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Affected by point and non-point source pollution, the Fenhe River Basin faces significant environmental challenges. This study aimed to analyze the distribution characteristics and influencing factors of antibiotics in the water and sediments of the Fenhe River Basin. Samples were collected from 23 sites within the basin, and 26 antibiotics from five different classes were detected and analyzed using high-performance liquid chromatography–tandem mass spectrometry (HPLC-MS/MS). The water–sediment partition coefficient (Kp) was calculated, and spatial analysis was conducted using geographic information system (GIS) technology. The results showed that 25 antibiotics were detected in the water, with concentrations ranging from 130 to 1615 ng/L, and 17 antibiotics were detected in the sediments, with concentrations ranging from 121 to 426 μg/kg. For quinolones (QNs), except for ofloxacin, all others could be calculated with overall high values of Kp ranging from 692 to 16,106 L/kg. The Kp values for QNs were generally higher in the midstream, with considerable point source pollution from industries and non-point source pollution from developed agriculture. The distribution of Kp is closely associated with risk. This study found that the Kp values of the antibiotics were influenced by various factors such as temperature, water flow, and the physicochemical properties of sediments. Correlation analysis revealed significant relationships between Kp and parameters such as river width, water depth, water quality (total nitrogen, total phosphorus, and chemical oxygen demand), and sediment pH and clay content. [ABSTRACT FROM AUTHOR]

We explore point source (PS) and non-point source (NPS) pollution impacts on surface water quality in Vinh Long Province, Vietnam. We used data from 60 surface water quality monitoring stations across dry, transitional, and wet seasons from 2017 to 2021, in addition to sampling data collected from 12 wastewater outlets from June to October 2021 to determine the sources of pollution loads. Surface water quality was assessed using both the water quality index (WQI) and the Vietnamese standards QCVN 08:2015, whilst cluster analysis (CA) and principal components analysis (PCA) were used to evaluate spatial variation and key influencing factors. We observed seasonal variation in surface water quality, with a decline in quality during the rainy season. Moreover, the water quality parameters such as chemical oxygen demand (COD), biochemical oxygen demand (BOD5), total nitrogen (TN), and total phosphorus (TP) frequently exceeded the QCVN 08:2015 standard. Across, the different monitoring fixed points and seasons, COD levels were found to range from 8.94 to 15.14 mg/L, while TN levels varied between 0.24 and 0.53 mg/L. The cluster analysis categorized the monitoring fixed points into three groups, based on their water quality parameters, while PCA identified four principal components that explain 69% of the variance, distinguishing between pollution sources and seasonal factors. Our findings emphasize that poor water quality in many areas is affected by non-point source pollution, underscoring the need for watershed and land management. The results and applied methodologies provide insights for watershed management, policy development, and adaptation, applicable to regions facing similar environmental challenges. Article Highlights: Pinpointing and quantifying sector-specific sources of pollution is essential to effective water resource management. Methods exist by which to use water quality data to begin to identify primary sources of pollution in complex watersheds. Water quality declined during the rainy seasons of 2017 to 2021, emphasizing non-point sources (NPS) as as leading causes of the decline. [ABSTRACT FROM AUTHOR]

The main objective of this research was to evaluate the presence of heavy metal pollution in the agricultural soil of the Kubaisa district in Anbar province, Iraq. The study focused on areas affected by dust emissions from a nearby cement factory, specifically Maktom District (k1), Kubais (k2), Elkader District (k3), and Agricultural Elkader District (k4). Soil samples were collected from these locations, and a comprehensive analysis of both chemical and physical characteristics was conducted. The concentrations of heavy metals were found to range from (0 - 17.3), (39.1 - 82.6), (33.3 - 182.8), and (0 - 236.5) mg kg-1 for Cd, Ni, Co, and Pb, respectively. These concentrations indicated elevated levels compared to the (Kapata, 2011) standard levels of 0.62, 34, 12, and 34 mg kg-1 for cadmium, Ni, Co, and Pb, respectively. In terms of the Geological Accumulation Index (Igeo), the agricultural districts showed uncontaminated cadmium with accumulation values of 0. Nickel (Ni) levels varied between -0.58 and 0.53, classifying the sediment from uncontaminated to moderately contaminated. Cobalt (Co) exhibited significant contamination, with values ranging from -0.58 to 3.56. Conversely, lead (Pb) concentrations varied from uncontaminated to extremely contaminated, with values spanning from -0.58 to 5.922. The study underscored that the elevated levels of heavy metals were attributed to airborne dust emissions from the Kubais cement factory and various human activities, such as motor vehicle transportation, industrial waste discharge, and household practices. Following established quality guidelines, the pollution levels in the study area were ranked in the order of Pb > Co > Ni > Cd, with lead (Pb) exhibiting the highest degree of contamination.

The main objective of this research was to evaluate the presence of heavy metal pollution in the agricultural soil of the Kubaisa district in Anbar province, Iraq. The study focused on the areas affected by dust emissions from a nearby cement factory, specifically Maktom District (k1), Kubais (k2), Elkader District (k3), and Agricultural Elkader District (k4). Soil samples were collected from these locations, and a comprehensive analysis of both chemical as well as physical characteristics was conducted. The concentrations of heavy metals were found to range from (0-17.3), (39.1-82.6), (33.3-182.8), and (0-236.5) mg·kg-1 for Cd, Ni, Co, and Pb, respectively. These concentrations indicated elevated levels compared to the (Kapata, 2011) standard levels of 0.62, 34, 12, and 34 mg·kg-1 for cadmium, Ni, Co, and Pb, respectively. In terms of the Geological Accumulation Index (Igeo), the agricultural districts showed uncontaminated cadmium with accumulation values of 0. Nickel (Ni) levels varied between -0.58 and 0.53, classifying the sediment from uncontaminated to moderately contaminated. Cobalt (Co) exhibited significant contamination, with values ranging from -0.58 to 3.56. Conversely, lead (Pb) concentrations varied from uncontaminated to extremely contaminated, with values spanning from -0.58 to 5.922. The study underscored that the elevated levels of heavy metals were attributed to the airborne dust emissions from the Kubais cement factory and various human activities, such as motor vehicle transportation, industrial waste discharge, and household practices. Following established quality guidelines, the pollution levels in the study area were ranked in the order of Pb > Co > Ni > Cd, with lead (Pb) exhibiting the highest degree of contamination. [ABSTRACT FROM AUTHOR]

Estimating the pollution loads in the Tuhai River is essential for developing a water quality standard scheme. This study utilized the improved output coefficient method to estimate the total pollution loads in the river basin while analyzing the influencing factors based on the STIRPAT (Stochastic Impacts by Regression on Population, Affluence, and Technology) model. Findings indicated that the projected point source pollution loads for total phosphorus (TP), chemical oxygen demand (COD), and ammonia nitrogen (AN) would amount to 3937.22 ton, 335,523.25 ton, and 13,946.92 ton in 2021, respectively. Among these, COD pollution would pose the greatest concern. The primary contributors to the pollution loads were rural scattered life, large-scale livestock and poultry breeding, and surface runoff. Per capita GDP emerged as the most influential factor affecting the pollution loads, followed by cultivated land area, while the urbanization rate demonstrated the least impact. [ABSTRACT FROM AUTHOR]

Sensitizers are used to prepare photosensitive materials for ink-printing and thermal-recording media. Typical sensitizers contain an aromatic ring and exhibit aryl hydrocarbon receptor-mediated activity. They can accumulate in aquatic biota, leading to the disruption of ecosystems. Effluent from paper recycling plants has been identified as a source of contamination, and the presence of sensitizers in toilet paper may represent a new source of contamination in aquatic environments. To examine possible sources of contamination by sensitizers, this study investigated the levels of sensitizers in recycled toilet paper. We also studied the prevalence of sensitizers in rivers receiving effluents from sewage treatment plants in Japan, from 2020 to 2022. We detected eight sensitizers and related compounds in both toilet paper and river water samples; their total concentrations ranged from 0.78 to 34 µg/g (mean: 12 µg/g) in toilet paper and 58–1167 µg/L (median: 77 µg/L) in water. In the water samples, sensitizers were partitioned between liquid and suspended solid phases, and in suspended solids, sensitizers accounted for an average of 42% of the total. Correlation analysis showed a high correlation between sensitizer composition in the water from a river receiving sewage treatment plant effluents and toilet paper. Since these compounds were also detected in the river water analyzed in this study, toilet paper should be considered a novel source of sensitizers contamination in sewage treatment systems. [ABSTRACT FROM AUTHOR]

Improper pesticide handling is the main cause of contamination of the environment in agricultural systems. This could be caused by leakage of spraying liquid, leftovers, and inappropriate washing of spraying equipment. This study assessed the ability of suggested biomixture modules for remediate repetitive cycles of high chlorpyrifos doses. In three consecutive treatments, four tested modules were contaminated with 160 µg g−1 chlorpyrifos. Chlorpyrifos residues, dehydrogenase activity, and microbial respiration were continuously monitored for 22 weeks. Six bacterial consortia were isolated at the end of the experiment from four treated modules (B+3, BF+3, S+3, and SF+3) and two from untreated modules (B and S). The isolated consortium efficiency in degrading chlorpyrifos was studied. The results revealed that the best chlorpyrifos removal efficiency was achieved when using the stimulated biomixture module (BF) recorded 98%, 100%, and 89%, at the end of three chlorpyrifos treatments, respectively. Such removal efficiency was compatible with the biological activity results of the tested modules: dehydrogenase activity and microbial respiration. There was no difference in the efficiency among the S, B, and BF+3 consortia. The results presented here demonstrate that the combination of vermicompost, wheat straw, soil, and NPK (stimulated biomixture module) can successfully reduce the risk of a point source of pesticide pollution. [ABSTRACT FROM AUTHOR]

Although phytoplankton is well known as robust bioindicators to aquatic environments, their indicating functions based on different community parameters remain to be understood. In order to filter effective bioindicators in aquatic ecosystems, four phytoplankton community parameters including species richness (SR), total biomass (SBP), functional groups (FGBP), and size-fractionated chlorophyll-a (SC) were demonstrated in a subtropical artificial lake with ecological restoration in South China. Our results indicated that all the above four parameters exhibited high sensitivity to environmental variations and illustrated distinct aspects of indicating functions to aquatic environments due to their individual biological characteristics. Based on FGBP, both spatial and temporal differences in phytoplankton community could be identified. SR and SBP only classified the spatial and temporal distributions, respectively, while SC could distinguish the sewage outfalls from other sites. In terms of ecological management, two parameters (SR and FGBP) could distinguish the restored waters from untreated environments as non-point source pollution, and another parameter SC could indicate the sewage outfalls as point source pollution. Therefore, the combination of the above two categories of phytoplankton community parameters could make the strongest indicating functions. Our study provided greater insight into indicating functions of phytoplankton community parameters in an ecological restored lake and enabled better managements in such artificial lakes. [ABSTRACT FROM AUTHOR]

Affected by point and non-point source pollution, the Fenhe River Basin faces significant environmental challenges. This study aimed to analyze the distribution characteristics and influencing factors of antibiotics in the water and sediments of the Fenhe River Basin. Samples were collected from 23 sites within the basin, and 26 antibiotics from five different classes were detected and analyzed using high-performance liquid chromatography–tandem mass spectrometry (HPLC-MS/MS). The water–sediment partition coefficient (Kp) was calculated, and spatial analysis was conducted using geographic information system (GIS) technology. The results showed that 25 antibiotics were detected in the water, with concentrations ranging from 130 to 1615 ng/L, and 17 antibiotics were detected in the sediments, with concentrations ranging from 121 to 426 μg/kg. For quinolones (QNs), except for ofloxacin, all others could be calculated with overall high values of Kp ranging from 692 to 16,106 L/kg. The Kp values for QNs were generally higher in the midstream, with considerable point source pollution from industries and non-point source pollution from developed agriculture. The distribution of Kp is closely associated with risk. This study found that the Kp values of the antibiotics were influenced by various factors such as temperature, water flow, and the physicochemical properties of sediments. Correlation analysis revealed significant relationships between Kp and parameters such as river width, water depth, water quality (total nitrogen, total phosphorus, and chemical oxygen demand), and sediment pH and clay content.

A portable toilet manufacturer in northwest Indiana (USA) released polyethylene microplastic (MP) pollution into a protected wetland for at least three years. To assess the loads, movement, and fate of the MPs in the wetland from this point source, water and sediment samples were collected in the fall and spring of 2021–2023. Additional samples, including sediment cores and atmospheric particulates, were collected during the summer of 2023 from select areas of the wetland. The MPs were isolated from the field samples using density separation, filtration, and chemical oxidation. Infrared and Raman spectroscopy analyses identified the MPs as polyethylene, which were quantified visually using a stereomicroscope. The numbers of MPs in 100 mL of the marsh water closest to the source ranged from several hundred to over 400,000, while the open water samples contained few microplastics. Marsh surface sediments were highly contaminated with MPs, up to 18,800 per 30.0 g dry mass (dm), compared to core samples in the lower depths (>15 cm) that contained only smaller MPs (<200 µm), numbering 0–480 per 30.0 g (dm). The wide variations in loads of MP contaminants indicate the influence of numerous factors, such as proximity to the point source pollution, weather conditions, natural matter, and pollution sinks, namely sediment deposition. As proof of concept, we demonstrated a novel remediation method using these real-world samples to effectively agglomerate and remove MPs from contaminated waters. [ABSTRACT FROM AUTHOR]

Monitoring and quantification of nutrient movement in soils could help farmers and policy makers to formulate effective nutrient loss reduction strategies and waste management. The study was conducted to monitor and quantify vertical and lateral movements of nitrate-nitrogen (NO3-N), phosphate (PO4) and sulphate-sulphur (SO4-S) in soils around manure dumpsites in Abeokuta, southwest Nigeria. The dumpsites investigated include a flush-type poultry litter, poultry litter mixed with beddings of wood shavings and cattle and pig waste open dumpsites. Soils were sampled at depths of 0–20, 20–40, 40–60 and 60–80 cm and at distances 2, 4, 6, 8, 10, 20, 40, 60 and 80 m away from the dumpsites. Soil samples were analysed for some physical and chemical properties and NO3-N, PO4 and SO4-S contents. Results indicated that there were more nutrients in the soil around the poultry manure slurry dumpsite compared with others while the soil pH increased with increase in soil depth, across dump sites. There was evidence of leaching of salts, and this correlated positively with the soil organic matter content (r = 0.41, p < 0.01). The soils were polluted with NO3-N, PO4 and SO4-S as deep as 80-cm depth; these nutrient amounts were higher than the maximum allowable (40, 15 and 7 mg kg−1, respectively) for southwest Nigerian soils. Due to high soil organic matter and for agronomic considerations, the soils are only suitable for cultivation at depths below 40 cm and 8 m away from the dump sites. There was significant pollution of the soils with nitrate, phosphate and sulphate, within 80 m distance from the dump site. This has serious implications for ground water recharges and shallow well sunk around these areas. There is potential risk of NO3-N, PO4 and SO4-S consumption through such water sources. [ABSTRACT FROM AUTHOR]

A portable toilet manufacturer in northwest Indiana (USA) released polyethylene microplastic (MP) pollution into a protected wetland for at least three years. To assess the loads, movement, and fate of the MPs in the wetland from this point source, water and sediment samples were collected in the fall and spring of 2021–2023. Additional samples, including sediment cores and atmospheric particulates, were collected during the summer of 2023 from select areas of the wetland. The MPs were isolated from the field samples using density separation, filtration, and chemical oxidation. Infrared and Raman spectroscopy analyses identified the MPs as polyethylene, which were quantified visually using a stereomicroscope. The numbers of MPs in 100 mL of the marsh water closest to the source ranged from several hundred to over 400,000, while the open water samples contained few microplastics. Marsh surface sediments were highly contaminated with MPs, up to 18,800 per 30.0 g dry mass (dm), compared to core samples in the lower depths (>15 cm) that contained only smaller MPs (

Excess loading of nitrogen and phosphorus to river networks causes environmental harm, but reducing loads from large river basins is difficult and expensive. We developed a new tool, the River Basin Export Reduction Optimization Support Tool (RBEROST) to identify the least‐cost combinations of management practices that will reduce nutrient loading to target levels in downstream and mid‐network waterbodies. We demonstrate the utility of the tool in a case study in the Upper Connecticut River Basin in New England, USA. The total project cost of optimized lowest‐cost plans ranged from $18.0 million to $41.0 million per year over 15 years depending on user specifications. Plans include both point source and non‐point source management practices, and most costs are associated with urban stormwater practices. Adding a 2% margin of safety to loading targets improved the estimated probability of success from 37.5% to 99%. The large spatial scale of RBEROST, and the consideration of both point and non‐point source contributions of nutrients, make it well suited as an initial screening tool in watershed planning. [ABSTRACT FROM AUTHOR]

Soil pollution in the European Union (EU) is poorly quantified, because of several years of reduced attention and limited funding on soil research and monitoring. Moreover, issues such as different monitoring methodologies within Member States (MS), and quantification methods focused on pseudototal rather than the available fraction of pollutants, has been limiting our understanding of risk under soil pollution. Despite that, thanks to efforts from the scientific community, it was possible to achieve some progress, which is by far insufficient for the problem at hand. In the anticipation of future policy demands and towards a common strategy for tackling soil pollution in the EU, it seemed relevant to describe the limited knowledge and main uncertainties. Such analysis should provide evidence for the development of efficient policies, as well as updating current ones to better tackle the interdisciplinary of soil. This perspective provides our view on current knowledge on soil pollution at EU scale, by compiling the most updated assessments made at EU scale, identifying soil pollution drivers, impacts on health and the environment, and evaluating current state of knowledge. Allowing us to infer about current level of uncertainties and knowledge gaps and identify solutions through future research and policies. Our suggestions are in line with an increasing investment on research and innovation, but also more frequent updates of current legislation already tackling pollution and welcoming the new proposal for a Soil Monitoring Law as an important driver for soil knowledge development and implementation of a European monitoring system. [Display omitted] • Various EU legislation considers pollution, but none is dedicated to soil entirely. • Knowledge gaps on soil pollution are significant in the EU and require a long-term plan. • Further investment in soil pollution is necessary, to ensure informed policy decisions. • Updates on current legislation and dedicated laws on soil are welcome. [ABSTRACT FROM AUTHOR]

Water resources serve as the foundation for high-quality urban development. As water pollution has become a major impediment to high-quality urban development, solving the problem of urban water pollution is critical for attaining high-quality urban growth. This research analyzes both point and non-point sources of pollution and constructs an urban water pollution simulation system model from four subsystems: population, industry, cultivated land, and livestock and poultry. This study selects 2020 as the base year and the current year’s development situation as the base scenario and then sets the other five simulation scenarios according to the research area development plan. Using Yichang data in this model, the research simulated and predicted the total amount of urban COD pollution under different scenarios. The results show that: 1) The difference between the simulation results of the constructed urban water pollution system and the 2010–2020 historical data is within 10%, which shows that the constructed system can analyze the reality. 2) Under the benchmark scenario, from 2020–2030, the total amount of urban COD shows a downward trend. The pollution from population and livestock subsystems are reduced by 20.20 and 35.29%, respectively, the industrial subsystem is increased by 40.60%, and the cultivated land subsystem is increased by 0.56%. 3) Compared with the benchmark scenario, the urban COD pollution in five scenarios has been reduced by 8,400, 42,000, 21,700, 100, and 72,300 tons, respectively, among which water pollution control measures in scenario five have the best effect. 4) Only by comprehensively controlling all pollution sources (scenario 5) can the total amount of urban COD pollution be controlled within 450,000 tons in 2030, which will be reduced by over 20% compared with 2020. An urban water pollution system can be used to simulate the source composition and total change amount of water pollution in the process of urban development, which is of great significance for government departments to provide accurate counter-measures for urban water pollution control and management decisions.

Watershed area and a bunch of relief, land use, and wastewater characteristics for 32 upland and 33 lowland small river courses are generated. Based on these characteristics, logistic binary regression models are trained to predict if the river achieves the good physico-chemical status, and discriminant analysis models are trained to predict the physico-chemical status class on a five-class scale.

In this study, Alaşehir River Sub-basin was selected as a pilot area considering its population, developing industry and agricultural activities, and it was aimed to examine the effect of pollution from point and diffuse sources on surface water quality. Urban and industrial wastewaters coming to the receiving environment were considered as point source pollutants while fertilizer use, livestock activities, land use, solid waste leachate, septic tank use and atmospheric convection were considered as diffuse source pollutants. A rough and easily applicable methodology was presented for calculating nitrogen (total nitrogen, TN) and phosphorus (total phosphorus, TP) loads from these sources. For determining the impact of these pollution sources on surface water quality, main streams of the basin were monitored for four periods in 2015-2016. The obtained results were evaluated over the conventional parameters in Table 2 of Annex 5 of the Surface Water Quality Regulation (10.08.2016, RG: 29797). In the light of the results, a significant part of the total TN and TP load (79% of TN, 61% of TP) occurred in the basin came from activities with diffuse sources. The major sources of diffuse pollution were fertilizer use (37% of TN, 48% of TP) and livestock activities (34% of TN, 41% of TP). Point source pollution was mostly caused by urban wastewater discharges (93% of TN, 95% of TP and 83% of COD). The surface water quality was generally defined as highly polluted (Class IV) and polluted (Class III). In the presence of organic parameters, point source pollutants were found as responsible for pollution. The water quality of the streams passing through the areas with point and diffuse pollutant sources deteriorated significantly. [ABSTRACT FROM AUTHOR]

Riparian areas are recognized for their buffering capacity regarding phosphorus and nitrogen from agricultural and urban runoff. However, their role in attenuating nutrient loads of rivers receiving point source nutrient inputs (e.g., from wastewater treatment plants, WWTPs) is still little understood. Here, we investigated whether ammonium (NH4-N), nitrate (NO3-N), and soluble reactive phosphorus (SRP) retention were influenced by the riparian land use in three Brazilian rivers receiving WWTP effluents. We hypothesized that nutrient attenuation would be potentially influenced by the hydrological connectivity between the main channel and riparian areas with native vegetation. We estimated retention from longitudinal patterns of dilution-corrected nutrient concentrations below the WWTPs. We assessed nutrient retention during periods with high (i.e., the wet) and low connectivity (i.e., the dry season). Relationships between non-conservative (nutrients) and conservative (chloride) solutes in both seasons were used to identify potential changes in the river chemistry due to the hydrological connectivity with the riparian areas. We also evaluated the relationship between net uptake velocities (Vf-net) and the accumulated percent native vegetation cover in the 100-m buffer using linear regressions, comparing the response for each nutrient between seasons with Analysis of Covariance. Slopes of regressions between nutrients and chloride significantly differed between seasons for NO3-N and SRP but not for NH4-N. The relationships between Vf-net and accumulated native vegetation in the riparian buffer presented steeper slopes for SRP in the wet than in the dry season. No significant relationships between NO3-N Vf-net and native vegetation cover were observed in either season. In contrast, increases in Vf-net with increasing vegetation cover were observed for NH4-N in the dry season. In periods with expected higher connectivity, NO3-N and SRP concentrations tended to be lower relative to chloride concentrations, with a potential effect of native vegetation in the riparian area on SRP retention. Our results suggest that seasonal connectivity between nutrient-rich river water and riparian areas is likely to induce changes in the predominant nutrient transformation processes, thereby favoring either nutrient retention or export in such rivers.

The control of point source discharges to rivers has become more significant since the establishment of environmental quality standards (EQSs). Many countries, including Turkey, have set EQS values for various contaminants. One important challenge regarding these EQSs is to reconcile the effluent limits that are technically and economically achievable with the ones that are required to accomplish the EQSs. The Tersakan sub-basin of Yeşilırmak River acquires good examples of this challenge due to the industrial and agricultural discharge activities present. In this study, a new, simplistic, and less data-driven approach is developed to facilitate this compromise and implemented for all suitable discharge points within the sub-basin. The foundation of this approach is that effluent discharges may mix and become diluted within negligibly short distances from the point of discharge where exceedance of EQSs can be permissible. The approach modularly combines different analytical solutions of the advective-dispersive mass transport equation that are applicable under different mixing conditions and estimates maximum allowable discharge concentrations of contaminants. The results of the case study in the Tersakan sub-basinindicate that none of the studied discharges need load reduction to achieve EQSs. However, in various points, tridecane, nickel, bis(2-ethylhexyl) terephthalate, NH4-N, total phosphorus, and free cyanide have consumed more than 10% of their discharge quotas estimated by the mentioned approach. Therefore, for the sub-basin, these six contaminants and their corresponding two discharge points may require more attention in the future. [ABSTRACT FROM AUTHOR]

Modelling and evaluating the resilience of environmental systems has recently raised significant interest among both practitioners and researchers. However, it has not yet been used to measure the absorption and recovery capacities of a river subject to varying levels of pollution due to natural and anthropic sources of contamination within the basin. Fast worldwide population growth and climate change are contributing to an increased degradation status in surface water bodies and to a decreased efficiency of their natural self-purification processes. Decision-makers are, therefore, more and more encouraged to implement alternative management strategies focussed on improving the system resilience to current and future perturbations. To this end, a novel Water Resilience Index (WRI), based on different quality parameters, was developed, and it is here proposed to estimate the ability of the river Bacchiglione, located in Northeast Italy, absorb continuous and unpredictable changes due to potential effects of point sources of pollution, that is, urban and industrial wastewater, and still maintain its vital functions. This new index is integrated in a mathematical model, which represents the river as an influence diagram where the nodes are the gauged stations and the arcs are the fluvial reaches among the stations, to identify the river reaches in need of resilience improvement. In addition, in order to simplify the analytical procedure and lower the costs and times of the monitoring activities, a principal component analysis is also used, as it is able to reduce the number of the water quality parameters to be collected from the sampling stations, distributed along the main river, and thus to calculate a minimum WRI. The good agreement between the results obtained by both the original and minimum WRI shows the effectiveness of the proposed methodology. This approach could be applied to all basins with the same issues, and not just in the Italian case study here analysed, as it might be a valid tool to plan interventions and mitigation actions, protecting the resource from pollution risks and achieving environmental quality and Sustainable Development Goals both in the water bodies and their surrounding territories. In addition, this strategy could be integrated in the existing models supporting local decision-makers and administrators, aiming at increasing the resilience of urban and rural areas to pollution phenomena and facilitating the development of effective policies to reduce the impacts of global change on water quality. [ABSTRACT FROM AUTHOR]

Well-defined targets for nitrogen (N) release into the local environment are essential for water management in creeks, but difficulties often arise from working with data that are too sparse to achieve reliable evaluations. Here, a simulation–optimization approach based on the QUAL2K model was developed to put forward strategies for nitrogen pollution control in a creek with sparse data in Shixi Creek, southeast China. The model showed good agreement with field observations from 22 sampling sites sampled over the period from March 2017 to February 2019, with normalized objective function (NOF) less than 0.360. Based on this model, the water pollutant sources in the creek were distinguished and analyzed. Rural sewage discharge in Shixi Creek was the major factor threatening water quality in the stream. Seasonal variations may influence the transformation of riverine N. To make more than 80% of the area in Shixi Creek meet the water quality standard of grade III, an optimized approach is to reduce more than 55% of the N pollution from point source pollution and 10% from nonpoint source pollution. This study proposed an approach that can effectively evaluate strategies for water management in a creek watershed with sparse data. [ABSTRACT FROM AUTHOR]

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[Display omitted] • A point pollution source identification method based on remote sensing inversion and water streamlines is proposed. • The method is designed to attempt to provide a deterministic solution for the uncertain inverse problem. • The method has high identification accuracy for both the location and released mass of pollution sources. The accurate identification of the location and released mass of pollution sources using remote sensing technology is essential for emergency responses and environmental conservation. However, pollution source identification is still difficult to perform effectively when based on remote sensing technology because of the uncertainty of the inverse problem. Based on a physical mechanism, a point pollution source identification method combined with remote sensing inversion and water streamlines is proposed. This approach is designed to attempt to provide a deterministic solution for the uncertain inverse problem through clustering estimations along streamlines. The method is carried out based on the reverse flow field, which is simulated by a two-dimensional hydrodynamic model. The spatial distribution of the water quality parameters obtained from remote sensing inversion is transformed into estimates of released pollutant mass. Hypothetical cases and real-world cases are conducted to validate the proposed method. In hypothetical cases, the relative errors of the identified released mass for continuous release cases are less than 5%, and the relative error for the instantaneous release case is 1.54%. In the real-world case, the relative errors of identified pollution source locations are less than 3.5%. The relative errors of the identified released mass of the two pollution sources are 5.50% and 4.42%, respectively. The results show that this method can provide high-accuracy identification results for the location and released mass of pollution sources without requiring observed water quality data. It will help improve the water environment in areas where data of pollution sources are lacking. [ABSTRACT FROM AUTHOR]

Accurate source identification/apportionment is essential for optimizing water NO 3 - -N pollution control strategies. This study conducted a meta-analysis based on data from 167 rivers across China from 2000 to 2022 to analyze the spatial and temporal variation patterns of nitrate pollution in seven major river systems and to quantitatively identify the source composition of riverine nitrate. The average ρ （NO 3 - -N） in the seven major river systems was （4.54±3.99） mg·L -1 ， with 9.6% of river ρ （NO 3 - -N） exceeding 10 mg·L -1 . The riverine ρ （NO 3 - -N） in eastern China were higher than that in western China， and the highest concentration was observed in the Haihe River system. Additionally， tributaries experienced more serious NO 3 - -N pollution than that in the main stream. The ρ （NO 3 - -N pollution in the dry season was higher than that in the wet season. Therefore， point source pollution such as domestic and production sewage discharge should be controlled in the Haihe River system， the Yangtze River system， the Liaohe River system， the tributaries and the downstream main stream areas of Yellow River system， and the downstream area of the Pearl River system， whereas non-point source pollution caused by the loss of fertilizer and soil nitrogen should be controlled in the Huaihe River system， the Songhua River system， the middle reaches of the main stream area of the Yellow River system， and the middle and upper reaches of the Pearl River system. The results can provide a scientific basis for the effective control of nitrate pollution in the river systems in China.3 - -N source was sewage/manure （ &gt; 50%） in the Yangtze River system， Haihe River system， Liaohe River system， and Southeast River system. Soil nitrogen was the main NO 3 - -N source in the Songhua River system （56.4%）， and the contribution of fertilizer nitrogen， soil nitrogen， and sewage/manure to NO 3 - -N pollution in the Pearl River system， Huai River system， and Yellow River system was 20%-40%. The contribution rate of sewage/manure to NO 3 - -N in the tributaries was higher than that in the main stream， whereas the contribution rate of soil nitrogen to NO 3 - -N in the main stream was higher than that in the tributaries. The contribution rate of soil nitrogen， fertilizer nitrogen， and atmospheric deposition nitrogen to nitrate nitrogen in the wet season was higher than that in the dry season， whereas the contribution rate of sewage/manure to NO 3 - -N pollution in the dry season was higher than that in the wet season. Therefore， point source pollution such as domestic and production sewage discharge should be controlled in the Haihe River system， the Yangtze River system， the Liaohe River system， the tributaries and the downstream main stream areas of Yellow River system， and the downstream area of the Pearl River system， whereas non-point source pollution caused by the loss of fertilizer and soil nitrogen should be controlled in the Huaihe River system， the Songhua River system， the middle reaches of the main stream area of the Yellow River system， and the middle and upper reaches of the Pearl River system. The results can provide a scientific basis for the effective control of nitrate pollution in the river systems in China.

Abstract The high cost of extensive pesticide monitoring studies, required for the protection of water resources, and the necessity of early identification of environmental threats, highlighted the need for prioritization of pesticides and sampling sites to be monitored. The aim of this study was to develop an optimum surface water monitoring network at a catchment scale including only the sites of a catchment vulnerable to pesticide pollution. The identification of sampling sites vulnerable to pesticide pollution (VPS) was based on the data of an intensive monitoring survey of 302 pesticides in 102 stationary sampling sites located on the surface water network of a river basin. In the proposed methodology the left-censored data of the analytical results derived from the above mentioned monitoring campaign were included in the statistical analyses by transforming all the raw data into categorical variables and arranging them in ordinal scales based on ecotoxicological thresholds derived from pesticide toxicity tests on aquatic non-target organisms. The categorized data were subjected to Categorical Principal Component Analysis with Optimal Scaling. For the identification of the VPS, the Squared Mahalanobis Distance criterion was applied on the extracted values (scores) of the significant principal components. With this methodology a 46% reduction in the number of the monitoring stations was achieved. This approach will be valuable in establishing more cost effective monitoring schemes in the future in other basins and in developing targeted measures to eliminate or limit the effect of critical pollution sources in surface aquatic systems. Moreover, by applying the proposed methodology, historical monitoring data can be used to initiate more efficient pesticide monitoring campaigns in the future. Graphical abstract Unlabelled Image Highlights • Optimization of an existing pesticide surface water monitoring network. • The methods used pesticide data, ecotoxicity thresholds, and in situ inspection. • The methodology based on CATPCA and Squared Mahalanobis Distance methods. • Identification of monitoring stations vulnerable to pesticide pollution. • A reduction of 46% of the stationary sampling stations was accomplished. [ABSTRACT FROM AUTHOR]

Here, we studied the shipyard impacts on the distribution of PAHs and PCBs in the semi-enclosed Xiangshan Bay, an important mariculture zone in China. The results showed that the shipyard caused a pollution plume for PAHs but not for PCBs. As characteristic pollutants of oil leakage, the PAHs had concentrations of up to 55.82 ng L−1 in the water, 2235.04 ng g−1 in suspended particulate matter (SPM), and 1489.60 ng g−1 in sediment. The PAHs in water and SPM were dominated by phenanthrene and pyrene that were mostly derived from lubricant and diesel, while those in sediments were dominated by the high-molecular-weight PAHs, such as indeno[1,2,3-c,d]pyrene. In contrast, the PCBs concentrations reached up to 10.17 ng L−1, 79.72 ng g−1, and 124.33 ng g−1 in the seawater, SPM, and sediment samples, respectively, and they did not show spatial patterns affected by the shipyard. Moreover, the health risk assessment indicated that the shipyard discharge caused a substantial PAHs ecological risk to the adjacent and downstream water environment. Therefore, point source discharge in semi-enclosed bays should be paid close attention to due to the strong pollutant transport effect. [Display omitted] • A shipyard emission caused a significant point-source pollution effect in Xiangshan Bay, China. • Around the shipyard a visible oil film was samples containing PAHs. • Phenanthrene and pyrene were the main compounds related to lubricant and diesel. • 4.The PCBs did not have an obvious distribution trend in the bay. • The shipyard emissions caused a substantial PAH ecological risk. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Hydrochemical and habitat characteristics depended on hydrological conditions. • Baseflow, as groundwater inputs, maintained stream discharge and diluted wastewater effluents. • Macroinvertebrate community structure varied due to hydrology and hydrochemical characteristics. • Variation partitioning depicted the influence of hydrology on macroinvertebrates. Abstract Mediterranean rivers are affected by natural disturbances and human pressures, which may alter their hydrology, water quality and habitat structure. In this study an analysis of macroinvertebrates community structure has been used to determine how distinct human pressures, such as point and non-point sources of pollution, together with groundwater withdrawal, may affect these ecosystems. A total of 4 sampling campaigns were conducted in the middle reach of the Onyar River (NE Spain), which was affected by agricultural and urban uses. Stream discharge and physicochemical parameters were measured in situ , and water samples and macroinvertebrates assemblages were taken and properly preserved for subsequent analysis and identification. Variation partitioning showed that macroinvertebrate community structure was particularly dependent on hydrochemical characteristics, but also on hydrological variations. In addition, results indicated that groundwater withdrawal altered stream hydrology, and the main reach of the Onyar River became intermittent and even completely dry in downstream positions. This reduction on stream discharge caused changes in habitat characteristics, as well as in the proportion of wastewater. Some wastewater dilution occurred, linked to groundwater with high nitrate concentrations inputs to the stream, and even though the macroinvertebrate community recovered its quality in some sampling campaigns, it presented a different structure than in sampling points not affected by any of these pressures. Therefore, the approach here used to analyze the hydrological effects on macroinvertebrate communities allowed us to determine their influence on hydrochemical and habitat characteristics. [ABSTRACT FROM AUTHOR]