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- 摘要：High-temperature Ca-based sorbents are considered promising candidates for industrial flue-gas CO2 capture due to their abundant feedstocks, broad operating temperature window, and high uptake capacity. However, a key limitation of Ca-based sorbents is rapid deactivation at high temperatures, leading to a sharp decline in adsorption capacity with the increase in cyclic number. To address this issue, CO2 sorbents were prepared using calcium gluconate as the Ca-based precursor and aluminum nitrate as a modifying agent. Their CO2 capture performance was then evaluated by simultaneous thermal analysis. The results show that, the calcium gluconate sorbent doped with 10% aluminum nitrate exhibited good cyclic stability during repeated CO2 capture/regeneration. After 20 cycles, the CO2 capture capacity remained at 8.92 mmol/g, and the cumulative CO2 uptake over 20 cycles reached 194.9 mmol/g. In comparison, the undoped calcium gluconate sorbent delivered a CO2 capture capacity of 7.39 mmol/g at the 20th cycle, with a cumulative uptake of 206.9 mmol/g over 20 cycles. For commercial CaO, the corresponding values were 3.64 mmol/g and 76.1 mmol/g, respectively. Notably, in a 100-cycle CO2 capture/regeneration test, the 10% aluminum nitrate-modified calcium gluconate sorbent still achieved a CO2 capture capacity of 7.83 mmol/g at the 100th cycle, which corresponds to 43.84% of the theoretical maximum uptake of pure CaO. These findings provide strong evidence that calcium gluconate-based sorbents doped with 10% aluminum nitrate possess enhanced CO2 adsorption performance and improved resistance to sintering.关键词：carbon capture;calcium gluconate;aluminum nitrate modification;CO2 capture capacity4|1|0更新时间：2026-04-17
- 摘要：Discontinuous vegetation patch restoration technology, which optimizes vegetation spatial layout, can effectively regulate river flow structure, promote material cycling, and enhance biodiversity. This study aims to systematically investigate the hydrodynamic regulation mechanisms of discontinuous vegetation patches and their ecological effects, providing a quantitative basis for ecological river design.A combined approach of flume experiments and large eddy simulation (LES) was employed. The flume experiments were conducted in a 20 m×0.8 m×0.5 m recirculating flume with a 1‰ bed slope, using artificial reed vegetation (height 0.25 m, diameter 8 mm). A 2×2 factorial experimental design was adopted with four distinct cases, varying vegetation density (254 and 423 plants/m²), gap length (0.5 and 1.1 m), and Reynolds number (42 900 and 89 374). Acoustic Doppler velocimetry (ADV) was used to measure three-dimensional instantaneous velocities. For LES, the Smagorinsky subgrid-scale model (Cs=0.1) was employed with an immersed boundary method to represent rigid vegetation stems. The computational domain measured 15 m×0.8 m×0.6 m. Inlet boundary conditions incorporated a synthetic eddy method to generate realistic turbulent inflow. Grid independence was verified using three structured grids (18.13 million, 147 million, and 254 million cells), with the medium grid (147 million cells) selected for all simulations, ensuring near-wall resolution of y+<3.2. Model validation against experimental data demonstrated excellent agreement (R2 > 0.96).Results revealed that vegetation density, gap length and Reynolds number are key factors governing flow velocity distribution. Under low-density conditions (N=254 plants/m²), longitudinal velocity decreased by 32% within vegetation zones and by approximately 58% within gap zones. High-density conditions (N=423 plants/m²) combined with high Reynolds number (Re=89 374) intensified the vertical velocity gradient across the canopy, with gap zone velocities (z/h<1) decreasing by an additional 13.6%–27.4% compared to high-density low-Reynolds conditions, creating favorable conditions for material deposition and biological habitat formation. Recirculation zone length expanded with increasing vegetation density, reaching a maximum of 0.6 m. Long gaps (L=1.1m) facilitated more stable velocity distribution and promoted flow recovery compared to short gaps (L=0.5 m), with gap zone velocities reduced by approximately 25.8% and depth-averaged velocity recovering to 0.98UU in the middle of the gap. Multi-patch arrangements exhibited cumulative effects, with flow velocities within the fourth vegetation patch decreasing by 15%–33% relative to the first patch. High Reynolds number significantly enhanced shear layer intensity at the canopy top, increasing turbulent kinetic energy by 45% and further reducing gap zone velocities. The LES successfully captured complex flow structures including canopy deceleration (15%–33% reduction), canopy acceleration (31%–34% increase), recirculation zones, and near-bed velocity enhancement induced by horseshoe vortices around vegetation stems.The optimized vegetation patch layout derived from experimental and numerical findings (N=250 plants/m², L=1.0–1.5 m) was applied to the Yulong River restoration project in Wuhan. Post-implementation monitoring over three years demonstrated significant improvements: water quality improved from Class V to Class IV and bank erosion depth decreased by 67%. This study reveals the "resistance regulation–recirculation habitat–ecological response" cascade mechanism of discontinuous vegetation patches, providing quantitative insights for vegetation parameter optimization in ecological river design. Future research directions include investigation of vegetation flexibility, non-uniform spatial arrangements, and coupled multi-factor effects on flow characteristics.关键词：ecological river;discontinuous vegetation patches;large eddy simulation;longitudinal velocity;recirculation zone;hydrodynamic regulation6|16|0更新时间：2026-04-10
- 摘要：Coastal areas are prone to experiencing the combined effects of rainfall, tidal levels, and storm surges, which can lead to complex flood disasters with intricate mechanisms. To deeply reveal the evolutionary characteristics and driving mechanisms of complex flood disasters in coastal plain river networks, the Qianshan River Basin in Guangdong Province was selected as the research object. Based on the conditional risk probability model, eight typical combinations of rainfall and tide encounters were identified and constructed. A one-dimensional and two-dimensional hydrological and hydrodynamic coupling model was built using basic data such as DEM and land use types. The model was validated by combining runoff coefficients and historical flood area data. The results showed that the model could accurately reflect the hydrological response and waterlogging characteristics of the study area, and the overall accuracy met the research requirements. Based on this, numerical simulations were conducted for eight typical scenarios involving rain and tide encounters. Flood grade classification standards were introduced to grade flood risks, systematically analyzing and revealing the characteristics of flood inundation and the spatial distribution patterns of risks in coastal plain river networks under rain and tide encounters. The research results indicate that under different scenarios of rain and tide encounters, the inundated areas are primarily distributed in Tanzhou Town, Sanxiang Town, and the surrounding areas of the Hongwanyong water outlet. As the tide level and rainfall recurrence period increase, both the total inundated area and the inundated areas of various water depth levels in the study area show a continuous growth trend. Moreover, the newly inundated areas are mainly concentrated in Tanzhou Town, indicating that this area has a high sensitivity to changes in rain and tide. The flood risk distribution is dominated by low and high risk levels, with medium risk areas accounting for a relatively small proportion. The high-risk areas are primarily concentrated in Tanzhou Town and significantly expand as the intensity of rain and tide increases. It is worth noting that seawater inundation will significantly expand the flood inundation range and have a pronounced amplification effect on the expansion of high-risk areas, which is one of the key factors affecting the spatial pattern of regional flood risk. In summary, this study reveals the driving mechanism of tidal level and rainfall variation on the evolution of compound floods in coastal plain river networks, and provides important scientific basis and technical support for flood disaster risk assessment and flood control and drainage engineering planning in such areas.关键词：scenario simulation;hydrodynamic model;compound flood;risk assessment;plain river network10|9|0更新时间：2026-04-10
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Study on Variation of Flood-Tidal Water Surface Profiles in Main Channel of the Xijiang River Delta AI导读
摘要：The main channels of the Xijiang River Delta are important flood discharge passages of the Pearl River, a major river in southern China.Both banks are located in the hinterland of the Guangdong-Hong Kong-Macao Greater Bay Area.Affected by natural climate variability and human activities, the flood tide water surface profile (FTWSP) of the main channels in the Xijiang River Delta has shown varying trends over different periods. This study starts from key influencing factors in FTWSP calculation—such as initial water level, design discharge, and channel topography—applies the Mann-Kendall test method to conduct trend analysis on water level, tidal level, and flood peak discharge at key hydrological stations, and collects riverbed topography data from different periods to analyze riverbed evolution. A one-dimensional hydrodynamic model is constructed using MIKE+ software to investigate new FTWSPs under changing boundary conditions.The results show: ① The water levels at Makou and Tianhe stations in the upper and middle reaches of the channel show a decreasing trend, while those at Da'ao and Zhuyin stations in the middle and lower reaches show little change, and water levels at the estuary stations, Denglongshan and Sanzhao, exhibit a significant rising trend. The flood peak discharge at Makou Station shows an increasing trend; ② The main channel of the Xijiang River has experienced continuous channel deepening from 1980 to 2020. The degree of channel deepening in the Xihai Channel is relatively moderate compared to its upstream, while the Modaomen Channel experienced severe incision from 1980 to 1999, followed by a slow rebound from 1999 to 2020; ③ Compared with historical FTWSPs, the FTWSP in the Modaomen Channel has risen, while those in the main Xijiang River channel and Xihai Channel remain generally unchanged. The updated FTWSP provides technical support for the construction of key embankments, navigation infrastructure, and storm surge defense along the river.关键词：Mann-Kendall test;riverbed evolution;MIKE model;flood tide water surface profile;Xijiang River Delta10|11|0更新时间：2026-04-10 - 摘要：The development of low-rank coalbed methane in the Fukang Block of Xinjiang has entered a bottleneck stage, necessitating an urgent enhancement and acceleration of exploration and exploitation initiatives. However, the inefficient methane desorption process within the microscopic pores of low-rank coal, combined with poorly understood adsorption and desorption mechanisms, has resulted in challenges such as low initial production rates, short durations of stable production, and suboptimal development performance in newly commissioned coalbed methane wells. To address challenges such as low recovery rates and the difficulty in mobilizing adsorbed-phase methane, low-rank coal from the Fukang block was selected as the study subject. The coal’s pore size distribution, molecular formula (C100H108O16N3) and molecular structure were characterized using elemental analysis, Low-temperature N2 adsorption, XRD, FT-IR, and 13C-NMR, enabling the construction of a slit-shaped pore model. Adsorption behavior under varying slit widths, pressures, and temperatures was simulated via the grand canonical Monte Carlo (GCMC) method, and a non-isothermal Langmuir equation was fitted to describe methane adsorption in the Fukang coal. Subsequently, isothermal depressurization desorption processes were analyzed using molecular dynamics simulations based on adsorbed methane configurations in slit pores at 10 MPa and 308 K. Key findings include: (1) The dominant molecular architecture of Fukang low-rank coal consists of aliphatic chains linking aromatic rings (benzene/naphthalene), functionalized with carboxyl, hydroxyl, and pyrrole groups; (2) At slit widths below 2 nm, strong nano-confinement deepens the adsorption potential well, leading to a “single-peak” methane density distribution, with micropore filling as the primary storage mechanism; above 2 nm, the density profile transitions to a “double-peak” pattern accompanied by a non-adsorption zone, indicating a shift toward surface-dominated adsorption; (3) Under high-pressure conditions, elevated temperature reduces adsorption potential energy, thereby promoting methane desorption—this effect is more pronounced in pores >2 nm, where both micropore filling and surface adsorption co-dominate, the central region of the slit still exhibits adsorbed methane; (4) In narrow slit (1 nm), high desorption energy barriers and low diffusion coefficients (0.075 Å2/ps) lead to significant desorption hysteresis, whereas wider slit (3 nm) exhibit lower energy barriers and higher diffusivity (0.647 Å2/ps), eliminating hysteresis. In conclusion, reducing the adsorption/desorption energy barrier in low-rank coal micropores is crucial for enhancing methane desorption efficiency and diffusivity. A synergistic strategy combining depressurization, aperture expansion, and thermal stimulation—implemented through pre-injected CO₂ combined with self-heating fracturing fluids, followed by well-pattern thermal fluid displacement—represents a promising pathway for improving recovery rates in low-rank coalbed methane reservoirs in the Fukang block.关键词：Fukang block;low-rank coal;coalbed methane;adsorption and desorption;molecular simulation;micropore filling19|9|0更新时间：2026-04-10
- 摘要：The scissors difference regulation demand formed by the persistent extreme fluctuations of new energy output and the surge of power load under extreme weather has become a huge challenge for the power and energy balance of the power grid. It is of great significance to quantify the regulation capacity of large watershed cascade hydropower stations for the continuous extreme fluctuations of new energy. Using the historical actual daily output data of new energy in a power grid in Southwest China from 2016 to 2024, six types of extreme fluctuations of new energy were identified by the double-threshold definition method, and the load fluctuation law during the occurrence of extreme events was obtained. The potential trends and correlations between extreme fluctuations of new energy and changes in load demand were revealed through linear equation fitting and Pearson correlation analysis. On this basis, considering the complex hydraulic and electrical connections, a quantitative evaluation model for the regulation capacity of cascade hydropower stations for the associated extreme fluctuations of load and new energy was established, which was efficiently solved by the Gurobi solver. Based on different load fluctuation scenarios, the regulation capacity of cascade hydropower under the working conditions of drawdown period and impoundment period was analyzed. The results show that extreme wind power fluctuations and extreme photovoltaic fluctuations occur 22 times and 20 times per year on average, respectively, and combined wind-solar extreme fluctuations occur 3 times per year on average. Among all extreme events, the probability that the direction of load fluctuation is opposite to that of extreme new energy fluctuation is about 48%, and only the extreme low photovoltaic fluctuation amplitude has an obvious downward trend and negative correlation with the load fluctuation amplitude. When cascade hydropower stations are in the drawdown period or impoundment period with moderate water levels, they have a certain regulation capacity for both associated extreme high and low fluctuations of load and new energy, and the regulation capacity in the impoundment period is stronger. The overall regulation capacity for combined wind-solar extreme fluctuations is weaker than that for single new energy extreme fluctuations. Therefore, when associated extreme fluctuations of load and new energy occur, cascade hydropower stations can provide certain support capacity for the power grid. However, for more extreme reverse fluctuations of load and new energy, it is necessary to resort to energy storage and other means, which provides a decision-making basis for the power grid to defend against such extreme events.关键词：Source-load matching;cascade hydropower stations;Extreme fluctuations of new energy;Regulation capacity;Quantitative evaluation12|30|0更新时间：2026-04-10
- 摘要：Microplastic pollution has emerged as a pervasive environmental concern in marine ecosystems worldwide. However, the long-term spatiotemporal evolution and transport dynamics of microplastics in estuarine environments remain inadequately constrained. As a major conduit for terrestrial inputs to the ocean, the Pearl River Estuary experiences intense anthropogenic pressures and highly complex hydrodynamic regimes, making it a critical natural laboratory for investigating the accumulation, migration, and redistribution of microplastics. Elucidating the spatial configuration of high-concentration zones and their associated transport pathways is therefore essential for advancing process-level understanding and informing targeted pollution management. In this study, monthly inversion-derived microplastic concentration data from 2019 to 2025 were analyzed to characterize the spatiotemporal distribution and migration patterns of microplastics in the Pearl River Estuary. High-concentration aggregation zones were delineated using the density-based spatial clustering of applications with noise (DBSCAN) algorithm. The annual displacement of microplastic concentrations was quantified via concentration-weighted centroid analysis, while directional trends and spatial dispersion were further evaluated using the standard deviation ellipse model. Additionally, kernel density estimation (KDE) was employed to identify persistent transport pathways and to assess their structural evolution over time. The results reveal pronounced spatial heterogeneity and distinct temporal variability in microplastic distributions. High-concentration zones predominantly formed a continuous belt along the western channel of Lingdingyang, whereas the eastern region exhibited a more fragmented pattern characterized by dispersed patches. Over the study period, the centroid of microplastic concentration exhibited a cumulative displacement of approximately 73 km, indicating substantial migration of pollution hotspots. Concurrently, the coherence of transport pathways progressively weakened, accompanied by enhanced local recirculation and the emergence of vortex-like structures, suggesting increasing complexity in estuarine transport processes. Peak concentrations, represented by the 95th percentile (P95), were observed in 2024, exceeding 200 mg·L⁻¹—approximately 57% higher than levels recorded in 2020. Overall, this study provides a quantitative assessment of the long-term spatiotemporal evolution of microplastic pollution in the Pearl River Estuary. By integrating concentration inversion, spatial clustering, centroid tracking, and kernel density analysis, the results elucidate not only the distributional characteristics of microplastic hotspots but also their migration trajectories and transport evolution under dynamic estuarine forcing. These findings advance the mechanistic understanding of microplastic accumulation in estuarine systems and provide a robust scientific basis for future monitoring, risk assessment, and the development of region-specific management strategies. Moreover, the methodological framework established herein is readily transferable to other estuarine environments subject to similar land–sea interactions and anthropogenic influences.关键词：microplastics;Spatiotemporal Evolution;Transport Paths;Spatial Clustering;Pearl River estuary18|18|0更新时间：2026-04-07
- 摘要：Urban waterlogging occurs when surface water cannot be drained in a timely manner due to heavy rainfall. This issue not only disrupts residents' travel but also causes significant economic losses. With rapid urbanization, waterlogging and its associated disaster impacts pose a great challenge to urban safety. The assessment of socio-economic losses caused by urban waterlogging often requires detailed classification of urban land use in the inundated area. Shenzhen, as one of the core cities in the Guangdong-Hong Kong-Macao Greater Bay Area (GBA), is densely populated and economically developed. Under extreme climatic conditions, urban waterlogging has become a common issue. This paper takes the western part of Shenzhen city as a typical study area and simulates waterlogging inundation processes under multiple scenarios, including design rainstorms with return periods of 2a, 5a, 10a, 20a, 50a and 100a, and multiple engineering situations such as reservoir flood discharge, and deep tunnel drainage. A one-dimensional (1D) and two-dimensional (2D) coupled model of urban waterlogging was used for these simulations. By classifying urban land use and assets such as buildings and cars according to different land use types during the inundation processes, this study conducted a refined asset loss assessment by establishing multiple types of inundation depth-asset loss curves. The results demonstrate that as the design return period of rainstorm increases from 2a to 100a, the disaster-affected area significantly expands from 3.98 km2 to 6.75 km2, and asset losses dramatically increase from 255-million-yuan to 912-million-yuan, Inundation depths are primarily less than 0.5 m accounting for 54.1% -64.7% of the total area affected. Roads make up the majority of the inundation land use types, accounting for 90.2% -91.5%. Asset losses are mainly concentrated in residential land and vehicles, accounting for 25.8%-35.2% and 18.0%-33.7%, respectively. Furthermore, the study evaluates the impact of water engineering plans: the inundated area and asset losses increase by 6.1% and 5.6%, respectively, under reservoir flood discharge scenarios, while asset losses decrease by 21.0% when considering deep tunnel drainage projects. These findings provide a scientific basis for assessing waterlogging losses and implementing local flood prevention and mitigation strategies in coastal cities under multiple extreme climate conditions and engineering plans.关键词：waterlogging simulation;Asset loss;Design rainstorm;land use;deep tunnel engineering;Guangdong-Hong Kong-Macao Greater Bay Area13|15|0更新时间：2026-04-07
- 摘要：River health assessment is an important method of understanding the state of a river and is fundamental to the sustainable development of river ecosystems. Traditional river health assessment frameworks primarily rely on panel data, such as monitoring points and statistical records, for evaluation, with indicators and data sources predominantly drawn from these sources. However, this type of data often reflects information from specific sections of the river, localised areas or survey points, and may lack the spatial data required to represent the river as a whole and its associated regions. More effective integration of panel and remote sensing data can provide a more comprehensive evaluation and a more accurate reflection of the actual health status of rivers. In this study, three river health assessment frameworks were applied to the Changsha section of the Xiangjiang River Basin (XRB) respectively based on panel data, remote sensing data, and a coupled approach integrating both types of data. A comparative analysis was conducted to evaluate the health of the Changsha section of the river across five dimensions: water quality, quantity, biology, physical structure and social services. This analysis yielded specific recommendations. The results show that: ①The river health assessment scores for the Changsha section of the XRB were 84.49, 75.73 and 80.29 under the panel-based, remote sensing-based and coupled frameworks, respectively. Different frameworks yielded different results, as approaches relying on either panel or remote sensing data alone may over- or underestimate the actual river health status. The coupled framework, which synthesises both panel and remote sensing data, is likely to provide a more balanced assessment.② Under the coupled assessment framework, the overall health status of the Changsha section of the XRB is rated as healthy, while certain river segments, localised areas or specific indicators remain sub-healthy or unhealthy. The primary factors influencing river health in the study area include water transparency, algal biomass (as indicated by chlorophyll-a concentration), the rate of wetland change, the fish retention index and the types of riparian land use. Among these, an unreasonable spatial configuration of riparian land use may be a key constraint. Therefore, when managing river health in the Changsha section of the Xiangjiang River, particular attention should be paid to the aforementioned indicators and associated health issues. The findings of this study provide insights into the selection of assessment indicators for river health studies and offer a reference for the management and planning of river health in this region in the future.关键词：river health assessment;panel data;remote sensing data;typical river section;Xiangjiang River Basin33|132|0更新时间：2026-04-07
- 摘要：Shiwandashan Mountain forms the watershed between the Xijiang River system and the rivers flowing into the Beibu Gulf. There are significant climatic differences between the northern and southern sides of the mountain. Precipitation characteristics on the northern and southern sides of the mountain were analysed using the precipitation concentration index (PCI) and the RClimDex software, based on daily precipitation data from eight meteorological stations during 1961—2023. The results showed that: ①From 1961 to 2023, the mean annual, daytime and night-time precipitation on the southern and northern sides of the mountain were 2 600.4 mm, 1 217.3 mm and 1 383.1 mm, respectively, indicating substantially higher precipitation on the southern side. Annual and daytime/night-time precipitation on the southern side showed a non-significant decreasing trend, whereas those on the northern side showed a non-significant increasing trend. ②The PCI on the southern side ranged from 17.2% to 18.2%, which was slightly higher than on the northern side (14.6% to 16.8%). From May to October, the southern and northern sides accounted for 79.1% and 72.9% of the annual precipitation total, respectively. The highest precipitation on the southern side occurred in July, reaching 562.9 mm and accounting for 21.1% of the annual total. On the northern side, the highest precipitation occurred in August, reaching 226.7 mm and accounting for 18.3% of the annual total. The lowest precipitation occurred in December on both sides, with values of 34.5 mm and 22.4 mm respectively, accounting for less than 2% of annual precipitation. The southern side's precipitation concentration index showed obvious interannual fluctuations, with an overall trend of 0.028% per year from 1961 to 2023. The interannual fluctuations of the precipitation concentration index on the northern side (10.7%~20.7%) were smaller than on the southern side and showed an overall downward trend of -0.012% per year from 1961 to 2023. However, trends on both sides did not pass the significance test (P > 0.05). ③Except for CDD (maximum consecutive dry days), all extreme precipitation indices on the southern side were higher than those on the northern side. Overall, the extreme precipitation indices on the southern side showed a decreasing trend, while those on the northern side showed an increasing trend. On the southern side, all indices except CDD exhibited negative trends, while CDD exhibited a positive trend (0.020 day/a). On the northern side, except for CWD, which exhibited a negative trend of -0.004 days per year, the other seven extreme precipitation indices exhibited positive trends. However, none of these trends were statistically significant, indicating that there were no significant changes in extreme precipitation on either the southern or northern sides of the Shiwandashan Mountain. Due to the terrain's blocking effect, there were significant differences in precipitation characteristics between the southern and northern sides of the Shiwandashan Mountain. This study provides a scientific basis for the efficient utilisation of water resources and disaster prevention and mitigation.关键词：daytime and nighttime precipitation;precipitation concentration degree;extreme precipitation;differences between north and south;Shiwandashan Mountain46|29|0更新时间：2026-04-07
- 摘要：CO2 foam can effectively reduce gas mobility and improve oil displacement system sweep efficiency, but the presence of oil phase will have a significant impact on the formation and stability of foam and the control of gas mobility in porous media. Therefore, it is very important to understand the interaction between foam and oil phase in porous media. This study systematically studied the effects of foam quality (fg) on its steady-state transport behavior, the effects of oil phase composition on foam strength, and the effects of foam generation mode (in-situ generated foam, pre-generated foam) on miscible flooding efficiency through supercritical CO2 foam steady-state flow experiments and core displacement experiments. The results show that the apparent viscosity of supercritical CO2 foam increases first and then decreases with the increase of foam quality. In the core with a permeability of approximately 28×10-3 μm2, the optimal foam quality is about 0.75, and the foam system shows the best mobility control ability. The oil phase composition significantly affects the foam strength. Compared with n-decane (C10), in the process of displacing hexadecane (C16), the apparent viscosity and pressure difference of foam are larger, the gas breakthrough time is lagging behind, the foam strength is larger, and the recovery rate is higher during displacement. In addition, the foam generation mode has an important influence on the efficiency of miscible flooding. Whether it is displacing C10 or C16, the recovery rate of in-situ generated foam is higher than that of pre-generated foam. The specific data show that the recovery rates of in-situ generated foam flooding C10 and C16 are 17.78% and 30.91%, respectively, while the recovery rates of pre-generated foam under the same conditions are 15.91% and 20.83%, respectively. This study clarifies the optimal foam injection quality and provides a direct basis for the optimization of field process parameters. At the same time, it clarifies the influence of oil phase composition and foam generation mode on CO2 foam performance and oil flooding efficiency, which lays a theoretical foundation for reservoir adaptability evaluation and injection process optimization.关键词：mobility control;oil phase composition;foam generation mode;supercritical CO2 foam;the steady-state transport characteristics;miscible flooding behavior49|30|0更新时间：2026-04-02
- 摘要：Against the backdrop of global climate change, this study investigates the spatiotemporal evolution characteristics of precipitation systems during the "Dragon-Boat Water Period" (May 21 to June 20) in the middle and upper reaches of the Beijiang River Basin, aiming to provide a scientific basis for regional flood prevention and disaster reduction. Based on daily precipitation data from 13 national meteorological stations in the middle and upper reaches of the basin from 1966 to 2025, methods including linear trend analysis, Mann-Kendall test, and wavelet analysis were employed to examine the characteristics of precipitation changes during this period. The main conclusions are as follows:(1) The precipitation pattern exhibits a characteristic of "consistent frequency across regions, but uneven intensity," forming a distinct high-value center under the influence of topography. During the Dragon-Boat Water Period, the spatial distribution of precipitation frequency within the basin is relatively uniform, indicating that the entire region operates under a consistent rainy season climate background. However, significant differences exist in precipitation intensity and total amount. Under the orographic lifting effect of the Nanling Mountains, a heavy precipitation center has formed in the area encompassing Fogang, Yingde, Yangshan, and Wengyuan. This region experiences large total precipitation and high precipitation intensity, reflecting the role of topography in the formation of this heavy precipitation center.(2) Precipitation during the Dragon-Boat Water Period shows a widespread increasing trend, with extreme precipitation indices exhibiting more significant increases, displaying a spatial pattern of "strong in the northwest and weak in the southeast." Over the past 60 years, both total precipitation and extreme precipitation indices (Rx1day, Rx3day, Rx5day) during the Dragon-Boat Water Period in the basin have shown consistent increasing trends, with the enhancement of extreme precipitation indices being more pronounced, suggesting that precipitation processes may be evolving toward greater instability. Spatially, the northwestern part (e.g., Shaoguan, Lianzhou) has experienced the most significant enhancement, while the southeastern part (e.g., Shixing, Nanxiong) shows relatively weaker increases, indicating regional differences in the hydrological response to climate change.(3) Precipitation amount during the Dragon-Boat Water Period demonstrates significant interdecadal oscillations, primarily modulated by 11.0-year and 5.5-year cycles. Time series analysis reveals that precipitation during this period is superimposed with pronounced interdecadal fluctuations. Among these, the most significant cycle (approximately 11.0 years) closely aligns with the sunspot cycle, providing a reference for understanding its long-term variation patterns and for conducting interdecadal climate predictions.Recommendations and countermeasures:(1) Implement a Zonal Defense Strategy. In the heavy precipitation center areas such as Fogang, Yingde, Yangshan, and Wengyuan, monitoring and early warning facilities should be intensified, and local rainstorm prevention measures should be strengthened. In regions experiencing sustained enhancement such as Shaoguan and Lechang, efforts should focus on preparedness for large-scale basin-wide floods. In areas with prominent short-duration heavy rainfall like Liannan, early warning for flash floods and evacuation drill exercises need to be reinforced.(2) Optimize Flood Control Operation and Emergency Preparedness. In response to the significant increasing trend of consecutive 3-day and 5-day rainstorms, upstream and downstream reservoirs should implement pre-releases based on weather forecasts to reserve sufficient flood control capacity and prevent cumulative flooding risks. Simultaneously, coordinated dispatching among mainstream and tributaries should be strengthened to enhance the capacity to respond to long-duration, regional rainstorms.关键词：Dragon-Boat Water Period;extreme precipitation;spatiotemporal evolution;wavelet analysis;Beijiang River Basin20|55|0更新时间：2026-04-01
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Differences in Drinking Water Standards and Update Mechanisms Across Four Asia-Pacific Countries AI导读
摘要：In response to the challenges posed by changes in the water environment and emerging pollutants, this paper aims to further optimize China's drinking water quality standards through international comparative research. It seeks to clarify the differences and advantages between China's standards, the World Health Organization (WHO) guidelines, and the standards of neighboring developed countries. Within the framework of the WHO guidelines, four representative countries, namely China, Japan, South Korea, and Singapore, were selected for a systematic comparative study using comparative analysis methods. The study covered dimensions such as indicator system setup, limit values for high-risk pollutants, and dynamic standard update mechanisms. The findings reveal that China's current GB 5749-2022 "Drinking Water Hygiene Standards" have advantages in terms of indicator breadth and system integrity, particularly in the comprehensive management framework for microorganisms and organic pollutants. However, there are still gaps compared to countries like Japan, South Korea, and Singapore in terms of the stringency of limit values for some high-risk pollutants, the refined management of radioactive indicators, and the flexibility of standard updates. Based on the comparative analysis, it is recommended that China focus on optimizing limit values for high-risk pollutants, improving the radioactive indicator system, and establishing a more flexible dynamic standard update mechanism in the future, in order to enhance drinking water safety governance capabilities.关键词：Drinking water;Drinking water quality standards;International comparison;Standard updating mechanisms;Health risk assessment30|60|0更新时间：2026-04-01 - 摘要：Saline lacustrine basin shale oil, as an important type of continental shale oil and gas resources, undergoes hydrocarbon generation processes regulated by multiple factors including sedimentation and diagenesis, exhibiting significant complexity and heterogeneity. Based on a systematic investigation of geological characteristics of shales from typical saline lacustrine basins in China, combined with the application results of experimental techniques such as closed-system MSSV (Microscale Sealed Vessel pyrolysis), semi-open-system hot-press simulation, and organic sulfur analysis, this study comprehensively explores the genetic mechanism of differential hydrocarbon generation in shales from Chinese saline lacustrine basins. The results indicate that saline lacustrine basin shales feature diverse lithofacies and organic facies with strong heterogeneity, and the main source rock sequences generally possess medium-to-high organic matter abundance, kerogen predominantly of Type Ⅰ-Ⅱ₂, and a thermal evolution degree ranging from 0.7% to 1.3% Ro. The hydrocarbon generation process of some typical shales presents distinct "double-peak oil generation" differentiation characteristics: shales in sulfate-type lacustrine basins exhibit a "low-mature oil-mature oil" double peak, while those in alkaline carbonate-type lacustrine basins are characterized by a "mature oil-high-mature oil" double peak. Organic sulfur reduces the hydrocarbon generation activation energy of kerogen through forming low-bond-energy C-S structures, thereby advancing the hydrocarbon generation threshold. Salt minerals, clay minerals, volcanic minerals, and alkaline minerals regulate the hydrocarbon generation pathways and product composition through organic-inorganic interactions such as catalytic reactions, hydrogen supply, and saponification reactions. Through the innovation of experimental techniques and the deepening of genetic mechanisms, dynamic simulation of hydrocarbon generation from microscopic compounds to macroscopic geological processes has been realized, providing key technical support for hydrocarbon generation kinetic modeling, resource potential evaluation, and "sweet spot" interval prediction of saline lacustrine basin shales. This study is of great significance for improving the theory of continental shale hydrocarbon generation and guiding the efficient exploration and development of continental shale oil and gas..关键词：shale oil;hydrocarbon generation mechanism;experimental techniques;organic sulfur;organic-inorganic interactions48|104|0更新时间：2026-03-31
- 摘要：The second section of the Xujiahe Formation in western Sichuan has abundant natural gas resources in the deep tight sandstone, but the low exploration rate, low utilization rate, and difficulty in upgrading of reserves have always been challenges for exploration and development in the region. The unclear distribution pattern and genesis of gas and water in both horizontal and vertical directions have hindered further understanding of gas reservoirs and drilling deployment research. To solve the dilemma of gas reservoir evaluation brought about by the complex distribution of gas and water, and effectively promote exploration and development deployment, based on actual drilling, logging, testing data and natural gas and core analysis and laboratory data, this study analyzed the characteristics of natural gas enrichment and production under different combinations of geological elements from macro and micro scales, plane and vertical dimensions, and the original state of gas reservoirs and actual drilling conditions. The differences in gas and water occurrence and electrical response in different depths of fracture development were sorted out, and the principles and methods for identifying gas and water in tight fractured reservoirs under wellbore conditions were summarized. Research has shown that: ①Macroscopically, the spatiotemporal coupling of the hydrocarbon source reservoir transport system controls the vertical and horizontal distribution of gas and water, with the scale and formation period of faults being key factors affecting gas and water distribution; ②At the micro level, small-scale fractures and microcracks control the filling behavior of natural gas. High maturity gas is difficult to achieve long-distance vertical and horizontal migration in matrix reservoirs. The depth range of fracture development has significantly higher gas saturation and natural gas maturity compared to adjacent matrix segments; ③Under actual drilling conditions, the deep invasion of mud filtrate significantly reduces the identification of gas and water layer resistivity in the fracture development depth range, which is an ideal target area for gas bearing identification. The new method, which uses gas logging C1/C2 as the key means and characterizes the rhythmic changes of natural gas maturity in different fracture development stages, effectively improves the gas water identification ability of tight reservoirs; ④The results of single well gas water identification show that in early fault controlled areas, the height of gas columns is usually less than 100m and the planar distribution radius of fault transmission conductors is small, while in late fault controlled areas, the height of gas columns and the planar distribution radius of fault transmission conductors are usually larger and related to the size of the fault. Under the guidance of the fluid identification methods and gas water distribution laws mentioned above, drilling deployment was carried out, and general principles for designing drilling trajectories and selecting test layers for target layers were established. Multiple new drilling wells achieved good oil and gas results, which strongly supported the high-quality exploration and development of deep tight sandstone in the second section of the Xujiahe Formation in western Sichuan.关键词：gas water distribution;transporting gas reservoir;cracks;gas maturity level;Western Sichuan Depression;second section of Xujiahe Formation24|56|0更新时间：2026-03-31
- 摘要：The potential of deep shale gas resources in the Sichuan Basin is huge, but due to its deep burial depth, the pressure-holding coring technology is difficult and costly. Therefore, how to accurately recover and evaluate the in-situ gas content through numerical simulation or experimental methods has become a key issue in the industry. Based on Nuclear Magnetic Resonance (NMR) isothermal adsorption data, this study employs adsorption potential theory to derive adsorption curves at various temperatures and establishes a prediction model for adsorbed gas under variable temperature and pressure conditions. Additionally, a free gas prediction model is developed using NMR free gas data and the equation of state. These models enable the analysis of adsorbed and free gas, as well as the prediction of in-situ gas content in the study area. Experimental results reveal comparable in-situ gas content between siliceous shales (6.2 cm³/g) and mixed siliceous shales (5.9 cm³/g), with statistically insignificant differences. Notably distinct gas phase partitioning is observed across lithologies, with free gas consistently predominating over adsorbed gas at ratios of 3:7 in siliceous shales and 4:6 in mixed siliceous shales, which reveals the differential control of lithology on the distribution of occurrence state. This difference in phase distribution is mainly related to clay mineral content and water saturation. In the deep high-pressure environment, although free gas is dominant, clay minerals play a key ' lock gas ' role, and water saturation is the ' short board ' of free gas enrichment. By changing the temperature and pressure gradient on the basis of the model, the temperature and pressure response characteristics of shale gas occurrence are revealed: the adsorbed methane has the conversion of the main controlling factors of temperature and pressure in the deep and shallow parts, and the favorable geological conditions for its occurrence are high pressure and low temperature conditions; free methane is mainly controlled by pressure, and the high pressure environment of deep shale in the study area is conducive to the occurrence of free methane.关键词：Sichuan Basin;Longmaxi Formation shale;adsorption potential theory;adsorption gas prediction model;free gas prediction model28|31|0更新时间：2026-03-30
- 摘要：The G Oilfield in the Ordos Basin has entered the middle to late stages of development and is confronted with the challenge of production decline due to depleted reservoir energy. Fracturing stimulation combined with water injection for energy replenishment is a commonly used production enhancement strategy. However, parameter mismatch in fracturing-induced energy storage within this oilfield often leads to water channeling and premature water breakthrough in adjacent wells, severely constraining development effectiveness. To address this issue, this study focuses on the integrated optimization of fracturing-induced energy storage parameters for the G Oilfield. Firstly, a geological model of a representative well group was established using the CMG numerical simulation software, and the mechanism of water injection for energy storage was thoroughly analyzed. Subsequently, the single-factor analysis method was employed to systematically identify key control parameters significantly impacting the 1 000-day cumulative oil production, including fracture-length ratio, fracture conductivity, injection intensity, daily injection volume, and well soaking time. Following this, the Response Surface Methodology was applied to construct a high-precision predictive model between these key parameters and the 1 000-day cumulative oil production. The reliability of the model was verified through residual analysis and numerical simulation validation. Finally, the Comprehensive Learning Particle Swarm Optimization algorithm was introduced to perform iterative optimization of the identified key parameters, with the objective of maximizing cumulative oil production. The application of this integrated optimization strategy significantly enhanced the development outcomes. The optimized scheme increased the 1000-day cumulative oil production by 5.98% compared to the simulation results under parameters optimized solely by the Response Surface Methodology. The study successfully determined the optimal parameter combination suitable for fracturing-induced energy storage in the G Oilfield. The results demonstrate that the integrated optimization method, combining single-factor analysis, Response Surface Methodology, and the intelligent optimization algorithm, effectively resolved the inefficient production problem caused by parameter mismatch in fracturing-induced energy storage, significantly improving crude oil production. The integrated optimization strategy proposed in this study provides a systematic and feasible technical solution for addressing common issues in low-pressure coefficient reservoirs, such as insufficient natural productivity and difficulties in enhancing development. It holds significant application value for the Ordos Basin and similar reservoirs.关键词：CLPSO;Energy Replenishment;fracturing;Process Parameter Optimization;RSM23|6|0更新时间：2026-03-27
- 摘要：Accurately estimating the probability and consequences of low-probability, catastrophic events such as dam failure remains a critical challenge. Existing studies on dam failure probability often insufficiently account for actual defects within the dam body and involve considerable subjectivity in assigning probabilities to basic events, leading to deviations between calculated and actual failure probabilities. Furthermore, few studies have integrated probability calculations with economic loss assessments to achieve a comprehensive quantitative evaluation of reservoir dam failure risk. Taking Nanshui Reservoir as the study object, two major categories comprising seven failure paths were established based on the event tree method. To reduce subjectivity in probability assignment, triangular fuzzy numbers were introduced to represent the probability of key failure stages along each path, and defect detection indicators were used to determine the optimism coefficients in fuzzy number quantification, enabling precise failure probability estimation. A coupled one-dimensional river channel–two-dimensional surface hydrodynamic model for the downstream area was constructed using the HydroMPM model cloud platform and calibrated with water level and discharge data from the June 2022 flood event. The DL BREACH model was employed to simulate flood inundation processes under 15 dam failure scenarios across the seven failure paths. Direct economic losses were quantified using depth–loss rate curves, and direct economic risk was comprehensively evaluated within the "risk = probability × consequences" framework. The results indicate that: ①Most structural indicators of Nanshui Reservoir are normal, with only localized voids or cracks in certain areas. Except for Path 3, the optimism coefficients for all other paths exceed 0.6, reflecting the dam's overall good condition.②The comprehensive dam failure probability of Nanshui Reservoir is 2.00 × 10⁻⁵, significantly lower than the historical annual average dam failure rate for reservoirs in China, indicating a high level of overall safety. Among the seven failure paths, Path 1 (overtopping due to dam settlement) exhibits the highest probability at 6.43 × 10⁻⁶. ③ Under the same failure mode, inundation area increases with flood return period, but the variation across different return periods is generally within 20%. The inundation extent from overtopping failure is significantly larger than that from piping failure, with Path 2 (overtopping caused by flood discharge facility failure) producing the largest inundation area. ④Direct economic losses from dam failure at Nanshui Reservoir all exceed 2 billion yuan, and the direct economic risk in the downstream area is 58,743.17 yuan. Analysis indicates that high-return-period (1000-year and 5000-year) loading conditions contribute the most to overall risk, suggesting that priority should be given to preventing extreme flood or earthquake events. This study provides a systematic and quantifiable new framework for dam failure probability and risk assessment.关键词：defect detection;fuzzy event tree;numerical simulation;dam failure probability;direct economic risk;Nanshui Reservoir24|45|0更新时间：2026-03-26
- 摘要：To reveal the influence of water on the CO2-ECBM (CO2-replacement of CH4) effect in deep coal seams, using Fuchang deep coal as the research object, experiments such as 13C nuclear magnetic resonance spectroscopy (13C-NMR) and X-ray photoelectron spectroscopy (XPS) were conducted. A coal matrix model was constructed using molecular simulation software, and the microscopic mechanism of water’s effect on the CO2-ECBM process in deep coal seams was studied using molecular simulation methods. The results show that after the coal matrix adsorbs gas, it undergoes significant expansion, and the pore volume significantly decreases. When saturated with adsorbed CH4, the coal matrix porosity decreases by 72.2% compared to the initial value; when the molar fraction ratio of CO2 to CH4 (
- 摘要：Ultra-deep pore-fracture-fault complex condensate gas reservoirs exhibit highly heterogeneous fluid flow behaviors. During production, the fracture system often experiences locally reduced pressure, leading to retrograde condensation, while the matrix pressure and overall reservoir pressure remain above the dew-point pressure. This discrepancy makes it difficult for traditional gas reservoir engineering methods—typically based on average reservoir pressure—to accurately identify the onset and extent of local retrograde condensation. To address this issue, this study investigates the Bozi condensate gas reservoir located in the Kuqa Depression of the northern Tarim Basin. The flow mechanism and pressure response characteristics of the pore-fracture-fault triple-medium system are systematically analyzed. Based on the variation patterns of wellhead oil pressure, the production process is divided into three distinct stages: a steady-decline period, an unstable-fluctuation period, and an accelerated-decline period. Abnormal fluctuations in the gas-oil ratio (GOR) are interpreted as early indicators of phase change. By examining GOR variations across different pressure intervals, this work characterizes the dynamic evolution of complex medium gas reservoirs at various production stages. A hybrid predictive framework is proposed that integrates the Long Short-Term Memory (LSTM) network and the Temporal Convolutional Network (TCN), whose hyperparameters are globally optimized using the Pelican Optimization Algorithm (POA). A weighted fusion strategy is employed to construct the POA-LSTM-TCN combined model, enabling stage-wise fitting and prediction of GOR. The results demonstrate that the optimized POA-LSTM and POA-TCN models achieve mean absolute percentage errors (MAPE) of 3.71% and 7.73%, respectively, whereas the POA-LSTM-TCN hybrid model achieves a significantly lower MAPE of 2.40%, outperforming the single models by 1.31% and 5.33%. Numerical simulation further verifies that the traditional gas reservoir engineering approach based on average pressure fails to effectively capture retrograde condensation occurring within fractures. In contrast, the POA-LSTM-TCN model not only provides high-accuracy and efficient GOR prediction but also identifies retrograde condensation when deviations exceed the prdefined threshold. Therefore, this study overcomes the limitations of conventional engineering methods in detecting local retrograde condensation and establishes an early-warning approach based on anomaly recognition. The findings hold substantial theoretical and practical significance for production dynamics analysis, retrograde condensation mechanism identification, and development optimization of complex condensate gas reservoirs.关键词：Tarim Basin;Bozi Gas Reservoir;complex media;condensate gas reservoir;gas-oil ratio;anti-condensate;neural network27|49|0更新时间：2026-03-24
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