Search Results (318)

The integration of water resources, water environment, and water ecology (hereinafter “three-water”) is essential not only for addressing the current water crisis but also for achieving sustainable development. Chaohu Lake is an important water resource and ecological barrier in the middle and lower reaches of the Yangtze River, undertaking such functions as agricultural irrigation, urban water supply, and flood control and storage. Studying the performance of “three-water” in the Chaohu Lake Basin will help to understand the pollution mechanism and governance dilemma in the lake basin. It also provides practical experience and policy references for the ecological protection and high-quality development of the Yangtze River Basin. We used the DPSIR-TOPSIS model to analyze the performance of the river–lake system in the Chaohu Lake Basin and employed an obstacle model to identify factors influencing “three-water.” The results indicated that overall governance and performance of the “three-water” in the Chaohu Lake Basin exhibited an upward trend from 2011 to 2022. Specifically, the obstacle degree of driving force decreased by 19.6%, suggesting that economic development enhanced governance efforts. Conversely, the obstacle degree of pressure increased by 34.4%, indicating continued environmental stress. The obstacle degree of state fluctuated, showing a decrease of 13.2% followed by an increase of 3.8%, demonstrating variability in the effectiveness of water resource, environmental, and ecological management. Additionally, the obstacle degree of impact declined by 12.8%, implying the reduced efficacy of governmental measures in later stages. Response barriers decreased by 5.8%. Variations in the obstacle degree of response reflected differences in response capacities. Spatially, counties and districts at the origins of major rivers and their lake outlets showed lower performance levels in “three-water” management compared to other regions in the basin. Notably, Wuwei City and Feidong County exhibited better governance performance, while Feixi County and Chaohu City showed lower performance levels. Despite significant progress in water resource management, environmental improvement, and ecological restoration, further policy support and targeted countermeasures remain necessary. Counties and districts should pursue coordinated development, leverage the radiative influence of high-performing areas, deepen regional collaboration, and optimize, governance strategies to promote sustainable development. Full article

The ecological environment of urban lakes affected by human activities is deteriorating rapidly. As a source and sink of pollutants in the lake environment, sediments have become the focus of environmental assessments. At present, most of the studies only conduct pollution assessments on surface sediments. In this study, taking the typical urban lakes GanTang Lake and NanMen Lake (G&N Lake) as the background, not only is the planar spatial distribution of their nutrient elements, seven kinds of heavy metals, and As analyzed in detail, but risk assessments are also carried out on the pollution conditions at different depths. The causes of pollution at different depths are analyzed. It is found that in this lake, with the increase in depth, the pollution situation decreases slightly, but the pollution of nutrient elements is severe. There is severe pollution of nutrient elements at a depth of up to 1 m in the whole lake sediment. In the sediments with a depth of up to 1 m, more than 90% of the areas in the whole lake are at or above the moderate pollution level of Hg, and more than 70% of the areas are under slight pollution of Cd, resulting in the ecological risk level of the whole lake being at or above the high-risk level. Urban lake sediment management is inherently complex, driven by multifaceted factors where intensive anthropogenic activities constitute the primary pollution source. This research provides insights to guide restoration strategies and sustainable development policies for lacustrine ecosystems. Full article

In recent years, under the influence of climate change and human activities, droughts and floods have occurred frequently in the Yangtze River Basin (YRB), seriously threatening socioeconomic development and ecological security. The topography and climate of the YRB are complex, so it is crucial to develop appropriate drought and flood policies based on the drought and flood characteristics of different sub-basins. This study calculated the water storage deficit index (WSDI) based on the Gravity Recovery and Climate Experiment (GRACE) and GRACE-Follow On (GFO) mascon model, extended WSDI to the bidirectional monitoring of droughts and floods in the YRB, and verified the reliability of WSDI in monitoring hydrological events through historical documented events. Combined with the wavelet method, it revealed the heterogeneity of climate responses in the three sub-basins of the upper, middle, and lower reaches. The results showed the following. (1) Compared and verified with the Standardized Precipitation Evapotranspiration Index (SPEI), self-calibrating Palmer Drought Severity Index (scPDSI), and documented events, WSDI overcame the limitations of traditional indices and had higher reliability. A total of 21 drought events and 18 flood events were identified in the three sub-basins, with the lowest frequency of drought and flood events in the upper reaches. (2) Most areas of the YRB showed different degrees of wetting on the monthly and seasonal scales, and the slowest trend of wetting was in the lower reaches of the YRB. (3) The degree of influence of teleconnection factors in the upper, middle, and lower reaches of the YRB had gradually increased over time, and, in particular, El Niño Southern Oscillation (ENSO) had a significant impact on the droughts and floods. This study provided a new basis for the early warning of droughts and floods in different sub-basins of the YRB. Full article

The Yangtze River Economic Belt (YEB), serving as a pivotal transportation corridor connecting eastern and western China and a national strategic development hub, plays a central role in driving high-quality economic development (HQAED) across the country. Based on the new development paradigm with emphasis on green transformation and transportation integration, this study proposes a comprehensive evaluation framework for an HQAED index (HQAED) across five core dimensions. Employing the entropy-weighted CRITIC method to quantify provincial HQAED values, combined with Dagum–Gini coefficient analysis to examine regional inequality patterns and determinants, and complemented by kernel density estimation (KDE) for temporal dynamics analysis, this research reveals four key findings: (1) There are significant disparities in HQEDI levels across the YEB, with a clear east–west gradient: the lower reaches > middle reaches > upper reaches. (2) While the dimensions of green development and shared development have shown steady growth despite initial disadvantages, the openness dimension faces structural challenges that require particular attention. (3) The overall Gini coefficient fluctuates between 0.068 and 0.094, indicating moderate regional disparities with relatively limited inequality. (4) The rightward shift in the HQEDI kernel density curves confirms overall progress, but also highlights widening disparities in the upstream regions and growth stagnation in the midstream areas. Practically, the entropy–CRITIC fusion methodology offers a transferable framework for emerging economies measuring sustainability-transition progress, while the quantified “green transportation empowerment” effects provide actionable levers for policymakers to optimize ecological compensation mechanisms and cross-regional infrastructure investments. Full article

With climate warming, the global precipitation patterns have undergone significant changes, which will profoundly impact flood–drought disaster regimes and socioeconomic development in key regions of human activity worldwide. The convergence zone of the Indian Ocean monsoon and Pacific monsoon in China covers most of the middle and lower reaches of the Yangtze River (MLRYR), which is located in the transitional area of the second and third steps of China’s terrain. Changes in precipitation patterns in this region will significantly impact flood and drought control in the MLRYR, as well as the socioeconomic development of the MLRYR Economic Belt. In this study, Huaihua area in China was selected as the study area to study the characteristics of regional precipitation change, and to analyze the evolution in the trends in annual precipitation, extreme precipitation events, and their spatiotemporal distribution, so as to provide a reference for the study of precipitation change patterns in the intersection zone. This study utilizes precipitation data from meteorological stations and the China Meteorological Forcing Dataset (CMFD) reanalysis data for the period 1979–2023 in Huaihua region. The spatiotemporal variation in precipitation in the study area was analyzed by using linear regression, the Mann–Kendall trend test, the moving average method, the Mann–Kendall–Sneyers test, wavelet analysis, and R/S analysis. The results demonstrate the following: (1) The annual precipitation in the study area is on the rise as a whole, the climate tendency rate is 9 mm/10 a, and the precipitation fluctuates greatly, showing an alternating change of “dry–wet–dry–wet”. (2) Wavelet analysis reveals that there are 28-year, 9-year, and 4-year main cycles in annual precipitation, and the precipitation patterns at different timescales are different. (3) The results of R/S analysis show that the future precipitation trend will continue to increase, with a strong long-term memory. (4) Extreme precipitation events generally show an upward trend, indicating that their intensity and frequency have increased. (5) Spatial distribution analysis shows that the precipitation in the study area is mainly concentrated in the northeast and south of Jingzhou and Tongdao, and the precipitation level in the west is lower. The comprehensive analysis shows that the annual precipitation in the study area is on the rise and has a certain periodic precipitation law. The spatial distribution is greatly affected by other factors and the distribution is uneven. Extreme precipitation events show an increasing trend, which may lead to increased flood risk in the region and downstream areas. In the future, it is necessary to strengthen countermeasures to reduce the impact of changes in precipitation patterns on local and downstream economic and social activities. Full article

A lake is a sink, source, and converter of phosphorus, and its ability to intercept phosphorus in water bodies is receiving increasing attention. In this study, the Nanyi Lake sediment in the middle and lower reaches of the Yangtze River basin was taken as the research object, and the phosphorus adsorption capacity and influencing factors of the sediment in the basin were investigated through a control variable experiment. The adsorption capacities of sediments at the sample points are L₁ > L₃ > L₂, with maximum values of 372.41 mg/kg, 332.53 mg/kg, and 346.27 mg/kg, respectively. Equilibrium adsorption is reached at approximately 5 h for L₁ and L_2, and 10 h for L₃. The interaction between sediment and phosphorus involves physical adsorption and mono-layer adsorption. The increase in temperature does not promote phosphorus migration from overlying water to sediments, but instead triggers phosphorus release from sediments, indicating an exothermic process for phosphorus adsorption on sediments. When the phosphorus concentration in overlying water is below and above 1 mg/L, increasing disturbance intensity results in enhanced phosphorus adsorption and release in sediments, respectively. The presence of humus in the overlying water, especially humic acid compared with fulvic acid, causes stronger adsorption of phosphorus on sediments. Overall, this study contributes to our understanding of phosphorus adsorption characteristics and mechanisms in Nanyi Lake sediments, providing valuable insights for managing and conserving this freshwater ecosystem. Full article

Mixed sowing of green manure in winter is a unique farming mode in southern China, which has the potential to replace or partially replace nitrogen fertilizer. To investigate how mixed sowing of green manure combined with nitrogen reduction regulates soil organic carbon and its fractions, this study was conducted in the 3/4 Chinese milk vetch × 1/4 rapeseed farming mode, without nitrogen fertilizer (CK), 100% N fertilizer (150 kg ha⁻¹, N1MR), 20% N fertilizer reduction (120 kg ha⁻¹, N2MR), 40% N fertilizer reduction (90 kg ha⁻¹, N3MR), and 60% N fertilizer reduction (60 kg ha⁻¹, N4MR). The main results were the N2MR treatment could guarantee stable and increased rice yield. The N1MR and N2MR treatments were more conducive to the accumulation of TOC. The N4MR and N2MR treatments were more conducive to the increase and accumulation of AOC and DOC. The effective spikes were positively correlated with TOC and ROC. The grain number per panicle was positively correlated with DOC. The seed-setting rate was positively correlated with ROC. Overall, mixed sowing of Chinese milk vetch and rapeseed combined with 20% nitrogen reduction ensures a stable yield and increase in rice. Nitrogen reduction by 60% and 20% is beneficial to the increase and accumulation of TOC, AOC, and DOC in soil. Full article

Aromia bungii Faldermann (Coleoptera, Cerambycidae) is one of the most serious stem-boring pests that infests Rosaceae fruit trees and ornamental trees. This study, based on occurrence data for this species, employed the MaxEnt model and meta-analysis method to predict the distribution range and centroid movement of A. bungii under the current and future climates in China. The study also analyzed the impact of environmental variables on its distribution. The meta-analysis results revealed that A. bungii has the highest distribution density within the altitude range of 0 to 300 m. The MaxEnt model identified six key environmental variables influencing the distribution of A. bungii, namely the minimum temperature of the coldest month (bio6), mean temperature of the wettest quarter (bio8), precipitation of the wettest month (bio13), precipitation of the driest month (bio14), precipitation seasonality (coefficient of variation) (bio15), and altitude. Under the current climate conditions, the most suitable distribution range of A. bungii is located between 92.6–120.38° E and 16.17–44.46° N, with highly suitable areas predominantly found in the North China Plain, the Shandong Hills, the area around the Bohai Sea, and the middle–lower reaches of the Yangtze River, covering a total area of 41.43 × 10⁴ km². Scenarios related to the future climate indicate a shift in the suitable habitats of A. bungii towards higher latitudes, with the centroid of the potentially suitable area shifting towards the northeast. This study provides supporting information for the control and management of this pest. Full article

As regulations ban legacy PFASs, many emerging PFASs are being developed, leading to their release into the aquatic environment and drinking water. However, research studies on these emerging PFASs in drinking water are limited, and current standards only cover a few legacy PFASs, leaving many emerging PFASs unregulated and their toxicity unknown. Therefore, a machine learning-based suspect screening combined with target screening was employed to comprehensively identify and quantify both legacy and novel PFASs in drinking water from the Yangtze River Delta, and their potential sources of contamination were determined through pollutant profile analysis. A total of 30 PFASs were identified, including 16 legacy and 14 novel PFASs, categorized into 11 classes. Quantitative and semi-quantitative analyses revealed that the maximum concentrations of 30 PFASs ranged from <LOQ (limit of quantification) to 48.92 ng/L. Notably, PFPeA (48.92 ng/L), perfluorobutanoic acid (PFBA, 44.83 ng/L), perfluorooctanoic acid (PFOA, 37.72 ng/L), perfluorobutanesulfonic acid (PFBS, 26.77 ng/L), and bis(trifluoromethanesulfonyl)imide (HNTf2, 15.02 ng/L) exhibited higher concentrations compared to other PFASs. The pollutant profile analysis suggested that PFASs in the Yangtze River Delta’s drinking water are more likely to originate from pollution in the upper and middle reaches of the Yangtze River rather than from local industrial emissions. Then, the identified PFASs were prioritized by integrating the PBT (persistence, bioaccumulation, and toxicity) properties of PFASs with environmental exposure data. In the prioritization and risk assessment process, ten high-concern PFASs had Risk Indexes (RIs) higher than those of ref-PFOA and ref-PFOS, including eight legacy PFASs and two novel PFASs. The drinking water of the Yangtze River Delta originates from the surface water of the lower Yangtze River, which accumulates pollutants from its upper and middle reaches, affecting the health of over 20 million people. Our findings indicated the presence of emerging PFASs in the region’s drinking water and demonstrated conceptual models for integrating chemical information from suspect screening with toxicity prediction and risk assessment. Although the current levels of emerging PFASs are relatively low, legacy PFASs still dominate. Further research is needed to identify, monitor, and assess the health and environmental risks of emerging PFASs. Full article

Fishery bycatch is a significant threat to biodiversity, with birds being frequent casualties. Current research mainly focuses on seabird bycatch in large-scale marine fisheries, while bird bycatch in inland freshwater areas remains poorly understood. Crayfish traps are extensively used in China’s freshwater environments, but their ecological impacts on birds are overlooked due to monitoring difficulties. Through iEcology approaches, we collected and analyzed 146 bird bycatch incidents in crayfish traps from Chinese social media platforms between September 2010 and December 2023. The results revealed 420 identified birds from 62 species (11 orders, 24 families), predominantly omnivorous and carnivorous, while 106 individuals could not be identified. Cases were concentrated in the middle and lower reaches of the Yangtze River, showing significant positive correlations with water area ratio and aquaculture production (p < 0.001). During fishing seasons, the number of cases, species, and individuals were significantly higher (p < 0.001), though mortality rates increased in off seasons. The middle and lower reaches of the Yangtze River are main production areas of red swamp crayfish (Procambarus clarkii) and Chinese mitten crab (Eriocheir sinensis), where intensive use of crayfish traps may increase bird bycatch risk. Despite existing regulations, systematic supervision is needed to minimize ecosystem impacts. Full article

This study investigated the impact of land use change on water quality in the Xinxian River Basin amidst rapid urbanization. While previous studies have predominantly focused on single-scale buffer analyses or specific land use types, the interactions between multi-scale riparian buffers and diverse land cover dynamics remain rarely understudied, particularly in a rapidly urbanizing county in the Yangtze River Basin. Land use type data for the Xinxian River Basin in 2000, 2010, and 2020 were acquired using GIS technology, and subsequent analysis quantified land use pattern changes over this 20-year period. Additionally, 2023 land use data for riparian buffer zones (50 m, 100 m, 200 m, 400 m, and 600 m) were obtained via GIS and subjected to Redundancy Analysis (RDA) with 2023 water quality monitoring data to evaluate the impact of land use on water quality. The results revealed significant land use conversion dynamics, particularly between natural and anthropogenic cover types. Forest cover exhibited negative correlations with riverine nutrient concentrations, while built-up areas displayed strong positive associations, especially at finer scales (50–100 m buffers). Notably, the dominant influencing factor shifted from built-up land at smaller buffer scales (50–100 m) to forest land at larger scales (400–600 m), whereas agricultural land showed no significant correlation. These findings highlight scale-dependent relationships between land use and aquatic ecosystems, emphasizing the critical role of spatial planning in mitigating urbanization impacts. The work is conducive to the sustainable development of Longgan Lake National Wetland Nature Reserve and the protection of water ecology in the middle and lower reaches of the Yangtze River. Full article

As a pivotal ecological–economic nexus in China, the Yangtze River Basin (YRB)’s spatiotemporal evolution of habitat quality (HQ) profoundly influences regional sustainable development. This study establishes a tripartite analytical framework integrating remote sensing big data, socioeconomic datasets, and ecological modeling. By coupling the InVEST and PLUS models with Theil–Sen median trend analysis and Mann–Kendall tests, we systematically assessed HQ spatial heterogeneity across the basin during 2000–2020 and projected trends under 2030 scenarios (natural development (S1), cropland protection (S2), and ecological conservation (S3)). Key findings reveal that basin-wide HQ remained stable (0.599–0.606) but exhibited marked spatial disparities, demonstrating a “high-middle reach (0.636–0.649), low upper/lower reach” pattern. Urbanized downstream areas recorded the minimum HQ (0.478–0.515), primarily due to landscape fragmentation from peri-urban expansion and transportation infrastructure. Trend analysis showed that coefficient of variation (CV) values ranged from 0.350 to 2.72 (mean = 0.768), indicating relative stability but significant spatial variability. While 76.98% of areas showed no significant HQ changes, 15.83% experienced declines (3.56% with significant degradation, p < 0.05) concentrated in urban agglomerations (e.g., the Wuhan Metropolitan Area, the Yangtze River Delta). Only 7.18% exhibited an HQ improvement, predominantly in snowmelt-affected Qinghai–Tibet Plateau regions, with merely 0.95% showing a significant enhancement. Multi-scenario projections align with Theil–Sen trends, predicting HQ declines across all scenarios. S3 curbs decline to 0.33% (HQ = 0.597), outperforming S1 (1.07%) and S2 (1.15%). Nevertheless, downstream areas remain high-risk (S3 HQ = 0.476). This study elucidated compound drivers of urbanization, agricultural encroachment, and climate change, proposing a synergistic “zoning regulation–corridor restoration–cross-regional compensation” pathway. These findings provide scientific support for balancing ecological protection and high-quality development in the Yangtze Economic Belt, while offering systematic solutions for the sustainable governance of global mega-basins. Full article

Aiming at the problem that rotary tiller knife rollers are prone to entanglement with straw in the wet and sticky soil environment of rice fields in the middle and lower reaches of the Yangtze River in China, an antitangling and sticking cutter was designed. The cutter reduces knife roller entanglement in order to reduce rotary tiller energy consumption and improve work efficiency, and its effectiveness was verified through theoretical analysis, discrete element simulation, and field trials. The design’s validity was verified through theoretical analysis, discrete element simulation, and field tests. The blade inclination design was completed through motion force analysis, and the tool geometry was optimized with a 36.87° inclination baffle and staggered arrangement. A simulation model of the soil–straw–rotary tillage knife interaction was established and we used the discrete element method to analyze the variation in torque between the antisticking knife and the China standard rotary tillage knife (IT245) at four different cutter shaft rotational speeds. In the simulation, the average torque for the antisticking knives was smaller than that of the national standard rotary tillage knives, with reductions of 37.1%, 52.1%, 52.8%, and 50.0%, respectively, demonstrating a remarkable effect. Field tests showed that the average operational efficiency of the antisticking knife was 0.57 hm²/h, with an operation qualification rate of 95.72%. The average torque results from simulation (with and without the antisticking knife) and field tests were analyzed, yielding correlation coefficients of 0.994 and 0.973 for the change curves of average torque between the antisticking knife and the national standard rotary tillage knife. This result confirms the accuracy of the simulation model and the consistency between the simulation and field test results. This study can provide some references for the design and test of antisticking of rotary tillers. Full article

This study aimed to investigate the relationships between the mechanical properties of plant roots and the soil reinforcement characteristics of the dominant species in the dominant riparian plants under various flooding durations. The objective was to comprehensively evaluate the optimal flooding duration for each plant under various flooding durations. This research was conducted to provide a scientific basis for plant restoration efforts. The primary focus of the study was on common species found in the middle and lower reaches of the Yangtze River, including Carex, Cynodon, and Eleusine. These species were cultivated in a local field setting and subsequently subjected to flooding tests of varying durations. The diameter of the root system gradually increases with prolonged flooding duration, while other root morphologies exhibit a trend of initially increasing and then decreasing. The flooding environment significantly influences the relationship between root diameter and the mechanical properties of the roots. This condition adversely affects Carex, whereas it has a beneficial impact on Cynodon and Eleusine. During the early stages of flooding, the shear strength of the plant root–soil complex increases; Carex is optimally applied in the restoration and protection of areas subjected to three to four months of flooding, with its ornamental value being particularly pronounced. Cynodon performs best in areas with up to six months of flooding, Eleusine is especially effective in regions with less than two months of flooding. Full article

The evaluation of water resource carrying capacity (WRCC) is crucial for guiding regional water management. This study established a WRCC evaluation index system and standards for the middle and lower Yangtze River, covering four subsystems: water resources, and social, economic, and ecological dimensions. The study improved the matter–element extension model by introducing triangular fuzzy numbers. The enhanced model was then used to assess the WRCC of seven provinces in the middle and lower Yangtze (2015–2023). Furthermore, GIS was used to examine the spatiotemporal variations and driving factors of WRCC. The main conclusions are as follows: (1) from 2015 to 2023, the evaluated level of WRCC in the Yangtze River’s middle and lower reaches remained stable and improved overall. Among them, the WRCC of Shanghai rose most significantly, from level III to level I. Zhejiang’s WRCC remained stable at level II, while Hubei and Hunan remained stable at level III, but with a trend toward improvement. Jiangsu’s WRCC fluctuated significantly. (2) The evaluation values of the subsystems in each region show a certain level of volatility. The water resource subsystem remained relatively stable in most regions, the social subsystem showed some variability, and both the economic and ecological subsystems developed well, showing positive effects in economic development and ecological protection in various regions. (3) The water resource subsystem had the greatest influence on WRCC. Per capita water resources, the urbanization rate, the greening coverage rate in built-up areas, and per capita GDP have the most significant impact on the WRCC in the Yangtze River’s middle and lower reaches. Full article