reduced P pollution resulting from improved wastewater treatment was able to mostly offset the negative impacts of climate change on macroinvertebrate communities.Our results demonstrate that using process‐based models to study networks of interacting stressors at a landscape scale can provide useful insights into the ecological impacts of anthropogenic global change, and adds support to the idea that management of local stressors has the potential to mitigate some of the impacts of climate change on ecosystems. [ABSTRACT FROM AUTHOR]

Water has recently become a final disposal site for wastewater. Land use has evolved with the global population growth and is generally transformed into settlements and industrial areas. These land use changes could potentially increase wastewater generation from both domestic and non-domestic activities. The Garang watershed, one of the watersheds in Central Java, flows through the Semarang Regency, Kendal Regency, and Semarang City. This study analyzed the water quality conditions in the Garang watershed and designed a real-time water quality monitoring system. The methods used in this study included SWMM modeling, the national sanitation foundation water quality index (NSF-WQI), and the internet of things. Samples were collected from 10 points in the Garang Watershed, with a sampling frequency of five times at each point. The results of the data analysis demonstrated that the differences in land use resulted in varying water parameter levels. The results of the SWMM modeling demonstrated an acceptable model value (NOF between 0 and 1). On the other hand, the WQI analysis results demonstrated that the quality status at the Garang watershed is "medium" at nearly all location points. The designed real-time water quality sensor tool successfully transmitted water quality data online and in real-time, particularly for temperature, pH, turbidity, and DO. This water quality monitoring system offers a variable percentage error value, with the pH sensor ranging between 0.16% and 9.86% and the temperature sensor ranging between 0.64% and 1.72%. [ABSTRACT FROM AUTHOR]

In developing countries, such as Brazil, public policies for monitoring surface water quality are precarious. Although the country has legal norms that establish water quality parameters, and the Water Quality Index (WQI) is used as an assessment tool, the management of surface water is neglected in cities such as Manaus. The objective of this study was to evaluate the water quality of the São Raimundo basin in Manaus during the years 2020 and 2021. The following parameters were evaluated: dissolved oxygen (DO), thermotolerant coliforms (Colif), biochemical oxygen demand (BOD), pH, temperature (Temp), total nitrogen (Ntotal), total phosphorus (Ptotal), turbidity (Turb), and total solids (Sol.T). ANOVA showed that the water quality is constantly low, and in no period of either year did it present acceptable levels for use. The Colif result having a mean value of 96.7 × 103 NMP 100 mL−1 in the month of February 2020. October 2020 and 2021 presented the worst results for the WQI with values of 27.7 and 28.2, respectively. Multiple regression showed DO, Turb, BOD, and Ntotal as being the most significant parameters, which indicates that the pollution probably originates from sewers and industrial effluents. This is the first study to monitor the waters of the São Raimundo basin using this approach. The results show the need for urgent treatment of the water in the basin via environmental preservation and recovery measures. This type of study could thus result in changes in the management of the water in this basin as well as in similar ones present in the Amazon region. [ABSTRACT FROM AUTHOR]

Owing to the recent developments in computer technology and nationally accumulated hydrology, land use, soil characteristics and flow and water quality monitoring data, high-level modelling results are required. However, as most catchments have a mixture of urban and rural areas, it is challenging to apply one effective model. This study applied a hydrological simulation program to a storm water management model for the Jeonju catchment, South Korea, which has complex land-use characteristics, to determine the hydrological cycle of the catchment, analyse the river water quality and examine the structure of discharge pollutants. The linked model includes an analysis of the sewer pipes, which are the main path of hydrology and pollution loads in urban areas, a low-impact development application, a water circulation improvement technique and an initial storm water treatment facility installation project. This linked model will be very useful for guiding future urban water quality policy. [ABSTRACT FROM AUTHOR]

As an important river in the western part of Jilin Province, the lower reach of the Nenjiang River is an important wetland water source conservation area in Jilin Province. Within the watershed, it governs the Momoge Wetland, the Xianghai Wetland, and the Danjiang Wetland in Jilin Province. The main problem in the lower reaches of the Nenjiang River is the uneven distribution of water resources in time and space, and the intensification of land salinization. Zhenlai County and Da'an City in the Nenjiang River Basin have sufficient surface water resources, with surface water as the drinking water source. Baicheng City and Tongyu County have scarce surface water resources, and both use groundwater as their domestic water source. The main polluted section in the basin is the Xianghai Reservoir, and the annual water quality evaluation is Class V. However, the water quality of the Tao'er River, the main stream of the Nenjiang River, is significantly better than that of the Xianghai Reservoir. In order to better study the water environmental pollution situation in the Nenjiang River basin, monitoring data from five sections of non seasonal rivers in the basin from 2012 to 2021 were selected for studying water quality. This in-depth exploration of the water pollution status and river water quality change trends in the Nenjiang River basin is of great significance for future rural development, agricultural pattern transformation, and the promotion of water ecological civilization construction. [ABSTRACT FROM AUTHOR]

In the wake of frequent and intensive human activities, highly urbanized areas consistently grapple with severe water environmental challenges. It becomes imperative to establish corresponding water environment models for simulating and forecasting regional water quality, addressing the associated environmental risks. The distributed framework water environment modeling system (DF-WEMS) incorporates fundamental principles, including the distributed concept and node concentration mass conservation. It adeptly merges point source and non-point source pollution load models with zero-dimensional, one-dimensional, and two-dimensional water quality models. This integration is specifically tailored for various Hydrological Feature Units (HFUs), encompassing lakes, reservoirs, floodplains, paddy fields, plain rivers, and hydraulic engineering structures. This holistic model enables the simulation and prediction of the water environment conditions within the watershed. In the Taihu Lake basin of China, a highly urbanized region featuring numerous rivers, lakes and gates, the DF-WEMS is meticulously constructed, calibrated, and validated based on 26 key water quality monitoring stations. The results indicate a strong alignment between the simulation of water quality indicators (WQIs) and real-world conditions, demonstrating the model's reliability. This model proves applicable to the simulation, prediction, planning, and management of the water environment within the highly urbanized watershed. [ABSTRACT FROM AUTHOR]

As the second deepest lake in Africa, Lake Tanganyika plays an important role in supplying fish protein for the catchment's residents and is irreplaceable in global biodiversity. However, the lake's water environment is threatened by socioeconomic development and rapid population growth along the lake. This study analyzed the spatial scale effects and seasonal dependence of land use types and landscape metrics on water quality in 16 sub-basins along northeastern Lake Tanganyika at different levels of urbanization. The results revealed that land use types had a higher influence on water quality in urban areas than that in rural areas; the explanatory variance in the urban area was 0.78–0.96, while it was 0.21–0.70 in the rural area. The explanatory ability of land use types on water quality was better at the buffer scale than at the sub-watershed scale, and the 500 m buffer scale had the highest explanatory ability in the urban area and rural area both in the rainy season and dry season, and artificial surface and arable land were the main contributing factors. And this phenomenon was more obvious in dry season than in rainy season. We identified that CONTAG was the key landscape metric in urban area and was positively correlated with nutrient variables, indicating that water quality degraded in less fragmented landscapes. The sub-watershed scale had the highest explained ability, while in rural area, the 1500 m buffer scale had the highest explained ability and IJI had the highest explanatory variance, which had a negative effect on water quality. Research on the relationship between land use and water quality would help assess the water quality in the unmonitored watershed as monitoring is expensive and time-consuming in low-income area. This knowledge would provide guideline to watershed managers and policymakers to prioritize the future land use development within Lake Tanganyika basin. [ABSTRACT FROM AUTHOR]

ivers and streams, in most cases, are used as a receiving body for municipal waste, which, without proper treatment, generates water pollution problems. In the study areas of this research, there is information from water quality monitoring published by the National Water Authority, where the results are not very understandable for a population that does not know about the subject. Water Quality Indices (WQI) are one of the most used tools to evaluate water quality, since they summarize the data on the physicochemical and microbiological parameters in a simple and easy-to-understand way. The objective of this research was to carry out the evaluation of the ICA in the Achamayo and Shullcas sub-basins through the Canadian methodology CCME-WQI (The Canadian Council of Ministers of the Environment - Water Quality Index). For this, data from water quality monitoring reports from 2015 to 2020, municipal discharges and geospatial information from rivers and basins were used. The Shullcas sub-basin obtained an AQI result of 46.2, which corresponds to a "marginal" water quality; this result is a consequence of the high concentrations of thermotolerant coliforms and Escherichia coli, while the Achamayo sub-basin obtained an AQI-CCME of 67.8, which corresponds to a "regular" quality, reaching the conclusion that the Shullcas subbasin is the most impacted by municipal discharges, which is why it is recommended to build wastewater treatment plants with activated sludge technology or MBBR moving bed bioreactors. [ABSTRACT FROM AUTHOR]

Water pollution has serious consequences for human health and water ecosystems, and accurate forecasting of water quality changes can aid in the early detection and treatment of such pollution. To better simulate the characteristics of water quality data, the development of a water quality prediction model must consider the non-smoothness of the data as well as the relationship between upstream and downstream water quality. Firstly, Optimal Variational Mode Decomposition (OVMD) technology is used to pre-process water quality monitoring data through linear decomposition into multiple components, with the components acting as a unit of prediction to reduce the difficulty of prediction. Secondly, to reflect the impact of upstream and downstream water quality relationships, comprehensive prediction modeling is carried out on the temporal and spatial correlation of water quality data between monitoring stations. Graph Attention Networks (GAT) are embedded in the Gated Recurrent Unit's (GRU) reset gate and update gate, and adaptive aggregation of data spatial characteristics of each site based on each station is used to achieve a multi-step prediction of water quality indicators. Finally, the predicted values of each component are then fused to form the final predicted values. Validation at 13 monitoring stations along the Mulan River demonstrated the effectiveness of the integrated prediction model. The results showed that, under different prediction steps, the Root Mean Square Error (RMSE) and Mean Absolute Error (MAE) values of the GAT-GRU water quality prediction model were reduced by about 11–20% (ammonia nitrogen, NH3–N) and 8–18% (total phosphorus, TP) compared with the GCN (Graph Convolutional Networks)-GRU, and the Nash–Sutcliffe efficiency coefficient (NSE) value was increased by about 20% (NH3–N) and 13% (TP), respectively. The RMSE and MAE values of the OVMD-GAT-GRU water quality prediction model were further reduced by about 52–57% (NH3–N) and 25–35% (TP) compared with GAT-GRU, and the NSE value was increased by about 19–43% (NH3–N) and 15–33% (TP), respectively. As the prediction steps increased, the advantages of OVMD-GAT-GRU over GAT-GRU and GCN-GRU became more pronounced. These results demonstrate that OVMD-GAT-GRU exhibits superior prediction performance, robustness, accuracy, and adaptability to water quality indicators. The development of the OVMD-GAT-GRU water quality prediction model can provide significant assistance in the prevention and management of water pollution. [ABSTRACT FROM AUTHOR]

Rivers have been pivotal to human progress, providing essential resources for ancient societies. The Ghaggar River, flowing through three states and one Union Territory, has been a cornerstone for settlements due to its fertile lands. However, its proximity to mining, agriculture, and industrial zones has altered its chemical dynamics, making the monitoring of its water quality a critical task. Recent literature reviews, utilizing comprehensive databases and search strategies, have highlighted the socio-economic significance of water quality. Economic shifts, land use changes, industrial growth, and increased chemical usage have impacted water quality, leading to accessibility, availability, and affordability issues. Moreover, gastrointestinal and skin ailments among the river's users underscore the urgency of the situation. Local communities are now facing a crisis as the degradation of this vital water source forces them to seek alternative solutions. [ABSTRACT FROM AUTHOR]

Rivers play a key role in ecosystems and society. With the development of local economies, the Haihe River Basin has been affected and threatened by human activities. It is necessary and important to develop a river health evaluation system and to quantitatively evaluate the river health status. In this study, we collected samples from 37 sites along the Haihe River Basin and assessed the health with ten indices which indicated its physical, chemical, and biological conditions. The weight of each index was estimated by using the principal component analysis (PCA). The integrated index of river health was constructed to assess the health status. The results showed that the whole Haihe River Basin health was in the fair category. The numbers of sites in healthy, sub-healthy, fair, sub-sick and sick categories were 1, 17, 13, 3, and 3, respectively. DO (dissolved oxygen), benthic integrated biotic index and physical habitat had positive effects on the river health, while nutrients and organic matter had negative effects on river health. The research results not only provide scientific basis and technical support for further research but guidance and suggestions for government to improve the river health. [ABSTRACT FROM AUTHOR]

The Fundão dam breach affected the Rio Doce's estuarine and marine environments with water, tailings, scoured soil and/or sediments, and other debris. Time series and standard exceedance analyses are typically used to assess water quality recovery to baseline conditions after deteriorating water quality events. In the absence of historical measurements, impacts to water quality from the Fundão Event were compared with measurements of nearby rivers. Similar river systems with available water quality measurements were grouped into affected and unaffected estuarine and marine waters. Statistical and temporal comparisons of marine waters unaffected by the Rio Doce with those affected by the Rio Doce were evaluated for systematic differences. Multivariate statistical techniques were also used to assess water quality differences. Our results demonstrate that the Fundão dam breach had a short‐term water quality impact on marine waters near the Rio Doce mouth. Principal component and comparative time series analyses clearly demonstrated this impact during the 2015/2016 and 2016/2017 wet seasons. The ephemeral effects of the breach, however, did not compromise marine water quality. Exceedances of CONAMA standards for metals remained either at zero or at very low levels during the affected period (<5.7%). Before the start of the next wet season in October 2017, water quality impacts from the Event were statistically indistinguishable from unaffected marine waters, indicating recovery to baseline conditions. Integr Environ Assess Manag 2024;20:99–116. © 2023 NewFields Companies, LLC. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC). [ABSTRACT FROM AUTHOR]

The document titled "Remote Sensing of Coastal Waters, Land Use/Cover, Lakes, Rivers, and Watersheds II" explores the significance of remote sensing in monitoring and analyzing coastal regions, land masses, lakes, rivers, and watersheds. It emphasizes the advancements in remote sensing technologies that have improved data collection and understanding of environmental changes. The document includes 22 research papers covering topics such as land cover change, ecological environments, wetlands and habitats, water quality, and marine disasters and environmental impacts. These papers offer valuable insights into the interactions between human and natural factors and aim to inform sustainable resource management efforts. The integration of artificial intelligence with remote sensing data further enhances accuracy and understanding. The authors express their gratitude to the contributors and reviewers for their valuable contributions to this Special Issue. [Extracted from the article]

Freshwater mussels are both critically important in their ecosystems and rapidly declining around the world. Damming is a key reason for this decline in many locations because it affects the flow and turbidity of river systems, leading to numerous detrimental effects on benthic communities. Although the ecological effects of impoundment have been well studied on timescales ranging from years to decades, the ecological effects of impoundment on longer (50–100 years) timescales are less well understood, with a key question being: how long after the building of dams and impoundments do we expect community structure to continue changing? In this study, we explore historical changes in the freshwater mussel assemblages in Kentucky Lake (dammed in 1944) using decades-long collections housed at Murray State University in combination with other historical records. After digitizing these collections and applying a robust rarefaction protocol to account for uneven sampling, we quantify changes in unionid assemblage structure alongside coeval water quality data collected through the Kentucky Lake Long-Term Monitoring Program. We find that subsampled richness exhibited declines after dam construction with losses among opportunistic taxa, channelization-tolerant taxa, and impoundment-intolerant taxa. We also find increases in the proportions of equilibrium taxa throughout the dataset. Overall, the assemblage composition reached an equilibrium by the year 2000 (50 years after impoundment). In concert, river water quality data show a decline in turbidity and increase in light penetration in the period 1988–2020. Although the geohistorical records treated in this study are patchy in time, we argue that they are nonetheless valuable and illustrate that freshwater ecosystems may serve as potential sites of restoration decades after anthropogenic disturbance. In turn, this emphasizes the importance of geohistorical collections to studying long-term changes in community structure and developing strategies for conservation and environmental remediation. [ABSTRACT FROM AUTHOR]

As an important river in the central part of Jilin Province, the Yinma River plays a crucial role in the daily lives of the people in Jilin Province. In this paper, 15 cross sections were selected in the Yinma River basin. Based on the water quality monitoring data from 2012 to 2021, referring to the Environmental Quality Standards for Surface Water (GB 3838 - 2002) and historical monitoring data of the river, dissolved oxygen (DO), five-day biochemical oxygen demand (BODS), permanganate index (CODMn), chemical oxygen demand (COD), ammonia nitrogen (NH4-N), total phosphorus (TP), and total nitrogen (TN) were determined as 7 evaluation indicators, and the water quality of 15 cross sections in the Yinma River basin was comprehensively evaluated. A characteristic analysis was conducted on the water quality of the Yinma River, and its pollution sources were identified. Based on the conclusions, constructive control measures were proposed. [ABSTRACT FROM AUTHOR]

The water quality of the Kaalspruit River, situated in the Gauteng province, South Africa, has been in question over previous years with concerns about the health risks potentially posed by the level of pollution to the surrounding communities. The study aimed to conduct a physico-chemical assessment of water and sediment in the river. In-situ water quality parameters were measured in the field using a multi-parameter water quality meter, while other parameters, such as organic and inorganic constituents were analysed at SANAS accredited laboratories. Water quality results revealed generally poor conditions with minimal seasonal variations, showing low dissolved oxygen and some metal concentrations present in toxic levels. Furthermore, the levels of faecal coliforms and E. coli were beyond the detectable levels in sampling areas of close proximity to informal settlements. Overall, this study revealed that the river system is of poor quality as a result of anthropogenic activities surrounding the Kaalspruit. [ABSTRACT FROM AUTHOR]

Water pollution in the Vam Co River basin is becoming more complicated due to untreated wastewater being directly discharged into rivers and canals from agricultural, industrial, and domestic activities. To assess the water quality in this area, this study conducted monitoring at ten sampling locations (S1-S10) from 2018 to 2022, calculated the Water Quality Index (WQI) for each parameter, and simulated water quality in 2022 using the 1D- MIKE 11 model developed by DHI with two main modules including HD and AD. The findings showed that most parameters did not surpass the allowable limits per QCVN 08-MT:2015/BTNMT on Vietnam National Technical Regulation on Surface Water Quality. However, organic and microbial pollution led to certain parameters, such as BOD5, COD, and Coliform, exceeding the limits. The lowest water quality was recorded in Long An province, especially at sampling locations S3, S4, and S6, with the average WQI for nine water quality parameters from February to July 2022 being 58.4, 67.8, and 21.1, respectively. Additionally, the simulation outcomes of the MIKE 11 model salinity, BOD5, DO, and NH4 aligned with the real measurements taken. It has been observed that the southern area of the Vam Co River Basin possesses poorer water quality than the northern part, with Long An province located downstream of the Vam Co River basin being the primary source of pollution. The development of this hydraulic model signifies a crucial milestone in comprehending and regulating the effects of pollution in monitoring and managing water management systems, controlling saline intrusion, and ensuring water supply for agricultural production and daily use in the Vam Co River basin. [ABSTRACT FROM AUTHOR]

In rural catchments, villages often feature their own, separate urban water infrastructure, including combined sewer overflows (CSOs) or wastewater treatment plants (WWTPs). These point sources affect the water quantity and quality of the receiving low order streams. However, the extent of this impact is rarely monitored. We installed discharge and water quality measurements at the outlet of two small, neighbouring headwater catchments, one that includes a village, a WWTP, and two CSOs, while the other is predominantly influenced by agricultural activities. We also deployed electrical conductivity (EC) loggers at the CSOs to accurately detect discharge times. Discharge from the WWTP and CSOs led to higher peak flows and runoff coefficients during events. Less dilution of EC and increasing ammonium-N (NH4 − N) and ortho-phosphorus (oPO4 − P) concentrations indicate a significant contribution of poorly treated wastewater from the WWTP. During CSO events, water volumes and nutrient loads were clearly elevated, although concentrations were diluted, except for nitrite-N (NO2 − N) and particulate phosphorus (PP). Baseflow nitrate-N (NO3 − N) concentrations were diluted by the WWTP effluent, which led to considerably lower concentrations compared to the more agriculturally influenced stream. Concentrations of oPO4 − P, NH4 − N, and NO2 − N, which are most likely to originate from the WWTP, vary throughout the year but are always elevated. Our study shows the major and variable impact rural settlements can have on stream hydrology and water quality. Point sources should be monitored more closely to better understand the interaction of natural catchment responses and effects caused by sanitary infrastructure. [ABSTRACT FROM AUTHOR]

Mongolia is a country with a quickly growing economy mainly based on mining of gold, copper, coal, and other minerals. Mining, urbanization, and agriculture impact the water quality in the upper Selenga River Basin in northern Mongolia, which is the center of the Mongolian economy. Previous measurements of pollution loads were alarming, but restricted to chemical measurements. Here, for the first time, we combine freshwater biomonitoring and laboratory water quality data across a broad gradient of water quality and land use intensity. We track the effects of different types of pollution on aquatic invertebrates and test their use as bioindicators. We collected water samples, environmental parameters, and macroinvertebrates at 36 sampling sites at the rivers of Tuul, Kharaa, and Orkhon and their tributaries Sugnugur, Boroo, Sharyn Gol, Gatsuurt, and Yeröö. PCA of catchment water quality distinguished three groups of pollutants prevalent at the sites: (1) nutrients, (2) saline components (Cl-, Na +, Mg2+, SO42-, Ca2+) and mining by-products (B, Sr, U, Mo), and (3) (heavy) metals, which often exceeded regulatory standards. We recorded a total of 59 macroinvertebrate taxa belonging to 32 families in seven insect orders plus Amphipoda and Gastropoda. Species diversity declined with higher impact. Five environmental factors structured macroinvertebrate community composition in RDA: elevation of sample location, site total nitrogen, dissolved oxygen, electrical conductivity, and water chemistry. We conclude that macroinvertebrate communities are an appropriate and inexpensive tool for monitoring water quality in Mongolia and suggest government action to establish a long-term monitoring program. [ABSTRACT FROM AUTHOR]

In the present work, an investigation was performed based on the genera and species stated in Palmer pollution index to show the extent of organic pollution in the surface water of the Tawi watershed in the Jammu province of the Union Territory of Jammu and Kashmir using algal pollution indices. Sampling was carried out for two seasons, pre-monsoon (PRM) and post-monsoon (POM), at 16 locations distributed over the entire Tawi watershed. The physico-chemical variables like water temperature, pH, electrical conductivity, TDS, total alkalinity, total hardness, DO, BOD, COD, nitrate, and phosphate were analyzed. The seasonal distribution of the pollution-tolerant algal genera and species was recorded and the algal pollution index for both genus (AGP index) and species (ASP index) was also calculated. The concentration of BOD, COD, and nitrate in the sampled river water was found to be higher during the PRM season as compared to the POM season. The lower stretch of the watershed (Jammu Sub-Watershed) falls in class IV–V as per the polluted river stretch priority ranking based on BOD levels as BOD levels are >3 mg/L in the downstream locations during both seasons. A total of 23 algal taxa belonging to 8 families, Chlorophyceae (4 algal genera), Cyanophyceae (2 algal genera), Bacillariophyceae (7 algal genera), Zygnematophyceae (3 algal genera), Trebouxiophyceae (2 algal genera), Ulvophyceae (1 algal genus), Mediophyceae (1 algal genus), and Euglenophyceae (3 algal genera), have been reported in the Tawi watershed. The results of the Palmer indices showed a lack of organic pollution in the upstream, varying pollution levels in the midstream, and partially high to very high organic pollution levels in the downstream of the watershed. Comparative temporal analysis of the distribution of pollution-tolerant algal genera and species showed more organic pollution during PRM. Navicula and Cymbella were found to be the most abundant genera in almost all the stations, whereas Ulothrix, Cocconeis, Anacystis, and Crucigenia were the least recorded genera in the entire watershed. The results will enhance the understanding of the health status of the watershed, and provide database for watershed vulnerability assessment for sustainability and watershed management with spatio-temporal improvement. [ABSTRACT FROM AUTHOR]

The Hindon River is the main tributary of river Yamuna and it is a significant source of surface water, which flows through the major cities of western Uttar Pradesh, India. The indiscriminate development of industries and urbanization along river basin coupled with rapid population growths contribute various amounts of pollutant in the river. Therefore, the present study was conducted to assess the spatial–temporal variability of river water quality (seventeen physicochemical parameters and eight heavy metals) during pre- and post-monsoon seasons for 5 years data at 19 sampling sites along the river stretch. Indices associated with water quality and heavy metals were computed to scale the accurate state of risk associated to its use for drinking and irrigation. During the pre- and post-monsoon seasons, only four sites were found having safe water quality index (WQI) values. The mean heavy metal concentrations are found in order of Zn > Fe > Pb > Cu > Cr > Cd > Ni > Mn. Considering the spatial and temporal distribution, the study benchmarked the water quality of Hindon River for priority attention. [ABSTRACT FROM AUTHOR]

We assessed the distribution of alien fishes in the Karun River Basin, Iran. Fish were collected from 39 sites during the November–December 2018 low-flow period. In total, 39 fish species from nine orders and 14 families were documented. Among these, 10 species were alien to the basin (986 individuals; 15.7%). Four species were the most abundant alien species and primarily in impounded, downstream reaches. Redundancy analysis (RDA) was conducted to identify the extent of changes in alien fish assemblages with environmental parameters. RDA1 and RDA2 accounted for 36.24% and 25.33% of the variation of alien species, respectively. Altitude, depth, electrical conductivity, water temperature, turbidity, dissolved oxygen, and river width were the most significant parameters affecting alien species distributions. We present a dual-pathway cause-and-effect hypothesis proposing that alien fish species presence causes declines in the ecological status of native fish communities. We then explore how human-induced aquatic ecosystem degradation creates opportunities for alien species to invade new ecosystems, further impacting native fish communities. Our study contributes insight into the cause and effect of the presence of alien fish species in the Karun River Basin and emphasizes the urgency of conservation measures to protect this critically endangered watershed. [ABSTRACT FROM AUTHOR]

Recent studies have shown that Lake Pontchartrain Estuary in Louisiana experiences frequent harmful cyanobacterial blooms (cyanoHABs). In 2019, the Bonnet Carré Spillway (BCS) that diverts Mississippi River water into the estuary opened twice in the same year for the first time in history to prevent flooding in New Orleans. Short-term water quality monitoring was conducted in shoreline areas with high public use for the presence of cyanoHABs and cyanotoxins to assess the public health risks. Field sampling methods and satellite imagery were used to determine water quality and quantify bloom intensity and toxicity across time and space. Long-term BCS opening created a fresh (salinity < 0.2) and nutrient-rich estuary that supported several cyanoHABs in warmer months during and after the second BCS closure. Cyanobacterial biomass ranged from 35 to 4972 µg PC L−1, while toxin microcystin ranged from undetected to 8.41 µg MC L−1. The highest biomass and toxin were detected on June 25 at the north shore, station LP8, Mandeville Beach, dominated by Microcystis and Dolichospermum species. CyanoHABs occurred mostly in the northern part of the estuary, where tributary discharge is also a strong influence. Some of these blooms exited the estuary and were transported to the Gulf of Mexico following passage through Lake Borgne and then Mississippi Sound. Modifications in the timing and duration of river diversion operations can create prolonged cyanobacterial blooms that can cause environmental and public health risks, especially in warmer months, and this may intensify due to a changing climate. [ABSTRACT FROM AUTHOR]

Recent anthropogenic sources and excess usage have immensely threatened the communities and habitat ecology of this region's medicinally and economically significant crops. Therefore, our study aims to evaluate the community structure and related environmental characteristics sustaining Nasturtium officinale communities along the river basin (RB) in Northwest Pakistan, using the clustering procedure (Ward's method) and Redundancy analysis (RDA). From 340 phytosociological plots (34 x 10 = 340), we identified four ecologically distinct assemblages of N. officinale governed by different environmental and anthropogenic factors for the first time. The floristic structure shows the dominance of herbaceous (100%), native (77%), and annual (58.09%) species indicating relatively stable communities; however, the existence of the invasive plants (14%) is perturbing and may cause instability in the future, resulting in the replacement of herbaceous plant species. Likewise, we noticed apparent variations in the environmental factors, i.e., clay percentage (p = 3.1 x 10-5), silt and sand percentage (p< 0.05), organic matter (p< 0.001), phosphorus and potassium (p< 0.05), and heavy metals, i.e., Pb, Zn, and Cd (p< 0.05), indicating their dynamic role in maintaining the structure and composition of these ecologically distinct communities. RDA has also demonstrated the fundamental role of these factors in species-environment correlations and explained the geospatial variability and plants' ecological amplitudes in the Swat River wetland ecosystem. We concluded from this study that N. officinale communities are relatively stable due to their rapid colonization; however, most recent high anthropogenic interventions especially overharvesting and sand mining activities, apart from natural enemies, water deficit, mega-droughts, and recent flood intensification due to climate change scenario, are robust future threats to these communities. Our research highlights the dire need for the sustainable uses and conservation of these critical communities for aesthetics, as food for aquatic macrobiota and humans, enhancing water quality, breeding habitat, fodder crop, and its most promising medicinal properties in the region. [ABSTRACT FROM AUTHOR]

Objective A prerequisite for managing a catchment is to comprehensively understand the changes in its water quality. Using different methods, this paper comparatively analyzes the spatiotemporal variation in water quality of the Yangtze River, including its main streams and tributaries. Method The study is based on water quality data collected from 2008 to 2018 from 16 monitoring sections within the basin. Various methods, including the comprehensive water quality index (WQI), water pollution index (WPI), and comprehensive water quality identification index (Iwq), were used to assess water quality. Additionally, statistical methods including the Mann- Kendall trend test, cluster analysis, and discriminant analysis were utilized to analyze the spatiotemporal variation in water quality. Result In flooding and non-flooding seasons, the section proximal to the Leshan Minjiang Bridge had minimum dissolved oxygen (DO) concentration, which is 2.86 mg/L and 3.16 mg/L, respectively. Conversely, the Nanchang Chucha section had maximum concentration of chemical oxygen demand (CODMn) and ammonia nitrogen (NH3-N), which was 10.00 mg/L and 6.45 mg/L, and 2.23 mg/L and 4.48 mg/L, respectively. In the nonflooding season, 31.82% of water in the Nanchang Chucha section achieved Class IV grade or higher (evaluated by WPI), whereas this figure reduced to 19.70% (evaluated by WQI) for the Leshan Minjiang Bridge section. The Iwq method yielded the highest water quality, followed by WQI and WPI. All three methods indicated that water quality had improved in the Leshan Minjiang Bridge, Changsha Xingang, and Nanchang Chucha sections. Water quality varied spatially, with poor quality observed in the Leshan Minjiang Bridge, Changsha Xinkang, and Nanchang Chucha sections, and slightly poor quality was found in the Minjiang, Xiangjiang, and Ganjiang sections. Conclusion The evaluation of water quality using different methods within the Yangtze River basin yielded varied results, with the WQI method working best. [ABSTRACT FROM AUTHOR]

One of the problems regarding water resources is the management and interactions with the environment in terms of ensuring conservation. An efficient way to assess problems arising from the interaction of water resources with management and the environment is to apply water quality indicators. In view of this, a water sustainability index for a watershed was developed. The watershed under study predominantly uses soil and water for agricultural purposes. The indicator was called water resources sustainability index (WRSI). The values range from 0 (worst condition) to 1 (best condition) based on an integration of water quality parameters, environmental sanitary conditions, and vegetation indexes analyzed by geoprocessing techniques and weighted by analytic hierarchy process. The results show that the lowest WRSI values are obtained in regions with predominantly agricultural activities and extremely poor basic sanitary conditions. Approximately 24% of the study area had WRSI values around 0.6, indicating a regular status; values above 0.9 would be desirable. Precarious conditions mean poor basic sanitary conditions and agricultural activities that, in addition to the high load of organic fertilizers, also produce a high load of sediments, causing degradation of the water environment. It is also noteworthy that urban areas, in comparison with rural areas, presented on average higher WRSI values, which is related to the population's access to better basic sanitation conditions and to low exposure to possible water contamination. [ABSTRACT FROM AUTHOR]