Search Results (2,746)

Lithium-ion battery-powered (LIB-powered) electric bicycles (E-bicycles) are widely used in China, with many accidental fires occurring in parking facilities in high-rise buildings. E-bicycle parking areas in high-rise buildings have become fire-prone zones. There is an urgent need to establish fire codes for the parking facilities in high-rise buildings. However, only limited research has been conducted on protecting against such fires. Uncertainties also remain about appropriate methods for fire barriers and fire suppression in parking facilities. To better understand parking facility fires in high-rise buildings, four fire scenarios and a total of six experiments on LIB-powered E-bicycle fires were studied in this paper, aiming to seek principles on how to prevent serious fire accidents by isolating E-bicycles parked in parking facilities. Fire spread between the LIB-powered E-bicycles and the propagation patterns of smoke generated by E-bicycle fires within parking facilities were studied. The effectiveness of different fire extinguishing methods in suppressing LIB-powered E-bicycles fires was discussed. The reasonable fire separation distance for E-bicycles was determined. It was found that LIBs with ternary lithium-ion batteries (such as nickel-cobalt-manganese) are more prone to initiate thermal runaway. Setting appropriate separation distances could effectively minimize the spreading of E-bicycle fires in high-rise buildings. A sprinkler system with a lower hazard class is proposed to operate under lower water pressure and flow rates. Fire control methods were proposed, including fire-resistive eave and fire barrier. The results can be used in setting up fire code. Full article

Post-fire plantations play a crucial role in recovering carbon stocks, yet how carbon is partitioned among vegetation, litter, and soil pools during stand growth dynamics remains insufficiently resolved for Quercus acutissima plantations. Forest ecosystems play a crucial role in the global carbon cycle. This study quantified carbon-storage allocation and identified stand characteristics and soil factors associated with carbon recovery in fire-affected Q. acutissima plantations. Using a chronosequence design, we compared five stand-age classes (4, 10, 25, 45, and 50 years) on Huangfu Mountain, China, and measured carbon stocks in tree organs, understory vegetation, litter, and the 0–30 cm soil layer. Ecosystem carbon stock increased from 31.64 t ha⁻¹ in 4-year-old stands to 230.66 t ha⁻¹ in 50-year-old stands, representing a 629% increase. Soil was the dominant carbon pool, with 0–30 cm soil carbon rising from 25.32 to 126.56 t ha⁻¹ (a 400% increase). The contribution of soil carbon to total ecosystem storage declined from approximately 80% in 4-year-old stands to 55% in 50-year-old stands, indicating a shift in allocation toward vegetation biomass over time. Carbon accumulation was primarily concentrated in the 0–10 cm layer. Tree basal area was significantly associated with ecosystem carbon stocks, identified as a key structural factor linked to carbon accumulation through potential direct and indirect pathways involving light availability and soil carbon. Soil organic matter and nitrogen were also positively correlated with carbon accumulation. These findings suggest that stand development and topsoil carbon formation are closely linked to post-fire carbon recovery processes. Future management measures should optimize stand density, maintain soil fertility, and protect surface carbon to enhance long-term carbon sequestration. Full article

As a major beef cattle producing country, China’s beef industry is expanding and undergoing structural transformation. A systematic assessment of the spatiotemporal evolution and driving factors of its water footprint is of great significance for the green and sustainable development of the beef cattle industry, and also provides a reference for understanding the current status of beef cattle water footprint, formulating environmental policies, and supporting the sustainable development of other livestock and poultry species. Based on the life cycle assessment (LCA) method, quantified the green, blue, and grey water footprints of China’s beef cattle industry “from cradle to farm gate” across 31 provinces from 2002 to 2022, covering three farming scales (small-scale, medium-scale, and large-scale) classified according to the proportion of beef cattle slaughter numbers (1–49 head, 50–500 head, and >500 head), and encompassing four stages: feed crop cultivation, beef cattle farming, manure leaching, and transportation and processing, covering three farming scales (small-scale, medium-scale, and large-scale) classified according to the proportion of beef cattle slaughter numbers (1–49 head, 50–500 head, and >500 head), and encompassing four stages: feed crop cultivation, beef cattle farming, manure leaching, and transportation and processing. Furthermore, kernel density estimation and standard deviational ellipse methods were employed to reveal the spatiotemporal evolution characteristics, and a Spatial Durbin Model (SDM) was constructed to identify the driving factors. The findings indicate that the total water footprint of China’s beef cattle industry first decreased and then increased, reaching 918.70 km³ in 2022. The grey water footprint accounted for an average of 90.85% annually, and the manure leaching stage contributed the largest share (averaging 62.24% annually), suggesting that this stage warrants priority attention from the perspective of this indicator. Large-scale farming exhibited the lowest water footprint per unit of beef (averaging 29.39 m³/kg), while small-scale farming had the highest (54.65 m³/kg). The spatial pattern showed a trend of “high in the west and low in the east, rising in the west and declining in the east.” The spatial model results revealed that the water footprint per unit of beef exhibited significant spatial agglomeration and spatial spillover effects. Full article

Türkiye is the world’s largest cherry producer by volume, yet the value of its cherry exports has stagnated since the mid-2000s. This study tests whether growth in output translates into stronger export competitiveness. The Balassa RCA, Vollrath RXA and Laursen RSCA indices were computed annually for Türkiye and four reference exporters (Chile, the United States, Spain, and China including Hong Kong SAR) from FAO trade data for 1990–2023. Structural break tests, HAC-robust trend regressions, Mann–Kendall and Sen’s slope tests, and a Box–Jenkins ARIMA(1,1,2) projection of domestic production to 2033 with rolling-origin validation were applied. Türkiye retained a revealed comparative advantage in every year (RSCA > 0), but a supremum-Wald test identified a break in 2006 (95% CI 2002–2009). Competitiveness rose over 1990–2004 (RSCA slope +0.026 yr⁻¹, p < 0.001) and declined over 2004–2023 (−0.023 yr⁻¹, p < 0.001), with RCA falling from 20.1 to 2.9. Production growth was positively associated with contemporaneous RSCA changes (β = 0.33, p = 0.015), yet the post-2004 period carried an independent decline of 0.051 index points per year (p = 0.002). Meanwhile, Chile consolidated dominance and China approached parity. Production is projected to reach 0.88–0.94 million t by 2033. The divergence between expanding output and weakening competitiveness is reported as an association, consistent with rising domestic absorption and limited post-harvest logistics and market diversification capacity. Full article

Optimizing construction and ecological land patterns enhances urban ecosystem services, with efficiency gains depending on accurately identifying focal local spaces of greatest potential. However, existing research has yet to comprehensively quantify the multi-dimensional characteristics of both land types or systematically identify such priority areas. To address this gap, this study reconstructs integrated indicators capturing the “scale, shape, and connectivity” of construction and ecological land. Using the Local Climate Zone (LCZ) framework and interpretable machine learning, this study identifies focal local spaces for ecosystem service improvement in Nanjing, China, and analyzes the nonlinear interactive effects of these indicators on services. Key findings are as follows: (1) Construction land exhibits high aggregation and morphological complexity, whereas ecological land shows strong connectivity and intact morphology, with marked spatial differentiation. (2) Mid-rise building zones are identified as the focal local spaces (R²: 0.52–0.80). (3) Within these zones, ecological land core areas positively drive carbon storage (22.5%) and soil conservation (24.5%), construction land area proportion enhances water yield (23.7%) and construction land core areas suppress habitat quality (24.3%). Synergistic effects exist between ecological land extent and core areas for carbon and soil services, whereas construction land extent and core areas jointly degrade habitat quality. (4) This study recommends enhancing ecological land structure and connectivity, regulating construction land intensity, and creating semi-natural transitional zones at their interfaces. The integrated indicators and LCZ-based diagnostic approach provide a practical basis for zonal optimization of urban ecosystem services and a methodological reference for improving spatial governance. Full article

The logistics industry remains a critical bottleneck for decarbonization due to its extensive physical networks and high-carbon path dependencies. To address the spatial heterogeneity and transition constraints in the logistics industry of China, this study proposes a Performance–Topology–Mechanism (PTM) framework. Analyzing panel data from 30 Chinese provinces, we integrate a Super-SBM model with the Global Malmquist–Luenberger (GML) index, Dagum Gini decomposition, and a panel Tobit model to decode the spatiotemporal dynamics of green innovation performance (GIP) and its underlying spatial lock-in mechanisms. The results reveal a steady but spatially uneven increase in the national GIP (from 0.4526 to 0.5724), characterized by a leading East and a lagging West/Northeast. GML decomposition indicates this growth is predominantly driven by outward shifts in the technological frontier rather than efficiency improvements, highlighting the weak spatial conversion of green technologies into transport optimization. Topological tracing demonstrates that inter-regional disparities have become the dominant source of spatial inequality, with their contribution rising from 60% to 75%. Spatial autocorrelation further exposes a deepening core–periphery polarization and persistent low-performance spatial lock-in. Crucially, the mechanism analysis identifies a pronounced infrastructure-based carbon lock-in. While economic capacity and green patents stimulate GIP, road network density exerts a significant negative effect, reflecting a systemic path dependence on high-carbon road freight. The findings suggest that decarbonizing transport logistics requires shifting from singular technological investments toward multimodal transport restructuring, overcoming physical network dependencies, and promoting the regional diffusion of green innovations. These findings provide an empirical basis for differentiated green-logistics policies, coordinated low-carbon transport infrastructure planning, and cross-regional diffusion of green technologies. Full article

Improving cropland carbon performance while maintaining food security is central to China’s agricultural transition and climate goals This study examines low-carbon cropland use performance (PCLU) and its model-implied interprovincial association network across 31 Chinese provinces from 2010 to 2023. A global super-efficiency slacks-based measure model estimated PCLU by incorporating agricultural output, carbon emissions, nonpoint-source pollution, and crop sequestration; annual directed networks were constructed with a modified gravity model and analyzed using social network analysis, a temporal exponential random graph model (TERGM), and complementary quadratic-assignment analyses. Mean PCLU increased from 0.524 to 0.861, while the interquartile range widened from 0.146 to 0.310; network density declined before partially recovering as hierarchy increased, indicating improvement without provincial convergence and reconnection within a more differentiated multi-hub structure. Persistence (β = 4.510) and reciprocity (β = 2.376) dominated network evolution, whereas shared partners produced neither additional triadic closure nor expanding open chains; similarities in urbanization and planting structure favored ties, while rural-income differences reflected socioeconomic complementarity. External validation showed moderate overall correspondence with green-technology patent collaboration (mean annual QAP r = 0.335) but limited overlap among the strongest dyads. Overall, China’s low-carbon cropland transition combined rising but increasingly uneven performance with a path-dependent and selective interprovincial structure, providing an empirical basis for differentiated coordination based on provincial performance and network position. Full article

Adjusting cropping structure is a key way smallholder agriculture adapts to changing labor availability, production costs, mechanization, and agricultural services. Most studies explain such change through macro-level factors—prices, policies, and resource endowments—and pay less attention to how farmers perceive these changes and adjust their crop choices over time. Taking Xiajin County, Shandong Province, China, as a case, this study combines sown-area data for major crops from 1980 to 2023, provincial cost–benefit records for wheat, maize, and cotton, and retrospective semi-structured interviews with 57 respondents to examine how changing crop choice criteria shaped county-level cropping structure transformation. The county shifted from cotton dominance to wheat–maize dominance, with rising structural concentration. Farmers’ criteria also changed: early decisions reflected drought tolerance, subsistence grain, and cash income, whereas later ones emphasized labor saving, income stability, mechanization compatibility, and outsourcing feasibility. Under labor out-migration, rural aging, rising labor opportunity costs, and service expansion, wheat and maize became more attractive than cotton because their key stages were easier to mechanize and outsource. County-level transformation thus emerged from the accumulation of farmers’ repeated crop choice adjustments under changing constraints, rather than from external change alone. Grain-oriented concentration should be balanced with crop diversity and sustainable farming systems. Full article

Sustainable settlement governance requires construction land to remain coordinated with population change, as persistent land–population mismatches undermine both resource sustainability and settlement quality, yet much of the land-use efficiency research still treats urban and rural space as a binary system. This study develops a city–town–village framework to examine the divergent evolution of construction land per capita and internal land allocation in 336 prefecture-level units in China from 2010 to 2020. Using national land survey data, population census data, location quotients, exploratory spatial analysis, hierarchical clustering, and regression models, the results indicate pronounced asymmetric decoupling of construction land from population across the settlement hierarchy. City-level land expansion was broadly synchronized with population growth, leaving per capita construction land almost unchanged; towns experienced expansion-driven decoupling as land expansion outpaced population growth; and villages showed severe decoupling: village construction land expanded by 17.6% while the population declined by 23.1%, raising village per capita construction land by 52.9%. At the national level, construction land increased by 24.2% while population grew by only 5.8%. Within prefectures, relative land allocation shifted away from cities and toward villages, with city location quotients declining and village location quotients rising in most prefectures. Regression analysis indicates that physical terrain, development stage, sectoral structure, fiscal expenditure capacity, administrative hierarchy, and regional location are jointly associated with these divergent outcomes. The findings indicate that towns are not simply small cities and that village land stranded by depopulation rather than active sprawl has become a major component of the national land–population imbalance. Policy should therefore extend land-use efficiency governance from metropolitan growth control to differentiated regulation of towns and villages. Full article

Hydrothermal variability, rising evaporative demand, and drought extremes increasingly threaten crop production in semi-arid regions, yet their relative contributions to maize yield variability remain unclear. Here, we examined maize yield responses to growing-season climatic conditions in Lyuliang City, North China, during 2005–2024 using yield statistics and ChinaMet climate data. Trend analysis, Pearson correlation, candidate regression models, standardized coefficients, and generalized additive models were used to identify dominant climatic predictors. Maize yield showed no significant temporal trend during the study period (Sen’s slope = 0.01 t ha⁻¹ yr⁻¹, p = 0.58), whereas growing-season potential evapotranspiration tended to increase (2.81 mm yr⁻¹, p = 0.06). Diurnal temperature range declined significantly (−0.04 °C yr⁻¹, p = 0.01), and minimum SPEI also decreased significantly (−0.04 yr⁻¹, p = 0.01), indicating intensified extreme dry conditions. Maize yield was most strongly correlated with aridity index (r = 0.72, p < 0.001) and water deficit (r = 0.72, p < 0.001), suggesting that hydrothermal balance explained yield variability better than precipitation or temperature alone. The highest-ranked regression model included aridity index, growing-season temperature, diurnal temperature range, and minimum SPEI, explaining 70% of interannual yield variation. Aridity index was the strongest positive predictor, whereas diurnal temperature range had a significant negative association with yield. Although extreme dry conditions intensified over time, minimum SPEI was not directly associated with annual yield, implying that drought impacts may depend on drought timing, crop phenology, and management buffering. These findings highlight the importance of maintaining favorable hydrothermal balance and reducing risks from increasing evaporative demand and temperature variability to support climate-resilient maize production in Lyuliang City and climatically similar rain-fed semi-arid regions of North China. Full article

Coal-bearing tight gas and deep coalbed methane (CBM) widely co-occur in China, and integrated commingled production outperforms separate development. Conventional separated simulation fails to capture coupled reservoir–wellbore gas–water flow. This study develops an integrated geomechanical coupled numerical model with multi-scale fractures and multi-phase wellbore flow: tight gas reservoirs use a stress-sensitive single-porosity model, deep CBM adopts a dual-porosity model for matrix desorption, and EDFM characterizes non-Darcy flow in hydraulic fractures. The Gray gas column and liquid column methods calculate layered bottomhole pressure according to reservoir vertical distribution, and matrix bordering solves the whole coupled system. Validated by field data of Well C-1 in Shanxi, the model yields average relative errors of 8.76% for daily gas output and 2.92% for daily water output. Sensitivity analysis on Well C-2 indicates vertical reservoir stacking controls interlayer pressure difference, and commingled gas curves show dual peaks with shifting dominant gas sources over production stages. A 3.9% rise in deep coalbed methane gas content significantly boosts mid-term peak production and cumulative gas output, making reservoir gas content the dominant geological factor governing commingled production performance. A 120.0% increase in tight gas saturation only delivers a slight uplift in cumulative production under low-porosity conditions. Elevated reservoir stress sensitivity triggers a cumulative gas production reduction of over 50%. Cumulative gas output varies proportionally with hydraulic fracture length, while fracture network width brings mismatched production improvement due to pressure drawdown funnel effects. Therefore, hydraulic fracturing operations should prioritize extending artificial fractures to expand the drainage area of commingled wells. Schemes with constant bottomhole flowing pressure and constant gas rate exert marginal influences on ultimate cumulative production and can be flexibly switched on site. To stabilize daily gas deliverability throughout the early, middle and late production stages, a bottomhole pressure drawdown rate of 0.05 MPa/d or a fixed daily gas rate of 4000 m³/d is recommended. This work provides theoretical support for optimizing commingled development of superimposed tight gas and deep CBM reservoirs. Full article

In response to the significant seasonal fluctuations in heating and cooling loads in greenhouses for high-value fruit trees in northern China, as well as issues such as heat accumulation on the ground-source side and high carbon emissions from coal-fired heating, this paper proposes a coupled energy supply system comprising a PVT system, a mine pit seasonal thermal storage unit, a ground-source heat pump and a cooling tower. Taking a 30,000 m² cherry greenhouse and an existing 15,000 m³ mine pit thermal storage reservoir in Weifang, Shandong Province, as the research objects, annual design-stage simulations with a 0.125 h time step were conducted using SketchUp-TRNBuild and TRNSYS. Discrete sensitivity analyses and engineering constraints were used to determine the PVT area and cooling tower outlet temperature. Heating demand mainly occurred from November to February, whereas cooling demand was concentrated from June to September. The selected 2452 m² PVT system supplied direct heating for 34 days, covered 23.05% of the seasonal heating demand, and achieved a storage efficiency of 69.17%. Without a cooling tower, the first-year soil temperature increased by 1.1 °C. With a 26 °C cooling tower outlet temperature, the soil thermal imbalance ratio decreased to 2.4%, and the 15-year soil temperature rise was limited to 0.28 °C. The recommended system required 1.3239 million kWh of net purchased electricity annually, reduced operating costs by approximately CNY 802,800 (USD 118,243) and operational emissions by 2027.8 tCO₂-eq per year relative to the baseline, and had a static payback period of 6.4 years. The annual operational emission reduction was linearly extrapolated over a 20-year assessment period under fixed weather, load, equipment performance, and grid emission assumptions, resulting in a scenario-based carbon reduction threshold of 40,556 tCO₂-eq. Net life cycle carbon savings would be possible if the additional emissions from construction, equipment replacement, and end-of-life treatment remained below this threshold. Full article

Climate change and sea-level rise are expected to intensify groundwater salinization in coastal aquifers, yet their relative contributions remain insufficiently quantified. This study developed a MODFLOW–SEAWAT model to compare the combined impacts of future precipitation change and sea-level rise on groundwater salinization in a representative coastal aquifer of the Pearl River Delta (PRD), China. The groundwater-flow component was calibrated using heads from 54 observation wells (R² = 0.878, RMSE = 0.699 m), and the initial salinity field was constructed and spatially evaluated using chloride concentrations from 142 sampling sites. Four scenarios, including baseline, sea-level rise, future precipitation (SSP5-8.5), and their combination, were simulated over 30- and 60-year periods. The scenario comparison indicates that sea-level rise alone slightly increases groundwater salinity, whereas the selected SSP5-8.5 precipitation series produces a stronger response through recharge and freshwater dilution. Under the SSP5-8.5 scenario, the combined area of high-salinity groundwater (Degrees IV and V) after 60 years decreases by approximately 50% compared with the baseline scenario. The combined scenario exhibits salinization patterns similar to those of the precipitation scenario, indicating that precipitation change has a stronger influence than sea-level rise under the selected scenario and hydrogeological conditions of the PRD. These findings suggest that targeted artificial recharge in recharge-sensitive inland transition zones could help mitigate groundwater salinization and support climate adaptation in coastal regions. Full article

Low-TOC saline lacustrine shales are widespread in Cenozoic basins of northwestern China and Central Asia, yet their organic matter accumulation (OMA) mechanisms under arid, saline conditions remain poorly understood. We analyzed TOC, major and trace elements, and C–O isotopes in 64 core samples from eight wells in the western Qaidam Basin, and reconstructed terrigenous input, weathering intensity, paleoproductivity, redox conditions, and salinity. TOC ranges from 0.04% to 1.10% (mean 0.32%), with a statistically significant upward trend from the Shangganchaigou (mean 0.25%) to the Shangyoushashan Formation (mean 0.43%) (Kruskal–Wallis, p = 0.010). The climate was dry–cold with progressive aridification (increasing δ¹⁸O and Sr/Ba). The water body evolved from closed, strongly reducing, and unstable to more open, weakly reducing, and increasingly saline. We propose that limited nutrient supply set a low baseline for organic enrichment. Weakened terrigenous dilution and enhanced water-column stability then drove the gradual TOC increase. This reveals that OMA can occur without concurrent productivity rise, sustained solely by long-term preservation improvement, offering new constraints for source rock evaluation in arid lacustrine basins. Full article

Rapid urban development has intensified conflicts between land development and ecological conservation, making spatially explicit land-use planning increasingly important for resource-depleted cities. This study develops a geoinformation-based decision-support framework for Huangshi, China, by integrating multi-scenario land-use modeling, production–living–ecological space analysis, landscape pattern assessment, and SDG 15 diagnostics. Four 2035 policy-oriented scenarios were compared: Business-as-Usual (BAU), Ecological Restoration Priority (ERP), Economic Development Priority (EDP), and Sustainable Development (SD). The results show that ERP delivers the strongest ecological performance, with ecological space reaching 46.47%, forest cover increasing from 35.40% to 36.80%, water area rising to 9.65%, net land degradation declining to −2.04%, and mean habitat quality reaching 0.484. SD provides a more balanced pathway, with ecological space of 44.80%, living space of 8.93%, a land-use stability rate of 96.36%, and a relatively low net degradation rate of 1.33%. BAU and EDP show higher ecological risks. The framework demonstrates how multi-source geospatial data and spatially explicit SDG diagnostics can support adaptive planning in resource-depleted cities. Full article