Search Results (4,508)

This study investigated rubber additives and relevant transformation products (RARTPs) in surface waters of Kaifeng, a city linking the Yellow River and Huaihe River basins. Seven of fifteen target analytes were detected in >10% of samples. The hydrolysis product 4-hydroxydiphenylamine (4OH) showed the highest detection frequency (70%), followed by 1,2-Dihydro-2,2,4-trimethylquinoline (TMQ, 57%) and N-(1,3-Dimethylbutyl)-N′-phenyl-p-phenylenediamine (6PPD, 27%). TMQ had the highest average concentration (6.16 ± 4.17 ng·L⁻¹). Urban rivers (14.20 ± 4.72 ng·L⁻¹) were contamination hotspots, driven by management practices (e.g., dredging of urban lakes). Although detected at lower levels (0.09 ± 0.21 ng·L⁻¹), 6PPD-quinone (6PPD-Q) was associated with elevated risk (risk quotient, RQ ≥ 1) at 19% of sites. The chronic daily intake assessment showed that drinking water ingestion contributed 66.7% of total exposure in daily use, whereas dermal absorption dominated during swimming. Children, especially girls, were the most vulnerable subgroup. Although estimated chronic daily intakes (CDIs) from surface water accounted for only a negligible proportion of the daily urinary excretion of p-phenylenediamine antioxidants (PPDs) reported in a Chinese population, the ecological risk of 6PPD-Q warrants continued attention. These findings highlight the need for improved management of water bodies receiving urban runoff and aquaculture inputs, and further health risk assessment of RARTPs. Full article

Drought is a widespread natural hazard in China that can sequentially trigger meteorological, hydrological, agricultural, and socio-economic drought types, yet traditional drought indices typically focus on a single hydrologic component and cannot capture integrated water deficits across multiple compartments. This study aims to systematically characterize the spatiotemporal evolution of comprehensive drought across China’s ten major river basins and to identify and quantify the main natural and anthropogenic factors associated with drought dynamics. We utilized the Gravity Recovery and Climate Experiment (GRACE) Mascon dataset spanning the entire mission period (April 2002–June 2017), which provides a continuous 15-year observation window suitable for detecting decadal-scale trends and inter-annual variability. Given the documented asynchrony between precipitation and terrestrial water storage changes, a zoned index framework was applied: the Combined Climatologic Deviation Index (CCDI) for arid basins and the Drought Severity Index (DSI) for humid basins. The Theil–Sen estimator and Mann–Kendall test, both non-parametric and robust to outliers, were employed for trend detection, and Pearson correlation analysis was used to evaluate statistical associations between drought indices and potential influencing factors. The results reveal a clear “dry gets drier, wet gets wetter” pattern during 2002–2017: severe drought episodes in humid basins (e.g., the Yangtze) were concentrated in 2002–2006, whereas those in arid basins (e.g., the Haihe) occurred mainly in 2013–2017. Groundwater storage anomaly (GWSA) constituted the primary component of total water storage changes in most basins, with the most rapid depletion rate of −45 mm yr⁻¹ in the northern arid basins. Land use/cover change, especially urban expansion, showed a significant statistical association with drought intensification in arid regions, with its standardized contribution being comparable to that of natural factors such as runoff. This study provides a systematic cross-basin assessment and offers scientific insights for differentiated drought mitigation strategies and water resources management. Full article

Jiaodong Peninsula is one of the regions with the most abundant medium–low-temperature convective geothermal resources in the eastern coastal area of China. Analyzing geothermal fluid characteristics can help understand its hydrochemical discharge characteristics and renewal capacity, and these characteristics also exhibit distinct geochemical symmetry that reflects the genesis and evolution of geothermal systems. In this study, we conducted a water quality analysis of 15 natural hot spring geothermal fluids, as well as their adjacent bedrock and Quaternary water, in the Jiaodong Peninsula. We measured deuterium and oxygen isotopes, and the γ Na/γ Cl and γ SO₄/γ Cl ratios of geothermal fluids, focusing on the geochemical symmetry of these indicators to reveal the evolutionary rules of geothermal fluids. The hydrochemical types of geothermal fluids in the Jiaodong Peninsula included Cl–Na, Cl–Na·Ca, HCO₃·SO₄–Na, and SO₄·HCO₃–Na, with mineralization degrees of 0.45–7.68 g/L and pH values of 7.3–8.63. The geothermal fluid primarily originated from the infiltration recharge of atmospheric rainfall and had no hydraulic connection with the shallow Quaternary water and adjacent bedrock water near the geothermal field. The geothermal fluid in the study area had not yet reached water–rock equilibrium. For geothermal fields with higher γ Na/γ Cl and γ SO₄/γ Cl ratios, the corresponding geothermal fluid circulation depth was relatively shallow, indicating a poorly sealed hydrodynamic environment with strong renewal capacity, where the geothermal fluid is in a continuous supply–runoff–discharge process. The γ Na/γ Cl and γ SO₄/γ Cl ratios of some geothermal fields were close to those of seawater; this symmetric difference was caused by the large circulation depth and long residence period of the geothermal fluid, which had experienced a high degree of decarbonization. Our findings on the hydrochemical characteristics and geochemical symmetry of medium–low-temperature geothermal fluids in the Jiaodong Peninsula will help deepen the understanding of the formation and evolutionary mechanism of this type of geothermal resource. Full article

This study investigates the synergistic regulation mechanism of water–heat–salt transport in the black soil of cold regions in Northeast China by combining field monitoring with HYDRUS-2D simulations. Four tillage treatments were evaluated: control group (CK), no-tillage with flat straw mulching (NM), ridge tillage with flat straw mulching (RM), and straw return with rotary tillage (RR). Monitoring data indicated that all straw incorporation treatments significantly improved soil moisture retention capacity. Compared with CK, soil water content under RM increased by 63.93% correspondingly; soil salinity in CK was 5.75–13.68% higher than that in straw-amended treatments. In addition, RM exerted a more prominent regulatory effect on soil temperature fluctuations relative to CK. Simulation results reveal that straw incorporation effectively reduces surface runoff, thereby substantially weakening the driving force for upward salt migration. Structural equation modeling (SEM) quantified path coefficients, revealing that straw incorporation optimizes the soil microenvironment. This integrated approach provides a mechanistic basis for black soil conservation in seasonally frozen regions, identifying RM as the optimal management practice to balance water retention and salt inhibition. Full article

This study investigates the hydroclimatic impacts of climate change on the Göynük Stream Basin, a snow-fed tributary within the Euphrates River Basin, utilizing flow, precipitation, and temperature data from 1975 to 2022. The Göynük Stream Basin is characterized by high-altitude, harsh continental conditions, with its flow regime heavily influenced by snowmelt, rendering it particularly sensitive to climate change. Employing a suite of trend analysis methods, including Mann–Kendall, Spearman Rho, Theil–Sen, Şen-Innovative Trend Analysis (ITA), and Innovative Polygon Trend Analysis (IPTA), the research evaluated annual and seasonal data from one stream and four meteorological stations across multiple significance levels (90%, 95%, 99%). Unlike conventional hydroclimatic studies based solely on monotonic trend detection, this study integrates classical trend tests, innovative trend approaches, temporal regime-based analysis (RAPS), and machine learning techniques within a unified assessment framework to evaluate both hydroclimatic variability and runoff predictability under climate change conditions. Key findings indicate a significant decline in annual flow rates by approximately 9.37%, with a notable decrease in maximum flow rates evidenced by a negative trend slope of −0.2726 m³/s/year. While precipitation trends were generally decreasing, temperature data exhibited significant increases, especially during winter and spring. Seasonal analysis revealed substantial flow reductions in summer and autumn, coupled with an earlier timing of the annual maximum flow, shifting from mid-May to late March/early April, suggesting earlier snowmelt. The study concludes that the Göynük Stream Basin is experiencing increasing hydroclimatic pressures attributable to climate change. These insights are crucial for water resource management and serve as a guideline for similar snow-fed sub-basins within the broader Euphrates River Basin. Furthermore, the integration of a machine learning approach, utilizing meteorological and seasonal data, demonstrated strong monthly runoff prediction capabilities with NRMSE of 4.11% and R² equal to 0.951. Feature importance analysis highlighted seasonality and temperature as primary predictive factors. However, a marked decline in model accuracy after 2011 was observed, indicating a non-stationarity in the hydroclimatic system, likely driven by climate change impacts and underscoring the need for adaptive management strategies. Full article

Climate and land-use changes are major drivers of hydrological and water quality dynamics in the Great Lakes Basin. This study investigates recent changes in climate, land use, runoff, and total phosphorus (TP) loading in selected illustrative watersheds within the Canadian Lake Erie Basin and Canadian Lake Ontario Basin during 2009–2022. Results suggest that recent warming and hydroclimatic variability have altered hydrological regimes in southern Ontario, including higher winter temperatures and shifts in seasonal runoff. Land-use changes, including the expansion of row crops and urban areas, have further influenced watershed responses. Variations in TP loading were associated with changes in hydroclimatic conditions and land use. These findings highlight the increasing importance of event-driven nutrient transport under changing hydroclimatic conditions and support adaptive watershed management approaches accounting for seasonal runoff variability and event-driven nutrient transport. This study provides insight into the combined impacts of climate and land-use changes on hydrology and nutrient loading in southern Ontario watersheds. The analysis results enhance understanding of water quality dynamics in the Great Lakes region and support the development of more effective, adaptive, and integrated watershed management strategies under future climate and land-use changes. Full article

Climate change and rapid urbanization increasingly threaten water security in large river basins, yet existing assessments often fail to capture the multi-scale interactions between hydroclimatic extremes and human activities. To address this gap, we developed an integrated framework combining risk assessment, multi-method driver diagnosis (Geodetector, Multi-Scale Geographically Weighted Regression (MGWR), and Structural Equation Modeling (SEM)), and Zoned Management. Using a landscape-derived Ecological Risk Index (ERI) as a proxy indicator of runoff and non-point source potential, based on established empirical linkages between landscape metrics and hydrological processes, we applied the framework to three major urban agglomerations in the Yangtze River Basin from 2000 to 2020. Our results reveal three distinct risk mechanisms: in the Chengdu–Chongqing area (CYUA), a 165.8% increase in impervious surfaces drives altered runoff; in the Middle Reaches (MRC), the q-value of the Standardized Precipitation Index (SPI) rose from 0.017 in 2000 to 0.146 in 2020, corresponding to a 759% relative increase. Although the absolute q-value of SPI remains moderate at around 0.15, its rapid rise suggests increasing hydrological sensitivity of the MRC’s river–lake system to precipitation extremes; in the Yangtze River Delta (YRD), socioeconomic activities exert overriding pressure. Based on these diagnostics, we propose tailored strategies for water environment management, adaptive planning, and disaster mitigation. This framework offers a scientific basis for differentiated water governance in large river basins facing coupled anthropogenic and hydroclimatic pressures. Full article

Low-impact development (LID) facilities can significantly mitigate runoff and purify pollutants. However, their operational efficiency is highly influenced by regional rainfall characteristics, posing challenges to sustainable development in urban water management. This study investigates the degradation of runoff control efficacy in two LID installations located in Xi’an (semi-humid region) and Yangzhou (humid region) and examines the impact of continuous rainfall across different climatic zones. The results reveal that in both study areas, over 75% of annual rainy days experienced continuous rainfall, accounting for more than 80% of total rainfall volume. During continuous rainfall, the declining infiltration capacity of LID facilities reduces their performance, and the operational effectiveness of the LID facilities may deviate to some extent from the design goals. The lower attenuation coefficients observed in Yangzhou indicate that its LID facilities were more strongly affected by continuous rainfall than those in Xi’an. Regarding the designed annual runoff control targets, Xi’an achieved an average effectiveness of 83.7% at 60–85% design levels, outperforming Yangzhou by 12.09%. When increasing design rainfall, Xi’an exhibited increments of 41.0–200.7% for targets ranging from 60% to 80%, whereas Yangzhou required substantially larger increases for targets of 60–70%. Notably, achieving control targets above 85% in Xi’an and 75% in Yangzhou solely through increased design rainfall proved unfeasible. The study highlights that continuous rainfall affects LID performance in both humid and semi-humid regions, with facilities in more humid climates being particularly susceptible. These findings underscore the need for climate-adaptive LID design strategies to support long-term sustainable urban development goals. Full article

Soil erosion is a critical environmental issue restricting ecological security and agricultural sustainable development in China. Traditional studies have predominantly focused on physical driving factors such as hydraulic and wind erosion, while the regulatory effects of hydrochemistry on soil erosion have long been neglected. To clarify the mechanisms and regulatory processes of hydrochemistry-driven soil erosion in China, this study collected 795 relevant publications from the Web of Science Core Collection spanning from 2000 to 2025. Based on bibliometric methods, visualization software including VOSviewer 1.6.20 and CiteSpace 6.4.R1 were adopted to analyze publication trends, author distributions, research institutions, and keyword co-occurrence characteristics. The results indicated that the number of publications concerning hydrochemistry-driven soil erosion in China has increased year by year since 2000. China ranks first in total publication output, showing a dominant research position in this field. The Chinese Academy of Sciences contributed the largest number of publications among all research institutions. Keyword co-occurrence analysis over the past 25 years demonstrated that soil erosion, runoff, and water erosion serve as the core research hotspots. Further analysis revealed the regulatory mechanisms of key hydrochemical parameters (e.g., pH value, ionic strength, and dissolved organic carbon) throughout erosion processes. In-depth keyword analysis confirmed that current research on hydrochemistry-driven soil erosion in China remains at the preliminary stage, lacking comprehensive exploration of microcosmic mechanisms and systematic regulation strategies. Therefore, intensified research efforts and optimized regulatory frameworks are urgently required in future studies. This study can provide theoretical foundations and technical references for improving the understanding of erosion driving mechanisms and enhancing soil erosion management efficiency across diverse regions of China. Full article

To address runoff forecasting inaccuracies caused by data gaps in reservoir operations, this paper proposes a collaborative modeling framework integrating deep learning, signal decomposition, uncertainty quantification, and transfer learning. Validated on the Wei River (source basin) and Yongding River (target basin) with similar hydrological characteristics, the framework first constructs a Pyraformer-BiLSTM-LSS point forecasting model to enhance characterization of non-stationary runoff sequences. Then, the BLSO-VMD optimization decomposition technique filters and reconstructs forecasting noise, improving model robustness. Subsequently, a probabilistic interval forecasting model is developed via multi-task learning to reliably quantify uncertainty. To tackle data scarcity in the target domain, a “decomposition–reconstruction–transfer” learning mechanism transfers model knowledge from the source domain to the target domain. Results show that the framework achieves excellent performance in the source domain and successfully transfers to the data-scarce target domain, significantly enhancing the accuracy and stability of both point and interval forecasts. By establishing a collaborative modeling framework combining transfer learning and multi-task learning, along with an adaptive signal decomposition method based on BLSO and a multi-scale deep learning model, this study effectively addresses the challenges of accuracy and reliability in runoff forecasting for data-scarce basins. It provides a transferable and scalable technical pathway for runoff simulation and reservoir operation in hydrologically underserved regions, supporting sustainable water resource management and ecological protection. Full article

Nitrogen applied in excess of plant demand in intensive agricultural systems can be lost through runoff and leaching into surface and groundwater, with potentially negative effects on water quality. Zeolites, due to their high cation exchange capacity and internal porosity, can adsorb ammonium (${NH}_4^{+}$) and help mitigate excessive nitrate (${NO}_3^{-}$) leaching. Owing to such properties, zeolites can play an important role in reducing the potential negative impact associated with the extensive use of nitrogen-based fertilizers. In this study, we investigated the effects of two commercial natural zeolites on selected hydraulic properties, water storage, and solute transport parameters of three sandy-loam soils with different pedological characteristics. Laboratory experiments were conducted on disturbed soil columns. The leaching of ${NO}_3^{-}$ and ${NH}_4^{+}$ ions was monitored using ion-selective electrode analysis. The results indicate that zeolite application reduces the mobility of nitrate and ammonium. This effect can be attributed to changes in the original pore size distribution of the investigated soils, characterized by a reduction in macropore regions and a corresponding increase in meso- and micropore regions. In the case of ammonium, adsorption mechanisms are also involved, which further contribute to retarding its mobility. These effects were consistently observed across the investigated soils. For a given soil, the magnitude of the observed effects depended on both the type of zeolite used and the amount of zeolite mixed with the soil. Finally, ANOVA tests and multivariate analyses were applied to the full dataset to provide statistical support for the observed changes in the selected parameters. Full article

Karst critical zones in Southwest China are highly vulnerable to soil–water loss because thin soils, exposed carbonate bedrock, well-developed epikarst, and strong surface–subsurface connectivity promote both surface erosion and subsurface leakage. Although soil erosion, subsurface leakage, karst rocky desertification, and ecological restoration have been widely studied, the coupling between landscape structural patterns and soil–water loss remains insufficiently synthesized. This semi-systematic critical review synthesizes evidence from karst hydrology, soil erosion, karst rocky desertification, landscape structure, and critical zone studies, with a primary focus on Southwest China. The reviewed evidence indicates that geomorphic setting, land use vegetation structure, bare-rock exposure, and epikarst development jointly regulate runoff generation, infiltration, sediment detachment, subsurface leakage, and sediment connectivity. Peak–cluster depressions commonly favor internal sediment storage and vertical leakage, whereas valley and canyon systems tend to enhance surface runoff connectivity and channelized sediment export. However, pathway dominance varies with rainfall intensity, soil moisture, soil thickness, land use, karst rocky desertification degree, and fracture–conduit connectivity. Long-term soil–water loss may further reshape landscape structure through soil thinning, vegetation degradation, bedrock exposure, and karst rocky desertification feedbacks. Current research is limited by insufficient quantification of subsurface soil loss, weak integration between landscape metrics and hydrological models, and scarce long-term monitoring data. Future studies should integrate field monitoring, tracers, remote sensing, landscape metrics, and coupled surface–subsurface models to support geomorphic-setting-specific karst rocky desertification control. Full article

Concentrated rear runoff is an important hydraulic factor that promotes slope instability and flow-like transport characteristics in mountainous landslides; however, the deformation–failure process of slopes and their response relationships under different runoff intensities remain unclear. In this study, the Shaziba landslide in Enshi, Hubei Province, China, was selected as the research object. Two-dimensional flume model tests were conducted under four runoff discharge conditions of 7, 15, 27, and 35 mL/s to investigate the effects of runoff intensity on the hydraulic response and failure mode of the slope. The results show that, as the runoff discharge increased from 7 to 35 mL/s, the initial response times of water content, pore water pressure, and earth pressure at the rear edge decreased from 1205, 1488, and 888 s to 160, 248, and 112 s, respectively. Meanwhile, the gully formation time shortened from 6810 to 336 s, and the time of the first evident collapse decreased from 5758 to 650 s. Under low-runoff conditions, slope deformation was dominated by infiltration-induced softening and progressive creep. Under moderate to high runoff conditions, gully incision and gully-wall collapse accelerated slope disintegration, resulting in soil–water mixed transport and enhanced mobility of failed materials. Concentrated rear runoff drives the slope through successive stages of initial deformation, structural disintegration of the slope, flow-like failure, and toe deposition. These findings provide experimental evidence for the identification and prevention of landslides controlled by rear runoff. Full article

Revegetation serves as a critical ecological safeguard, while these interventions have added complexity to the evapotranspiration processes and water balance. Dalinor Lake basin (DLB), located in the southeast of Inner Mongolia Plateau, serves as a vital habitat for migratory birds and plays an important role in the ecological security of northern China. To enhance biodiversity, numerous ecological restoration projects have been carried out in this area in recent years. Dalinor Lake, a large inland lake within the basin, has experienced persistent shrinkage. Although existing studies have explored its driving factors, the potential influence of revegetation activities on lake shrinkage remains unclear. In this study, we used remote sensing imagery, combined with supervised classification and visual interpretation methods, to extract changes in the surface areas of lakes within the DLB (i.e., Dalinor Lake and Ganggeng Lake), and analyzed the effects of total terrestrial evapotranspiration (ET_t), precipitation (PPT), runoff, soil moisture content, and the vapor pressure deficit on these changes. Results showed that the Dalinor Lake’s area decreased by 18.68% from 2000 to 2020, and was mainly influenced by ET_t, with the Normalized Difference Vegetation Index (NDVI) contributing the most to ET_t (54.02%). In contrast, Ganggeng Lake expanded by 5.68% and was strongly driven by PPT. Compared with Ganggeng Lake, there have been more revegetation activities around Dalinor Lake, resulting in significant increases in NDVI and ET_t, together with widespread declines in soil moisture in its surrounding areas, suggesting that revegetation exerted non-negligible water pressure on Dalinor Lake. These findings can provide valuable information for policymakers to balance large-scale ecological restoration with sustainable water management in semi-arid regions. Full article

Climate change remains among the most pressing environmental challenges confronting the world, exerting profound pressure on both ecological systems and socio-economic development. To advance understanding of the evolution patterns and driving mechanisms governing hydroclimatic systems in arid and semi-arid regions, this study employed an integrated framework encompassing trend testing, change-point detection, periodicity and persistence analysis, and machine learning-based attribution. Focusing on the Mu Us Sandy Land from 1982 to 2023, we systematically investigated the spatiotemporal evolution, periodic characteristics, and driving mechanisms of hydroclimatic factors. Furthermore, future climate risks were assessed using CMIP6 multi-model data. The results showed that: (1) All four variables exhibited positive slopes, but only soil moisture showed a statistically significant long-term wetting trend (β = 0.025 × 10⁻³, p = 0.0008) and a clear global abrupt change in 2011; the upward tendencies of precipitation (p = 0.3946), potential evapotranspiration (p = 0.4970), and surface runoff (p = 0.1097) did not reach the 0.05 significance level. (2) Meteorological elements showed weak periodicity and strong anti-persistence (mean Hurst index = 0.379 for precipitation and 0.222 for PET), whereas hydrological elements exhibited clear seasonal–interannual periods and more random future variability with greater spatial heterogeneity (mean Hurst index = 0.436 for runoff and 0.414 for soil moisture). (3) Monthly changes were mainly associated with local surface processes. Vegetation dynamics were key predictors of precipitation, runoff, and soil moisture, while potential evapotranspiration was dominated by atmospheric demand, with limited influence from large-scale climate indices. (4) Under high-emission scenarios, imbalanced water–heat increases may lead to a higher likelihood of drought conditions. Full article