Regional Water Quality Research Articles

An Analysis of the Spatiotemporal Variability of Key Water Quality Parameters in China

Intensifying anthropogenic disturbances have caused water pollution in China in recent decades. China has a vast territory with diverse climate conditions, land use types, and human activities, leading to significant water quality variability. However, few studies have investigated nationwide spatiotemporal patterns of key water quality parameters. In this study, we analyze monthly water quality observations from 3647 gauge stations to understand how water quality changes over time and space in China. We group the stations by water resource regions and adopt Python and SPSS to analyze the spatiotemporal variability and intercorrelations of eight water quality parameters. Results indicate that the concentrations of biochemical oxygen demand of 5 days (BOD5), chemical oxygen demand (COD), dissolved oxygen (DO), ammonia nitrogen (NH3-N), total nitrogen (TN), and total phosphorus (TP) show similar spatial patterns, with higher concentrations in the northern parts than the southern regions of China. The concentrations of COD and TP are higher in the rainy season than in the dry season, while DO, NH3-N, and TN show the opposite seasonal patterns. Strong positive correlations were found between BOD and COD, NH3-N and TP. The annual cumulative distribution figures demonstrate that all parameters showed slightly lower concentrations in 2022 and 2023 than in 2021, except for DO and TN. The TN/TP ratios across different water resource regions in China are significantly higher than 16, indicating that phosphorus is the limiting factor of eutrophication. This investigation provides a comprehensive understanding of the spatiotemporal variability of water quality parameters across China. The results of this study are highly valuable for investigating mechanisms regulating water quality across large spatial scales, thus providing valuable implications for improving water quality and mitigating water pollution.

Hydrochemical characterization and evaluation of irrigation water quality using indexing approaches, multivariate analysis, and GIS techniques in K'sob Valley, Algeria

Irrigation plays a vital role in addressing increasing need for food production and promoting economic advancement. To meet the demands for food supply and economic progress, it is essential to underscore the significance of assessing water quality in dry regions. The current study was carried out to evaluate and predict the suitability of water quality for agricultural use in the K'sob valley in the M'sila region (Northeast Algeria). A combination of irrigation water quality indices (IWQIs), Geographic Information System (GIS) analysis and multivariate statistical methods were used for this purpose. Several physicochemical parameters, such as temperature (T°), hydrogen ion concentration (pH), electrical conductivity (EC), total dissolved solids (TDS), turbidity (Turb), chemical oxygen demand (COD), Ca2+, Mg2+, Na+, K+, HCO3−, Cl−, SO42−, NO3−, NO2−, NH4+, PO4− and SiO22+ were all measured from 40 samples collected at ten surface water locations during four seasons. The concentrations of the main cation and anion were shown as follows: Na+>Ca2+> K+ > Mg2+, and SO42− > HCO3− > Cl− > NO3− indicating mixed Na-Cl-K or Na-SO4 water facies. Significant seasonal variation for each parameter (T, pH, Turbidity, Salinity, COD, NH4+, Cl−, SO4−, and NO2−) was reported (p < 0.05). Additionally, a significant spatial variation (p < 0.05) was observed among different stations for the parameters: TDS, EC, Ca2+, Na+, HCO3−, SO4−, NO3−, and PO43− (p < 0.05). The irrigation water quality index (IWQI), sodium adsorption ratio (SAR), sodium percentage (Na%), Kelly index (KI), and permeability index (PI) had values varying between 28.1 and 56.8, 5.65 and 12.45, 75 and 87, 2.61 and 6.54 and 83, and 97, respectively, and a significant seasonal effect was recorded. According to the Wilcox diagram, 70% of samples were unsuitable for irrigation, while 30% of samples were questionable. The IWQI map revealed that 50% of the samples fell within the very poor category for irrigation, while 20% and 30% of the samples were inside the poor and unsuitable categories, respectively. The principal component analysis (PCA) and hierarchical cluster analysis (HCA) of K'SobValley water revealed three different categories of water based on elemental composition and seasonal variations. The results obtained in this study can be valuable for surface water management. Furthermore, the developed methodology can serve as a useful tool for identifying critical hydrogeochemical components in arid and semi-arid environments related to surface water.

Interpretable prediction, classification and regulation of water quality: A case study of Poyang Lake, China

Effective identification and regulation of water quality impact factors is essential for water resource management and environmental protection. However, the complex coupling of water quality systems poses a significant challenge to this task. This study proposes coherent model for water quality prediction, classification and regulation based on interpretable machine learning. The decomposition-reconstruction module is used to transform non-stationary water quality series into stationary series while effectively reducing the feature dimensions. Spatiotemporal multi-source data is introduced by using the Maximum Information Coefficient (MIC) for feature selection. The Temporal Convolutional Network (TCN) is used to extract the temporal features of different variables, followed by the introduction of External Attention mechanism (EA) to construct the relationship between these features. Finally, the target water quality sequence is simulated using Gated Recurrent Unit (GRU). The proposed model was applied to Poyang Lake in China to predict six water quality indicators: ammonia nitrogen (NH3-N), dissolved oxygen (DO), pH, total nitrogen (TN), total phosphorus (TP), water temperature (WT). The water quality was then classified based on the prediction results using the XGBoost algorithm. The findings indicate that the proposed model's Nash-Sutcliff Efficiency (NSE) value ranges from 0.88 to 0.99, surpassing that of the benchmark model, and demonstrates strong interval prediction performance. The results highlight the superior performance of the XGBoost algorithm (with an accuracy of 0.89) in addressing water quality classification issues, particularly in cases of category imbalance. Subsequently, interpretability analysis using the SHapley Additive exPlanation (SHAP) method revealed that the model is capable of learning relationships between different variables and there exists a possibility of learning the physical laws. Ultimately, this study proposes a water quality regulation mechanism that improves TN and DO levels by stepwise changing the magnitude of water temperature, which significantly improves in the case of data limitations. In conclusion, this study presents an overall framework for integrating water quality prediction, classification and improvement for the first time, forming a complete set of water quality early warning and improvement management strategies. This framework provides new ideas and ways for lake water quality management.

Antibiotic Pollution and Its Effects on the Spatiotemporal Variation in Microbial Community Structure and Functional Genes in Sediment of Baiyangdian Lake

Microbial communities play an important role in water quality regulation and biogeochemical cycles in lakes, and their community structure and function are affected by environmental factors. Therein, antibiotics affect the abundance, diversity, composition, and function of microbial communities. In this study, Baiyangdian Lake was selected as the study area. Sediment samples of 16 sites were collected in August 2018 and April 2019, respectively. Ultra-high performance liquid chromatography-mass spectrometry （HPLC-MS/MS） was used to determine the content of typical antibiotics-quinolones （QNs） in sediment. Through high-throughput sequencing technology, the structure and function of microbial communities was analyzed in the sediments to explore the spatiotemporal variation. Thereinto, redundancy analysis （RDA） was used to identify the key influencing factors of spatiotemporal variation of microbial communities. The results showed that： ① From August to April, the average ω（QNs） showed an increasing trend, and its mean value changed from 3.91 ng·g-1 to 6.34 ng·g-1, with significant seasonal differences in oxolinic acid （OXO） and total QNs content （P &lt; 0.05）. ② In terms of temporal variation, the dominant bacteria were Proteobacteria and Chloroflexi. The relative abundance of Proteobacteria showed a decreasing trend, whereas Chloroflexi showed an increasing trend； at the genus level, the dominant bacteria genera in August were norank_ f__Anaerolineaceae and Thiobacilus, and the dominant bacteria genera in April were Acinetobacter and norank_ f_Anaerolineaceae, and the dominant bacteria genera had significant seasonal differences （P &lt; 0.05）. ③ In terms of temporal variation, the index of Simpson, Chao, Ace, and OTU number all showed an increasing trend, and the seasonal differences were significant （P &lt; 0.05）. ④ In terms of spatial variation, there were no significant spatial differences among functional genes of COG. In terms of temporal variation, there were significant seasonal differences in functional genes of energy production and conversion, carbohydrate transport and metabolism, transcription, cell wall/membrane/envelope biogenesis, and signal transduction mechanisms （P &lt; 0.01 and P &lt; 0.05）. ⑤ Microbial community structure and functional genes were significantly correlated with QNs （P &lt; 0.01 and P &lt; 0.05）, and QNs were the main influencing factors. Therefore, QNs were the main factor affecting the changes in microbial community structure and functional genes in sediments of Baiyangdian Lake. Thus, comprehensive control of antibiotic pollution in sediments should be further strengthened.

Unlocking Biological Activity and Metabolomics Insights: Primary Screening of Cyanobacterial Biomass from a Tropical Reservoir.

Cyanobacterial harmful algal blooms can pose risks to ecosystems and human health worldwide due to their capacity to produce natural toxins. The potential dangers associated with numerous metabolites produced by cyanobacteria remain unknown. Only select classes of cyanopeptides have been extensively studied with the aim of yielding substantial evidence regarding their toxicity, resulting in their inclusion in risk management and water quality regulations. Information about exposure concentrations, co-occurrence, and toxic impacts of several cyanopeptides remains largely unexplored. We used liquid chromatography-mass spectrometry (LC-MS)-based metabolomic methods associated with chemometric tools (NP Analyst and Data Fusion-based Discovery), as well as an acute toxicity essay, in an innovative approach to evaluate the association of spectral signatures and biological activity from natural cyanobacterial biomass collected in a eutrophic reservoir in southeastern Brazil. Four classes of cyanopeptides were revealed through metabolomics: microcystins, microginins, aeruginosins, and cyanopeptolins. The bioinformatics tools showed high bioactivity correlation scores for compounds of the cyanopeptolin class (0.54), in addition to microcystins (0.54-0.58). These results emphasize the pressing need for a comprehensive evaluation of the (eco)toxicological risks associated with different cyanopeptides, considering their potential for exposure. Our study also demonstrated that the combined use of LC-MS/MS-based metabolomics and chemometric techniques for ecotoxicological research can offer a time-efficient strategy for mapping compounds with potential toxicological risk. Environ Toxicol Chem 2024;43:2222-2231. © 2024 SETAC.

Temporal dynamics of microbial communities in the water of polyculture pond system for Chinese swimming crab Portunus trituberculatus

Microorganisms as the vital component of aquaculture ecosystems, were involved in nutrient cycling, water quality regulation, and the health of cultured species. In this study, aquatic water samples were collected monthly to reveal microbial community compositions, functions, and interactions in different habitats (pond and waterway) during the culture stages of the Chinese swimming crab Portunus trituberculatus in Shandong Province. Due to the semi-closed conditions with limited water exchange, the α diversities were lower in the polyculture pond. The relative abundances of the dominant phyla varied dramatically, and most biomarkers were identified in the polyculture pond. The β diversity of the microbial communities significantly differed among culture stages and habitats. Furthermore, the heterogeneity of prokaryotic microorganisms was greater than that of eukaryotic microorganisms. In the polyculture pond, the microbial community was sensitive to nutrient cycling, with abundant functions related to “photoautotrophy”, “nitrogen_respiration” and “nitrate_respiration”, corresponding to P. trituberculatus culture activities. The co-occurrence network of the microbial community in the polyculture pond tended to be looser than that in the waterway, with a lower number of taxa and correlations. In addition, these networks had nonrandom patterns and formed “small world” topological structures. The low-abundance genera with a higher level of betweenness centrality scores were the hubs or connectors in the networks and might play an essential role in microbial community composition. Furthermore, potential pathogens (Vibrio, Acholeplasma, Photobacterium, and Flavobacterium) deserve more attention during P. trituberculatus culture. This study will be useful for understanding microbial communities in polyculture pond systems and will provide a reference for the health aquaculture of P. trituberculatus.

The effect of sampling frequency and spatial and temporal variation in the density of fecal indicator bacteria on the assessment of coastal bathing water quality

The time and location of sampling as well as the number of samples per season can influence a reliable assessment of bathing water quality. In this study, we investigated the spatio-temporal variation of fecal indicator bacteria (FIB) density and the effects of FIB variability and sampling frequency on the assessment of a single sample and the annual and final assessment of coastal bathing water quality. Increasing the number of samples from 10 to 20 per bathing season had a significant impact on bathing water quality assessment at sites where water quality fluctuations had previously been observed, resulting in a change in water quality to a lower category in 36 % of annual and 54 % of final assessments, suggesting that the minimum number of samples per season should be increased at such sites. Increasing the number of samples at sites assessed as excellent over a longer period had no impact on water quality assessment.Spatial and temporal variations in FIB density were significant at a considerable number of sites both in the single sample assessment and in the annual and final assessment. Bathing water quality was spatially unrepresentative at a quarter of the sites analyzed and temporally unrepresentative at a fifth, as there was at least one additional point with a lower bathing water quality than the official sampling point or the bathing water quality was lower in the afternoon than in the morning.When revising the current recreational water quality regulations, the impact of sampling frequency of and of spatio-temporal variation of FIB density on the relevance of bathing water quality assessment at sites subjected to pollution needs to be seriously considered.

Rainfall Dependency and Water quality Assessment of springs of three villages of Rudraprayag District: An analysis of veins of Uttarakhand Himalaya

A spring is a crevice in the substrate that forms naturally and allows water to pour out directly from the earths subsurface. Every major river in the country has a system of springs that serve as a symbolic representation of its source. But this very fundamental source of many resources is in peril. The problem is mainly related with the reduced discharge rate of water from the spring. The reason of truncate discharge rate is variability in the rainfall pattern in the recharge area due to the climate change over the years.To ensure the quality and security of the public's water supply, regular quality assessments of drinking water sources are required. In consequence, this study not only analyse the rainfall dependency of springs but also evaluated the spring water quality for drinking, using water quality index, in three villages located in Jakholi block of Rudraparayag district, Uttarakhand. The ten foremost physiochemical elements that regulate water quality—Nitrate, Fluoride, Iron, pH, Turbidity, Chloride, Residual Chlorine, Magnesium, sulphate, and Hardness—were investigated to ensure compliance with guidelines defined by the Bureau of Indian Standards IS: 12500:2012. After examining the data, it became apparent that all of the indicators pointed to acceptable water quality, making it ideal for drinking. However, because of its low discharge and great reliance on rainfall, its position is getting more detrimental.

Proposal of an Automated Monitoring System of Aquamarine Water Quality in Coral Reef Regions

Proposal of an Automated Monitoring System of Aquamarine Water Quality in Coral Reef Regions

Quantitative Effects of Anthropogenic and Natural Factors on Heavy Metals Pollution and Spatial Distribution in Surface Drinking Water Sources in the Upper Huaihe River Basin in China.

The water quality of sources in the Huaihe River Basin significantly affects the lives and health of approximately 16.7% of China's population. Identifying and quantifying pollution sources and risks is essential for effective water resource management. This study utilized Monte Carlo simulations and Geodetector to assess water quality and eutrophication, as well as to evaluate the sources of heavy metals and the associated health risks for both adults and children. The results showed that eutrophication of water sources in Huaihe River was severe, with an overall EI value of 37.92; 67.8% of the water sources were classified as mesotrophic and 32.2% classified as eutrophic. Water quality and eutrophication levels in the southern mountainous regions were better than those in the densely populated northern areas. Adults were found to have a higher carcinogenic risk than children, whereas children faced a higher noncarcinogenic risk than adults. Cr presented the highest carcinogenic risk, affecting more than 99.8% of both adults and children at levels above 1 × 10-6 but not exceeding 1 × 10-4. The noncarcinogenic risk from metals did not surpass a level of 1, except for Pb. As was primarily influenced by agricultural activities and transportation, whereas Cd, Cr, and Pb were mainly affected by industrial activities, particularly in local textile industries such as knitting and clothing manufacturing. The analysis demonstrated that the influence of anthropogenic factors on heavy metal distribution was significantly enhanced by indirect natural factors. For example, the explanatory power of Precipitation and Road Network Density on As was 0.362 and 0.189, respectively, whereas their interaction had an explanatory power as high as 0.673. This study indicates that the geodetector method is effective in elucidating the factors influencing heavy metal distribution in water, thereby providing valuable insights into pollution sources in global drinking water.

Threats to the integrity of urban streams in the southwest amazon

This study characterized the physical integrity, hydromorphology, and limnology of ten urban streams in the Southwestern Amazon. The objective was to investigate how these characteristics covary and identify threats to the health of these ecosystems. The physical integrity of the streams was assessed using a Habitat Integrity Index (HII), hydromorphology based on width, depth, flow, and substrate type, and limnological characterization through 14 physico-chemical parameters during dry and rainy seasons. Three streams were classified as preserved, two as intermediate, and five as degraded. Anthropogenic alterations were observed in hydromorphological characteristics, especially in width, depth, and substrate type across different integrity categories. Limnological analysis revealed that chemical and biochemical oxygen demands, ammoniacal nitrogen, nitrate, dissolved iron, and sulfides exceeded the limits established by Brazilian water quality regulations (CONAMA 357/2005). The alteration of these parameters reveals that the primary threat to the integrity of these ecosystems is sewage collection and treatment issues, reflecting the absence of basic sanitation. Redundancy Analysis (RDA) indicated the influence of specific substrate types on parameters in degraded streams, while preserved streams showed a correlation between dissolved oxygen with riparian forest conditions and the absence of anthropogenic influence. Cluster analysis emphasized the importance of integrating environmental, hydromorphological, and limnological metrics for a comprehensive assessment of ecosystem health. Given the heterogeneity of Amazonian aquatic ecosystems, this study may contribute to the establishment of criteria based on regional characteristics for accurate assessment and guidance of public policies aimed at protecting and ensuring the integrity of these ecosystems. Keywords: limnological characteristics, microbiological analysis, Porto Velho, urbanization.

Ecological assessment of water quality in freshwater wetlands based on the effect of environmental heterogeneity on phytoplankton communities in Northeast China.

Phytoplankton community characterized by strong vitality response to environmental change in freshwater ecosystems. This study aims to evaluate the effectiveness of using phytoplankton diversity as a water quality indicator in wetlands, and find out the main environmental variables affecting the distribution of phytoplankton. From 2020 to 2021, we examined phytoplankton assemblages and water environmental variables in spring, summer, and autumn at eight sampling sites from Hulanhe Wetland, Northeast (NE) China. The results showed that Bacillariophyta was the dominant species. Phytoplankton composition and abundance differed among sampling sites in each season; the abundance in summer (613.71 × 104 ind. L-1) was higher than that in autumn and spring. The water quality assessment of the trophic state index (TSI) based on the four physicochemical indicators was compared with phytoplankton diversity indices, which indicated that the phytoplankton community was stable, and these two indices were significantly lower in summer than in spring and autumn. According to redundancy analysis (RDA), total phosphorus (TP) and nitrogen (TN) were the main environmental variables affecting the distribution of phytoplankton. Temperature and dissolved oxygen (DO) changes also played a role, and their impact on the community was discussed. This work can provide relevant scientific references on the usefulness of phytoplankton diversity structure in assessing water quality in cold regions, in which the succession can be significantly affected by nutrients and temperatures.

Impact of total phenolic compounds on ecological and health risks of water and sediments from Timsah Lake, Suez Canal, Egypt.

This study aimed to measure spatial and temporal distributions of total phenolic compounds and their ecological and health hazards using UV-vis spectrophotometers as a low-cost, fast, simple method in water and sediments collected from Timsah Lake, Suez Canal, Egypt, 2022. Also, assessing highly adaptive fungal species associated with contamination is designed. Due to human and environmental activities and industrial waste discharges, Timsah Lake is increasingly threatened by all kinds of pollutants. The results indicated that the seasonal concentration means of the phenolic compounds were winter (0.229) > spring (0.161) > summer (0.124) > autumn (0.131) mg/l and winter (3.08) > summer (2.66) mg/g in water and sediment samples, respectively. The result has shown that the phenol concentrations in all stations were more than 0.005 and 0.1 mg/l for Egyptian National Standards and World Health Organization (WHO) for drinking water but less than the limits of 1 mg/l for wastewater. Notably, the fungi recorded the highest counts during spring, totaling 397 colonies/100 ml of water and 842 colonies/gram of sediment. Four isolates of fungi were identified and deposited in the GenBank database by Aspergillus terreus, Aspergillus terreus, Penicillium roqueforti, and Penicillium rubens under accession numbers OR401933, OR402837, OR402878, and OR424729, respectively. Moreover, ecological risk (RQ) for the total phenolic compounds was > 1 in all investigated stations for water and sediments. The hazard quotient is HQ < 1 in all seasons in water and sediments except winter. The hazard index (HI) in water and sediments for children is higher than for adults. It can be concluded that the low-cost, fast, simple method for determining phenolic content in water and sediment samples, using UV-vis spectrophotometry, was useful for predicting the reactivates of a wide variety of phenol and their derivatives. Furthermore, it can be concluded that Periodic assessments of water quality and strict regulations are necessary to safeguard this vital resource from pollution and ensure the well-being of future generations. Finally, policymakers and water treatment specialists might use the information from this research to reduce these chemical pollutants in Egypt.

Ecosystem functions and services in urban stormwater ponds: Co‐producing knowledge for better management

Abstract Urban stormwater management ponds (SWMPs) are widely employed for stormwater control, but knowledge about their contributions to urban ecosystem function and service delivery remains unclear. We organized a workshop that brought together researchers, managers and students to assess and discuss current information on SWMP ecosystem function and services, identify perceived knowledge gaps and prioritize research needs, to advance understanding and management of SWMPs in Ontario, Canada. Workshop participants identified habitat provisioning and regulation of water quality and quantity as key ecosystem functions in SWMPs. They also recognized carbon sequestration, flood prevention, water purification, educational potential, human health promotion and community engagement as important ecosystem services provided by SWMPs. Despite the availability of engineering information and practitioner knowledge, workshop participants suggested that information on the impacts of maintenance operations, biological condition, water quality, costs and benefits and impact on surrounding landscape are important gaps that hinder a modern approach to design and management of SWMPs for multiple co‐benefits. Participants suggested current gaps can be tackled with a combination of continuous water‐quality monitoring, field, laboratory and mesocosm experiments. They also suggested that future SWMP studies take advantage of existing community and governmental databases using meta‐analyses to summarize knowledge and provide future directions. Practical implication: By linking knowledge gaps to management needs, this practice insight provides a road map that can be used to advance management of SWMPs in Ontario and elsewhere.

Spatial distribution of physicochemical parameters and drinking and irrigation water quality indices in the Jhelum River, Pakistan.

Sustainable management of river systems is a serious concern, requiring vigilant monitoring of water contamination levels that could potentially threaten the ecological community. This study focused on the evaluation of water quality in the Jhelum River (JR), Azad Jammu and Kashmir, and northern Punjab, Pakistan. To achieve this, 60 water samples were collected from various points within the JR Basin (JRB) and subjected to a comprehensive analysis of their physicochemical parameters. The study findings indicated that the concentrations of physicochemical parameters in the JRB water remained within safety thresholds for both drinking and irrigation water, as established by the World Health Organization and Pakistan Environmental Protection Agency. These physicochemical parameters refer to various chemical and physical characteristics of the water that can have implications for both human health (drinking water) and agricultural practices (irrigation water). The spatial variations throughout the river course distinguished between the upstream, midstream, and downstream sections. Specifically, the downstream section exhibited significantly higher values for physicochemical parameters and a broader range, highlighting a substantial decline in its quality. Significant disparities in mean values and ranges were evident, particularly in the case of nitrates and total dissolved solids, when the downstream section was compared with its upstream and midstream counterparts. These variations indicated a deteriorating downstream water quality profile, which is likely attributable to a combination of geological and anthropogenic influences. Despite the observed deterioration in the downstream water quality, this study underscores that the JRB within the upper Indus Basin remains safe and suitable for domestic and agricultural purposes. The JRB was evaluated for various irrigation water quality indices. The principal component analysis conducted in this study revealed distinct covariance patterns among water quality variables, with the first five components explaining approximately 79% of the total variance. Recommending the continued utilization of the JRB for irrigation, we advocate for the preservation and enhancement of water quality in the downstream regions.

Comparative evaluation of spatiotemporal variations of surface water quality using water quality indices and GIS

AbstractThere is a need for a comprehensive comparative analysis of spatiotemporal variations in surface water quality, particularly in regions facing multiple pollution sources. While previous research has explored the use of individual water quality indices (WQIs), there is limited understanding of how different WQIs perform in assessing water quality dynamics in complex environmental settings. The objective of this study is to evaluate the effectiveness of three WQIs (Canadian Council of Ministers of the Environment (CCME), National Sanitation Foundation (NSF) and System for Evaluation of the Quality of rivers (SEQ-Eau) and a national water quality regulation in assessing water quality dynamics. The pilot study area is the Acısu Creek in Antalya City of Turkey, where agricultural practices and discharge of treated wastewater effluents impair the water quality. A year-long intensive monitoring study was conducted includig on-site measurements, analysis of numerous physicochemical and bacteriological parameters. The CCME and SEQ-Eau indices classified water quality as excellent/good at the upstream, gradually deteriorating to very poor downstream, showing a strong correlation. However, the NSF index displayed less accuracy in evaluating water quality for certain monitoring stations/sessions due to eclipsing and rigidity problems. The regulatory approach, which categorized water quality as either moderate or good for different sampling sessions/stations, was also found less accurate. The novelty of this study lies in its holistic approach to identify methodological considerations that influence the performance of WQIs. Incorporating statistical analysis, artificial intelligence or multi-criteria decision-making methods into WQIs is recommended for enhanced surface water quality assessment and management strategies.

Uneven consequences of global climate mitigation pathways on regional water quality in the 21st century

Future socioeconomic climate pathways have regional water-quality consequences whose severity and equity have not yet been fully understood across geographic and economic spectra. We use a process-based, terrestrial-freshwater ecosystem model to project 21st-century river nitrogen loads under these pathways. We find that fertilizer usage is the primary determinant of future river nitrogen loads, changing precipitation and warming have limited impacts, and CO2 fertilization-induced vegetation growth enhancement leads to modest load reductions. Fertilizer applications to produce bioenergy in climate mitigation scenarios cause larger load increases than in the highest emission scenario. Loads generally increase in low-income regions, yet remain stable or decrease in high-income regions where agricultural advances, low food and feed production and waste, and/or well-enforced air pollution policies balance biofuel-associated fertilizer burdens. Consideration of biofuel production options with low fertilizer demand and rapid transfer of agricultural advances from high- to low-income regions may help avoid inequitable water-quality outcomes from climate mitigation.

DAPSI(W)R(M) put into practice for a nature-based solution: Framework applied to the coastbusters approach

Nature-based Solutions (NbS) can be applied to alleviate negative human impacts on ecosystems and promote the general health or well-being of the environment. Human-induced activities, including installation of NbS, are governed by legislative requirements (e.g. Environmental Impact Assessments (EIA)), especially when such activities occur in Marine Protected Areas (MPA's). A correct and thorough description of the legislative framework governing the application and development of NbS is therefore essential. The Drivers-Activities-Pressures-State change-Impacts (on human Welfare)-Responses (using Measures) or DAPSI(W)R(M) framework is valuable when environmental assessment procedures include a NbS, as well as when policy and industry require guidance for the practical application of a NbS concept. In this study, we applied the DAPSI(W)R(M) framework to the Coastbusters approach, in which mussel beds (Mytilus edulis) and tubeworm aggregations (Lanice conchilega) are installed in the Belgian part of the North Sea with the aim of improving coastal resilience and maritime infrastructure works. Within the context of the Coastbusters approach, the various elements of the DAPSI(W)R(M) framework were elucidated. Coastal defense is a driver, with activities including the integration of coastal infrastructure and aquaculture practices. Pressures related to these activities on benthic habitats were described using the MarESA sensitivity approach. State change assessments were performed based on the various marine regulations (e.g. Marine Strategy Framework Directive, Habitat Directive, Water Framework Directive) which together outline a precise set of criteria and indicators designed to assess the sustainability and health of ecosystems. The present study provides a detailed framework for the environmental evaluation of seaward NbS, from state changes to impacts on human welfare. Three quantitative estimations of ecosystem service indicators (coastal protection, carbon retention and water quality (N) regulation) were used, with the indicators quantified by in-situ measurements and data from literature. Subsequently, the 10-tenets approach for taking measures (e.g. use of biodegradable material, local species, etc.) was used to develop responses that facilitate the optimal implementation of NbS. The approach outlined in this study can be used as a guide for stakeholders as they move through the environmental evaluation processes that are required for successful development of a seaward NbS. Our results underscore the importance of a favorable institutional environment for NbS and suggest that public acceptance and stakeholder involvement play a crucial role in successful implementation. This study contributes to the understanding and operationalization of Nature-based Solutions in coastal management.

Microbial community dynamics and nitrogen transformation associated with turbid-turned culture stage of Pacific white shrimp, Litopenaeus vannamei in small greenhouse farms

Small greenhouse farms have experienced rapid expansion of Litopenaeus vannamei culture in China in recent years. To investigate microbial community dynamics and nitrogen transformation during the early critical stage, known as the turbid-turned stage in small greenhouse farms, microbial samples from the water column of small greenhouses were analyzed by 16S rRNA and 18S rRNA high-throughput sequencing, along with the detection of ammonia nitrogen in water. The results of water quality analysis revealed that accumulated ammonia nitrogen was converted to nitrite as the water color transitioned from clear green to turbid brown. High-throughput sequencing data demonstrated a shift in dominant microorganisms from zooplankton to algae and bacteria during the turbid-turned stage, and the main functional microbial taxa, such Marivita and Chlorella, were enriched. The results of Linear Discriminant Analysis Effect Size and canonical correlation analyses indicated that the compositions of key microbial communities were correlated with environmental factors. Furthermore, analysis of functional genes indicated that ammonia-oxidizing bacteria were present in the early growth stage, while the abundance of nitrite-oxidizing bacteria was low during the early culture stage. Overall, the findings suggest that microorganisms during the turbid-turned stage in small greenhouses may play a crucial role in regulating water quality and promoting shrimp health within a stable small greenhouse environment.

Water quality indices for the evaluation of the groundwater quality in southwestern Libya

ABSTRACT An investigation was undertaken to consider the quality of the groundwater. The samples were collected from the Southwestern Libya. Forty-one water samples (41) were analyzed for hydrochemical characteristics and suitability for drinking purposes. The parameters for water quality, including calcium, magnesium, sodium, potassium, chloride and bicarbonate, sulfate, nitrate, pH and total dissolved solids (TDS), were examined. The most common worldwide used standard (ST-WQI) and the weighted arithmetic (WA-WQI) water quality indices were selected. The majority of the samples (87.5% wells) described the quality of groundwater in the Alshatti area as excellent to moderate and in the Ghat region (three wells) water quality ranges from excellent to good and is appropriate for direct consumption. In the Wadi al-Ajal areas, 62.5% (10 wells) of samples described the groundwater quality as excellent to good and the rest of the others were poor or unsuitable water. In contrast, most of the obtained results from the Sabha and Ghadduwah areas showed poor to unsuitable water quality for drinking use. Furthermore, samples are higher with pH and alkalinity values. The alkalinity does not pose a health risk but can cause esthetic problems. Generally, most of the areas’ water quality indices for physicochemical parameters indicated suitability for drinking purposes.