Global change is the result of the synergistic interaction between natural processes and human activities, representing a structural transformation of the Earth system dominated by human actions. Its core lies in the contradiction between the Earth system’s limited carrying capacity and humanity’s unlimited developmental demands, manifesting as changes in climate, ecosystems, and socio-economic systems. Interactions among the Earth’s spheres are key drivers of global change. Precise analysis and prediction of the mechanisms, dynamic evolution, and corresponding climatic, environmental, and ecological effects of these interactions can help uncover the underlying mechanisms of global change, accurately assess the risks of abrupt shifts in the Earth system, and design feasible pathways for sustainable development. This special issue focuses on cutting-edge scientific questions related to global change and inter-sphere interactions, elaborating on mechanisms of critical interfacial processes of the Earth system and their feedback relationships with human activities through Earth system observation, modeling, and governance. The collection reviews the current state of development and progress in research on global change and inter-sphere interactions, identifies challenges and frontier scientific issues in Earth system science, and outlines future directions. The aim is to provide robust theoretical support for addressing global change, fostering harmonious humans-nature coexistence, and achieving sustainable development of socio-ecological systems.

The interaction between deep- and surface-Earth processes is an important component of Earth system science research. Deep-Earth processes drive the material and energy cycling between the deep and shallow Earth through various mechanisms, such as tectonics and volcanism, thereby influencing the Earth’s surface system. These influences are specifically manifested in the following ways: (1) Tectonics, by reshaping landscapes, regulate erosion and sedimentation processes at the watershed scale. (2) Volcanism and tectonics drive climate change on geological timescales, by affecting atmospheric composition and circulation patterns, with silicate weathering playing a significant role in regulating atmospheric CO₂ levels. (3) Deep-Earth processes have a dual impact on ecosystem evolution, potentially causing species extinction while also promoting biodiversity. (4) Earthquakes and geological disasters impact the stability of socio-ecological systems; the impacts may be further exacerbated by global climate change. The cascading disasters triggered by earthquakes and their long-term impacts on social systems warrant attention and research efforts in disaster-prone China. With the advancement of observational technologies, earth system science studies will achieve a deeper understanding of the coupling mechanisms between deep- and surface-Earth systems. This includes quantifying the intensity of interaction, predicting the evolution of natural disasters, and enhancing the resilience of socio-ecological systems to such disasters. This paper provides a systematical review of the cross-scale coupling of deep earth-surface earth-socio-ecological processes, helping to understand the earth system evolution.

The interactions between tectonics, geomorphology, climate, and ecosystems constitute the foundation of surface-Earth system dynamics. Investigating these complex interactions and their implications is a central objective of systems science. For instance, tectonic processes not only drive landscape evolution but also exert significant influence on climate change and ecosystem dynamics. Conversely, climate change drives landscape transformation and ecosystem shifts, while ecosystems, through biogeochemical cycles, provide feedback mechanisms that influence landscape evolution and climate regulation. The evolution of the surface-Earth system inherently depends on the synergistic interactions among these components. Over geological timescales, plate tectonics and landscape reorganization have triggered regional climate shifts and biological turnovers. On modern timescales, these couplings maintain the dynamic equilibrium of Earth’s surface environment. Systematic research into these interactions is critical for understanding the sustainability of the surface-Earth system. This study reviews the coupling relationships between tectonics, climate, and landscapes, as well as between landscapes, climate, and ecosystems. It aims to uncover the dynamics of tectonics-geomorphology-climate-ecosystem interactions and establish a systematic framework for surface-Earth system science. The Tibetan Plateau, with its unique tectonic activity, complex geomorphology, diverse climatic zones, and sensitive ecosystems, serves as a natural laboratory for studying these dynamics. Comprehensive investigations into the interactions on the Tibetan Plateau will address key scientific questions in surface-Earth system science and offer valuable insights into global environmental change. Advancing research on tectonics-geomorphology-climate-ecosystem dynamics requires quantitative studies on the coupling and co-evolution of these factors. This can be achieved through interdisciplinary integration, field observations, laboratory analyses, big data approaches, and deep learning in artificial intelligence. Developing dynamic coupling models of Earth’s systems will enhance our understanding of the interactions among Earth’s spheres and provide theoretical support to tackle challenges posed by global change.

The soil sphere, a critical interface connecting the atmosphere, hydrosphere, biosphere, and lithosphere, plays a pivotal role in the Earth’s surface system. Here, we review the interfacial processes that govern the formation and evolution of soils, emphasizing their intricate interactions and feedback mechanisms. The formation and evolution of the soil sphere are influenced by physical and chemical weathering processes, gas-water-rock heterogeneous reactions, and biological-organic matter-mineral interactions. These processes vary under different geographical, climatic, and biological conditions, leading to the heterogeneity and material diversity of soils. The paper categorizes interfacial processes into two main types: interactions among inorganic spheres and interactions between the biological and inorganic worlds. Interactions among inorganic spheres include the alteration of rocks by air and water, heat exchange, wind erosion, water-rock reactions, and diagenesis. These processes are crucial for the physical breakdown and chemical transformation of parent materials. Interactions between the biological and inorganic worlds encompass organic carbon input and output through photosynthesis, respiration, and microbial degradation of organic matter, as well as bioweathering, which involves the release of biogenic mineral nutrients and the formation of mineral-organic matter aggregates. The paper also explores the relationship between the soil sphere and the biosphere, highlighting the exchange of matter and energy and the support provided by soils to ecosystems. Additionally, it discusses the role of soils in ecosystem services, such as productivity, biodiversity maintenance, and climate regulation. Finally, the paper emphasizes the importance of multi-temporal and multi-spatial scale studies to understand the impact of surface processes on soil sphere evolution and identifies future research hotspots. Collectively, this paper provides a detailed overview of the interfacial processes that drive soil formation and evolution, highlighting their significance in maintaining ecological balance, supporting human activities, and addressing global environmental challenges.

Under the context of global change, the spatiotemporal scope of eco-hydrological research has expanded significantly. Eco-hydrology studies originally focused on the mutual feedback between water and living organisms, which now encompass the interactions and evolutionary mechanisms of water, non-living elements (e.g., atmosphere, soil, and rocks), and human activities. Based on the concept of Earth system science, and considering current research gaps and paradigm shifts, this paper reviews eco-hydrological processes from multiple dimensions including the Soil-Plant-Atmosphere Continuum (SPAC), the Earth’s Critical Zone, and watersheds. It first discusses the mechanisms of water, energy, and matter transfer and exchange between bedrock, soil, vegetation, and atmospheric interfaces. The paper then elucides the co-evolution of bedrock weathering, soil formation, and eco-hydrological processes under the influence of climate change and human activities, and their impacts on the hydrological cycle and material balance. It also highlights the importance of watersheds as crucial intermediate units connecting global and local scales. In response to the water and ecological resources sustainability, the paper disscusses potential breakthroughs for eco-hydrological research in the context of artificial intelligence, including multi-source data fusion, modeling methods that integrate physical processes with machine learning, and interdisciplinary collaborative research paradigms. As such, this paper aims to shed lights into the synergistic development of ecology, hydrology, and society, which may enhance the ecosystem quality and promoting green socio-economic development.

Watersheds (catchments) represent relatively self-contained units or subsystems within the Earth’s surface system. Systematic and integrated studies of watersheds provide valuable insights into the interactions across multiple spheres. The biogeochemical cycles within watersheds constitute a critical component of global biogeochemical cycles, reflecting the energy and material exchange dynamics among these interconnected subsystems. Moreover, these cycles exert reciprocal influences on the functioning and stability of each sphere. This review explores the mechanisms linking biogeochemical cycles in watersheds with multi-sphere interactions, focusing on the impacts of intensive anthropogenic activities and global climate change in the Anthropocene. Firstly, the characteristics of watershed biogeochemical cycles and their interconnections with global change are systematically analyzed. Secondly, the feedback mechanisms between watershed biogeochemical cycles and global environmental change emphasize profound anthropogenic disturbances. Thirdly, the intricate linkages between watershed processes and global ecosystems are elucidated through their underlying interaction mechanisms. Comprehensive analysis reveals that intense anthropogenic activities have substantially disrupted or accelerated certain material cycles, pushing critical environmental parameters beyond ecological thresholds. These disruptions have far-reaching consequences for the stability of multi-sphere material cycles and the overall stability of the Earth system. Finally, in light of the current trends and challenges in watershed science, this study identifies research frontiers in watershed biogeochemical cycles. These include transformative research paradigms, the integration of interdisciplinary approaches such as artificial intelligence (AI) and multi-isotope techniques, exploration of microbial and other multi-factorial driving mechanisms, and advancements in dynamic system modeling. The efforts aim to provide a scientific foundation for a deeper understanding of the operational mechanisms of surface Earth system interactions and for promoting sustainable human development.

Surface earth system science (SESS) emphasizes the holistic nature, dynamic balance, and feedback mechanisms among Earth’s surface spheres, providing a new theoretical and methodological framework for studying the structure, function, and evolution of ecosystems. From the perspective of SESS, this review discusses the importance of ecosystem science (ES) in related research fields, and outlines current hot topics and challenges. We first discuss how SESS and ES are related: the former focuses on the interactions and collective behavior of various Earth’s surface spheres, while the latter investigates the co-evolutionary mechanisms with other spheres through the study of energy and material flows within ecosystems. Secondly, the theoretical innovations brought by SESS to ES’s research are explored, particularly the introduction of the multi-sphere coupling framework and complex systems theory, which have transformed ES’s research from local to global scales. Based on the current trend from local to global integrated studies, we also discuss the important applications of systematic observation and data integration, cross-scale modeling techniques, and emerging technologies and indicators in ES-related research. Within the framework of multi-sphere interactions, this review examines the relationships between ecosystems and other Earth’s surface spheres in the context of global change, as well as the response and adaptation mechanisms of ecosystems. The results indicate that integrating interaction mechanisms between different Earth’s surface spheres can provide a crucial scientific basis for studying ecosystem stability and service functions. Finally, in light of intensified global change due to human activities, the review points out that ES needs to further integrate emerging technologies such as remote sensing, big data analytics, and artificial intelligence to deeply uncover the evolutionary patterns of ecosystems in the Anthropocene, as well as nonlinear response mechanisms and critical thresholds, thereby providing scientific evidence and decision-making support for global sustainable development.

With the intensification of global change, the land/ocean-atmosphere interface, as a key material and energy exchange area in the Earth system, has become an important window for understanding climate change, ecological evolution, and the feedback mechanism of the Earth system. The land/ocean-atmosphere interface processes involve the exchange of energy and materials between the atmosphere and the land and ocean surfaces. They determine the dynamic changes of terrestrial and marine ecosystems, and directly affect the evolution of the Earth system. The research on the land/ocean-atmosphere interface processes is crucial to a deep understanding of the dynamics of the Earth system, which is one of the most important cutting-edge issues in Earth system science. This paper first synthesizes the research on the land/ocean-atmosphere interface from the perspective of Earth system science, summarizes the land/ocean-atmosphere interface and its role in the Earth system, and the relationship between the material and energy exchange processes in the land/ocean-atmosphere interface and global change. Secondly, we reviewed the impact of the land/ocean-atmosphere interface processes on the atmospheric environment, the impact of the land/ocean-atmosphere interface processes on the elemental (e.g., carbon, nitrogen) and hydrological cycles in ecosystems, as well as the feedbacks between the land-ocean-atmosphere system and global climate change. Finally, the research frontiers and challenges in the field of the land/ocean-atmosphere interface science are proposed, including the construction of a multi-scale interdisciplinary research system for the land/ocean-atmosphere interface science, such as the optimization of the integrated space-air-ground stereoscopic observation system, the Earth system modelling and multi-scale coupling mechanisms of the land/ocean-atmosphere interface processes, the land/ocean-atmosphere interface science research in the era of artificial intelligence, as well as the land/ocean-atmosphere interface processes and their impact in climatic and ecological sensitive areas such as polar, alpine and coastal areas. The land/ocean-atmosphere interface science will play a more important role in the fields of climate change response, ecological environmental protection and sustainable development.

Social-ecological systems science provides essential theoretical insights and practical approaches for addressing the global challenges of sustainable development in the Anthropocene. This study begins by analyzing the key obstacles to achieving global sustainable development goals, examining them through four critical dimensions: social, economic, environmental, and ecological. It then explores the theoretical foundations and historical evolution of social-ecological systems science, emphasizing the potential of this interdisciplinary approach in the context of global environmental change. Furthermore, the study investigates the pivotal role of social-ecological systems science in fostering cross-sector collaboration, optimizing resource allocation, and driving policy innovation, underscoring its importance in advancing the global sustainable development agenda. Finally, the study concludes by discussing future research directions, with a particular focus on the transformative potential of interdisciplinary collaboration, systems modeling, and technological innovation in achieving sustainable development goals.

Earth system models are essential tools for understanding and predicting global change and have made significant strides in recent years. These advancements are evident in the more detailed representation of coupled processes across Earth’s spheres and the integration of increasingly sophisticated physical and chemical processes within them. The reduction in model uncertainties has been driven by the adoption of innovative methods and cutting-edge technologies. Nonetheless, challenges persist, including limitations in capturing complex interactive processes, difficulties in simulating socio-ecological systems, and the need to enhance the modeling of regional extreme events. Moving forward, efforts should prioritize fostering interdisciplinary collaboration, harnessing emerging technologies to improve data acquisition and predictive accuracy, and deepening research into socio-ecological processes and their impacts. Such initiatives will bolster the ability to model and predict regional extreme events while paving the way for next-generation Earth system models that seamlessly integrate land, ocean, atmosphere, and human interactions. These advancements are vital for supporting sustainable development and providing a robust scientific foundation to address and anticipate global changes.

The Earth system comprises the geosphere, biosphere, and anthroposphere, which interconnected each other. A central focus of Earth system science lies in investigating the exchange of materials and energy within and between these spheres, as well as their dynamical mechanisms. Such exchanges are governed primarily by hydrological and biogeochemical cycles of major and trace elements, making the biogeochemical cycling of elements the link among Earth’s subsystems and a critical mechanism driving or modulating global change. Furthermore, under rapid socioeconomic development, human activities profoundly alter these biogeochemical cycles, inducing unprecedented transformations in the Earth system. Key challenges in Earth system science include precisely characterizing biogeochemical cycles, unraveling their dynamical mechanisms, predicting their future trajectories, and evaluating their ecological impacts. Isotopic techniques provide robust tools for tracing cross-sphere material fluxes and biogeochemical processes, playing an indispensable role in studying sphere interactions and global change. This paper reviews recent advances in applying traditional and non-traditional stable isotopes to track sphere interactions and global change, synthesizes typical isotopic signatures across Earth’s subsystems, delineates isotopic fractionation mechanisms at sphere interfaces, traces anthropogenic impacts on environmental-ecological systems, and identifies critical scientific challenges and frontiers in isotope geochemistry within the Earth system science framework. Future research should integrate isotopic approaches with emerging fields like geography, ecology, molecular biology, Earth system modeling, artificial intelligence, and big data analytics to refine isotope-enabled theoretical frameworks for biogeochemical cycling under multi-sphere, multi-process, and multi-element coupling. Such integrative efforts will deepen understanding of sphere interactions, human-global change linkages, and environmental-life coevolution.

The evolution of Earth’s habitability is closely linked to changes in the atmospheric and oceanic oxygen levels, particularly the Great Oxidation Event (GOE) and the Neoproterozoic Oxygenation Event (NOE), two key oxidation events. These events not only affected Earth’s iron mineral processes but also had profound impacts on the nitrogen cycle, such as enhancing the bioavailability of nitrate through increased oxygen concentrations. Similarly, the halogen cycle, including halogenation and dehalogenation processes, may also have been influenced by the oxidative environment of early Earth. Halogenating enzymes, such as haloperoxidases and halogenases, require oxygen to oxidize halogen elements and generate organohalides. Therefore, oxidation events may have played a role in both the abiotic formation of organohalides (e.g., through Fenton reactions and iron ions) and the increase and spread of halogenating enzymes, thus promoting the production of thousands of organohalides on Earth. With the rise in natural organohalides, the evolution of organohalide-respiring microorganisms and the horizontal gene transfer rates of dehalogenation genes (e.g., reductive dehalogenase genes) may have accelerated. Obligate organohalide-respiring microorganisms Dehalococcoidia, such as Dehalococcoides and Dehalogenimonas strains, are inferred to have emerged during the Cambrian. These microorganisms play a crucial role in the biogeochemical cycling of organohalides. However, there is still limited information regarding their origin and evolution, as well as the evolution of dehalogenation genes, which hinders our understanding of the halogen cycle on geological time scales. This study aims to explore the role of halogens in the evolution of Earth’s habitability, particularly the origin of organohalides and the evolution of organohalide-respiring microorganisms. By approaching this topic from a geological time scale and integrating the perspective of biogeochemical cycles, we will analyze the production of organohalides, the distribution and evolution of organohalide-respiring microorganisms, and the role of halogenating enzymes and dehalogenases during Earth’s oxidation events. Through this research, we hope to gain a deeper understanding of the significance of the halogen cycle in the evolution of Earth’s habitability and provide scientific evidence for future environmental management and bioremediation.

The climate of the Yunnan-Guizhou Plateau is significantly influenced by diverse monsoon systems, displaying a complex pattern of climatic changes. This study investigates the relationship between local environmental changes and global climate dynamics using sediment core 2023CH(D) from Caohai Lake in Guizhou Province. Employing high-resolution X-ray fluorescence (XRF) scanning and paleomagnetic dating, combined with multivariate statistical analysis of magnetic susceptibility, grain size, and elemental data (including Al, Si, K, Ca, etc.), this research explores the paleoenvironmental evolution of the Caohai region since 0.78 Ma. The findings identify five climatic phases: 1) Stage I (0.78-0.66 Ma), where the local climate essentially mirrored global climatic changes; 2) Stage II (0.63-0.33 Ma), dominated by global climate patterns but significantly modulated by Earth’s obliquity and precession cycles; 3) Stage III (0.32-0.22 Ma), characterized by a relatively mild glacial climate with cool, humid conditions that substantially promoted carbonate leaching; 4) Stage IV (0.21-0.12 Ma), predominantly cold and dry, with initial and final phases experiencing slightly warmer and more humid conditions, reflecting precession cycles in the relative intensity of physical and chemical weathering; 5) Stage V (0.12-0.02 Ma), generally trending towards colder and drier conditions, yet characterized by rapid oscillations between cold-dry and warm-humid states on sub-orbital scales, with an increasing amplitude. The climatic evolution in Caohai is influenced by both orbital and sub-orbital cycles, with varying responses among different palaeoenvironmental proxies. Vegetation coverage, primarily controlled by the intensity of the Asian monsoon and global climate conditions, exhibits sensitivities to these cycles, while variations in the intensity of physical and chemical weathering and precipitation are more closely aligned with obliquity and precession cycles. The climatic fluctuations in the Caohai region have shown a trend towards increased frequency and extremity. Overall, the response of Caohai’s climate to global changes is notably complex, and the underlying mechanisms driving these changes require further investigation.

With the coupled influence of multiple factors, such as climate change and human activity, the excessive input of reactive nitrogen has exacerbated the loss of nitrogen from terrestrial ecosystems to aquatic ecosystems, which has seriously affected the quality of water in the basin. Identifying the spatiotemporal variation characteristics of nitrogen sources and their transformation processes within the watershed system has become a primary objective for preventing and controlling the loss of pollutants and improving regional ecological quality. Understanding the nitrogen cycle in the watershed system faces challenges owing to the diversity of nitrogen sources, complexity of biogeochemical processes, and coupled influence of many factors in the watershed. Among the research approaches, model simulation has become an important tool to reveal the nitrogen transport, transformation and dynamic change processes at the watershed scale owing to its high flexibility, high systematicity, and the ability to simulate and analyze multiple scenarios. This review summarized the characteristics of watershed hydrological models and nitrogen transport models for soil, surface water, and groundwater in watershed, as well as research examples of various models. The models were compared based on their principles, characteristics. Among the many factors affecting the nitrogen cycle, it is analyzed that uncontrolled anthropogenic disturbances and extreme climate change have become important factors disturbing the nitrogen cycle in watersheds. Hydrological process-driven processes and mechanistic studies of water and nitrogen are particularly important. Hydrological biogeochemical models (e.g., CNMM-DNDC, PIHM) constructed based on these models have become an important for obtaining high-precision spatial and temporal distribution patterns of nitrogen in the watershed system and its prediction and analysis. In addition, the combination of big datasets and processes modeling has become an important way to reveal the complexity of the nitrogen cycle process. By synthesizing the applicability of many models to the spatial pattern and intensity of anthropogenic impacts, we sorted the applicable models of nitrogen cycling in the river network area of the coastal plain, which is subjected to strong anthropogenic disturbances. These models may deepen the scientific knowledge of nitrogen cycling under the interactions of surface water, groundwater, and seawater in coastal watersheds of the intertwined zone of sea and land, and assess the quality of the water environment and the environmental effects of the river system of the coastal plain in a more comprehensive and scientific way.

The nitrogen cycle is an essential component of the global biogeochemical cycles. The intensification of human activities has led to an increase in the emission of reactive nitrogen, causing an imbalance in the nitrogen cycle and a series of ecological and environmental issues. Nitrogen is an important component of atmospheric aerosols. Atmospheric organic nitrogen, including amino acids (AAs), has a significant impact on the nitrogen cycle and environmental changes. This article reviews the detection methods, molecular composition, spatiotemporal distribution, sources and transformation processes of atmospheric free (FAAs) and combined AAs (CAAs), as well as their environmental effects. Instruments such as liquid chromatography-mass spectrometry (LC-MS), gas chromatography-mass spectrometry (GC-MS), and gas chromatography-isotope ratio mass spectrometry (GC-IRMS) can be used to detect the concentrations of AAs, or even chiral L-AAs and D-AAs, and compound-specific stable isotopic composition of AAs such as glycine (Gly). The composition, size distribution and spatiotemporal variation of AAs in atmospheric aerosols are influenced by sampling time, geographical location, and atmospheric transport processes. Gly is usually the most abundant FAA/CAA in atmospheric aerosols. The sources of AAs are diverse, including biological and soil emissions, bubbles bursting in seawater, biomass burning, anthropogenic emissions, and secondary formation. AAs can affect atmospheric chemical processes, act as cloud condensation nuclei to influence the climate, serve as a bioavailable nitrogen source, and threaten human health. Although many studies have been conducted on atmospheric AAs, there are still deficiencies, such as the need for standardized detection methods for spatiotemporal comparison, the combination of multiple methods for source apportionment to improve the accuracy, and a lack of quantitative assessment of the environmental, climatic and health effects of AAs. Besides, analyzing and solving related issues from the perspective of land/ocean-atmosphere interface science, and even earth system science, conducting comprehensive, multi-sphere and interdisciplinary innovative research, can help fully understand atmospheric AAs’ cycling processes and environmental impacts.

The photoelectrotrophic metabolic pathway of non-photosynthetic microorganisms plays a pivotal role in energy cycle within ecosystems. Oceanic euphotic zone provides key conditions for triggering photoelectrochemical nutrient metabolism, such as the availability of natural light, intense material and energy exchanges, and active biochemical processes. However, the photoelectrochemical responses of its photosensitive substances and microbial communities remain underexplored. This study examines the composition, spatial distribution, and photoelectrochemical responses of photosensitive substances, and microbial community structure in the photic zone across the estuarine, nearshore, and offshore regions of the Minjiang River estuary. The findings show that all three regions contain photosensitive substances, including suspended semiconductor particles, natural pigments, and dissolved organic matter (DOM), with concentrations decreasing with distance from shore. Notably, the nearshore region harbors the highest abundance of photosynthetic microorganisms. Photoelectrical measurements further reveal that the nearshore region exhibits the most pronounced photoelectric effect, likely due to its higher concentration of photosensitive substances and fewer interference from coexisting materials. Microbial community analysis demonstrates a clear photoelectrochemical response pattern, with a significant positive correlation between the abundance of electroactive microorganisms and the concentrations of photosensitive substances, highlighting that the distribution of electroactive microorganisms closely aligns with regions of efficient photoelectrochemical conversion of photosensitive substances. Consequently, the synergistic interaction between natural photosensitive substances and electroactive microorganisms may provide new theoretical insights into the biogeochemical cycling of elements such as carbon and nitrogen in marine ecosystems.

Sea-land breezes (SLB) are a mesoscale atmospheric circulation phenomenon driven by thermal differences between land and ocean during the day and night, resulting in obvious diurnal variations in wind direction in coastal areas. It is one of the most prominent mesoscale atmospheric circulations in coastal regions. The intensity of the SLB influences the atmospheric boundary layer height, atmospheric chemical processes, air quality, and radiation balance in coastal areas. As a direct thermal condition affecting the SLB, the diurnal variation of sea surface temperature (SST) is influenced by multiple factors, including solar radiation, ocean heat capacity, wind speed, and cloud cover. However, the impact of SST diurnal variation on the occurrence and development of SLB in coastal areas remains unclear. This study utilizes high-resolution SST simulation data combined with the Weather Research and Forecasting (WRF) model to analyze the characteristics of SST diurnal variation and its impact on the SLB in typical coastal areas of China. The results show that the average SST in China’ s coastal regions decreases from south to north, with the Bohai Sea having the lowest annual mean SST of 10.78 ℃, the East China Sea exhibiting a 94.6% higher annual mean SST than the Bohai Sea, and the South China Sea having the highest annual mean SST of 25.19 ℃. The diurnal variation of SST in the Bohai Sea exhibits the greatest annual fluctuation, reaching up to 0.55 ℃, with a minimum of only 0.03 ℃ and an average of 0.25 ℃. The diurnal SST variation in the East China Sea fluctuates moderately, with an annual average diurnal temperature difference of 0.20 ℃. The maximum SST diurnal variation during the study period was 0.45 ℃, about 82.0% of the Bohai Sea’ s extreme value and more than 33% higher than the South China Sea. Comparing scenarios that consider diurnal SST variation with the traditional assumption of constant SST in models, the results indicate that diurnal SST variation can lead to an increase in the number of SLB days in typical coastal areas of China. The number of SLB days in the South China Sea coastal region increased by 14 days annually, with a growth rate of approximately 56.0%, while the number of SLB days in the northern Bohai Sea coastal region increased by 7 days annually, with a growth rate of 20.0%. Seasonally, the diurnal SST variation increased the number of SLB days in winter and decreased them in summer, with little effect on the spring and fall. This results in a reduction in the seasonal difference of SLB days along China’ s coastline.

Red soil plays an important role in the sustainable development of agriculture and socio-economy in China. The red soil critical zone is the earth’s surface system which consists of water-soil-air-life-rock under the actions of natural and human activities in the red soil region. This paper summarizes the progresses on the acidification situation of red soil, the process and mechanism of proton (H⁺) production and consumption in the red soil critical zone, as well as the ecological and environmental effects. In the critical zone, carbon cycle is the main source of H⁺ in the natural soil acidification process. Atmospheric acid deposition (H⁺, nitrogen, sulfur) and the net uptake of base cations (K⁺, Na⁺, Ca²⁺, and Mg²⁺) by plants are the main sources of H⁺ in natural ecosystems. However, H⁺ from the nitrogen transformation process caused by chemical nitrogen fertilizer and base cations carried away by plant harvest are the main reasons for the intensification of red soil acidification in farmland ecosystem. The transformation of nitrogen in soil and the production process of H⁺ are complex. The source of nitrate ($\mathrm{NO}_3^{-}\mathrm{-N}$) in water can be quantified by using dual isotopes of nitrogen and oxygen, so as to quantify the contribution of different sources of nitrogen to H⁺ production in soil. Mineral weathering, cation exchange, iron and aluminum oxide buffering, special adsorption of sulfate and acid buffering of organic matter are important acid buffering mechanisms in the red soil critical zone. These processes are intertwined, so it is difficult to quantify individual buffering processes and the acidification rate of red soil. Based on the stoichiometric relationship between base cations and silicon released by mineral weathering, the proportion of H⁺ used for silicate weathering and base exchange in red soil regions with different weathering degrees can be distinguished, so as to better understand the difference of buffering pathways for H⁺ in red soil with different weathering degrees. Acidification will not only change the physical and chemical properties of the soil, activate heavy metal elements, cause aluminum toxicity, but also affect the growth of soil microorganisms and plants. $\mathrm{NO}_3^{-}\mathrm{-N}$ migration and deep accumulation caused by nitrogen transformation will bring potential risks to groundwater pollution. The process of H⁺ consumption can alleviate the negative effect caused by H⁺ production. The runoff water in the red soil region remained neutral, indicating that the soil consumed all input H⁺ and still had acid buffering capacity. In view of the above research status of H⁺ production and consumption in the red soil critical zone, this paper puts forward the prospects of future research and scientific issues that need to be further explored in the red soil critical zone.

As a type of emerging pollutants, microplastics have become pervasive contaminants affecting ecosystem safety and human health. Microbial biodegradation of microplastics has attracted significant attention due to its environmentally friendly and sustainable attributes. Recent advancements have been achieved in the microbial biodegradation of pollutants through biofilms, enzyme engineering, and gene regulation. Biofilms influence the microplastics degradation by altering surface properties, leaching additives, enzyme or radical attacks, and permeation decomposition. Extracellular enzymes cleave the macromolecular structures, while intracellular enzymes modify substrate structures and process metabolites. Current research focuses on constructing highly efficient enzyme systems. Genetic engineering has enabled the cultivation of engineered bacteria, while bioinformatics aids in identifying functional genes and elucidating the degradation pathways. Metagenomic modification has been used to enhance biodegradation efficiency. This article reviews recent progress in microbial biodegradation of microplastics, encompassing diverse degrading microorganisms, clear degradation metabolic pathways and mechanisms. Multiple microorganisms including bacteria, fungi, and microalgae possess degradation capabilities. Composite microbial consortia synergistically drive the degradation process. Bacteria mainly degrade microplastics by secreting hydrolases and oxidases, which can break the macromolecular chains or change the chemical structure of plastics. Fungi, on the other hand, rely on the secretion of intracellular and extracellular enzymes as well as biological surfactants to break down microplastics into monomers. The mycelium can also enhance the degradation effect. Microalgae can promote degradation by means of photosynthesis, secreting toxins, enzymes, and extracellular polymeric substances. Microplastic degradation typically occurs in four stages: bio-deterioration, fragmentation, assimilation, and mineralization. Different microorganisms exhibit varying efficiencies and mechanisms for microplastics degradation such as polyethylene and polystyrene. By summarizing current research findings, this review provides a theoretical foundation for further in-depth exploration of microbial biodegradation mechanisms and offers potential methods and techniques for eliminating the microplastics in the environment.

Ship-emitted SO₂ form sulfate aerosols (PSO₄) in the marine atmosphere, which have significant impacts on climate, primarily through direct radiative effects (DRE) and indirect radiative effects (IRE), leading to a net cooling effect on the Earth system. This study, using an Earth system model and a global ship emissions inventory, investigates the changes in shipping PSO₄ and its radiative effects under the current global 0.5% sulfur content regulation (0.5% S), as well as a scenario in which the 0.1% sulfur content regulation in certain controlled zones is extended globally (0.1% S). The results show that under the 0.5% S control, the global average burden of shipping PSO₄ is 58.2±6.5 μg·m^-2, producing a DRE of -10.4±1.6 mW·m^-2. The indirect effect is the dominant part of the radiative effect, with the IRE of shipping PSO₄ under the 0.5% S control being approximately -64.7±40.5 mW·m^-2. The average burden of shipping PSO₄ on shipping routes is about 200 μg·m^-2, and the radiative effect is about 600 mW·m^-2. Compared to the current 0.5% S regulation, in the 0.1% S scenario, the concentration of shipping PSO₄ decreases by about 80%. Regarding radiative effects, the DRE decreases to -2.1±0.4 mW·m^-2, and the IRE decreases to -15.2±11.2 mW·m^-2, resulting in a 77% reduction in total radiative effects. The spatial and temporal distribution of shipping PSO₄ radiative effects is highly uneven. Globally, the highest values are concentrated in the Northern Hemisphere, especially along the shipping routes in the North Atlantic, North Pacific, and the coastal areas of the North Indian Ocean, where total radiative effects can reach up to approximately -350 mW·m^-2. The strongest radiative effects in both hemispheres occur during their respective summer seasons. On a global average, the total radiative effect of shipping PSO₄ is strongest in summer (-34.9 mW·m^-2), with some areas approaching -1200 mW·m^-2; it is weakest in winter, being less than a quarter of the summer value. The global use of cleaner ship fuels will significantly reduce the cooling radiative effects of shipping PSO₄, while also reducing air pollution

The Eocene-Oligocene Transition (EOT) represents one of the most significant global cooling events of the Cenozoic era, marking a key shift in the Earth’s climate system from a “greenhouse” to an “icehouse” mode. While deep-sea sediment records consistently document this cooling event, numerous terrestrial records reveal significant spatial variability in climate responses across different regions, highlighting the importance of the interaction between global climate background and regional environments. The uplift of the Tibetan Plateau has significantly influenced global continental weathering patterns and is closely linked to Cenozoic global climate changes. Therefore, the evolution of continental weathering around the plateau provides an excellent indicator of both global and regional climate changes. This paper summarizes the weathering evolution records from the margins of the Tibetan Plateau during the Late Eocene to Oligocene, combining our weathering history from the Lühe Basin (35.5-25.5 Ma) in the southeastern Tibetan Plateau, to explore the commonalities and differences in weathering evolution during this period. The results show that in most regions of the northern Tibetan Plateau, weathering intensity decreased from the Late Eocene, coupled with cooling and aridification processes, while at the southeastern margin exhibited multi-stage temperature fluctuations and a sustained humid climate. This regional difference is mainly driven by the combined effects of global cooling, tectonic uplift, and the evolution of the monsoon system. This study provides crucial insights into the weathering patterns and driving mechanisms of different regions of the Tibetan Plateau during the EOT.

Biogenic volatile organic compounds (BVOCs) are critical trace reactive organic gases in the Earth system, playing vital roles in global carbon cycling, atmospheric chemistry, and climate regulation. BVOCs react rapidly with atmospheric oxidants (e.g., OH, O₃, and NO₃), driving the formation of secondary organic aerosols (SOA), which modulate radiative forcing and influence regional and global climates. Furthermore, BVOCs interact with tropospheric and stratospheric ozone and alter hydroxyl radical (OH) concentrations, indirectly affecting the lifecycles of greenhouse gases. Global BVOC emissions are estimated to exceed 1000 TgC annually, with forests being the primary source and isoprene and monoterpenes dominating the emissions. Recent advancements in BVOC emission monitoring technologies have significantly improved the resolution and accuracy of emission measurements. Traditional offline sampling and gas chromatography-mass spectrometry (GC-MS) have been complemented by high-temporal-resolution online techniques such as proton-transfer-reaction mass spectrometry (PTR-MS) and time-of-flight mass spectrometry (PTR-ToF-MS). Additionally, multi-scale monitoring tools, including drones, satellite remote sensing, and ground-based flux towers, provide unprecedented capabilities for studying the spatial and temporal dynamics of BVOC emissions. By integrating dynamic chamber methods, eddy covariance techniques, and modeling approaches, researchers are progressively refining BVOC emission inventories, paving the way for deeper insights into the complex feedback mechanisms between BVOCs and climate change.

Environmental factors regulating BVOC emissions have been extensively studied. Light and temperature are key drivers, with light intensity directly influencing photosynthesis and isoprene emissions, while rising temperatures accelerate BVOC biosynthesis and volatilization. Elevated CO₂ concentrations may modulate BVOC emissions through photosynthetic regulation and reduced stomatal conductance, although long-term effects vary by plant species and adaptive strategies. Increased ozone (O₃) concentrations exert dual effects on BVOCs, inducing stress-related defensive emissions while potentially damaging foliage and suppressing emissions. Aerosol concentrations exhibit critical positive feedback mechanisms with BVOCs—high BVOC emissions promote SOA formation, and SOA, in turn, modifies photosynthesis and BVOC emissions via light scattering effects. Changes in the nitrogen cycle also impact BVOC emissions, with elevated nitrogen inputs altering nutrient allocation and metabolic pathways, thereby enhancing or suppressing BVOC synthesis depending on the compound type.

Under future global change scenarios, climate warming, frequent extreme weather events, and rising CO₂ concentrations may significantly alter BVOC emission patterns and their coupling with atmospheric chemistry and climate systems. Advancing observation and modeling approaches to study multi-factor interactions and long-term trends in BVOC emissions is essential for elucidating the cross-sphere coupling mechanisms of BVOCs. Such research will provide critical insights into the interactions between climate change and atmospheric chemistry.

The response and feedback of phytoplankton elemental stoichiometry to their ambient available nutrients is a vital approach to understand the relationship between structure and function of aquatic ecosystems. The change of silicon (Si) to carbon (C) stoichiometric ratio in water can reflect the coupling of Si-C biogeochemical cycles to some extent; however, the pattern of phytoplankton Si∶C ratio interacting with the ambient dissolved silicon (DSi) and CO₂ and the underlying mechanisms are still unclear yet. Here, we found that phytoplankton Si∶C molar ratio converged towards the DSi∶CO₂ molar ratio with years (i.e., Si-C stoichiometric convergence), and this convergence was driven by phytoplankton community succession in lakes. The large-scale survey across different inland waters (including rivers, lakes, reservoirs, and wetlands) showed that there was significant spatial difference in phytoplankton Si∶C and DSi∶CO₂ molar ratios, and most of them deviated greatly from the Redfield ratio. Random forest analysis indicated that the relative abundance of diatoms, water temperature, and dissolved inorganic nitrogen were important predictive factors for phytoplankton Si∶C ratio. Metatranscriptomic evidence suggested that phytoplankton community succession and its matched protein turnover in response to the changing DSi∶CO₂ ratio resulted in a Si-C stoichiometric convergence in water. The study will provide some new insights into phytoplankton stoichiometry, and the Si-C stoichiometric convergence could characterize the interaction between the lithosphere, hydrosphere, and biosphere in surface-earth system to some extent and provide a quantitative pattern for describing the structure and function of aquatic ecosystems in response to environmental changes.

The coastal wetland ecosystem is one of the important ecosystems and is sensitive to environmental changes. Changes in sea level directly affect the material sources of coastal wetlands, thereby influencing the development of wetland ecosystems. However, the impact of long-term sea level change on coastal wetland ecosystems has not been fully understood due to the lack of reliable geological records. This article aims to explore the impact of Bohai sea level changes on the development of coastal wetland ecosystems since the Last Glacial Maximum (LGM; ~22000 a BP) based on sedimentary organic matter (SOM) molecular composition. This article analyzed the SOM molecular composition on the west coast of the Bohai Sea with ultra-high-resolution Fourier transform ion cyclotron resonance mass spectrometry technology. The results show that the proportion of endogenous aliphatic compounds in the sediments was relatively high during the LGM. The sea level was averagely ~130 m lower than the modern and no wetlands around the modern coast of the Bohai Sea were developed during this period, suggesting that the region may have developed local water systems and lacustrine environments. The sea level rose rapidly since the Holocene. Two marine facies in the core of this article recorded two marine transgression events during ~7100-6900 a BP and ~6000-5650 a BP. The sea level was relatively constant since ~5650 a BP and gradually retreated thereafter, resulting in 6 ancient coastlines and 6 stages of lagoon and depressions. The results suggest that the SOM CHO-component is sensitive to environmental changes induced by sea level change. Variations in H/C and O/C ratios indicate that the coastal wetlands underwent terrestrial-marine-terrestrial transformations from ~8050 to 4850 a BP. The higher O/C and lower H/C ratios during ~8050 a BP and ~4850 a BP indicate that wetlands and lagoon depressions might have developed on the west coast of the Bohai Sea, and changes in the SOM can be mainly ascribed to changes in terrestrial, semi-aquatic vegetation and soil microbial communities. The proportion of endogenous aliphatic compounds was higher during ~5700 a BP, suggesting that coastal wetlands have transformed into marine environments and the SOM sources have shifted to plankton. Endogenous organic components account for 15.68% during ~1350 a BP, significantly higher than those during ~8050 a BP and ~4850 a BP, indicating that the wetland ecological evolution may have been disturbed by strong human activities. This article provides new evidence and perspectives for understanding the impact of sea level change on the development of coastal wetland ecosystems.

Active tectonics in southern Tibetan Plateau create favorable pathways for the formation and release of deeply-sourced CO₂-rich fluids, making it a globally significant carbon source at present. However, in the case of southern Tibetan Plateau, estimating the deep carbon outgassing flux for tectonic degassing in the geological past remains challenging but is crucial for reconstructing the geological carbon cycle that operates in the India-Asia continental collision zone. Here, we report, for the first time to our knowledge, the hydrothermal CO₂ fluxes during the Quaternary period for representative active faults in southern Tibetan Plateau based on an integrated dataset of U-Th ages, mineralogical, elemental, and C-O isotopic compositions of travertine deposits. The U-series dating results show that the travertines were formed during the Middle Pleistocene to Holocene periods (267.3-1.8 kyr B.P.), with the deposition rates ranging approximately from 0.02 to 1.49 mm·yr^-1. These Quaternary travertines, primarily composed of calcite with rare samples exhibiting mixed calcite and aragonite in mineral assemblage, have an average CaCO₃ content of 94.2 wt.%. Carbon and oxygen isotopic compositions (δ¹³C_V-PDB=-3.1‰ to +8.6‰; δ¹⁸O_V-SMOW=-0.5‰ to +15.0‰) suggest a thermogenic origin influenced by varying degrees of CO₂ degassing, spring boiling, and evaporation, with deep metamorphic CO₂ being the primary carbon source of the travertines. Based on the volume, porosity, CaCO₃ content, and deposition ages of the travertines, the CO₂ outgassing fluxes accompanied with travertine deposition are estimated to be in the magnitude of 10⁴ to 10⁶ mol·km^-2·yr^-1 for the study areas, comparable to some travertine deposits in tectonically active regions of the central and western Italy. Our results provide new insights into the deposition ages, genesis, and CO₂ outgassing fluxes of Quaternary travertines in southern Tibetan Plateau and would contribute to our understanding of geological carbon cycle in the India-Asia continental collision zone.

Volcanic activity and deep earth processes significantly influence climatic and environmental changes, making them a critical topic in global change research. The uplift of the Tibetan Plateau during the Cenozoic was accompanied by multiple phases of volcanic activity and deep carbon release, while atmospheric CO₂ concentrations underwent periodic changes. During this period, the Asian climate shifted from being predominantly controlled by planetary wind systems to a monsoon-dominated regime. However, whether there is an intrinsic connection between volcanic activity on the Tibetan Plateau and climatic-environmental changes remains unclear due to the lack of direct constraints on the output of deep carbon release from volcanic activity. This study focuses on post-collisional volcanic activity on the Tibetan Plateau, analyzing Miocene volcanic rocks from the Chazi and Mibale areas of the Lhasa block and Oligocene volcanic rocks from the Yibuchaka, Ejumaima, and Yulishan areas of the Qiangtang block. Using laser in-situ Raman spectroscopy, the CO₂ concentrations in melt inclusions within phenocrysts of these volcanic rocks were determined. Combined with parameters such as volcanic rock volume and age, we estimated the CO₂ output from volcanic activity in the Lhasa block and Qiangtang block. The results show that the average CO₂ concentrations in volcanic rocks from the Lhasa block and Qiangtang block are approximately (1.73±0.59)% and (0.46±0.07)%, respectively. Based on volcanic rock volumes, the estimated CO₂ flux from volcanic activity in the Lhasa block and Qiangtang block is (0.252±0.091) Pg·a^-1 and (0.012±0.002) Pg·a^-1, respectively. The lower CO₂ flux from Oligocene volcanic activity in the Qiangtang block is consistent with the rapid decline in atmospheric CO₂ concentration during this period, while the higher CO₂ flux from Miocene volcanic activity in the Lhasa block may have contributed to the peak in atmospheric CO₂ concentration during the Middle Miocene Climate Optimum. The approximate synchronous variation between deep carbon outflux from volcanic activity on the Tibetan Plateau and atmospheric CO₂ concentration suggests that volcanic activity induced by the India-Asia continental collision and subduction was a key factor influencing the Cenozoic atmospheric carbon budget.

In recent years, amino acids in aerosols, including free amino acids (FAAs) and combined amino acids (CAAs), have attracted widespread attention. This is due to the significant roles these proteinaceous substances play in global climate change, the removal efficiency of air pollutants, the bioavailability of atmospheric nitrogen, the formation of secondary organic aerosols, and their effects on human health. This paper focuses on the application of stable nitrogen isotopes of compound-specific amino acids, a new technique, in tracing the sources and transformation processes of atmospheric amino acids. It reviews the stable nitrogen isotope characteristics of individual amino acids in potential atmospheric protein emission sources, as well as the mechanisms of stable nitrogen isotope fractionation during combustion processes and atmospheric transformations. Future research should further investigate the isotopic fractionation mechanisms of individual amino acid under different particle sizes, meteorological conditions, and special pollution events. This will help clarify the role and contribution of amino acids in cloud and precipitation formation, climate change, and pollution events.

River plays a critical role in biogeochemical cycling of toxic heavy metal, mercury (Hg), across Earth’s surface spheres, thus it is important to identify the sources, transformations and fates of Hg in river system. Over the past fifteen years, the unique “three-dimensional” Hg isotopes system has been widely used as a powerful tool for tracing the biogeochemical cycling of Hg, which has largely improved the understanding of Hg systematics in rivers. In this study, the recent development of pretreatment and analysis methods essential for Hg isotopes study is first summarized, including the anion-exchange resin and purge and trap for dissolved Hg, the pyrolysis and digestion for particulate Hg, and the distillation-gas chromatography and distillation-ion exchange resin for methylmercury (MeHg). Then we introduce systematically three application aspects of Hg isotopes in rivers, with the first to quantitatively determine the sources of different Hg species and their contributions, the second to reveal the geochemical behavior of Hg and its migration into the ocean, and the third to clarify the environmental and ecological effects of riverine Hg. Finally, Hg isotopes are integrated into the river-coastal Hg flux model, and the source-sink balance is examined. As the study on Hg isotopes in rivers is still at the beginning, future research should be systematically performed not only to develop the analysis method, but also to advance our knowledge of Hg isotope fractionation mechanisms during the interaction between riverine Hg with other ecosystems such as soil, atmosphere, and ocean, with a goal to better constrain the fate of riverine Hg and its environmental and ecological effect.

High-energy cosmic rays and their secondary particles interact with atmospheric and surface material atoms, generating meteoric and in-situ cosmogenic nuclides. Meteoric ¹⁰Be is primarily produced by nuclear reactions between spallation neutrons and oxygen and nitrogen in the atmosphere. It becomes adsorbed onto aerosols, migrates through the atmosphere, and is deposited on the Earth’s surface via wet and dry deposition. Compared to ¹⁴C, meteoric ¹⁰Be has a much longer half-life (1.387 Ma), enabling its use for dating over timescales of several million years. Unlike in-situ ¹⁰Be, meteoric ¹⁰Be is a proxy for geochronology and chemical weathering. Additionally, it is valuable for reconstructing paleomagnetic field intensity and paleo-precipitation changes. Its broad range of applications, higher natural nuclide concentration, and simple laboratory preparation make meteoric ¹⁰Be wellsuited for extraction and accelerator mass spectrometry analysis. Despite its widespread application across various disciplines, a comprehensive review and critical analysis of meteoric ¹⁰Be’s utility in paleomagnetic intensity reconstruction, precipitation studies, weathering flux quantification, and geochronology applications remain lacking. This paper reviews the basic principles of atmospheric ¹⁰Be production and highlights its applications in Earth science, including samples of marine sediments, loess deposits, ice cores, and river sediments. It explores the potential of meteoric ¹⁰Be in advancing surface Earth system science and provides a preliminary outlook on the opportunities and challenges for future research.

Trace metal elements play crucial roles in biological systems, with their concentrations and distributions being strictly regulated by biological processes and influenced by external environmental factors. Copper and zinc play specific functions in immunoregulation, protein synthesis, and catalytic reactions. Disruptions of these two metals in biological homeostasis can lead to oxidative stress responses, inflammatory damage, and even diseases. The recently-developed isotope approach of these two metals has shown great potential for tracing not only their transformation in various environments, but also during different metabolic processes, as metal stable isotopes primarily fractionate during the changes of redox reactions and ligand binding energies. Therefore, studying the composition, distribution, and balance of metal stable isotopes in various organisms would enhance our understanding of metal homeostasis and related metabolic processes. In this study, copper and zinc isotopes were taken as examples to show the potential of metal stable isotopes for tracing special life processes especially the cancer progression. We first summarized Cu and Zn isotopic compositions in the human body and the relative influence factors such as sex, age, dietary habits, and environmental exposure, and then discussed the imbalance of Cu and Zn isotope homeostasis during cancer progression. Although Cu and Zn isotope ratios in various tissues have been found to be influenced by sex and dietary habits, the significant enrichment of light Cu isotopes in blood and light Zn isotopes in urine of cancer patients compared to the healthy controls during cancer progression highlights the potential of metal stable isotopes in cancer diagnosis and prognosis. In the future, the extended human metal isotope database could help identify the mechanisms of metal isotope fractionation during special metabolic processes such as cancer progression, which would in turn help to explore the potential clinical applications of metal stable isotopes.

Hydraulic conductivity (K) is a fundamental hydraulic property for characterizing groundwater flow. However, studies on the variation of K in riparian shallow aquifers at different scales are rare. This study focuses on the loose sandy unconfined aquifer of the Luanhe River Estuary. We used three methodologies, including laboratory permeability test, slug test, and analytical inversion, to calculate effective K at the core, well-bore, and field scales. The findings reveal a clear trend of increasing K with scales, with the median K values of 0.71 m/d, 12.31 m/d, and 191 m/d at the corresponding scales, respectively. At smaller scales, the measured K captures the local heterogeneity of the aquifer. As the scale increases, more preferential flow paths are included, leading to a remarkable increase in K. At the large scale, the parameter reflects the homogenized characteristics of the aquifer system as a whole. The significant differences in K across scales highlight the importance of selecting scale-appropriate values tailored to specific engineering requirements and research objectives when studying groundwater-related processes, such as groundwater movement in unconfined aquifers affected by seawater intrusion and surface water-groundwater exchange. Moreover, this study provides essential data for the development and utilization of the aquifer in the Luanhe River Estuary, offering valuable methodological references for understanding water movement within aquifers in other regions.

In the past one hundred years, water demand and supply in the Beijing-Tianjin-Hebei region increased greatly due to rapid socio-economic development, accelerated urbanization, expansion of crop land as well as climate change. It has resulted in substantial reduction of regional water resources that cannot meet the total water requirement. This situation has substantially alleviated in the recent years when executions of comprehensive measures of large-scale intra-basin water transfer, water conservation, and economic structure adjustments. As the low-carbon and greening development policy has announced for controlling global change and will be executed in future, the socio-economy and ecological environment in the region will be further adjusted. It brings new challenges and opportunities to make schemes of balancing available water resources and demands. This study divides the hydrological regime and the evolution of water resources supply/demand in the Beijing-Tianjin-Hebei region into three stages, based on the characteristics of water resources and supply/demand relationship, and their causes, treating measures and pathways. The shifts in the drives of the water resources evolution in different stages of the “S-type” curve are systematically analyzed. The impact of low-carbon development, green growth, and climate change adaptation on the transformation of water resource supply and demand patterns is elucidated. Then, we propose the approaches to enhance the local water recovery capacity through the study of the water cycle mechanism, as well as pathways to improve the water resource security capacity in response to extreme climate change. This study will provide scientific support for the sustainable utilization of water resources in the Beijing-Tianjin-Hebei region and other water-scarce areas.

Urbanization and urban development are among the most significant human activities impacting the ecological environment. Accompanied by population growth and increased consumption levels, urbanization has triggered a series of complex water resource and water environment issues. Inadequate urban drainage systems, particularly in developing countries, exacerbate the deterioration of water environments and pose a serious threat to urban health and sustainable development goals. Therefore, it is a key scientific issue to explore the complex relationship between the three-dimensional urban subsurface structure, hydrological processes and water resources management from the perspective of earth system science. This study, based on the ‘Earth’s critical zone science’ and ‘social-ecological system science theory’, systematically reviews the coupling mechanisms between urban surface structures, dynamic changes in the water cycle, water quality, and the sustainable utilization of water resources. By integrating physical, chemical, and biological processes, this study reveals the impact mechanisms of impervious surface expansion on the precipitation-runoff-infiltration dynamic balance, pollutant transport, and the supply-demand distribution of water resources. We emphasizes the importance of the coupling between social and natural systems for the optimization of water resource management. In addition, the study combines the linkage between hydrological processes and ecosystem services, analyses the role of hydrological dynamics in regulating the functioning of ecosystem services and human well-being, and initially proposes a framework for the sustainable management of urban water resources based on the social-ecological system theory. This framework provides scientific support for understanding the coupling mechanism of structure-process-function of urban hydrological systems. This review not only helps to understand the complex relationship between urban hydrological dynamics and ecological services, and to break down the barriers between hydrological subdisciplines, but also provides a theoretical basis and practical guidance for managing urban water resources and setting policies.