Although the global population continues to grow,the coming decades will witness the most rapid expansion of urban population in human history,primarily,driven by large-scale rural-to-urban migration.This migration alleviates human pressure significantly in rural areas,promotes the transformation of land use patterns and ecosystem restoration,and profoundly reshapes regional land spatial configurations.These changes directly or indirectly affect local ecological environments,thereby presenting both new opportunities and challenges for biodiversity.The southwestern region of China serves as a critical ecological security barrier for the country.It is not only a key area for global vegetation greening and plant diversity conservation,but also a typical region experiencing marked rural-urban migration and a pronounced decline in rural population.The ongoing and accelerating outflow of rural population in this region is profoundly reshaping local human-land relationships.Moreover,its distinctive karst landforms and ecological fragility make it highly sensitive to human disturbances.While large-scale rural population decline is reshaping the ecological environment,it also creates opportunities for ecosystem restoration.However,the response mechanisms of plant diversity to rural population decline and its threshold effects remain unclear,which hinders a deeper understanding of the coupling mechanisms in human-earth systems and constrains the scientific rigor and effectiveness of regional ecological conservation strategies. This study focuses on southwestern China as the research area.Based on vascular plant species richness data,the spatial pattern of plant diversity from 2000 to 2020 was reconstructed using a Random Forest model.The K-means algorithm was employed to identify urban-rural boundaries,revealing the spatiotemporal evolution characteristics of the rural population and examining the impact of rural population decline on plant diversity and its threshold effects.Using the human footprint index to characterize human pressure,the relationship between the release of human pressure induced by rural population decrease and the increase in biodiversity was analyzed.Through relative contribution rate decomposition,the driving contributions of climate change and human pressure were quantified.The study addresses the following key questions:(1)Spatiotemporal patterns of population decline in southwestern rural China;(2)Impacts of population decline on the spatial distribution of plant diversity and underlying mechanisms;(3)Threshold responses of plant diversity to changes in population density;(4)Relative contributions of climate change and human pressure to plant diversity changes. The results indicate that between 2000 and 2020,southwestern China experienced a rural population decrease of approximately 137 million,a 5.23％reduction in human pressure,and a significant 44.32％increase in plant diversity.Over 60％of the areas with rural population loss showed significant increases in plant diversity,with an average increase of approximately 0.73 species per 100 km2,across an area of 266,600 km2,Further analysis revealed a nonlinear relationship between rural population density and plant diversity:when population density fell below 336.68 persons·km-2,population decline exerted a suppressive effect on plant diversity;within the range of 336.68 to 956.73 persons·km-2,this suppressive effect gradually weakened;and when density exceeded 956.73 persons·km-2,population decline transitioned to a positive facilitative effect.Decomposition of driving factors showed that changes in rural human pressure contributed 38.64％to plant diversity changes,while climatic factors accounted for 61.36％,indicating that climate change remains the dominant factor influencing regional plant diversity. This study quantifies and reveals for the first time the nonlinear relationship and key thresholds between rural population decline and plant diversity in southwest China.It systematically elucidates the response mechanisms of plant diversity to population decline and human pressure,and clarifies the relative contributions of human activities and climate change.By analyzing the response patterns of plant diversity to rural population outmigration and identifying critical thresholds of population density effects,this research provides a scientific basis for understanding the mechanisms by which rural-urban migration influences biodiversity.The findings offer important insights for biodiversity conservation and regional sustainable development in southwest China.

It is essential to distinguish the effects of climate signals and cave microenvironments on speleothem 518O, 513C, and element/Ca records, because cave microenvironments can interfere with the reconstruction of climate signals preserved by speleothems. However, it remains difficult to separate the impacts of direct climate signals and cave microenvironments-including cave air temperature and CO2 concentration-on these proxies, even after numerous cave monitoring and laboratory simulation experiments. In this study, we compared outdoor Artificial Cave monitoring with natural cave monitoring, providing an innovative and efficient method to discriminate the effects of climate signals and cave microenvironments on the proxies. We presented seven years of time-series data from Shawan Cave (natural cave) and more than two years of time-series data from the outdoor Artificial Cave located in Guizhou Province, Southwest China, for 518O, 513C, and elemental compositions of cave drip water along with microenvironmental conditions. In Shawan Cave, the seasonal changes in drip water 518O and 513CDIC, which showed a significant inverse correlation with cave airpCO2, were attributed to the wide range of cave air pCO2 (972-21,627 ppm), The irregular seasonal changes in drip water Mg/Ca were affected by the opposing seasonal variations in rainfall amount and cave airpCO2. In contrast, in the Artificial Cave, the wider range of cave air temperature (11.78-25.25 degrees C) appeared to influence the seasonality of cave water 518O and Mg/Ca values. Meanwhile, the 518O and Mg/Ca values of water isolated from the cave were mainly affected by rainfall 518O and rainfall amount, respectively. The 513CDIC values in cave water and in water isolated from the cave were primarily influenced by rainfall amount, because the narrow range of cave airpCO2 was insufficient to drive a notable change in cave water 513CDIC. Our study highlights that cave microenvironments, rather than direct climate signals, are key drivers of seasonal amplitudes in speleothems proxies in caves with wide ranges of cave air temperature and pCO2. When the ranges of cave air temperature and pCO2 are narrow, speleothem proxies primarily record precipitation and air temperature.

Cave drip water is a fundamental carrier of climatic and environmental information, and its geochemical signatures are widely employed in speleothem-based paleoclimate reconstructions. While are well established, the role of rainfall intensity and vegetation-driven infiltration dynamics in shaping these signals remains insufficiently constrained. To address this, we carried out seven years of monitoring in Shawan Cave, a shallow karst cave system in Southwest China, integrating rainfall observations, continuous drip rate measurements at 30-minute resolution, and stable isotopes and elements/Ca data from drip water. Our results showed that drip water was present in both the dry and wet seasons from 2017 to 2019, whereas it was intermittently interrupted from 2020 to 2023 drip water, with more observed during the wet season and less during the dry season. This may be attributed to the deeper root systems of vegetation, which alter soil moisture and the amount of rainfall required to penetrate the soil and generate infiltration into the karst cave system, thereby changing the water reservoirs feed drip water over time. We propose that vegetation recovery, by influencing evaporation, can modulate drip water flow paths and thereby drive the enrichment of drip water 518O. Intriguingly, although drip water 518O during 2017-2018 did not fully reflect changes in rainfall 518O, during 2022-2023 it appeared to inherit the 518O signal of heavy rainfall. This indicates that drip water 518O has gradually evolved from reflecting annual or multiyear rainfall amounts to primarily recording the heavy rainfall of the summer monsoon. These observations demonstrate that drip water signals are not simply a direct record of rainfall but are mediated by subsurface hydrological processes. We propose that the combined effects of reservoir-feeding drip water and flow path change over time are critical in governing the transmission of rainfall signals into cave environments. Recognizing the influence of vegetation change and reservoir evolution refines the interpretation of speleothem proxies, enabling more reliable reconstructions of monsoon variability at sub-annual to interannual timescales.

Weathering is a crucial geological process where surface rocks and minerals are gradually transformed into loose deposits or soil through both physical crushing and chemical decomposition in the natural environment. This dynamic process is intrinsically linked to the entire evolution of the Earth's surface system. Weathering is a fundamental driver of surface topography, leading to the erosion and eventual flattening of steep mountains and promoting the accumulation of nutrient-rich soil in plain areas. It also directly supports the development and maturity of the pedosphere, provides a basic carrier for terrestrial ecosystems, and plays an indispensable role in global material circulation. Crucially, the continuous weathering processes of the Earth fundamentally influence the resilience and recovery capacity of ecosystems by precisely regulating material and energy exchange across the six fields. In the field of global carbon cycle, the chemical weathering of silicate minerals is a fundamental, long-term geological process that acts as a major carbon sink, removing atmospheric carbon dioxide by converting it into dissolved bicarbonate and carbonate ions, thus acting as a crucial natural mechanism to slow global warming. In the aspect of element supply, nitrogen, phosphorus, potassium, and other nutrients released into the biosphere through the natural process of weathering are fundamental for the stability and operation of ecosystems. Traditional geography, while studying the interaction and formation of natural and human elements on the Earth's surface, has not fully recognized the ecological significance and functional value of weathering as a crucial interface connecting life and the environment. This leads to the following three shortcomings in understanding weathering. (1) The disconnection between geological time scales and ecological process research limits the thorough analysis of ecological response mechanisms of climate change events. (2) Biogeochemical cycle models generally face challenges in accurately quantifying biologically driven weathering. (3) An effective quantitative index for the influence of human activities on the flux of weathered materials has not been established. Therefore, the establishment of the "weathering geography" discipline is essential for managing critical environmental challenges and preserving ecological balance. In this paper, the hierarchical research model of geography (from individual organisms to ecosystems) is combined with the mineral geochemical analysis methods of geology to bridge traditional disciplinary boundaries, and the disciplinary system of "rock weathering-material migration-biological response" in weathering geography is constructed. Weathering geography is a new interdisciplinary subject formed by the intersection of ecological geology and geography. It mainly takes the lithosphere, pedosphere, biosphere, atmosphere, hydrosphere, and human sphere as the research objects. By analyzing the influence of physical, chemical, and biological weathering processes on ecosystems and ecological processes, weathering geography integrates the three-dimensional dynamic processes of lithospheric material decomposition, biosphere element utilization, and human sphere intervention and adjustment. This paper reveals the general laws and causes of the relationships between various components of ecosystems and ecological processes in different environmental gradients. Furthermore, a multi-sphere interactive feedback theoretical system of "water-rock-soil-gas-life-people" is constructed. At the same time, it is emphasized that establishing a multi-scale coupling system of "in situ observation-model inversion-application verification" is crucial for realizing a comprehensive, whole-chain analysis from element cycles to continental weathering patterns. This system will reveal the coupling mechanism of energy flow and material circulation in the Earth's surface system, provide a new theoretical tool for ecological simulation in extreme environments, address the cognitive deficiency of traditional geography by linking the complex interactions between deep geological processes and surface ecological responses, and offer a new paradigm for solving the complexity crisis in ecosystem modeling.

Unbalanced urban–rural development remains a critical global challenge, particularly in developing countries where widening gaps hinder economic growth and threaten social stability. Traditional Lewis dual-economy theory explains the origins of income disparity but overlooks infrastructure mobility, modern agricultural technology, and the tertiary sector's expanding influence. To address these limitations, this study investigates the Chengdu-Chongqing Economic Circle—an emblematic region of western China with pronounced urban–rural divides—using nighttime light (NTL) data to reveal spatial economic dynamics. A refined spatial division of urban and rural areas was established, and a spatial entropy–based Urban-Rural Development Equilibrium Index (UREDI) was constructed to assess spatial heterogeneity. Pearson correlation and partial correlation analyses, coupled with the XGBoost-SHAP attribution model, were employed to identify key drivers of urban-rural balance. Results show that: (1) high NTL intensity and economic richness are concentrated in Chengdu and Chongqing, with diffusion to surrounding areas after 2010; however, internal disparities have widened. (2) The number of secondary and tertiary industry employees, enterprises above designated size, mechanized harvest area, urbanization rate, and road density are significantly and positively correlated with UREDI. (3) After controlling for other factors, only urbanization rate remains significant (R = 0.394, p < 0.001), and its and its mean absolute SHAP value (0.307) far exceeds others, highlighting it as the core driver of urban–rural equilibrium through factor mobility, industrial integration, and technology diffusion. This study refines the Lewis model framework and provides insights for addressing urban–rural imbalance in developing regions globally.

Agricultural land transformation significantly affects ecosystem services (ES), yet its impacts across different topographic gradients remain unclear, hindering integrated land management in karst mountainous areas. Using Puding County, Guizhou Province, as a case study, this research employed the land-use transfer matrix, the InVEST model, and Spearman correlation analysis to examine the spatiotemporal patterns and relationships between agricultural land transformation and ES from 2004 to 2024. The findings indicate: (1) Agricultural land transformation shows distinct topographic differentiation: non-agricultural conversion and agricultural intensification dominate low-topographic positions; ecological land use conversion and agricultural intensification coexist in mid-topographic positions; and ecological land use conversion prevails in high-topographic positions. (2) ES vary consistently along topographic gradients: soil retention and carbon storage increase with elevation, food supply concentrates in low topographic positions, and water yield changes are most pronounced at low topographic positions. (3) Topography regulates the ecological effects of transformation pathways: ecological land use conversion enhances regulating services in high-topographic positions, while farmland abandonment increases erosion risk; composite transformation promotes a dynamic balance between services in mid-topographic positions; and agricultural intensification improves food supply but intensifies water competition in low-topographic positions, whereas non-agricultural conversion degrades multiple ecosystem services. This study provides a scientific basis for zoned land management and sustainable development in karst mountainous areas.

Karst regions are among the most complex and fragile ecosystems globally, playing a critical role in the carbon cycle. However, systematic assessments of carbon storage (CS) dynamics and their driving mechanisms remain limited. This study focuses on Guizhou Province, a global karst hotspot, using it as a case study. By integrating multi-source remote sensing data with the PLUS and InVEST models, and incorporating the ecological protection red line into future predictions, we systematically analyze the spatiotemporal dynamics of CS from 1990 to 2060. A CatBoost-SHAP-PDP machine learning framework is applied to effectively reveal the nonlinear relationships and interactive driving mechanisms influencing CS changes in these ecosystems. The results show that between 1990 and 2020, the overall CS in Guizhou exhibited a fluctuating downward trend, decreasing by 1.4%, with the Karst region showing a more significant decline (2.08%), far exceeding that of non-Karst regions (0.35%). Future scenario predictions suggest that under natural development and cropland protection scenarios, CS would further decrease by 8.25% and 6.85% respectively by 2060, while ecological protection scenarios could restore CS to near-1990 levels. The driving mechanism analysis identified NDVI, evaporation, and SPEI as the primary driving factors, explaining 68.2% of the variation in CS. These factors demonstrate complex nonlinear relationships and interactive effects. CS increases under favorable ecological conditions, including healthy vegetation cover (NDVI > 0.5), moderate evaporation, adequate moisture, and warm temperatures. Peak CS occurs when dense vegetation is coupled with optimal climate and water availability.. This research provides a methodological framework for long-term CS assessment and mechanistic analysis in karst regions, while offering scientific support for land-use optimization and ecological protection policy formulation under regional “dual carbon” goals.

Southwest China’s karst mountainous areas (KMA) face rocky desertification, man-land conflicts and agricultural fragmentation. Understanding the evolution of agricultural production space (APS) is key to balancing ecological conservation and agricultural development. This study establishes a theoretical framework, uses Puding County as a case study, applies methods such as land use transition matrices and reveals the process and driving mechanisms of its APS transformation. Results indicate that: (1) APS transformation entails functional reallocation rather than simple contraction, with mountainous areas transitioning toward ecological restoration and high-value industries while basin areas shift to intensive production; (2) Initial natural drivers were later superseded by policy and socioeconomic factors, whose effects amplified through interactions with topography; (3) The region achieved preliminary transition from traditional agriculture to diversified and sustainable systems, with distinct pathways emerging across different mountain-basin configurations. This study elucidates APS transformation mechanisms in karst mountain-basin systems, offering a theoretical basis for regional agricultural development and practical support for sustainable development in ecologically fragile zones worldwide.

Global change is accelerating the chemical weathering of silicate rocks and the associated phosphorus release. However, the effects of phosphorus release on the global patterns of plant phosphorus limitation remain unclear. Here, we show that approximately 47% of the exposed areas in global silicate rocks are subject to phosphorus limitation of vegetation growth, as estimated using the ratio of leaf nitrogen to phosphorus resorption efficiency. Phosphorus-limited areas are projected to expand markedly with global warming, and the proportion may reach 54 - 59% according to two model scenarios (the shared socioeconomic pathways SSP2-4.5 and SSP5-8.5). Nevertheless, phosphorus release from accelerated chemical weathering of silicate rocks mitigates this limitation, with a relative contribution of approximately 15.5%. This work highlights the implications of accelerated chemical weathering of silicate rocks and its resulting phosphorus release for the global patterns of phosphorus limitation, providing a scientific foundation for phosphorus management strategies.

The magnitude and distribution of organic carbon (OC) transport from the terrestrial surface to the oceans is not well understood on a global scale. This hinders our understanding of terrestrial and marine carbon cycles. In this study, we determined the characteristics of OC flux. Our results showed that approximately 420 Tg C/yr of OC are transported from the terrestrial surface to the oceans, including 220 Tg C/yr of particulate organic carbon (POC) and 200 Tg C/yr of dissolved organic carbon (DOC). Asia, with only 32.46

Large-scale rural depopulation has altered the rural environment and reshaped the distribution pattern of species. However, the impact of rural depopulation on biodiversity is unclear. Based on plant species richness data, we used random forest model (RFM) and generalized additive model (GAM) to explore the impact of rural depopulation on plant diversity. The results showed that a 1.82 % decrease in human pressure in rural depopulation areas in China promoted vegetation restoration and increased plant diversity. Plant diversity in rural decreased by 2.25 % on average, while it increased by 3.75 % in rural areas that experienced depopulation. Plant diversity was 1.48 times greater in the severely depopulated rural areas than in the slightly depopulated areas. When the total population reaches around 1.33 billion, the plant diversity affected by population changes will reach a threshold. This research helps understand the potential positive impacts of rural depopulation on environmental restoration and plant diversity increase.

Understanding the evolution of the social-ecological system (SES) in Southwest China's karst mountain areas (KMA) is important to sustainable development. Current research still has certain shortcomings in analyzing rural SES's evolution and sustainable development path in ecologically fragile areas. This study constructs a framework for the evolution of SES to reveal the evolution characteristics of this evolutionary process and summarizes typical sustainable development models for rural areas in KMA. The results show that: (1) Land use transition in KMA has significantly improved vegetation cover and socioeconomic conditions, demonstrating strong coupling between social system and ecosystem. (2) The SES shifted from an imbalanced to a coordinated state, progressing through inefficient development, transitional restructuring, and sustainable development stages. (3) The sustainable development models of rural SES are influenced by natural environments, socioeconomic conditions, and policies, with effective policy guidance particularly crucial for socio-ecological development. This study systematically summarizes the evolution of SES in KMA, providing insights into regional development strategies. The framework and cases offer references for rural revitalization and ecological development in similar regions worldwide.

As a crucial water conservation area in the upper reaches of the Yangtze River,the Mawei River Basin in Guizhou holds a significant position in maintaining the ecological balance and sustainable development of the upper reaches of the river.Thus,it is of great importance to explore the spatial and temporal differentiation characteristics of ecosystem service value(ESV)and the driving mechanisms in the Mawei River Basin and to reveal the degree of influence and the complex relationships of different categories of driving factors on various ecosystem services to promote the effective allocation of resources and the maximization of ecological benefits in the Mawei River Basin and upper reaches of the Yangtze River.Based on land-use type data of the Mawei River Basin from 2000 to 2020,we assessed its ESV using the equivalent factor method and the spatial autocorrelation model,coupled the random forest(RF)model with the Shapley additive explanations(SHAP)method to reveal the dominant factors of ESV drivers and the nonlinear influence characteristics and their influence effects,and explored the interaction paths of the drivers using the partial least squares(PLS)method.The study produced several interesting results:① The ESV of the watershed exhibits a change trend of decreasing initially and then increasing,with a total decrease of 295 million yuan.Among the services,the regulation service makes the greatest contribution rate to the ESV of the watershed,accounting for 67.31%of the total in 2020,and the ESV presents a spatial distribution pattern of being high in the east and west and low in the north,south,and central parts of the watershed,which is dominated by higher-value area and medium-value area.② Socioeconomic factors are the dominant factors driving the change of ESV,with a contribution of 61.12%.There is an obvious nonlinear relationship between ESV and each single factor.ESV is significantly negatively correlated with human activity intensity(HAI),DEM,and slope and positively correlated with per capita GDP,soil conservation amount,and rainfall.As an index characterizing the intensity of human disturbance to the ecosystem in a certain area,HAI is evidently more important than other factors.③ Aside from the land-averaged GDP and population density having no obvious interaction with the other factors,the effect of each factor with interaction effects on ESV varies in different ranges.Socioeconomic factors have the strongest direct effect on ESV,and topographic factors affect ESV indirectly by influencing other factors.The research results are intended to provide data support and scientific basis for the balanced realization of the dual benefits of ecology and economy in the Mawei River Basin,as well as for ecological security regulation and optimal allocation of land resources.

Identifying priority protected areas based on biodiversity and ecosystem services is crucial for ecological planning and sustainable development.Guizhou is an important ecological barrier in the upper reaches of the Yangtze River and the Pearl River,with a complex ecosystem and rich biodiversity.However,most studies delineated protected areas based on a single target of biodiversity or ecosystem services,often neglecting the combination of the two.Therefore,taking Guizhou Province as an example,this article determines priority protected areas based on dual objectives by combining biodiversity and three different ecosystem services.The results show that the priority protected areas for biodiversity are in the southwest of Guizhou Province,and the priority protected areas for ecosystem services are in the eastern region;The overlap of priority protected areas between the two is mainly concentrated in the central part of Tongren,Qiannan,and Qiandongnan,with a spatial overlap area of 10.88％;The priority protection area for biodiversity is relatively large(49.7％),while the protection area for ecosystem services is relatively small(19.5％).In the Qiandongnan,Qiannan,and Bijie regions,new protected areas can be built and existing protected areas can be expanded in the future.The establishment of protected areas should consider the combination of biodiversity and ecosystem services,and the results can provide reference for the development and utilization of natural resources,sustainable development,and the expansion of protected areas.

Emerging evidence suggests that female education levels play a role in ecological restoration by indirectly attenuating human stress through fertility and migration. However, this relationship is difficult to quantify and has not yet been investigated in China. Here, a comprehensive analytical framework for national multi-source data is constructed, multiple types of data are integrated to quantify the associations, and regression analyses and geodetector model are applied to explore the mechanisms influencing the changes in female education levels and ecological environments. The results showed that the population density in the areas with decreasing and increasing vegetation cover increased by an average of 31 and 1 person/km2, respectively, i.e., there is a high degree of overlap between the degraded vegetation areas and the areas with high population density distribution. The Average years of schooling for female increased from 6.34 years in 1996 to 9.47 years in 2021, with an average annual growth rate of 0.12/yr, which was 1.33 times and 1.2 times that of male and the national average, respectively, and it is expected that around 2035, the education level of female will be the same as that of male, or surpass male. The fertility rate declines by 0.37 for every year of female schooling; for every 1 % of schooling. These findings have initially elucidated the key role of female educational advancement in alleviating human-land conflicts, promoting ecological restoration and educational development, and providing effective references for relevant policies.

Since the Industrial Revolution, significant changes in global land-use patterns have occurred, which have disrupted terrestrial carbon emissions. However, the disturbance processes, change trends, and distribution patterns are not clear. Therefore, the changes in terrestrial carbon emissions (Eluc) caused by land-use change (LUC) since 1850 were analyzed in this study. The results showed that, owing to the sharp decrease in forestland (-13.39 %; 84.26 × 105 km2) and significant increases in built-up land (+1360.4 %; 7.21 × 105 km2), cropland (+175.8 %; 130.88 × 105 km2), and grassland (+162.6 %; 239.73 × 105 km2), the global Eluc increased from 0.42 Pg C in 1850 to 11.05 Pg C in 2018, with an average annual increase of approximately 3.42 Pg C yr-1, while the average annual carbon emissions after the 21st century reached 9.65 Pg C yr-1. Among them, direct Eluc increased by approximately 0.80 Pg C yr-1 and indirect Eluc increased by 2.62 Pg C yr-1. In addition, from 1850 to 2018, global Eluc was approximately 578.26 Pg C, with North America, Europe, and Asia being the largest regional sources. Our results highlight the changing trend and distribution pattern of global terrestrial carbon emissions under the influence of LUC since the Industrial Revolution and provide a scientific basis for regional and sectoral formulation of low-carbon emission-reduction policies and planning of low-carbon land-use patterns.

Microplastics (MPs) are now pervasive in the environment, with annual emissions estimated to range from 10 to 40 million metric tons. Aging (weathering) processes induced by environmental changes, gradually degrade MPs into smaller particles with higher surface reactivity. These particles readily adsorb surrounding heavy metals (HMs), forming complex pollutants. Such composite contaminants can bioaccumulate through the food chain, ultimately posing significant threats to ecosystems and human health. At present, this type of combined pollution has emerged as a pressing global challenge requiring urgent attention. Although research on the impact of MPs aging processes on the environmental behavior of HMs has increased in recent years, there remains a lack of systematic reviews. Therefore, there is an urgent need to collate relevant studies to better assess and mitigate the risks of composite pollution by MPs and HMs. This paper provides a comprehensive review of the effects of aging processes on the physicochemical properties of MPs and explores the mechanisms of adsorption, mobility, and bioavailability of HMs by aged MPs, systematically summarizing the key environmental factors influencing the interactions between aged MPs and HMs. Finally, the prospects for research on the co-occurrence of MPs and HMs in the environment were discussed. This review provides a scientific basis for the environmental risk assessment of such combined pollution and holds substantial practical significance for advancing ecological conservation.

Constructing an ecological security pattern is important for maintaining the stability of the ecosystem in karst areas and promoting the sustainable development of regional social economy.This study takes the Nanming River Basin,a typical karst basin in Guizhou Plateau,as the research object,combines multi-source data,evaluates the ecosystem service(ES)of the basin by using the InVEST model,and identifies ecological source areas scientifically by combining ecological sensitivity,MSPA analysis,and landscape connectivity.The circuit theory is used to identify the ecological corridor and determine the points and obstacles,analyze the integrity and connectivity of the basin ecosystem,reveal the development trend of the basin ecological security,and finally form the ecological security pattern of the Nanming River Basin with the combination of"point-line-plane."The results show that:① From 2000 to 2020,the ecosystem services of the Nanming River Basin showed a spatial feature of high in the northeast and low in the southwest.② The ecological sensitivity of the Nanming River Basin was mainly low sensitivity,concentrated in the upper and middle reaches of the basin;the overall level of landscape connectivity was high,with uneven spatial distribution,showing a distribution pattern of high in the northeast and low in the southwest.③ Patches with better habitat quality were selected as ecological sources,and 52,52,and 65 ecological sources were identified in 20 years,with a total area of 460.36,436.74,and 435.11 km2,respectively,concentrated in the downstream of the basin with woodland and grassland as the land use types.④ In this study,116,126,and 190 ecological corridors were extracted in 20 years,and short-distance corridors were mainly distributed in the northeast of the basin with a large number,whereas the southwest showed the opposite.A total of 419,455,and 460 ecological nodes were identified in 20 years,among which the pinch points were mainly concentrated in the downstream of the basin with high vegetation coverage,which should be the key area for ecological protection.The obstacle points were concentrated in the upper and middle reaches of the basin with frequent human activities.The research results aim to provide theoretical and scientific basis for the improvement of ecosystem functions and ecological protection in the Nanming River Basin.

The karst geological carbon sink, formed through the chemical weathering of carbonate rocks, is an important part of the global terrestrial carbon sink. It has substantial potential and plays a crucial role in the global carbon cycle and regional carbon neutrality efforts. The fifth (AR5) and sixth (AR6) assessment reports of the Intergovernmental Panel on Climate Change (IPCC) have clearly affirmed the existence of geological carbon sinks associated with the chemical weathering of carbonate rocks, stating that carbon capture and geological storage are key mitigation schemes. However, numerous studies have shown that exogenous acids are widely involved during the chemical weathering of rocks, adding complexity to the carbon sequestration process and its driving mechanisms. This increases the uncertainty in assessing the carbon sequestration potential. Therefore, a key task is to accurately estimate the geological carbon sinks generated by the chemical weathering of carbonate rocks to resolve the problem of the global carbon sink loss, balancing the carbon budget, and achieving carbon neutrality. In this review, we examine assessments of the carbonate rocks chemical weathering carbon sink influenced by exogenous acids, focusing on the principles, frameworks and methodologies of carbon sink estimation. We also highlight recent advancements, key influencing factors, and underlying driving mechanisms. Looking ahead, we highlight key challenges in enhancing the accuracy and precision of carbonate rocks chemical weathering carbon sink assessments under the influence of exogenous acids. Addressing these issues will support more informed policy decisions on pathways to global carbon neutrality.

In the study of global change, one of the key issues is the global and regional carbon cycle, and estimating the carbon sink magnitude and determining the spatiotemporal pattern of carbon sources have attracted considerable attention from the academic community and are of great scientific significance. The Chinese karst region, which has considerable potential for carbon sequestration, is the principal area for carbon sequestration in China and even in the world. Changes in temperature and precipitation caused by global warming not only affect the hydrological processes in the karst region but also profoundly impact its carbon sink capacity. Nevertheless, no studies have as yet revealed the magnitude and spatial pattern of carbon sinks in the Chinese karst region, as well as the mechanism of the impact of climate change (CC) and human activities (HA) on the region. Therefore, to elucidate the spatial and temporal patterns of carbon sinks in Chinese karst ecosystems and reveal their responses to CC and HA, this paper employed data on climate, lithology, and ion concentration, in combination with a random forest model, a maximal potential dissolution model, and partial derivative analysis. According to the results: (1) during 2000-2020, the average annual flux of the ecosystem organic carbon sinks (NEP) and the total amount were 148.04 t C km(-2) a(-1) and 374.54 Tg C a(-1), respectively, while NEP showed a steady growth trend with an average annual growth rate of 2.35 t C km(-2) a(-1). (2) The average annual flux of carbonate rock weathering carbon sinks (CCSs) and the total amount were 5.32 t C km(-2) a(-1) and 13.45 Tg C a(-1), respectively, while the average annual growth rate of the CCSs was 0.04 t C km(-2) a(-1). (3) The average annual flux of the ecosystem carbon sink was123.49 t C km(-2) a(-1) and the total amount was 319.24 Tg C a(-1). (4) The carbon sink of the Chinese karst ecosystem exhibited an increasing trend, with an increase rate of 2.16 t C km(-2) a(-1), while precipitation (P), temperature (T) and solar radiation (SR) respectively contributed 15.91%, 13.12%, and 17.85% to changes in the ecosystem carbon sink. The contribution of CC to changes in the ecosystem carbon sink was 46.88%, and the contribution of HA was 53.12%. (5) In the karst region, the total increase in the area of the ecosystem carbon sink was 184.73x10(4) km(2), while the decrease in the area was68.27x10(4) km(2). Furthermore, areas of growth in the carbon sinks were considerably larger than areas of decline. As the main factor influencing changes in the ecosystem carbon sink, HA was largely concentrated in the southern karst area, with a principal area of 64.66x10(4) km(2). This study will facilitate the realization of China's "dual carbon" goal, thereby providing an important reference for diagnosing the country's global carbon neutrality capacity. By integrating long time series of multisource data and advanced modeling analysis, this study systematically quantified the dynamic changes in ecosystem carbon sinks in China's karst region with respect to scale, spatial distribution, and driving mechanism. Not only do these results provide a scientific basis for realizing China's "double carbon" goal, but they also serve as an important reference for the formulation and implementation of global carbon-neutral strategies. To provide more in-depth scientific support for global climate governance in the future, the quantitative assessment of the balance between regional carbon sinks and carbon emissions can be further strengthened to explore the long-term stability of the carbon sink function and the risk of extreme climate events.