The Pearl River Source Region (PRSR), a fragile karst ecosystem in southwestern China, faces severe biodiversity threats from habitat fragmentation and rocky desertification driven by extensive economic development. This study constructs and evaluates the Ecological Security Pattern (ESP) for the PRSR to identify critical conservation elements and strategies. By integrating ecosystem service and the Minimum Cumulative Resistance (MCR) model, 133 ecological corridors were mapped among 57 ecological sources. Key network elements (patches, corridors, pinch points) were further evaluated using Circuit Theory (cumulative current centrality) and Graph Theory indices (dIICconnector, dPCconnector): Five patches (P14, P22, P24, P43, P49) were identified as extremely important sources, with the Pearl River Source Nature Reserve (P43, dIIC = 1.40, dPC = 4.82; P49, dIIC = 1.15, dPC = 3.49) emerging as the network core, Zhanyi Tiankeng Group (P42, dIIC = 0.30, dPC = 0.37) as a secondary hub. Crucially, corridor 42-49 sustains landscape connectivity in human-impacted areas, acting as a conduit for species migration and genetic exchange between tiankeng, the Pearl River Source, and distant regions, effectively reducing extinction risks. Besides, connectivity challenges were pronounced: western corridors exhibited high resistance due to long distances and intensive human pressure (agriculture, industry), while eastern corridors, though shorter, contained dense ecological pinch points (bottlenecks) exacerbated by transportation infrastructure and farmland encroachment. To mitigate fragmentation and enhance biodiversity conservation, this study proposes: (1) Strict protection of key sources via ecological redlines and reserve boundary optimization; (2) Restoration of priority corridors through vegetation rehabilitation and stepping-stone habitats; (3) Pinch points mitigation via wildlife-plant crossings and farmland-to-wetland conversion; (4) Economic-ecological coordination through eco-compensation, native broadleaved reforestation, and eco-industry development. This integrated ESP framework provides a replicable model for conserving biodiversity in globally vulnerable karst regions.

China’s coastal regions are facing an evolving air pollution pattern characterized by the joint occurrence of fine particulate matter (PM2.5) and ozone(O3). Rapid urban expansion has reduced ecological land, weakening its capacity to act as a “sink” for atmospheric pollutants. This study aims to evaluate the coupling coordination of P-O synergistic pollution and to quantify the “sink” role of ecological land. The Coupling Coordination Degree (CCD) model was applied to evaluate the P-O synergy. Spatial econometric models were then employed to investigate the "sink" function of ecological land in mitigating P-O pollution and associated spatial spillover effects, and the Geographical Detector model was employed to assess the interactive influence of multiple factors. Results show: (1) Significant north–south disparities exist in P-O CCD, exhibiting strong positive spatial autocorrelation. (2) FOREST (λ = -2.19, P < 0.05), GRASS (λ = -9.44, P < 0.01), and FARM (λ = -1.30, P < 0.1) effectively suppress P-O pollution, with FOREST and GRASS demonstrating the strongest sink capacity. FARM shows mixed effects, indicating its net ecological function depends on management quality. (3) PRE (λdirect = -1.73***, λindirect = -3.15***) and SEI (λdirect = -5.56, λindirect = -93.5**) significantly influence regional P-O spatial spillover effects, while ecological land's impact is primarily localized. (4) Meteorological factors exhibit stronger interactions with other drivers; ecological land is the most explanatory factor for P-O synergy. These findings highlight that optimizing land-use structure and ecological management can serve as a practical pathway for synergistic air pollution control and sustainable coastal development.

The coordinated enhancement of wood production and carbon sequestration in plantations is increasingly important for sustainable forest management and climate-change mitigation. However, quantitative evidence on how forest management can jointly improve these two functions remains limited. Based on 847 Pinus massoniana plantation plots (yielding 1184 consecutive-period observations) from China’s 7th–9th National Forest Inventories (covering 2004–2018), we quantified the degree of coordination between wood productivity and tree-layer carbon sequestration rate. Linear mixed-effects models, the piecewise structural equation model, and XGBoost-SHAP analyses were subsequently applied to identify the major drivers and threshold ranges of key stand factors. The results showed that mean carbon sequestration rate and wood productivity were 1.16 Mg/ha/yr and 4.17 m3/ha/yr, respectively. Among the examined management categories, plots with standing-volume harvest intensity < 0.15 (i.e., removing less than 15% of stand volume) showed the highest tree-layer carbon sequestration rate and wood productivity. Overall, wood productivity and tree-layer carbon sequestration rate showed broadly consistent responses across the examined management conditions, suggesting a generally high degree of coordination between the two functions. Stand structural attributes were the primary determinants of the degree of coordination, whereas management factors tended to strengthen this coordination both directly and indirectly through modifications of stand structure. Within the sampled range, a higher degree of coordination was associated with stand DBH values of 7.5–10.6 cm, stand density below 1071 trees/ha, stand age exceeding 29 years, and standing-volume harvest intensity approaching 0.12. These findings provide a quantitative basis for balancing timber production and tree-layer carbon sequestration, and offer practical implications for adaptive management of subtropical plantations under climate-mitigation and timber-supply objectives.

Rainfall-induced soil erosion is an escalating global environmental concern, yet the spatiotemporal variability of rainfall erosivity and its attribution to natural and anthropogenic forcings remain insufficiently understood. This study aimed to analyze global patterns, attribute changes to anthropogenic forcings, and project future trends. We utilized a daily empirical model based on the Gridded Network Rainfall Estimates (REGEN) dataset and employed the optimal fingerprinting method with simulations from nine Coupled Model Intercomparison Project Phase 6 (CMIP6) models under multiple forcing scenarios. Results revealed a significant global increasing trend in rainfall erosivity (3.24 MJ mm & centerdot;ha(-1)& centerdot;h(-1)& centerdot;a(-2), p < 0.001), with notable rises in the frequency and intensity of erosive rainfall events. Anthropogenic forcings were robustly detected as the primary driver, with greenhouse gas increases significantly elevating erosivity in Northern Europe, the Russian Arctic, East Siberia, and Central Australia, while aerosol forcing dominated in the Arabian Peninsula. Future projections across all Shared Socioeconomic Pathways (SSPs) scenarios indicate widespread increases in rainfall erosivity by the late 21st century, ranging from +15.7 % to +35.1 %, with amplified risks at high latitudes of the Northern Hemisphere. This study provides robust evidence of human influence on rainfall erosivity and underscores the need for targeted adaptation strategies to address escalating rainfall erosivity risks under climate change.

Karst tiankengs are established hotspots of biodiversity for macro-organisms. In contrast, the soil micro-food web, structured around microbes, protozoa, and nematodes, represents a critical yet understudied component of subsurface ecosystem diversity and functioning. Its patterns of diversity and underlying maintenance mechanisms remain largely unresolved. To address this, we conducted a three-year bidirectional soil translocation experiment between the interior and exterior of a tiankeng, assessing responses of the soil micro-food web and soil multifunctionality to these distinct habitats. We found that soil translocation significantly altered the diversity, composition, and structure of the micro-food web, with variation in responses across different trophic levels. These shifts were primarily driven by the contrasting environmental regimes, including temperature, humidity, and soil resource availability, between the tiankeng interior and the external environment. Specifically, outward translocation negatively impacted key attributes of the micro-food web. Enhanced competitive interactions between bacteria and fungi exerted bottom-up control, restructuring the entire network. Notably, the tiankeng interior sustained a more complex and stable soil micro-food web, supported higher levels of soil multifunctionality, and demonstrated that micro-food web complexity is pivotal in regulating multifunctionality. Our findings underscore the potential of tiankengs to act as climate refugia and biodiversity reservoirs under future climate change scenarios. Moreover, tiankengs can serve as natural open‑top laboratory models, offering a novel and powerful perspective for simulating the responses of subsurface ecosystems to climate change.

Accurately quantifying the ecological functions of small and micro green spaces in high density urban environments supports urban ecological planning and management. This study assessed 271 pocket parks in the main urban area of Fuzhou, China, using multi-source remote sensing data from the growing seasons of 2019 to 2024. Six indicators were derived, including NDVI, NPP, WET, NDBSI, ISI, and LST. A composite Eco-environmental Index (EEI) was constructed using the entropy weight method. We combined the coefficient of variation, Theil-Sen slope estimation, the Mann-Kendall test, and the Hurst exponent to quantify spatial heterogeneity, interannual stability, and short-term persistence. We also examined climatic associations using correlation analysis. Pocket parks consistently outperformed their surrounding 500 m buffers across all indicators, and park buffer contrasts increased for most indicators. The mean EEI significantly increased from 0.563 in 2019 to 0.650 in 2024, with a pronounced step increase around 2022. At the site level, 261 of 271 parks (96.3%) exhibited an upward trend in EEI, indicating widespread ecological improvement. Specifically, park vegetation greenness (NDVI) rose from 0.413 to 0.578, widening the gap with surrounding areas. Parks consistently maintained a lower land surface temperature (LST) than their buffers, with a cooling magnitude ranging from 3.5 degrees C to 4.6 degrees C. Precipitation was positively associated with NDVI and NPP, while LST was positively associated with air temperature and negatively associated with precipitation. These findings support the planning and adaptive management of pocket parks to strengthen urban ecological resilience.

Surveys of microorganisms and antibiotic resistance genes (ARGs) in edaphic systems have centered on those in human-impacted environments, with relatively little information from primitive environments. The karst tiankeng (also known as sinkholes) is the largest negative terrain on the earth's surface, and the trapped terrain keeps the interior relatively pristine. In this study, three of the most representative tiankeng types (severely, moderately, and non-degraded tiankengs) were selected, and microbial composition, function, and their association with ARGs were determined using metagenetic techniques. The dominant phyla in karst tiankengs were Proteobacteria, Actinobacteria, and Acidobacteria; the dominant archaea were Crenarchaeota; and the dominant fungi were Ascomycota. The non-degrade tiankeng maintains a complex and stable microbial network. The major functional profiles of the microorganisms are involved in amino acid metabolism and carbohydrate metabolism. A total of 145 ARGs were annotated, and the dominant ARGs in karst tiankeng were CeoB, AcrB, and MexF. Paraburkholderia, Rhodococcus, Bradyrhizobium, and Agromyces were the main hosts of ARGs in karst tiankengs. Compared with ARGs, microorganisms were more influenced by soil factors. These results provide a novel insight into microbes and ARGs in unexplored karst tiankeng ecosystems. IMPORTANCE Currently, knowledge regarding the origin of antibiotic resistance genes (ARGs) in pristine soil environments remains limited, with some potentially linked to ancestral genetic diversity. In this study, metagenomics was employed to investigate the distribution of ARGs across nine relatively pristine karst tiankengs. We identified the predominant microbial communities and prevalent types of ARGs within these tiankengs. Soil factors primarily influenced the microbial community structure but had little effect on ARGs. This study offers insights for in-depth research on the microbial composition and risk assessment of antibiotic resistance genes within pristine karst tiankeng ecosystems.

Microbial resource limitation is critical to ecosystem function and processes. However, knowledge about the patterns and mechanisms of microbial resource limitation in karst fragmented habitats is still lacking. In this study, the karst negative topography fragmented habitat—Zhanyi Tiankeng Group was taken as a model system, and the microbial resource limitations of the tiankeng ecosystem were studied. Tiankeng soil microbes were co-limited by C and P. Compared to outside the tiankeng sites, the tiankeng provides a refuge for the survival of microbes and alleviates microbial resource limitations. Habitat fragmentation has altered microbial resource limitations. Lower microbial C limitation on larger tiankengs, suggested that larger fragment habitats could create a unique habitat for soil microbial survival in the degraded karst landscapes. Microbial C and P limitations were mainly affected by soil water content and dissolved organic carbon, indicating that soil physicochemical properties were important factors in maintaining microbial metabolism in tiankengs. Our study provides meaningful insights into ecosystem functions and soil biogeochemical cycles in karst fragment habitats.

Known as the largest negative terrain on the earth's surface, the karst tiankeng is isolated by vertical cliffs and maintains a unique ecosystem within it. However, knowledge of the microbial ecology of karst tiankengs does not match their importance. To this end, we conducted extensive sampling across 16 karst tiankengs and 2 sites and used high-throughput sequencing methods to analyze soil bacteria and fungi. This study found abundant and diversified microbial communities in karst tiankengs, with Proteobacteria, Acidobacteriota (Bacteria), and Ascomycota, Basidiomycota (Fungi) being the main phyla. Compared to the degraded karst landscape, karst tiankengs maintained a higher richness of bacterial taxa. The common and exclusively microbial taxa in karst tiankengs follow copiotrophic and opportunistic strategies, and these taxa are associated with high soil nutrients (TN and SOM) and water content. Karst tiankeng maintained a stable microbial network structure through cooperation, and the dispersal limitation dominated the bacterial and fungal community assembly. Our results enhance the understanding of microbiomes in subterranean karst ecosystems, highlighting that karst tiankengs are important refuges for microbial diversity in degraded karst landscapes.

The future state of global evapotranspiration (ET) estimation under climate change remains uncertain. Current formulations primarily developed based on the high emission CMIP5 scenario, have been widely used to represent conditions under elevated greenhouse gas pathways. However, these formulations may not adequately capture the enhanced vegetation–climate interactions projected under the lower-emission scenarios of CMIP6. Without updates to account for evolving plant physiological responses to rising CO2, projections may overlook critical feedbacks between atmospheric CO2 concentrations, vegetation behavior, and hydrological processes. To address this, developing CMIP6-specific formulations is essential to leverage its improved datasets and reduce uncertainties in future ET simulations. In this study, we update the Penman-Monteith evapotranspiration (PM-ET) model by incorporating the CO2-vegetation coupling effect. This is achieved using outputs from four Coupled Model Intercomparison Project Phase 6 (CMIP6) global climate models (GCMs) under four Shared Socioeconomic Pathways (SSP1-2.6, SSP2-4.5, SSP3-7.0, SSP5-8.5). Results indicate a sustained historical increase in potential evapotranspiration (Ep). The inclusion of CO2 physiological effects reduces the deviation in projected ET trends by approximately 15 %–20 % compared to CMIP5-based frameworks, accounting for the increase in stomatal resistance driven by CO2 concentrations rising from ∼284 to ∼ 935 ppm. Furthermore, our model predicts an increasing dependence of ET projections on emission scenario, highlighting the growing influence of pathway-specific feedbacks. Overall, our approach demonstrates greater compatibility with CMIP6 simulations, allowing for more accurate representation of ET responses to future CO2 increases. These findings provide valuable insights for advancing the analysis of nonlinear vegetation-atmosphere interactions and hydrological uncertainty under climate and physiological forcings.

Monitoring drought-flood abrupt alternation (DFAA) using monthly indices presents limitations, particularly in identifying event timing and accounting for precipitation neutralization effects. This study introduces a daily drought-flood abrupt alternation index (DFAI) to overcome these challenges. Using a gridded observational dataset and simulations from five global climate models (GCMs), we analyse the spatiotemporal characteristics and evolution of DFAA events across mainland China. Validation against historical disaster records shows that the daily DFAI detects DFAA events missed by the monthly DFAI; and identifies the Southwest Monsoon Convergence Zone as a high-frequency hotspot, contrasting with the fragmented patterns of the monthly index analyses. Long-term trend analysis reveal significant nationwide increases in DFAA frequency and intensity; under Shared Socioeconomic Pathways (SSP1-2.6, SSP3-7.0, SSP5-8.5), the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP3b) projections indicate no overall increase in future DFAA frequency but a consistent intensification, particularly under SSP5-8.5, where mainland China may experience stronger events. The improved index enables higher-resolution DFAA detection and supports enhanced risk assessment and adaptive strategies for managing compound hydrometeorological hazards.

In contrast with extensive knowledge of microbial spatial distribution of on positive slopes, we know little about the microorganisms in negative slopes. In this study, we used positive slope (peak clusters) and negative slope (tiankengs) of Haifeng Nature Reserve in Yunnan Province, China were used as model systems to explore the spatial distribution, resource limitation patterns, and potential influencing mechanisms of soil microorganisms. Results revealed significant differences in composition, structure, and resource limitations of soil microbial communities across slope gradients. Compared with positive slopes, negative slopes exhibited higher microbial diversity, with microbial survival strategies predominantly characterized by r-strategies. Fungal networks exhibited higher complexity in negative slopes, while the bacterial networks exhibited higher complexity in positive slopes. As slope position increased, microbial carbon (C) and phosphorus (P) limitations exhibited a gradual upward trend, and negative slope exhibited lower microbial C and P limitations. Heterogeneous soil nutrient distribution along the gradient plays a dominant role in shaping microbial distribution and resource limitations. This study broadens our understanding of the distribution and resource limitations patterns of soil microorganisms in positive and negative karst topography, and emphasizes that karst tiankeng may be a unique habitat for soil microorganisms to survive in karst areas.

Evaluation ecosystem service value (ESV) is critical, as “lucid waters and lush mountains are invaluable assets”. To assess the incremental effects of ecological assets on soil and water conservation in subtropical mountains, we developed a remote-sensing-driven mountainous equivalent factor (RS-MEF) method to estimate the ESV of Changting County, China. This method is a hybrid of a conventional equivalent factor framework and remote sensing techniques for mountains, achieving several advancements, including spatial adjustment using vegetation activity merged with productivity, improved spatial resolution, and the removal of topographic effects. Using the RS-MEF method, we estimated that the ESV of Changting County was approximately CNY 15.80 billion in 2010 and CNY 34.83 billion in 2022. Specifically, the ESV per unit area of the major soil erosion area (MSEA) in the county was less than that of the non-major soil erosion area (n-MSEA); however, the ESV growth rate of the MSEA from 2010 to 2022 was faster than that of the n-MSEA. Therefore, the ESV gap between the two areas was reduced from 28.99% in 2010 to 15.83% in 2022. Topographic gradient analysis illustrates that areas with elevations of 385 to 658 m and steep slopes achieved a high ESV, while high-elevation areas with gentle slopes will be a focus of control in the next phase. Our study demonstrates that significant achievements have been made in ecological restoration from an ESV perspective, with a notable reduction in low-ESV areas in the MSEA; the insights gained into ESV growth and its underlying factors are valuable and instructive for future soil and water conservation efforts.

The bay area contains terrestrial forests and coastal mangroves with vital ecosystem functions, which provide essential ecosystem services such as carbon sequestration and biodiversity maintenance. Meanwhile, the bay area usually hosts intensive socioeconomic activities. High-intensity anthropogenic activities in the bay area have threatened the terrestrial ecosystem and marine environment. Harmonizing the relationship between terrestrial ecosystem conservation, marine environmental governance, and socioeconomic development is crucial for realizing the national “coordinated land and marine development” strategy and promoting sustainability in the bay area. This study constructed a coupling coordination assessment system of the terrestrial ecosystem, marine environmental system, and socioeconomic system. Taking the bay area of the Fujian River Delta as a case study, multiple ecological models were integrated to quantify the coupling coordination degree between these three systems and present its spatial distribution characteristics. Furthermore, the constraint types on the coupling coordination degree were spatially revealed in the bay area. The results suggested that there are significant spatial differences in the coupling coordination degree of the three systems in the bay area of the Fujian River Delta. The areas with a relatively low coupling coordination degree are mainly focused on the central part of the Xiamen Bay area and the southeastern part of the Quanzhou Bay area. Regions with high socioeconomic development tend to present weak terrestrial or marine eco-environmental conditions. The critical constraint factor of the coupling coordination degree in the Zhangzhou Bay area is its backward socioeconomic development level. The backwardness of both the terrestrial ecosystem and marine environmental system exists in most districts of the Xiamen Bay area. In addition, the marine environmental conditions in the Xiamen Bay area are worse than those in the Quanzhou Bay Area and the Zhangzhou Bay area.

Karst tiankeng is a typical terrestrial habitat island-like system, known as an oasis in a degraded karst landscape. However, we know little about the composition, structure, and life strategies of soil microbial communities in the karst tiankeng ecosystem. In this study, we use amplicon sequencing to investigate the soil bacteria and fungi of 26 karst tiankeng in two typical karst tiankeng groups. The results showed that the composition and structure of bacterial and fungal communities were significantly different at two dimensions (among and within the karst tiankeng group). Bacteria showed more sensitivity to variation in the karst tiankeng area and isolation than fungi. With the increase of karst tiankeng area and isolation, the bacterial life strategies shift from K-strategist to r-strategist, likely due to the changes in soil properties (total phosphorus, Ca, and soil water content). Abundant and rare taxa play different roles in karst tiankeng ecosystems; abundant taxa serve a key role in nutrient cycles and life strategy shifts by occupying the key status in networks. Considering the key role of soil microbes in ecosystems, more attention must be paid to the impact of habitat loss on soil microbial life strategies, particularly in the ecological impact of life strategies change of abundant and rare taxa

How energy saving and emission reduction measures influence the interrelationship between carbon emissions and environmental sustainability of cement industry is not very clear, and this could lead to trade-off. This study investigates effects of three representative energy saving and emission reduction measures (steam Rankine cycle power generation (SRC), organic Rankine cycle power generation (ORC) and carbon capture and utilization (CCU)) on environmental performance of cement production using an improved emergy analysis and carbon emissions amounting. The proposed approach can investigate resource efficiency and emissions' impact as well as carbon footprint of a system in study simultaneously. A cement enterprise, in Jilin Province in China, as a case, is explored using the proposed combined approach based on scenario analysis. The results illustrate that combination of SRC + ORC can promote environmental sustainability of cement production and carbon emission reduction by 4.61 % and 4.28 % respectively, mainly derived from SRC application (by 4.06 % and 3.81 %), (2) CCU can promote carbon emission reduction by 3.97 % but weaken the environmental sustainability by 2.10 % due to enhancing share of purchased nonrenewable electricity, and (3) combination of SRC + ORC + CCU can promote the environmental sustainability (by 2.43 %) and carbon emission reduction by 8.25 %. In addition, due to strong dependence on nonrenewable resources, combination of SRC + ORC + CCU is still limited in improvement of environmental performance of the industry. In the future, China's cement industry should further enhance environmental performance of CCU and efficiency of ORC, as well as improve the resource structure of this industry.

Potential toxic metal (PTM) is hazardous to human health, but the mechanism of spatial heterogeneity of PTM at a macro-scale remains unclear. This study conducts a meta-analysis on the data of PTM concentrations in the soil of 164 major cities in China from 2006 to 2021. It utilizes spatial analysis methods and geodetector to investigate the spatial distribution characteristics of PTMs. The geographic information systems (GIS) and geodetector were used to investigate the spatial distribution characteristics of PTMs, assess the influence of natural factors (NFs) and anthropogenic factors (AFs) on the spatial heterogeneity of PTMs in urban soils, and identified the potential pollution areas of PTMs. The results indicated that the pollution levels of PTMs in urban soils varied significantly across China, with higher pollution levels in the south than in the north. Cd and Hg were the most severely contaminated elements. The geodetector analysis showed that temperature and precipitation in NFs and land use type in AFs were considered as the main influencing factors, and that both AF and NF together led to the PTM variation. All these factors showed a mutually enhancing pattern which has important implications for urban soil management. PTM high-risk areas were identified to provide early warning of pollution risk under the condition of climate change.

The value realization of ecological products is currently a rapidly evolving research topic; however, the definition of its concept, type, and operation mechanism remains relatively ambiguous. Operating in accordance with the PRISMA guidelines, this review employs keyword retrieval and screening, utilizing VOSviewer and word cloud mapping for analysis, in order to reveal three primary research domains related to ecological product value realization. Based on thorough screening and the analysis of high-quality literature, this study comprehensively accomplished the following objectives: (1) clarifying the fundamental concepts of ecosystem services and ecological products, their interrelationships, and the scope of research on ecological products; (2) clarifying the basic connotation of realizing the value of ecological products; (3) demonstrating government-led approaches, market-driven approaches and collaborative pathways for realizing the value of ecological products; (4) reviewing international cases related to realizing the value of public ecological products, quasi-public ecological products, and operational ecological products. The academic contributions of this study are (1) expanding the theoretical framework for realizing the value of ecological products; (2) providing a Chinese perspective on global research on pathways to realize value from ecological products; and (3) offering a novel approach to revitalizing regional economies and improving local ecological environments. Based on this research, several shortcomings and future directions in this field are identified: (1) insufficient clarity, standardization, and uniformity in evaluation and measurement methods; (2) the absence of comparison between ecological products and urban economic products; (3) inadequate exploration of multi-stakeholder allocation and coordination mechanisms; (4) limited research on the role of capital markets in allocating ecological product resources.

The implementation of some energy-saving and emission reduction measures can effectively offset the energy consumption and carbon emissions in the wastewater treatment process. Integrated policy-making information on carbon-energy-economy of these technologies is not clear in national wastewater treatment industry. This study investigated energy self-sufficiency, carbon neutralization potential and economic performance of wastewater treatment industry, as well as related synergy effect among the three aspects using the proposed approach. Then the approach was used to investigate energy-saving and carbon emission reduction potential of the three technologies (photovoltaic power (PV), combined heat and power (CHP) and water source heat pump (WSHP)) and technological combinations as well as related economic performance in urban wastewater treatment of Chinese different provinces in 2021. The results showed that (1) The national energy self-sufficiency is 95%; therein, 13 provinces have the potential to achieve or exceed energy self-sufficiency of 100%, and the top 3 provinces are Heilongjiang, Yunnan and Hunan. (2) The national carbon neutral potential is 87%; therein, 9 provinces have the potential to achieve or surpass carbon neutralization of 100%, and the top 3 provinces include Beijing, Hunan and Shaanxi. (3) these technologies or their combinations are potentially economically viable (net economic benefit ratio > 1), and the top three provinces are Beijing, Shaanxi, and Inner Mongolia. (4) Generally, there are 13 provinces with synergy effect > 1 in the country; the top three provinces are Liaoning, Heilongjiang and Hunan. Finally, targeted policy suggestions are provided for Chinese urban wastewater treatment. The proposed approach can also act as one of decision-making tools for wastewater treatment industry in other countries or areas in the world.

Extreme heat events caused by climate change have seriously threatened the sustainable human-environment system development.It has become the frontier of integrated geography to scientifically assess the comprehensive impact of heat waves on the urban system and to provide stakeholders with decision support services to cope with extreme heat.This study constructed an"exposure-susceptibility-adaptive capacity"framework for urban heat vulnerability and an early warning index system based on the perspective of the human-environment system.We then proposed key early warning technologies,including an urban heat index model,multi-subject adaptive capacity coupling technology,and a multi-group vulnerability assessment criteria library.Taking urban diversified groups and urban administrators as the service target,we designed the urban heat vulnerability early warning system.The system mainly comprises a mobile application that provides users with an interactive interface,and a dedicated management backend.The mobile application has four main functions:Urban heat index forecast,Crowd heat vulnerability risk warning service,Outdoor work guidance service,and Public facility-assisted adaptation and decision support menu.The layer data and the warning message are mainly handled by the dedicated management backend.The system provides hourly location-based heat vulnerability warnings and targeted healthy living tips for tourists,the elderly,children,and people with heat-sensitive conditions.Additionally,the system can provide a scientific basis for communities to improve their adaptive capacity to heat waves.As a pilot,the system was deployed in Xiamen City to provide personalized support services for healthy living in hot weather to residents and communities.In September 2021,the"Urban Heat Index"module was officially launched on the"Zhi Tian Qi"public meteorological service platform of the Fujian Province.The research perspective and methodology,based on a multiscale vulnerability framework,provide an effective method to dynamically and finely characterize the impacts of extreme natural hazards.The research results support urban multi-stakeholders in managing production and life during hot weather and help authorities develop targeted disaster prevention and mitigation plans for specific areas.Moreover,the findings provide a scientific reference for planning departments to improve and optimize the spatial allocation of emergency resources.