Search Results (462)

The quality of water in households can be affected by plumbing design and materials, water usage patterns, and source water quality characteristics. These factors influence stagnation duration, disinfection residuals, metal release, and microbial activity. In particular, stagnation can degrade water quality and increase lead release from lead service lines. This study employs numerical modeling to assess how combined corrosion control and flushing strategies affect lead levels in household taps with lead service lines under reduced water use. To estimate potential health risks, the U.S. EPA model is used to predict the percentage of children likely to exceed safe blood lead levels. Lead exceedances are assessed based on various regulatory requirements. Results show that exceedances at the kitchen tap range from 3 to 74% of usage time for the 5 µg/L standard, and from 0 to 49% for the 10 µg/L threshold, across different scenarios. Implementing corrosion control treatment in combination with periodic flushing proves effective in lowering lead levels under the studied low-consumption scenarios. Under these conditions, the combined strategy limits lead exceedances above 5 µg/L to only 3% of usage time, with none above 10 µg/L. This demonstrates its value as a practical short-term strategy for households awaiting full pipe replacement. Targeted flushing before peak water use reduces the median time that water remains stagnant in household pipes from 8 to 3 h at the kitchen tap under low-demand conditions. Finally, the risk model indicates that the combined approach can reduce the predicted percentage of children with blood lead levels exceeding 5 μg/dL from 61 to 6% under low water demand. Full article

Urban vegetation monitoring is essential for sustainable city planning but is often constrained by the high cost and limited frequency of field-based inventories. This study evaluates the use of the Normalized Difference Vegetation Index (NDVI), derived from Sino-Brazilian CBERS-4A satellite imagery, as a spatially explicit and low-cost proxy for urban tree census data. CBERS-4A provides medium-resolution multispectral data freely accessible across South America, yet remains underutilized in urban environmental applications. Focusing on Aracaju, a metropolitan region in northeastern Brazil, we compared NDVI-based classification results with official municipal tree census data from 2022. The analysis revealed a strong spatial correlation, supporting the use of NDVI as a reliable indicator of canopy presence at the urban block scale. In addition to mapping vegetation distribution, the NDVI results identified areas with insufficient canopy coverage, directly informing urban greening priorities. By validating remote sensing data against field inventories, this study demonstrates how CBERS-4A imagery and vegetation indices can support municipal tree management and serve as scalable tools for environmental planning and policy. Full article

Chiral molecules are crucial in the field of optical devices, molecular recognition, and other novel functional materials due to their unique spatially asymmetric configuration and optical activity. In this study, a chiral molecule, Cholest-3-yl (E)-3-(4-carbamoylphenyl)acrylate (CCA), was combined with dyes containing large conjugated structures, tetramethylporphyrin tetrasulfonic acid (TPPS), and Nickel(II) phthalocyanine-tetrasulfonic acid tetrasodium salt (TsNiPc), and composite LB films of CCA/TPPS and CCA/TsNiPc were successfully prepared by using Langmuir-Blodgett (LB) technology. The circular dichroism (CD) test proved that the CCA/TPPS composite film had a strong CD signal at 300–400 nm, and the composite film showed chirality. This significant optical activity provides a new idea and option for the application of LB films in chiral sensors. In the Surface Enhanced Raman Spectroscopy (SERS) test, the CCA/TPPS composite film was sensitive to signal sensing, in which the enhancement factor EF = 2.28 × 10⁵, indicating that a large number of effective signal response regions were formed on the surface of the film, and the relative standard deviation (RSD) = 12.08%, which demonstrated that the film had excellent uniformity and reproducibility. The high sensitivity and low signal fluctuation make the CCA/TPPS composite LB film a promising SERS substrate material. Full article

Community-based systems present a key option for water services, especially in rural areas. Our goal is to achieve a state-of-the-art understanding of joint rural water supply development in Finland over 150 years. A mixed-methods approach was used: a literature survey and a questionnaire to selected experts. Based on the literature, a table including 23 decisions considered the most influential strategic events from 1872 to 2022 was produced. The table was sent to 10 selected experts known to be deeply familiar with the theme, all of whom replied. Joint rural water services in Finland have evolved based on demand through co-operative principles. The first documented scheme was constructed in 1872, while governmental financial support to rural water services started in 1951. It expanded in various forms until it dramatically declined in recent years. Multi-locality may increase the need for these services in the future. The expert survey revealed the following most influential long-term decisions: the first official water co-operative established in 1907, the land reform for immigrants and war veterans introduced in 1945, the Committee for Rationalisation of Households established in 1950, the start of domestic manufacturing of plastic pipes in 1954, and the Water Act enacted in 1962 to start water pollution control. This paper reminds us that urban and rural services are not contradictory but can supplement each other. Full article

Cresols are aromatic organic compounds widely used in industrial and agricultural production. They have been detected in large quantities in aquatic environments, posing health risks such as skin irritation, gastrointestinal stimulation, and chronic neurological effects. In this study, we investigated the exposure concentration of cresols in the water bodies of Lake Xingkai (i.e., Daxingkai and Xiaoxingkai Lakes) during four typical hydrological periods (30 April, 22 June, 5 September, and 1 November 2021), assessed the human health risk from phenolic contaminants using the mean value method, and determined the health risk of adult cresol exposure in the Lake Xingkai watershed based on local population exposure parameters. This study developed a water environmental pollution health risk assessment model based on the methodology proposed by the United States Environmental Protection Agency (US EPA). It further evaluated the health risks to humans posed by phenolic pollutants via the drinking water pathway. The results revealed that the concentration range of cresols in water bodies was between 5.91 × 10⁻¹ ng·mL⁻¹ and 6.68 ng·mL⁻¹. The adult drinking water health risk values of cresols in the Lake Xingkai watershed were between 3.15 × 10⁻⁴ and 3.57 × 10⁻³, and all water samples from the 10 sites had hazard quotient (HQ) values less than 1, indicating that the non-carcinogen risk was small or negligible. The cresol HQ value in the water of Xiaoxingkai Lake was 4.6 times that found in Daxingkai Lake. Full article

With the rapid development of the global economy, urban flood events are occurring more frequently. Scientific risk assessment methods are of great significance in reducing the loss of life and property. This study is devoted to developing an integrated urban flood risk assessment approach based on improved structural equation modeling and the extensible matter-element analysis method. Firstly, a flood risk assessment index system containing four dimensions (hazard, exposure, vulnerability, and regional shelter capability) is established according to a hydrological–hydrodynamic model and a literature survey. Subsequently, improved structural equation modeling (ISEM) coupled with Pearson’s correlation coefficient is introduced to determine indicator weights while eliminating correlations among indicator variables, thereby enhancing the accuracy of the weight calculation. Finally, the extensible matter-element evaluation analysis method (EMAM) is employed to conduct the urban flood risk assessment, providing a more scientific evaluation of urban flood risks through the calculation results of the correlation degree between index factors and risk levels. The integrated flood risk assessment approach was applied in the Liwan District in Guangzhou City, China, and the results demonstrated that the novel approach effectively enhances the accuracy of urban flood risk assessment by 23.69%. In conclusion, this research offers a novel and high-precision methodology for risk assessment, contributing to decision-making in disaster prevention and control. Full article

Nitrous oxide (N₂O) emissions from paddy soils significantly contribute to global warming; however, the regulatory mechanisms of microbial denitrification remain poorly understood. This study investigated the biotic and abiotic drivers of N₂O production and reduction across seven paddy soils spanning China’s major rice-growing regions, using integrated qPCR, incubation experiments, and multivariate analyses. Results demonstrated niche partitioning among denitrifying microorganisms. Pearson correlation analysis demonstrated significant positive correlations between potential N₂O production rates and the abundances of denitrification genes (nirS, nirK, and fungal nirK), as well as between N₂O reduction rates and nosZ gene abundances (both clade I and II). Key soil chemical properties, including pH, total carbon (TC), and NH₄⁺-N content, showed significant relationships with both potential N₂O production rates and reduction rates. Furthermore, random forest analysis identified nirS, fungal nirK, TC, and pH as key predictors of N₂O production, while nosZ (clade I and II), TC, and pH governed N₂O reduction. Structural equation modeling revealed that nirS-type bacteria predominantly drove N₂O production, whereas nosZ II-encoded microorganisms primarily mediated N₂O reduction. Moreover, TC exhibited direct positive effects on both processes, while pH indirectly influenced N₂O production by regulating nirS abundance and affected reduction via nosZ Ⅱ modulation. These findings provide a mechanistic framework for mitigating agricultural denitrification-derived N₂O emissions through a targeted management of soil carbon and pH conditions to optimize complete denitrification. Full article

The occurrence of toxic metal(loid)s in surface freshwater is a global concern due to its impacts on human and ecosystem health. Conceptual and quantitative metal(loid) models are needed to assess the impact of metal(loid)s in watersheds affected by acid rock drainage. Few case studies have focused on arid and semiarid headwaters, with scarce hydrological and hydrochemical information. This work reports the use of WASP8 (US EPA) to model Al, Fe, As, Cu, and SO₄²⁻ concentrations in the Upper Elqui River watershed in north–central Chile. Calibrated model performance for total concentrations was “good” (25.9, RRMSE; 0.7, R²-d) to “very good” (0.8–0.9, R²-d). The dissolved concentrations ranged between “acceptable” (56.3, RRMSE), “good” (28.6, RRMSE; 0.7 d), and “very good” (0.9, R²-d). While the model validation achieved mainly “very good” (0.8–0.9, R²-d) predictions for total concentrations, the predicted dissolved concentrations were less accurate for all indicators. Sensitivity analysis showed that the partition coefficient is a sensitive constant for estimating dissolved concentrations, and that integrating sorption and sediment interaction reduces the model error. This work highlights the need for detailed and site-specific information on the reactive and hydrodynamic properties of suspended solids, which directly impact the partition coefficient, sedimentation, and resuspension velocity calibration. Full article

Compared with real fish, bionic fish have significant gaps in terms of swimming speed and efficiency, turning performance, and agility. The complicated underwater working environment necessitates monitoring equipment that can deal with the dynamic interference of dense fish schools and aquatic vegetation. An agile and flexible bionic fish with a fast swimming speed would be better suited to underwater monitoring tasks. In this study, a bionic greenfin fish robot is designed in detail, and a hydrodynamic simulation analysis of the designed bionic greenfin fish robot is carried out using STAR CCM+ and Fluent software to analyze the effects of different parameters on the propulsion performance of the pectoral fins, the steering of the caudal fins, and the emergency stop function. The swimming efficiency was found to be highest when the angle of attack was changed sinusoidally by 10° and the frequency was the same as that of the pectoral fin flutter. The feasibility of an emergency stop of the tail fin with negative-phase swinging and the adjustment of the pectoral fin uneven flutter monitoring position were also confirmed. Full article

Over the past two decades, extensive coastal development in China has led to numerous small-scale enclosed coastal water bodies. Due to complex shoreline geometries, these areas suffer from disturbed hydrodynamic conditions, weak water exchange, which quickly leads to sediment accumulation, and difficulty maintaining ecological water levels, posing serious environmental threats. Enhancing seawater exchange capacity and achieving coordinated optimization of exchange efficiency and ecological water level are critical prerequisites for the environmental restoration of eutrophic enclosed coastal areas. This study takes the Ligao Block in Tianjin as a case study and proposes a real-time sluice gate regulation scheme. By incorporating hydrodynamic conditions, engineering layout, and present characteristics of the benthic substrate environment, the number, width, location, and operation modes of sluice gates are optimized to maximize water exchange efficiency while maintaining natural flow patterns. The result of the numerical simulation of hydrodynamic exchange and intelligent optimization analysis reveals that the optimal sluice gate operation strategy should be tailored to regional tidal flow characteristics and substrate conditions. Through intelligent scheduling of exchange sluice gates, systematic gate parameter optimization, and active control of gate opening, this approach achieves intelligent seawater exchange, optimized flow dynamics, active exchange, and sustained ecological water levels in enclosed coastal water bodies. Full article

Microplastics (MPs) and heavy metals are commonly present in soil at significant concentrations and can interact in complex ways that pose serious threats to environmental and ecological systems. The effects of combined contamination by different types of heavy metals and microplastics on plants, as well as on soil microbial communities and their functions, remain largely unexplored. In this study, a series of pot experiments was conducted to investigate the effects of composite contamination involving two heavy metals (Cd and Pb) and two types of microplastics polylactic acid (PLA) and polybutylene succinate (PBS) at varying concentrations (0.1% and 0.5%, w/w). The impacts on water spinach (Ipomoea aquatica) growth and heavy metal accumulation were evaluated, and the rhizosphere bacterial and fungal community structure and diversity were analyzed using high-throughput sequencing. The presence of Cd, Pb, and microplastics significantly inhibited the growth of water spinach, reducing both its length and biomass. Under combined microplastic–heavy metal contamination, phytotoxicity increased with rising concentrations of PLA and PBS. Microplastics were found to alter the mobility and availability of heavy metals, thereby reducing their accumulation in plant tissues and decreasing the levels of available potassium and phosphorus in the soil. Furthermore, microplastic–heavy metal interactions significantly influenced the composition and diversity of soil microbial communities, leading to an increased abundance of heavy-metal-tolerant and potential plastic-degrading microorganisms. A strong correlation was observed between microbial community structure (both bacterial and fungal), soil physicochemical properties, and plant growth. Functional predictions using PICRUSt2 suggested that the type and concentration of microplastics significantly affected rhizosphere microorganisms’ metabolic functions. In conclusion, the present study demonstrates that combined microplastic and heavy metal contamination exerts a detrimental effect on soil nutrient availability, resulting in alterations to soil microbial community composition and function. Furthermore, this study shows that these contaminants can inhibit plant growth and heavy metal uptake. The findings provide a valuable contribution to the existing body of knowledge on the ecotoxicological impacts of microplastic–heavy metal composite pollution in terrestrial ecosystems. Full article

The exacerbation of the global energy crisis has brought the development of efficient and sustainable hydrogen energy to the forefront of contemporary research endeavors. Molybdenum disulfide (MoS₂), recognized for its outstanding electrocatalytic performance as a two-dimensional material, has attracted significant interest for its potential in the hydrogen evolution reaction (HER). This review delves into the heteroatom-doped modification strategy centered on MoS₂ and its effectiveness in enhancing electrocatalytic hydrogen evolution. The influence of various doping elements (including noble metals, transition metals, and non-metals) on the electronic structure and catalytic efficiency of MoS₂ is also analyzed, elucidating the mechanism by which heteroatom doping enhances the catalytic performance and stability of MoS₂. Looking ahead, the integration of multiple doping elements, utilization of advanced computational techniques, and advancement of novel synthetic methods position MoS₂ for practical applications in the field of hydrogen energy, driving the progress and improvement of sustainable energy initiatives. Full article

Wearable technology can nowadays be used to improve para-swimming coaching; however, the extent to which individual anatomy affects features of swimming variability is unclear. Six paralympic swimmers were recruited, their upper-limb segment lengths were measured, and their absolute bilateral limb asymmetry indices (${AbsLAI}_{UL}$) were calculated. They were instrumented with a sacrum-worn inertial measurement unit and performed an in-water, fatiguing, freestyle aerobic test at incrementally faster paces. Stroke-to-stroke outcome and execution variability were calculated, respectively, using sample entropy (SampEn) and fractal dimension (FD) on forward and mediolateral linear acceleration signals. Significantly increased perceived exertion scores (F(4,28) = 154.1, p < 0.001) were observed. Execution and outcome variability increased in the forward (SampEn = F(4,25) = 11.86, p < 0.001; FD = F(4,24) = 6.17, p = 0.001) and mediolateral (SampEn = F(4,25) = 9.46, p < 0.001; FD = F(4,24) = 27.64, p < 0.001) directions. Modelling of FD (only) improved with ${AbsLAI}_{UL}$ as a covariate (forward = F(1,24) = 9.68, p = 0.005; mediolateral = F(1,24) = 8.57, p = 0.021), suggesting that ${AbsLAI}_{UL}$ affects only execution, but not outcome, variability. This information could help coaches determine which coordination indices should be personalized when monitoring variability during para-swimming training. Full article

The rapid urbanization in the Kabul River Basin has increased the demand for water for both drinking and commercial purposes, leading to domestic and industrial water insecurity. Assessing the groundwater potential of the Kabul River Basin is highly crucial for effective water management. The aim of this paper is to identify potential zones for groundwater by employing a Geographic Information System and an Analytical Hierarchy Process approach to formulate a cumulative score based on seven thematic images—rainfall, geology, lineament density, drainage density, land use/land cover, soil type, and slope—within the Kabul River, with assigned weightages of 32%, 27%, 12%, 10%, 8%, 6%, and 5%, respectively, with a consistency ratio of 0.053 (5%), demonstrating the reliability of the results. The study shows that the first three factors contribute more to the percentages of Groundwater Potential Zones. The identified groundwater potential is classified into very good, good, medium, poor, and very poor zones, covering 35.45% (19,989 km²), 37.2% (20,978 km²), 23.16% (13,063 km²), 4.13% (2332 km²), and 0.06% (19 km²), respectively. Groundwater potential in the basin is predominantly classified as good to medium; however, there are notable variations across sub-basins. The Swat sub-basin and western parts of the Kabul River Basin, encompassing the Panjshir and Parwan districts, exhibit exceptionally high groundwater potential. In contrast, the Panjkora sub-basin (Dir district) and southwestern areas of the Kabul River Basin, covering parts of the Ghazni and Wardak districts, have very limited groundwater potential. Full article

Colibacillosis in nursery pigs, caused by Escherichia coli (ETEC, EPEC, and STEC pathotypes), remains a major economic concern in the swine industry. This study evaluated the effects of in-feed or in-water chlortetracycline (CTC) administration on the fecal prevalence of virulence genes and pathotypes associated with colibacillosis. A total of 1296 weaned piglets (21 days old) were allocated to 48 pens (16 pens/treatment; 27 piglets/pen) and assigned randomly to no CTC, in-feed CTC, or in-water CTC groups. CTC was administered from days 0 to 14. Fecal samples from five piglets per pen on days 0, 14, and 28 were enriched, screened by 11-plex PCR, cultured for pathotypes, and tested for CTC susceptibility and tetracycline resistance genes. None of the 360 fecal samples or 3267 E. coli isolates were positive for bfpA or aggA. Prevalence of estB (96.9%) and astA (92.8%) was highest. ETEC was the dominant pathotype (41.2%), with astA (29%) and estB (21.9%) as predominant enterotoxin genes. CTC administration had no significant effect on fecal prevalence of virulence genes or pathotypes (p > 0.05). stx2 and STEC were detected only at day 28, all harboring stx2e. All pathotypes were CTC-resistant, with tetA as the predominant resistance gene. Full article