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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.

[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.

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]

The protection of the Yangtze River is an important national strategy in China, but it faces many problems such as difficult water environment protection, unclear pollution sources, and low integration of measures. Aimed at addressing watershed scale multi-source pollution together with facing the bottleneck method, by combining research data analysis, mechanism model, and intelligent algorithm optimization, this study built the framework for accurate pollution apportionment, measures evaluation, and overall measure optimization. Shun'an watershed in Tongling City of Anhui Province was set as an example for the application. The results showed that the new method could accurately quantify the impacts of planting industry, rural life, livestock and poultry breeding, aquaculture, industrial sewage, and domestic sewage in the watershed and evaluate the overall effects of various measures. The multi-objective optimization algorithm provided a cooperative multi-source pollution control scheme with higher cost performance and better environmental benefit by comparing the cost effectiveness of various schemes systematically. The optimization scheme showed that total nitrogen could be reduced by 1274.24 t·a -1 in wet years, 855.24 t·a -1 in normal years, and 381.96 t·a -1 in dry years. Total phosphorus was reduced by 321.42 t·a -1 in wet years, 159.80 t·a -1 in normal years, and 42.93 t·a -1 in dry years, such that the water quality reached the surface class Ⅲ water quality standard. These research results can be extended to other watersheds and provide a method reference for water environment protection under the background of the high-quality development of watersheds.

Microplastics are emerging contaminants ubiquitously distributed in the environment, with rivers acting as their main mode of transport in surface freshwater systems. However, the relative importance of hydrologic processes and source-related variables for benthic microplastic distribution in river sediments is not well understood. We therefore sampled and characterized microplastics in river sediments across the Meramec River watershed (eastern Missouri, United States) and applied a hydrologic modeling approach to estimate the relative importance of river discharge, river sediment load, land cover, and point source pollution sites to understand how these environmental factors affect microplastic distribution in benthic sediments. We found that the best model for the Meramec River watershed includes both source-related variables (land cover and point sources) but excludes both hydrologic transport-related variables (discharge and sediment load). Prior work has drawn similar and dissimilar conclusions regarding the importance of anthropogenic versus hydrologic variables in microplastic distribution, though we acknowledge that comparisons are limited by methodological differences. Nevertheless, our findings highlight the complexity of microplastic pollution in freshwater systems. While generating a universal predictive model might be challenging to achieve, our study demonstrates the potential of using a modeling approach to determine the controlling factors for benthic microplastic distribution in fluvial systems. [Display omitted] • Riverbed sediment was collected to characterize benthic microplastic distribution. • Microplastic content was related to environmental variables through modeling. • Source-related variables were the best indicators for microplastic pollution. • Hydrologic transport-related variables were not important for the final model. • Our approach can help identify controls on microplastic distributions in watersheds. [ABSTRACT FROM AUTHOR]

Characterizing the spatial patterns of surface water quality is of great significance for water resources management and protection. A great number of studies have addressed the fact that water quality is often subjected to surrounding land use patterns, but the relationship between them remains obscure. In this study, we develop a self-organizing map (SOM)-based approach to explore the relationship between land use and water quality in Deqing County, Zhejiang Province, which locates in the hinterland of the Yangtze River Delta in the Taihu Lake Basin. Water samples were collected from 163 streams, ponds or lakes and then clustered into six groups based on five water quality variables: pH, ammonium-N, total phosphate, dissolved oxygen and permanganate index using the SOM approach. The proportion of eight land use categories, which are forest, cropland, shrubland, grassland, water, wetland, impervious land and bare land were associated with water quality to explain its spatial variation. The altitude decreases from west to east and the eastern part of Deqing County is characterized by floodplain and streams network, which makes watershed delineating real hard work. Therefore polder and multiple buffer scales were considered to carry out the spatial discretization process. For land use parameters, sub-watershed scale was surpassing buffer scale in the elevated area, but only buffer scale can be applied in the whole area. Polders totally failed to reveal the relationship between land use and water quality. Our results demonstrate whether point source (PS) or non-point source (NPS) pollution exerts greater influence on water quality in different clusters. The methods and the results demonstrated in this research can help local government improve water resources and land use management strategies practically. [Display omitted] • A self-organizing map was performed in a floodplain-hill coupled administrative area. • Buffer scale reveals land use-water quality relationship better than others on floodplain. • Spatial pattern of the land use-water quality relationship was analyzed. • The contribution of different sources of pollution to water quality varies among clusters. [ABSTRACT FROM AUTHOR]

The sources of pollution, in general, are divided into nonpoint sources and point sources. Cutoff wall as a low-permeability vertical barrier has been widely employed for control and containment of these two types of pollution sources. Previous cutoff wall models mainly were limited to the nonpoint source pollution with constant concentrations. Hence, this study developed a novel two-dimensional analytical model for rapidly assessing the service performance of cutoff walls under time-dependent point source pollution. The present model considers a transient migration process coupling advection–dispersion-sorption-biodegradation in a multi-layer system, and its general solutions are derived using a combined approach of Laplace transform, finite Fourier cosine transform, variable substitution, and global matrix method. Results reveal that the service life of a cutoff wall increases exponentially with the decrease of release time for finite pulse point sources, and it increases linearly with the increase of decay coefficient for decay point sources. The previous hypothesis about the Gaussian distribution of contaminant concentration at the entrance to a cutoff wall is invalid when the point sources are separated by more than 1 m. Moreover, a comprehensive design method of a cutoff wall system under point sources pollution is proposed. [ABSTRACT FROM AUTHOR]

Surface water pollution seriously restricts the development of the city and results in the citizens yearning for a better life. Mountainous cities have their own characteristics in surface water environment and pollution compared with those of plain cities due to their unique topography. In August and October 2019, surface water and sediments were collected in a typical river (Qingshuixi River) in the main urban area of Chongqing. These samples were analyzed for nutrients such as carbon, nitrogen, and phosphorus as well as other basic physicochemical indicators. The results showed that the surface water of the Qingshuixi River was inferior to Category V at present, and it was also at a serious pollution level according to the comprehensive pollution index evaluation system. Among all the water quality indices, NH 4 and TP showed the most serious pollution. The tributaries of the Qingshuixi River exhibited higher surface water quality than that of the main stream, and the water quality during the rainfall season was better than that during the non-rainy season. Pollution sources, tailwater/tributary inflow, and river self-purification capacity determined the spatial distribution of nutrients in the surface water of the mainstream of the Qingshuixi River. Point sources such as the direct discharge of source sewage and pollution overflow in the middle and lower reaches were the most important sources of surface water pollution in the mainstream of the Qingshuixi River. Non-point source pollution had a limited impact on water quality. The "sink" or "source" role transformation of river sediments would occur under different water volume conditions in the river, reflecting the complexity of endogenous pollution. Surface water quality of the main stream showed a gradual improvement tendency along the downstream due to the dilution of the tail water/tributary inflow and the increased self-purification capability of the surface water in the mountainous rivers due to the increased DO content. To summarize, this study suggests that the water environment of the Qingshuixi River should be improved in comprehensive ways, which might be reducing the input of point source pollution by the deployment of the municipal pipe network in key areas, upgrading the sewage treatment plants to decrease pollutant concentrations or fluxes or channel dredging at the reaches with low DO content, etc.+ and TP showed the most serious pollution. The tributaries of the Qingshuixi River exhibited higher surface water quality than that of the main stream, and the water quality during the rainfall season was better than that during the non-rainy season. Pollution sources, tailwater/tributary inflow, and river self-purification capacity determined the spatial distribution of nutrients in the surface water of the mainstream of the Qingshuixi River. Point sources such as the direct discharge of source sewage and pollution overflow in the middle and lower reaches were the most important sources of surface water pollution in the mainstream of the Qingshuixi River. Non-point source pollution had a limited impact on water quality. The "sink" or "source" role transformation of river sediments would occur under different water volume conditions in the river, reflecting the complexity of endogenous pollution. Surface water quality of the main stream showed a gradual improvement tendency along the downstream due to the dilution of the tail water/tributary inflow and the increased self-purification capability of the surface water in the mountainous rivers due to the increased DO content. To summarize, this study suggests that the water environment of the Qingshuixi River should be improved in comprehensive ways, which might be reducing the input of point source pollution by the deployment of the municipal pipe network in key areas, upgrading the sewage treatment plants to decrease pollutant concentrations or fluxes or channel dredging at the reaches with low DO content, etc.