Water Quality Standards Research Articles

Lack of basic sanitation influence on the enteropathogen presence in a river of the Brazilian Legal Amazon.

Water systems globally are declining in water quality, largely due to anthropogenic activities, with freshwater contamination reaching unprecedented levels. The Brazilian Legal Amazon (BLA), holding 13.56% of the world's fresh water, is affected due to the lack of basic sanitation. This study assesses the quality of the Lontra River, in southeastern BLA, by monitoring physicochemical and microbiological parameters and detecting DEC E. coli and Salmonella spp. over 16months, following current regulations. The data were analyzed using Pearson's chi-square and Fisher's exact test (p ≤ 0.05), Kruskal-Wallis test (p ≤ 0.05), with Tukey post hoc (α = 0.05), and Spearman's correlation (p ≤ 0.05). Results showed pH levels were below the optimal range established by Brazilian water quality indices and legislation, with seasonal variations, and dissolved oxygen also below acceptable limits. Thermotolerant coliforms (TtC) exceeded thresholds, signaling microbiological contamination. DEC E. coli and Salmonella spp. were detected in 32.14% and 67.85% of samples, respectively, even in those with low TtC levels. No correlation was found between TtC and pathogen presence, suggesting that meeting minimum water quality standards does not guarantee the absence of pathogenic microorganisms. These findings reveal significant environmental and public health risks related to surface water quality in the Lontra River. Also highlight discrepancies between regulatory water quality standards and the actual conditions observed, underscoring the need for regionally adapted water monitoring and management practices to protect both environmental and public health in the BLA.

Fungicides in English Rivers: Widening the Understanding of the Presence, Co-Occurrence and Implications for Risk Assessment

Fungicides are commonly found in freshwater; however, the understanding of their wider presence, co-occurrence, and potential risk remains limited. This study examined English national datasets to highlight knowledge gaps and identify improvements to monitoring and risk assessment. The analysis found that at least one fungicide was present in 91% of samples collected from English rivers over a 5-year period, with four fungicides detected at rates exceeding 50%. Co-occurrence occurs widely, with up to nine different fungicides detected within the same sample and four detected the most frequently, raising concerns for synergistic interactions. The semi-quantitative nature of much of the available data precludes a clear determination of the potential risk of detrimental effects on aquatic biota. Fully quantitative analysis is required, and ecotoxicity-based water quality standards need to be agreed upon. The monthly sampling regime reflected in the national datasets will infrequently capture high flow events and so is unlikely to fully represent fungicides transported to rivers via rainfall-driven processes. Several information gaps exist, including the risk posed by fungicides in sewage sludge applied to land and the extent to which fungicides in the aquatic and terrestrial environments contribute to antifungal resistance. Improvements in spatial and temporal information on fungicide use are needed.

Fluoride and nitrate contamination in groundwater of Naini Industrial Area, Uttar Pradesh: assessing non-carcinogenic human health risk

Groundwater is the main source of drinking water globally; however, its quality has been deteriorated due to various geogenic and anthropogenic activities. The groundwater quality of Naini Industrial Area, Prayagraj was studied seasonally to evaluate the fluoride and nitrate contamination pertaining to human health risk assessment. The samples were collected from 60 locations in the pre- monsoon, monsoon, and post-monsoon season. The fluoride and nitrate were assessed with the help of Ion chromatography. The NO3– concentration exceeded the Indian drinking water quality standards in 27% of the groundwater samples. The NO₃⁻ contamination is predominantly associated with agricultural practices, while F⁻ can be linked to natural geological sources. The non-carcinogenic human health risk assessment was quantified by calculating the Hazard Quotient (HQ) and Hazard Index (HI) were calculated as per USEPA methodology for male, female and child population. The findings indicate that the child population is particularly susceptible to health risks associated with the ingestion of F– and NO₃⁻ through the drinking water pathway. Across all the sampled sites, the Hazard Index (HI) values varied from 0.10 to 12.3 for males, 0.09 to 10.6 for females, and 0.16 to 19.7 for children suggesting substantial risk to the local populace at more than half of the locations which is largely related to nitrate contamination. Thus, the study suggests that groundwater at many locations is unsuitable for drinking without treatment pertaining to the probable health risk they pose to consumers advocating upgraded water management plan for the residents.

Baseline tritium measurements in Thailand's water bodies: Supporting sustainable nuclear energy development.

Tritium, a radioactive isotope produced naturally through cosmic radiation interactions and anthropogenically through nuclear weapons testing, poses potential environmental risks, particularly within the water cycle. This study measured tritium concentrations in surface water across Thailand to establish a baseline dataset for monitoring potential contamination from nuclear activities and accidents. Surface water samples were collected from 14 large reservoirs during the wet season in October 2023 and the dry season in February 2024, providing a total of 28 samples. Tritium concentrations were analyzed using electrolytic enrichment and liquid scintillation counting techniques. The results, presented with combined uncertainty, revealed tritium levels ranging from 1.21±0.19 to 2.74±0.23 TU (0.14±0.02 to 0.32±0.03 Bq·L-1), with an average of 1.94±0.01 TU (0.23±0.00 Bq·L-1). The highest concentrations were observed in the north (2.26±0.02 TU), followed by the northeast (2.13±0.04 TU), central (1.91±0.05 TU), east (1.72±0.03 TU), and south (1.55±0.04 TU). All measured tritium levels were below the natural background threshold of 10 TU and complied with the surface water quality standards set by the Thailand's Pollution Control Department. Tritium concentrations were positively correlated with latitude, distance from the coast, and elevation, while showing an inverse relationship with pH. No significant seasonal variations or correlations were observed with ion concentrations, water temperature, electrical conductivity, salinity, dissolved oxygen, or total dissolved solids. These baseline measurements are essential for supporting sustainable nuclear energy development and ensuring effective monitoring of environmental radioactivity. The dataset provides a critical reference for Thailand's regulatory agencies, such as the Office of Atoms for Peace, to safeguard public and environmental safety under both normal operations and potential radiological emergency scenarios.

The Environmental Evaluation of the Sp. Opi – Babatan Saudagar – Srijabo Road

The Public Works Agency for Highways and Spatial Planning of South Sumatra Province has the task of deconcentration in the field of roads and has authority over 88 roads with a length of 1,779.27 km spread across 17 districts and cities in South Sumatra Province. Not all provincial roads have an environmental evaluation document. The objective of the current research was to evaluate the environmental impact resulting from road operational activities in South Sumatra Province by taking data on ongoing activities, geological and topographic conditions, flora and fauna, socio-economic and cultural activities in the area, as well as measuring quality standards, which include air quality standards, noise, vibration, and water quality standards on the Sp. OPI - Babatan Saudagar - Srijabo Road. The conclusion of the current research shows that the ambient air quality, noise intensity, and vibration are still good and meet quality standards. The potential hydrogen (pH) and dissolved oxygen (DO) parameters in the Ogan River branch at the time of sampling for surface water quality did not meet the quality standards due to the type of soil, which tends to be acidic. Furthermore, the results of groundwater quality analysis show that the pH of groundwater measured in all locations is less than 6.5 or does not meet quality standards, which can cause an unpleasant taste when consumed, so processing is needed to increase the pH of groundwater.

THE PHYSICOCHEMICAL WATER POLLUTION OF RIVER GINZO’S SEASONAL VARIATIONS FOR IRRIGATION, KATSINA METROPOLIS, KATSINA STATE, NIGERIA

A study on water quality in relation to irrigation was conducted at River Ginzo. The aim of the study physicochemical water pollution of River Ginzo’s seasonal variations for irrigation, Katsina State. Improper monitoring the level of water quality in the river may lead to contamination of the water and low yield of irrigation. Water samples were collected at ten points in wet and dry seasons 2023/2024 each i.e., ten samples stations, thirteen parameters were analyzed using standard laboratory techniques. The parameters include Temperature (T), pH, Electric Conductivity (EC), Total Dissolve Solid (TDS), Turbidity (Tur), Total Hardness (TH), Chloride (Cl), Nitrate (NO3), Dissolve Oxygen (DO), Biological Oxygen Demand (BOD), Ammonia (NH3), Nickel (Ni), and Lead (Pb). Data was analyzed pair ‘t’ test and related with FAO standards. Based on findings this research reveals 69.23% of parameters shows there is no significant relationship between the parameters and standards of water quality for irrigation due to variations exist between and within different parameters in the river both temporally and spatially. Future research needs to concentrate on heavy metals to continue monitoring the quality of the river.

Hydrogeochemical characterization of shallow and deep groundwater for drinking and irrigation water quality index of Kathmandu Valley, Nepal.

A comprehensive hydrogeochemical analysis of 156 groundwater samples (106 shallow and 50 deep) was conducted in the Kathmandu Valley, Nepal. This study addresses a significant research gap by focusing on the hydro-geochemical composition and contamination of groundwater in the Kathmandu Valley, an area with limited detailed assessments. The novelty of this work lies in its comprehensive analysis of both shallow and deep groundwater, particularly concerning the high concentration of contaminants like arsenic, microbial pathogens, and ammonium, which are critical for public health. The results indicate that the mean concentration of turbidity, iron (Fe), and total coliform (TC) was exceeded the permissible range by National Drinking Water Quality Standards (NDWQS). Hydro-geochemical analysis using the Piper and Chadha diagrams showed the Ca2⁺-Mg2⁺-HCO₃ dominance, suggesting carbonate rock weathering and ion exchange as primary processes. Gibbs and mixing diagrams further supported these findings. The Water Quality Index ranged from 3.93 to 442.11 (mean: 66.87) for shallow water while 8.07 to 252.87 (mean: 79.24) with turbidity, iron, and ammonia significantly contributing to the overall index. Salinity hazard assessment considering total dissolved solids, sodium adsorption ratio, sodium percentage, magnesium adsorption ratio, and Kelly ratios, indicated that shallow and deep groundwater samples are suitable for irrigation, as confirmed by Wilcox diagrams. This study provides valuable insights into the groundwater quality of Kathmandu Valley and highlights the need for effective management strategies to ensure sustainable use of this vital resource, providing a nuanced understanding of groundwater quality and its implications for water management in the region. The findings can inform water treatment practices, policy-making, and future research, ultimately aiding in the development of safer and more sustainable groundwater management practices for the region.

АНАЛИЗ И ОЦЕНКА КАЧЕСТВА ПОВЕРХНОСТНЫХ ВОД БАССЕЙНА РЕКИ ЕЛЕК В ЗОНЕ ВОЗДЕЙСТВИЯ ТЕХНОГЕНЕЗА

The article provides an overview of anthropogenic factors negatively affecting the geosystems of the Ilek River basin. The accumulation of chemical elements and their introduction into the environment result from human industrial and agricultural activities. The article examines natural and anthropogenic causes that adversely impact the qualitative composition of surface waters in the Ilek River basin. It also considers the hydrological regime of the Ilek River and its major tributaries based on field observations conducted in 2024. The study identifies natural and anthropogenic factors that have been influencing the geosystems of the Ilek River basin for decades. Results of chemical analyses of surface water samples from key sites demonstrate a clear correlation with elements of the technosphere. It has been established that first- and second-order tributaries of the Ilek River, located in the northeastern part of the basin, are polluted with heavy metals due to mining and geological exploration activities. The Water Pollution Index (WPI) was calculated for the Ilek River and its major tributaries. The findings indicate that while the water bodies of Aktobe oblast, which remain underresearched, generally meet surface water quality standards, the surface waters in the middle reaches of the Ilek River are classified as highly polluted. This highlights the necessity for more comprehensive investigations to prevent further deterioration and to develop measures for reducing pollution levels.

Ground-Based Green Façade for Enhanced Greywater Treatment and Sustainable Water Management

Urban areas face challenges with water scarcity, and the use of non-conventional water resources for uses not requiring potable quality is being promoted more and more by governments and international agencies. However, non-conventional water resources, such as rainwater and greywater, need to be treated before use to avoid health risks and possible nuisance (smell, bacteria and algae proliferation in storage tanks, etc.). This study is aimed at demonstrating the feasibility of a system reusing treated greywater for toilet flushing, relying on a nature-based treatment technology—ground-based green façades—with limited maintenance requirements which is therefore easily replicable for decentralized treatment systems, like those of greywater reuse at building scales. The demonstrative system has been installed at the University of Jordan’s Al-Zahra dormitory in Amman and uses a degreaser as the primary treatment followed by ground-based green façade technology as a secondary treatment mechanism. The effluent is stored in an underground tank and directed to a tertiary treatment mechanism with UV lamps to remove pathogens before being reused for lawn irrigation and toilet flushing. Samples from influent and effluent were analyzed for various physical, chemical, and microbiological characteristics. The degreaser significantly reduced turbidity, TSS, total BOD5, and total COD levels in greywater. When combined with the green wall façades, the system demonstrated high removal efficiencies, particularly for turbidity, TSS, total COD, and total BOD5. The treated effluent met irrigation reuse standards for all the parameters, including total coliform and E. coli concentrations. The UV disinfection unit proved to be an effective post-treatment step, ensuring that water quality standards for reuse were met. The system’s overall performance highlights its ability to manage low- to medium-strength greywater. Results suggest the applied green wall system has significant potential for wider adoption in urban settings.

Pengujian Kualitas Air Sumur di Daerah Pesisir dan Daratan Provinsi Papua Barat Daya

Water is a vital component for life on Earth. Currently, many people still struggle to access sufficient water due to limited availability. This research aims to determine the pH, TDS, salinity, conductivity, turbidity, TSS, and temperature of well water. The results of testing several physical parameters indicate the quality of well water in Pulau Doom and SP4, Sorong Regency. Measurements of pH, TDS, conductivity, salinity, turbidity, and temperature of the tested well water samples did not meet the quality standards set forth in the Ministry of Health Regulation Number 2 of 2023 concerning Environmental Health. The average pH level of the well water was 8.2, while the values for TDS, salinity, and conductivity were 0. The turbidity measurement was 0.26 NTU (still above the standard). Based on the initial testing, it can be concluded that filtration and treatment, such as boiling, are necessary to minimize the negative impacts of consuming well water. The second test was conducted to identify the quality of the dam water in SP4, Sorong Regency, to determine its suitability for use. This test used physical and chemical parameters measured with a pH meter, AMT03 AMTAST pH/EC/TDS Meter, and TSS LH-XZ03 Turbidity Meter, which provide direct and concrete data. The testing technique involved laboratory measurements. However, both water sources still meet the drinking water quality standards specified in the Ministry of Health Regulation Number 2 of 2023.

Sebaran Potensi Mata Air dan Kearifan Lokal Masyarakat dalam Rangka Upaya Konservasi Sumber Daya Air di Kecamatan Akabiluru Kabupaten Lima Puluh Kota

The need for water is very important for life, both agriculture, industry and daily life, causing people to have to look for existing sources to meet their water needs. This study aims to analyze the location of existing water sources and determine the feasibility of water sources by conducting laboratory tests, after that to maintain water sources, community cooperation is needed, one of which is the form of local wisdom in maintaining water sources in Akabiluru District. The method used is descriptive quantitative. The results of the study stated that there are 22 springs spread across Akabiluru District, laboratory tests were carried out with samples of 3 springs, namely Luak Napa, Luak Canduang, Pancuran Duo. The three springs showed good physical water quality, colorless, tasteless and odorless. Meanwhile, the results of the chemical parameter laboratory tests, the water pH is normal except in Pancuran Duo with a pH of 6.1 and the manganese content does not exceed the standard, the mineral content such as calcium, potassium, and magnesium does not exceed the maximum levels allowed according to the drinking water quality standards, and for the microbiological parameters, the coliform content is quite high in the three samples, namely >.2400 MON / 100 ml and 43 MPN / 100 ml. Local wisdom in Akabiluru District in maintaining existing springs is still carried out in several villages such as prohibiting taking water at noon, cleaning springs, and making several water sources sacred springs.

A water footprint inventory for a textile organization: A Case Study in Denim Washing Industry based on the Integrated Reverse Osmosis System.

The consideration of scarcity and overexploitation of freshwater at the organizational level increased interest in the water footprint. The water footprint measures freshwater use for activities, taking into account water consumption and pollution contamination by classifying consumed water into groundwater and surface water (blue water), rainwater (green water), and polluted water (grey water). This study aims to identify a comprehensive water footprint inventory analysis for a denim washing organization and assess the grey water footprint (GWF) based on the effluent concentration of pollution indicators (chemical oxygen demand (COD), suspended solids (SS), ammonium nitrogen (NH4-N), and phenol) measured monthly in 2021. The company used well water for its operations, which constituted 61.79% of the total water use of the facility, water used by the organization by reverse osmosis accounted for 37.60% of total water consumption, and rainwater made up 0.61% of the volume of water used overall. The grey water footprints of COD, SS, NH4-N, and phenol were calculated as 59981.53 m3, 31747.21 m3, 10514 m3, and 48190 m3, respectively. The results illustrated that the COD, which accounted for 40% of the pollutants, had the highest grey water footprint in the organization, corresponding to the amount of freshwater required to assimilate pollutants to meet water quality standards. In addition, the effect of the reverse osmosis system on the blue water footprint of this organization was analyzed by considering two different scenarios. Reverse osmosis considerably impacted the blue water footprint, accounting for over 37% of this organization's water use. It suggests that a wastewater treatment plant using reverse osmosis is an ideal option for recovering water. The main contributions of this study are comprehensively assessing the water footprint components of the denim washing company and understanding sector-specific water footprint at the organization level.

Section 303(d) of the Clean Water Act: What does it mean for fisheries?

ABSTRACT The Clean Water Act (CWA) was passed by the United States Congress in 1972. It established regulations for the quality of discharges from point sources and a framework to assess water quality condition, identify what must be done for impaired waters to meet water quality standards, and work with stakeholders to improve water quality conditions. Section 303(d) of the CWA specifically outlines a framework for authorized states, territories, and tribes to identify polluted waters. It also requires plans be written that describe how water quality can be restored. Implementation of Section 303(d) can affect the condition of waterbodies as well as the fisheries that they support. In this paper we describe the 303(d) process and explain how fisheries professionals and the species they manage can benefit from the data produced through this process and the required public engagement. In addition, we provide two examples where involvement of fisheries professionals in the 303(d) process has resulted in both improved water quality and fisheries. Finally, we encourage fisheries professionals to become engaged in the 303(d) process to improve water quality and fisheries outcomes.

Feasibility Analysis of the Bonto River, Tomon 1 Village, Dekai District, Yahukimo Regency as a Source of Raw Water

Rivers are one of the sources of water for the life of living things. Rivers are often used in various ways by humans. The Bonto River is one of the rivers in Yahukimo Regency that is used as raw water for drinking water. In order to meet the need for clean water, it is necessary to analyze the water quality of the Bonto River. Determining the source of raw water in an area is the first step in determining the location or place as a raw water supplier for clean water treatment purposes. The purpose of this study is to identify the water quality of the Bonto river and evaluate the condition of the Bonto river water with the water quality standards that have been set to be used as an alternative source of raw water for clean water treatment. Water sampling in this study was carried out by observation and measurement directly in the field, and laboratory tests. Raw water quality data is compared to the current raw water and drinking water quality standards. The water quality standards used are the Decree of the Minister of Health of the Republic of Indonesia Number: 492/MENKES/SK/IV/2010, dated April 19, 2010 concerning the Terms and Conditions and Supervision of Drinking Water Quality, and in accordance with the water quality requirements. Each sample of water and sediment is examined in the laboratory to be analyzed according to its needs, namely regarding water quality. Testing of water quality samples was carried out at the Papua Regional Health Laboratory Center.

Assessing heavy metal content of a rural stream Southeast Nigeria for drinking and irrigation purposes

The heavy metal concentrations of a rural stream in Southeast Nigeria were evaluated between November 2021 and October 2022 in 3 stations. Water Pollution Index (WPI) and non-carcinogenic health risk assessment were used to determine the water’s suitability for human consumption and irrigation. Eight heavy metals were evaluated using standard methods and compared with Nigerian Drinking Water Quality and Food and Agriculture Organization Irrigation Water Quality standards. The concentrations were; iron (0.34 – 3.78 mg/l), manganese (0.10 – 1.05 mg/l), copper (0.06 – 0.84 mg/l), zinc (0.22 – 1.87 mg/l), chromium (0.04 - 0.37 mg/l), lead (0.03 - 0.31 mg/l), cadmium (0.03 - 0.23 mg/l), and nickel (0.01 - 0.18 mg/l). Iron, manganese, chromium, lead, cadmium, and nickel exceeded acceptable limits. The WPI values – 5.02 – 6.57 (drinking) and 1.49 – 1.92 (irrigation) were greater than 1, indicating heavy pollution. The ingestion hazard indices (HI) 4.50 – 5.85 (adults) and 6.32 – 8.22 (children) were higher than the threshold value (1). Anthropogenic activities and seasons influenced the concentration of the metals, while chromium and cadmium were responsible for the observed adverse health risks. The burden of the health risk was more on the children. In conclusion, the Azueke stream’s water is unsuitable for human consumption and irrigation.

Suitability of Water Quality for Irrigation Purposes Using GIS‐Based Irrigation Water Quality Index

ABSTRACTIn this study, surface water quality was assessed on the basis of irrigation water quality indices and the irrigation water quality index (IWQI) via GIS. The study was carried out on the basis of analyses of samples collected in August (dry) and November (wet) 2023 from 12 designated points along the Yıldız River in Sivas. The sodium adsorption ratio (SAR), Kelly index (KI), sodium percentage (Na%), permeability index (PI), residual sodium carbonate (RSC), magnesium hazard (MH) indices and IWQI were calculated to determine the classification of irrigation water quality. Additionally, analyses of Ca2+, Cl−, Fe2+, K+, HCO3−, Mg2+, Mn, Na+, pH and SO42− were conducted on the samples. The spatial distributions of the calculated parameters were mapped via GIS, and irrigation water quality assessment was performed according to the US Salinity Diagram and irrigation water quality standards. The IWQI values ranged from 401 to 61 during the rainy season and from 42 to 67 during the dry season. In the rainy season, two surface water samples were classified as ‘poor (MR: moderate restriction, IWQI: 55–70)’ and nine as ‘very poor (HR: high restriction, IWQI: 40–55)’. In the dry season, three surface water samples were classified as ‘poor (MR: moderate restriction)’ and nine as ‘very poor (HR: high restriction)’. According to the US Salinity Diagram, the majority of surface water samples in both the rainy and dry seasons fell into categories C3S1 (high‐salinity hazard–low‐sodium hazard) and C2S1 (medium‐salinity hazard–low‐sodium hazard), respectively. The results highlight the effectiveness of these methodologies in evaluating surface water quality, assisting in the development of informed management strategies for sustainable water resource use in agricultural environments. The IWQI has proven to be a good tool for assessing the quality of irrigation water in the study area and managing water quality and can help decision makers manage water resources more effectively for sustainable agriculture.

Addressing drivers and data gaps in Spain's non-compliance of drinking water quality standards.

In 2021 Spain passed a new law regarding the quality of drinking water, increasing the transparency and introducing a risk assessment approach to the catchment area, which ascribe to the shift in recent years in how drinking water management is understood in the European Union legislation. Good data quality is important to ensure the correct implementation of policies. We used the drinking quality data uploaded to Spain's National Drinking Water Information System to gauge the state of the drinking water reporting in Spain, the differences between rural urban and rural areas in both quality and reporting and identify which variables at catchment level influence the probability of a municipality incurring in drinking water quality non-compliance. Random forest modeling was used to assess the drivers of non-compliance, including environmental (e.g., land cover, lithology, climate, state of the water supply source) and demographic (e.g., tap water expenditure, population density) data. We found that rural municipalities are more vulnerable both because of a lack of reporting but also because they have higher non-compliance rates for arsenic, microbiological and contaminants and nitrogen compounds (e.g. nitrate). We also found different spatial patterns of non-compliance according to each group of contaminants (e.g., microbiological violations are widespread in the northern half of Spain). The random forest model suggests that agriculture and confined livestock farming are behind nitrogen and microbiological non-compliances. Climate drivers have also emerged for all the groups of contaminants, which underscores the importance of studying drinking water quality non-compliance on a case-by-case basis in order to properly adapt to local realities and enhance compliance across Spain.

Drivers analysis and future scenario-based predictions of nutrient loads in key lakes and reservoirs of the Yangtze River Catchment.

The excessive nutrient loading in lakes and reservoirs poses significant threats to water quality and ecological health, especially under the influence of global climate change and intensified human activities. This study focuses on the long-term trends in nutrient content and ratios, as well as their driving factors in six major lakes and reservoirs (Chaohu Lake, Danjiangkou Reservoir, Dianchi Lake, Dongtinghu Lake, Poyanghu Lake, and Taihu Lake) within the Yangtze River Catchment from 2002 to 2021. Utilizing Redundancy Analysis, Random Forest and Generalized Additive Model, we identify the shifts in natural and socio-economic factors influencing nutrient concentrations and predict future trends under various scenarios. The main driving factors of nutrient content and their ratios have undergone significant changes at different historical stages, with livestock poultry breeding (LPB) and hydraulic retention time (Res_time) being consistently influential. Our findings highlight the dominant role of livestock and poultry breeding and hydraulic retention time in shaping TN content, whereas TP levels are significantly affected by both natural factors (Temperature and Rainfall) and socio-economic activities. Scenario analyses reveal that despite improvements in water management, nutrient loads remain high, posing ongoing risks of eutrophication. Future lakes nutrient content can meet existing water quality standards under socio-economic development scenarios that significantly reduce hydraulic retention time and the contributions of livestock poultry breeding and other socio-economic drivers.

Dynamic coupling of qualitative–quantitative models for operation of water resources based on environmental criteria

Concerning issues include the distribution of scarce water resources, the quality of utilized water, environmental repercussions, and regulations for the sustainable use of water resources. In the management of water resources, optimal qualitative–quantitative exploitation of surface water bodies is regarded as a desirable strategy. The Dez River surface water system from the Dez regulatory dam to Band-e-Ghir is selected in the current paper to create a qualitative–quantitative model that can determine the best exploitation strategies. A dynamic linkage between qualitative and quantitative models is built in order to simulate the current exploitation conditions under the umbrella of the best-case scenario. In this coupled system, hydraulic relationships are established between all of the system’s components. The available data are shared between two models in this structure to simulate the qualitative and quantitative effects of surface water. Then, a new structure is produced to derive the best policies for exploiting the dam and the river by connecting the multi-objective particle swarm optimization algorithm with the qualitative–quantitative coupled model body. The monthly river environmental demand is one of the decision variables in the ideal scenario, and the goals include boosting the percentage of supply demands and minimizing the violation of quality standards. The best-case scenario’s implementation increases the likelihood that all plain demands will be met, regardless of priority. Furthermore, in comparison with the reference scenario, the results of the optimal scenario show that not only are the concentrations of contaminants and qualitative parameters increased, but there are also only minimal violations of the quality and pollution standards of the river water in the majority of river points, particularly in the locations of agricultural withdrawals. The findings demonstrate that using the qualitative–quantitative dynamic relationship between water resources and the development of the coupled model using the NSGA-II algorithm allows us to better plan for the appropriate use of existing water resources by taking into account all stakeholders in such a way that, in addition to meeting needs, maintains the river quality close to standard limits throughout the exploitation period. By using this strategy, users will be informed of the negative effects of their actions, as well as the encroachment on river boundaries and associated consequences.

Enhancing water productivity of solar still using thermal energy storage material and flat plate solar collector

In this research, the impact of integrating solar still with thermal energy storage material and flat plate solar collector (FPSC) on the freshwater productivity was experimentally investigated. The experiments were conducted on three types of similar-sized solar stills under climate conditions of Saudi Arabia. The first type was a conventional solar still (CSS), without any modifications. The second type was a modified solar still (MSS-1), CSS integrated with natural stones in the still basin. The third type was a modified solar still (MSS-2), CSS integrated with both natural stones and FPSC. Three types of natural stones with same quantity were selected and individually tested in the MSS-1 and MSS-2 simultaneously (each stone type on one day). The corresponding experimental results of MSS-1 showed a 11–32% increase in the daily freshwater yield, compared to CSS, indicating a minimal effect of natural stones utilization on the freshwater productivity. The MSS-2 showed a 155–183% increase in the daily freshwater yield, compared to CSS, indicating a significant effect of basin water heating on the freshwater productivity. The total dissolved solids (TDS) level was measured at 112 ppm, which complies with the permissible limits for drinking water quality standards. The economic analysis revealed that the cost to produce one liter of freshwater is 0.028, 0.022, and 0.027 $ from CSS, MSS-1, and MSS-2, respectively. Additionally, the benefit–cost ratio (BCR) analysis demonstrated the economic feasibility of the constructed solar still, with a BCR value of 2.1.