Longitudinal zonation and hydrothermal variation jointly influence the bacterioplankton community assembly in peatland rivers in the Tibetan plateau.

Agricultural activities are one of the important sources of water pollution in small agricultural watersheds. It is of great significance to understand the current status of water quality and non-point source pollution in small agrarian watersheds, estimate their pollution load, and explore pollutant reduction methods for sustainable water environmental management and protection. In this paper, the small watershed of Mudong River in Huixian Wetland was selected as the study area, and the water quality monitoring indicators were dynamically simulated by using the WASP model. Combined with the preparation of nano-titanium dioxide films and photocatalytic degradation experiments, the water quality reduction of each river section was systematically evaluated. Then, based on the simulation results, the reduction of pollution load into the river was estimated, which provided a scheme for the field reduction of pollutants in agricultural watersheds. The results showed that the WASP model was effective in simulating the water quality of the upper Mudong River in a typical karst area. The simulation inverted the reduction in pollution loads in the upper Mudong River for each indicator. Moreover, it calculated non-point source pollution reduction rates of ammonia nitrogen (NH3-N) (31%, 9.91%, 2.18%), total nitrogen (TN) (24.59%, 21.95%, 10.58%), total phosphorus (TP) (26.64%, 29.39%, 25.15%), Chemical Oxygen Demand (CODcr) (46.46%, 13.39%, 0.99%), and Biochemical Oxygen Demand (BOD5) (37.67%, 31.04%, 23.09%) at 24, 12, and 6h of the reaction, respectively. In short, this method would improve river water quality if the nano-titanium dioxide material were promoted for outdoor use.

To understand the status of fish diversity in the middle reaches of the Yangtze River’s Yuanshui River basin during the ten-year fishing ban, this study employed environmental DNA (eDNA) metabarcoding technology. Fish resources were surveyed and diversity analyzed across 38 sampling points within seven river sections of the Yuanshui River basin in September 2023. The results were compared with data obtained using conventional fishing gear methods from four identical sections (Changde, Yuanling, Chenxi, Hongjiang) to explore the application of eDNA technology for fish resource monitoring in the Yangtze River basin and to investigate the similarities and differences in monitoring outcomes between the two methods. The eDNA metabarcoding approach identified a total of 94 fish species, belonging to 10 orders, 17 families, and 57 genera. Cypriniformes was the most abundant order (65 species, 69.15%), and Cyprinidae dominated (54 species, 57.45%) within families. Among the 94 species, 12 were endemic to the Yangtze River basin, 11were key protected wildlife species in Hunan Province, and 3 were non-native species. The predominant ecological traits of the fish assemblage were characterized by lentic-resident habits (56.38%), omnivorous feeding (63.83%), and demersal habitat utilization (45.74%). Diadromous migrants, herbivorous feeders, and lower water column species were relatively scarce. A comparative study in four identical sections of the Yuanshui River utilized environmental DNA (eDNA) metabarcoding and conventional fishing gear to assess fish diversity. Across all sections, eDNA detected a total of 89 fish species while conventional methods detected 93 species, with 62 species co-detected by both approaches. Site-specific comparisons revealed that within the Changde section, eDNA identified 70 species compared to 55 species captured by conventional gear, resulting in 40 shared species. In the Yuanling section, eDNA detected 71 species against 53 species from conventional sampling, yielding 35 co-detected species. The Chenxi section showed eDNA detection of 44 species and conventional gear detection of 38 species, with 20 species found by both methods. Similarly, in the Hongjiang section, eDNA recorded 49 species and conventional methods 47 species, also sharing 20 species. Both the total number of fish species and the number of shared species detected in the Changde and Yuanling sections were significantly higher than those in the Chenxi and Hongjiang sections. Within the same river section, the Shannon diversity index and Pielou evenness index calculated based on the conventional fishing gear data were consistently greater than those derived from the eDNA analysis. This study demonstrates the high credibility of environmental DNA (eDNA) technology for monitoring fish stocks within the Yangtze River Basin. Combining eDNA methods with conventional fishing gear surveys provides a more comprehensive assessment of fish diversity throughout the basin. These findings offer valuable references for evaluating the effectiveness of fishing bans, protecting fish resources, and informing fisheries management strategies in the Yuanshui River and broader Yangtze Basin.

Distribution and ecological risk of iodinated and gadolinium-based contrast agents in an impacted basin of central Mexico.

This research examines the otolith microchemical characteristics of the critically endangered kunming snout trout (Schizothorax grahami) collected from the sources section endemic to the Chishui River, China, a tributary of the upper Yangtze River, and the metal concentrations in the water of fish habitats. Among the analyzed elements, strontium (Sr) exhibited consistent distribution patterns across otolith rings, as observed through face-scan imagery (scanning the polished surface of the otolith cut), with a relatively low coefficient of variation. Statistical analysis using a paired two-tailed t-test revealed significant differences in Sr:Ca ratios among samples from the three river sections. Notably, magnesium (Mg) levels in the otolith core during the early life stages of the fish were notably higher compared to non-core regions. Similarly, Mg concentrations of water were elevated in the spawning grounds relative to non-spawning areas. This suggests that otolith Mg content may be influenced by the specific water conditions of the spawning grounds. Furthermore, Mg:Ca ratios in the otolith core displayed significant variation among samples from U3, L2, and other sites, implying that the fish in these samples originated from distinct spawning locations. These findings demonstrate that strontium and magnesium in otoliths can serve as effective markers for reconstructing the life history of S. grahami in the Chishui River and can contribute to the management of different fish stocks.

CALCAREOUS CYANOBACTERIA IN THE LATE MIDDLE ORDOVICIAN BIOHERMS AND BIVALVE BANKS OF THE MOYERO RIVER SECTION ( <i>north of the Siberian Platform</i> )

Public participation in water governance has grown under the River Chief System in China, but the effects of government-related factors on participation remain inconsistently addressed. This study empirically investigates the influence of government performance outcomes and process-related factors on public participation in China’s water governance. Utilizing a hierarchical linear model, this study draws on survey data from 922 respondents and objective environmental metrics across 30 river sections in Guangzhou (2018–2019). Results reveal that public participation remains limited and sporadic, partly driven by process-related factors. Specifically, the perceived transparency of environmental information and government responsiveness are statistically significant predictors of increased participation. Conversely, performance-driven factors, whether subjective or objective government performance, show no significant effects. These findings underscore the critical role of process legitimacy in understanding public participation and highlight the need to prioritize transparency and responsiveness in institutional designs to encourage and sustain public involvement in government-led participatory spaces.

To investigate the impact of different water and sediment conditions on the morphological shaping of the middle reaches of the Tarim River, this study establishes an erosion-deposition evolution model for the Yingbazha to Wusiman River section under the 2018 shoreline conditions using MIKE21 software and conducts validation. Five working conditions were selected for typical years of high-flow, normal-flow, and low-flow, as well as years of extreme floods and extreme droughts, to simulate the river channel’s erosion and deposition evolution under varying water and sediment conditions. By analyzing metrics such as erosion and deposition volume, depth of scour and fill, changes in the channel’s planform morphology, thalweg elevation variations, and cross-sectional changes along the river reach, the patterns of erosion and deposition evolution in this segment were systematically examined. The results indicate that: (1) Under different representative year conditions, the river was always in a net deposition state. The sediment deposition was highest in the extreme flood year (1.885 × 107 tons, accounting for 34% of the incoming sediment) and lowest in the extreme drought year (1.109 × 106 tons, accounting for 83% of the incoming sediment). The unit runoff sediment transport efficiency increased by 54% with the increase in flow. However, when the runoff exceeded the critical threshold of 3.7 × 109 m3, the increase in scour volume (+440%) far outpaced the deposition volume (+143%), revealing a critical turning point in the erosion-deposition mechanism. (2) The erosion-deposition process follows a three-stage evolutionary pattern of “deposition-scouring-redeposition”: At low flow, insufficient sediment-carrying capacity leads to continuous deposition. After surpassing the critical flow, the sediment-carrying capacity dominates scouring. Under high flow conditions, the water and sediment volume increases sharply, restarting deposition. The deep pool elevation exhibits corresponding “rise-drop-rise” periodic fluctuations. (3) Through analysis of typical cross-sections, it is shown that in extreme flood years and typical wet years, the lateral swinging of the main channel causes scouring. However, the collapse of the bank and the widening of the river channel result in increased deposition in the main channel, leading to an overall elevation of the riverbed. In typical drought years and extreme drought years, due to lower flow, water levels, and flow velocities, the erosion-deposition process only occurs within the main river channel. The research results provide a better understanding of the erosion-deposition evolution trend of the meandering section of the Tarim River’s main channel, offering scientific guidance for the future development, management, and sustainable development of the middle reach of the Tarim River.

Abstract Background Over the past few centuries, human impacts on river ecosystems have resulted in significant physical and ecological degradation of aquatic ecosystems. While the implementation of restoration measures has led to morphological improvements in rivers, positive biological responses, especially for benthic macroinvertebrates, are often limited. Alongside morphological degradation, recovery of invertebrate diversity is constrained by other factors acting at larger spatial scales, such as chemical pollution. Yet the extent to which chemical pollution limits the recovery of aquatic communities in restored river sections remains poorly studied. The application of current water quality monitoring methods may lead to inaccurate predictions of the effects of such stressors on river ecosystems. Therefore, effect-based methods (EBMs) are proposed as a complementary screening tool for the integrative assessment of river status. Results In this study, we provided a comprehensive assessment of the effects of local restoration measures by integrating ecological metrics, ecotoxicological tools, and chemical analyses. Although restoration measures were found to have a positive effect on habitat quality, no recovery of good ecological status in restored sections was found. The main pressure acting as a limiting factor for the improvement of benthic macroinvertebrate communities was found to be the prevailing chemical pollution. The effect of restoration age on benthic invertebrate communities and, for the first time, on ecotoxicological effects in response to hydromorphological river restoration showed no effect on ecological metrics or toxicity parameters. Conclusion In summary, the success of restoration needs to be assessed using a more integrative and multi-dimensional approach to identify limiting factors and to differentiate cases where restoration measures have not yet had time to take effect from cases where additional interventions may be required. The present results underscore the necessity for restoration initiatives to address not only individual stressors, such as morphological degradation, but also to incorporate comprehensive ecotoxicological monitoring to identify and mitigate any adverse effects that may compromise their effectiveness.

Introduction. Urban riparian corridors are critical for biodiversity conservation, hydrological regulation, and ecosystem connectivity. However, anthropogenic pressures and extreme climate events have disrupted their ecological integrity, particularly in rapidly urbanizing Andean regions. Objectives. This study aims to characterize the floristic composition and structural attributes of woody vegetation in a riparian section of the La Vega River microwatershed (Tunja, Boyacá), which was disturbed by dredging activities following the 2010– 2011 La Niña event. Materials and methods. Field sampling was conducted through 20 transects (50 × 2 m; total area 0.2 ha) along both riverbanks within the university campus. All woody individuals with a diameter at breast height (DBH) &gt; 1 cm were recorded. Structural parameters (density, dominance, frequency, Importance Value Index), species richness estimators, and diversity indices (Shannon-Wiener, Simpson, Margalef) were calculated. Results. A total of 782 individuals were recorded, comprising 37 species, 28 genera, and 21 families. The family Fabaceae was dominant, with exotic species such as Acacia decurrens (IVI = 139%), A. mearnsii, and A. melanoxylon prevailing across the site. Native species including Juglans neotropica, Sambucus peruviana, Quercus humboldtii, and Prunus serotina showed lower abundance but play important ecological roles. Conclusions. The high dominance of exotic Acacia species indicates ongoing ecological alteration within the riparian corridor. Active management and restoration strategies are needed to curb the spread of invasive species and promote the recovery of native riparian vegetation.

Land adjacency effects (LAEs) significantly bias satellite-derived aquatic remote sensing reflectance (Rrs), particularly in small water bodies and narrow rivers. Although several algorithms have been developed for oceans and lakes, their performance in fluvial environments remains poorly understood. Here, we evaluated six atmospheric correction (AC) algorithms using Landsat-8/9 OLI and Sentinel-2 MSI data, supported by in situ measurements from three Yellow River sections with varying turbidity and terrain. For all OLI and MSI matchups (N = 54), without LAE correction, the mean absolute percentage error (MAPE) averaged 57.8%, with red and near-infrared bands performing better than blue bands. Incorporating LAE correction substantially improved accuracy (MAPE = 27.6%), and the TSDSF-RAdCor method achieved the best results (MAPE = 17.4%), especially in visible bands. Further analysis reveals that performance varied with river morphology and turbidity: riffle-dominated reaches showed higher accuracy than canyon sections, and highly turbid waters improved correction efficiency. Suspended particulate matter estimates from LAE-corrected Rrs were 16-30% more accurate than those from uncorrected Rrs. These findings highlight the necessity of LAE correction in fluvial remote sensing to enhance the reliability of riverine water quality retrievals and support large-scale environmental monitoring and management.

To investigate the distribution characteristics of microplastics in the middle and lower reaches of the Yellow River， this study selected 18 sites on the Yellow River through Zhengzhou to collect sediment samples， and microplastics were analyzed quantitatively and qualitatively by body-viewing microscopy and Fourier infrared spectroscopy to explore the distribution characteristics of microplastic contamination. The relationship between microplastics and the physicochemical properties of the sediment was examined using Pearson correlation analysis， and the diversity index was used to analyze the potential source of the microplastics. The results showed that the abundance of microplastics in the sediment of the Zhengzhou section of the Yellow River ranged from 533.33 to 2 866.67 n·kg-1， with a mean value of （1 140.74±496.76） n·kg-1. The color was dominantly blue， green， and black； the most abundant shape was fibrous； and the dominant particle size was less than 1 mm， with microplastics with a particle size of 0.5-1 mm accounting for the largest proportion of the microplastics. The microplastic polymers differed greatly among the points， but polyethylene terephthalate （PET） was dominant. Their abundance was only weakly correlated with physical and chemical properties of the sediment， but the morphological features showed a degree of correlation. Diversity index analysis showed that the surrounding anthropogenic activities were the main source of microplastics in the Yellow River sediment.

Abstract Reservoirs are essential for global water management and energy regulation, but sedimentation threatens their longevity. This study investigates a 130 km section of the Yellow River between the Sanmenxia and Xiaolangdi dams, using deep learning to predict long‐term erosion and deposition patterns. From 2009 to 2023, we gathered water depth data from 56 sites (840 measurements) with unmanned survey boats and drone‐based LiDAR (Light Detection and Ranging), alongside flow and sediment records. After preprocessing, we evaluated three machine learning models: Convolutional Network for Multimodal Time Series (CNN‐MTS), Convolutional Transformer for Multimodal Time Series (CNN‐Transformer‐MTS), and Convolutional Bi‐LSTM for Multimodal Time Series (CNN‐BiLSTM‐MTS). The CNN‐BiLSTM‐MTS model excelled, achieving a mean absolute error (MAE) of 17.84 m, a coefficient of determination (R2) of 0.9916, and reducing errors by up to 26% compared to alternatives. Key drivers of sediment dynamics included sediment load, maximum sediment concentration, and maximum flow. Data from 2009 to 2023 showed elevation shifts from −0.21 m near the dam to +1.158 m at the reservoir's tail. Predictions for 2024 to 2050 suggest varied riverbed changes, with the Guxian Reservoir's operation in 2036 expanding elevation ranges from −0.625 to 0.875 m. These findings highlight deep learning's potential for efficient sediment management in reservoirs and offer insights for sustainable hydraulic engineering. However, uncertainties persist in scaling the model, improving data resolution, and coordinating across regions.

Evaluating tryptophan-like fluorescence to quantify E. coli concentrations in a combined sewer overflow impaired watershed.

The problem of determining the pollution load capacity for a river section has an important meaning in protecting the water environment for the purpose of sustainable development. This is a complex optimization problem that only has an analytic solution in simple cases. This paper presents a method for obtaining an analytical solution for a river section in the case of dispersed waste sources distributed along the river, taking into account the influence of decay and dispersion processes. The results show a quantitative relationship between the decay coefficient, the dispersion coefficient and the load capacity of the river. The obtained results can be applied to more complex real-world problems.

Abstract Wing dams, used in rivers like the Mississippi and Danube, improve navigation by increasing water depth during low flow. Their hydromorphological effects are complex, and their influence on flood risk remains debated. Here we developed an approach that identifies local physical patterns from detailed numerical calculations, enabling extension to larger river sections and longer time scales previously difficult to study. We apply this numerical method to assess wing dam impacts on water and bed levels over decades to centuries. Our results show that rivers with bed materials prone to armouring tend to experience long-term water level increases due to wing dams, while others may see decreases. Adjustments to new stable conditions take decades, with temporary water level rises even in uniform beds. For the Mississippi River, wing dams likely caused initial water level increases, but effects declined over time, indicating evolving riverbed responses. These findings help design flood risk–optimal wing dam configurations.

Abstract. Dissolved oxygen (DO) is a fundamental indicator for water quality and ecosystem health, particularly in the context of anthropogenic impacts and climate change. This study presents the first large-scale dataset of DO concentrations combined with its stable oxygen isotope ratios (expressed as δ18ODO), particulate organic carbon concentrations (POC), and respiration / photosynthesis (R / P ratios) from five seasonal campaigns along the entire Danube River in 2023 and 2024. Our findings reveal pronounced seasonal DO driven by temperature, biological activity, and hydrodynamic conditions. During spring and summer, enhanced photosynthesis increased DO up to 0.40 mmol L−1, with δ18ODO values down to +12.1 ‰ and POC up to 0.25 mmol L−1 in two highly productive river sections. Low R / P ratios of 0.1 further indicated strong net autotrophic conditions. Strong correlations between δ18ODO and POC additionally confirm the influence of primary producers (i.e., photosynthetic organisms) in a river section where a reduced slope led to slower flow and lower turbulence. Notably, δ18ODO values were lower than those expected for atmospheric equilibrium (+24.6 ‰ ± 0.4 ‰), a pattern rarely documented in large river systems. In contrast, tributary inflows from the Tisa and Sava rivers diluted biomass and organic material inputs and led to declines in DO and POC. By late summer, intensified respiration reversed photosynthetic signals, led to the lowest DO concentrations down to 0.16 mmol L−1, and raised δ18ODO up to +23.7 ‰, particularly in the Sava River. In fall, DO levels partially recovered despite continued respiration, as indicated by the highest observed δ18ODO values of +25.9 ‰ and the highest R / P ratios of the entire season, reaching 8.9. In winter, oxygen input from the atmosphere became dominant with minimal biological influences. Overall, this study provides new insights into oxygen sources and sinks across the river continuum over several seasons. These new insights underscore the need for continuous DO monitoring, particularly in late summer when oxygen levels can become critically low. Understanding these interactions can help to establish efficient aqueous ecosystem management and conservation strategies in the face of land use and climate change.

The geological environment is characterized by continuous dynamic changes. Landslide activity characteristics can reflect the geological environmental background that affects the landslide development in different historical periods. A comprehensive methodology framework for landslide susceptibility assessment based on landslide activity is proposed. The core concept involves classifying landslide samples into active and inactive categories. Focusing on the Baiyu–Batang section of the upper Jinsha River in the Qinghai–Tibet Plateau, the influence of landslide activity characteristics on landslide susceptibility assessment is investigated. Both ancient and recent landslides are widely distributed. A total of 366 landslides are identified, which are categorized into three subsets: Dataset A (190 active landslides), Dataset B (190 active and 176 inactive landslides), and Dataset C (176 inactive landslides). Eight disaster-causing factors are selected, and the weighted information value model is utilized to perform the landslide susceptibility assessment. Results show that regions exhibiting very high and high landslide susceptibility are mainly situated along riverbanks such as the Jinsha River, Baqu River, and Ouqu River, exhibiting a distinct linear distribution pattern aligned with the river systems. The landslide susceptibility based on Dataset A demonstrates the highest accuracy, suggesting that incorporating landslide activity significantly enhances the reliability of landslide susceptibility assessment in the current geological environment.

Over the past two decades, riverbeds in mountainous areas have been manipulated by humans due to their tourist attractions. Today, river geomorphology has entered a new era and turns to the basis of studying environmental changes which are used to River canal management. So, studying the trend of hydromorphological of this river is very essential. The purpose of this study was to evaluate the hydromorphological conditions of a part of Jajrood River from Meghun to Fasham using MQI method. In this regard, the desired information was collected using field observations, remote sensing science and geographic information system. After preparing satellite images, the river was intercepted and divided into 7 sections using the MQI method. The first and second phases determined the quality of the intervals and the number of changes. The study results show that there have been many changes in the bed in this part of the river. In the northern parts, due to the limitation of the river on both sides, the intensity of changes is less, while in the middle parts of the river, according to the numerous constructions on both sides of the river, the intensity of destruction is also higher. One of the most important issues in using MQI method is the researcher level of expertise. Data collection is based on a combination of remote sensing, GIS analysis and field navigation and should be done by operators with background and appropriate training in river geomorphology because having specialized knowledge of river geomorphic concepts is necessary for the application of MQI.

In recent years, a growing global effort has been underway to reduce the Earth’s carbon footprint. One of the main strategies to achieve this goal is the utilization of available renewable energy resources. Among the largest and most inexhaustible is hydro-power. This paper presents an experimental study of three hydrokinetic turbines tested under real river conditions, aiming to evaluate their effectiveness in harnessing the kinetic energy of flowing water. The experiment is described in detail, including velocity field measurements conducted within the river section used for testing. Based on the experimental data, the main performance characteristics of the three turbines are presented, specifically their power output and efficiency. The importance of selecting an optimal riverbed site and customizing turbine runners to local flow conditions is highlighted, as even slight velocity fluctuations can significantly impact performance. Among the tested designs, the K1–6 turbine runner showed the highest power and efficiency, while the K2–4 runner provided superior rotational stability, making it promising for consistent energy output in variable flow environments