We analyzed the submissions, acceptances, reviews, and grant funding of various projects of National Natural Science Foundation of China in the Environmental Geosciences in 2022 and pointed out the issues with the submission and review processes. We also summarized the main research progresses and outcomes of the funding projects by the Division of Environmental Geosciences completed at the end of 2021.
The Qinghai-Tibet Plateau is a region vulnerable to natural disasters. There are many natural meteorological disasters occurring on the Qinghai-Tibet Plateau， such as snow disasters， droughts， strong winds， thunder and lightning， hail， and floods. Droughts are the most serious type of meteorological disaster in the region， apart from snow. With climate change and the increase in human activities， the losses caused by natural disasters on the Qinghai-Tibet Plateau are increasing over time. Focusing on the regional characteristics of the Qinghai-Tibet Plateau， we evaluate the situation of meteorological droughts. The main results of meteorological drought research are systematically summarized， and the basic temporal and spatial distribution characteristics of meteorological droughts are revealed. The current technical methods for meteorological drought monitoring and forecasting are clarified， and the laws of meteorological drought disaster risk are elucidated in the Qinghai-Tibet Plateau. The results show that the high-incidence areas of droughts are in the north， northeast， southwest， and southeast of the plateau. The high incidence periods were the 1980s and the 2000s. Drought monitoring is mainly conducted based on the drought index and using drought-prediction climate models based on drought influencing factors. The southern part of the northeastern area is a high-risk region for drought disasters impacting agriculture and animal husbandry， while the northeast， southwest， and southeast are higher-risk areas. The alpine grasslands face a higher risk of drought disasters than alpine meadows. Numerical models based on future scenarios revealed that temperature and precipitation may increase in the Qinghai-Tibet Plateau in the 21st century. However， owing to the obvious unevenness in the temporal and spatial distribution of the increased precipitation， the possibility of seasonal and regional meteorological droughts in the future is still remarkably high. Finally， remaining problems in the study of meteorological droughts in the Qinghai-Tibet Plateau， in terms of data， technical methods， and model applications， are discussed. Combining existing local problems and international perspective， the key scientific issues and technical fields concerning meteorological droughts in the Qinghai-Tibet Plateau are highlighted.
Submarine gullies belong to the submarine micro-geomorphology， which are smaller than the scale of submarine canyons and channels. Submarine gullies are less than 10 km long， less than 1 km wide， and less than 100 m deep. They form deep-water sediment-transport systems with submarine canyons and channels. Owing to the limitation of survey data resolution in previous studies， the important role of submarine gullies has been ignored in the evolution of the continental margin and the process of deep-water deposits. Submarine gullies are the "capillaries" of the deep-water sediment transport system occurring at dozens or even hundreds of times the sum of submarine canyons and channels. Moreover， submarine gullies are mainly distributed in the head of the deep-water sediment transport system， including continental slopes， island-and-reef margins， estuarine alluvial fan fronts， submarine canyons， and channel interiors. Submarine gullies are closely related to the safety of deep-water engineering and islands-and-reefs， process of deep-water deposits， and prediction of deep-water oil and gas reservoirs. The research progress of submarine gullies is introduced from the aspects of identification characteristics， sedimentary environment， influencing factors， and formation mechanisms. From the aspects of distribution area， slope gradients， shape， and sedimentary characteristics， the differences and relationships between submarine gullies， submarine canyons， and channels are discussed， and a method for distinguishing them is given. By summarizing the characteristics of submarine gullies around the world， submarine gullies are defined as linear grooves characterized by erosion or deposition caused by gravity flows in the steep seafloor （slope gradients >2°）， which show the characteristics of submarine gullies as narrow， short， shallow， and straight （curvature≈1）. Moreover， submarine gullies caused by sheet-like turbidity currents have group characteristics that are parallel to each other and equally spaced.
Geo-information Tupu, which is the origin of the geomorphic information spectrum, is introduced and the concept and development of the geomorphic information spectrum are then discussed. From the perspective of specific research, the research types and status of the geomorphic information spectrum are summarized, including the geomorphic morphological characteristic spectrum (such as, surface slope spectrum, section spectrum, two-dimensional pattern spectrum, and topographic texture spectrum) and the geomorphic development spectrum. Combined with the development of remote sensing, computers, artificial intelligence, and other technologies, the prospect of the combination of knowledge graph and information spectrum in future geomorphic research is analyzed, and the research progress and key technologies of geomorphic information spectrum such as geomorphic information extraction, geomorphic information classification, and geomorphic mapping are summarized. The future development of geomorphic information spectrum is prospected using three aspects: constructing a complete geomorphic information spectrum system, improving key technologies of geomorphic information spectrum, and strengthening the refinement and quantitative research of global geomorphic patterns and evolution. This study can provide a reference for the digitization, informatization, and intellectualization of digital geomorphology to serve as the major strategy for the management of national resources and the environment and promote the development of geomorphology.
Marine science is a discipline developed on the basis of continuous observation data accumulation, and major breakthroughs in marine science development history are inseparable from the updating of ocean datasets. The time extension of existing gridded datasets has become the main form of updating ocean data products. This review summarizes the current development of gridded marine environment datasets. First, the historical development of ocean observations is divided into three stages: an initial accumulation period dominated by sparse observations, a rapid growth period guided by international observation programs, and a high-quality development period driven by data assimilation and ocean reanalysis. Starting from the three key elements of temperature, salinity, and ocean current, we focus on the global gridded ocean environment datasets published and updated internationally in recent decades, including six flow field datasets, such as HYCOM and OFES, and ten thermohaline datasets, such as Argo and IAP. Based on previous studies, the sources, characteristic information, advantages, and disadvantages of these datasets are briefly reviewed to provide a reference for marine scientists. Finally, the future development direction and research focus of ocean gridded datasets are discussed.
The ecologically fragile region in China and Mongolia is among the regions with the largest distribution area, the largest type of fragile ecology, and the most evident ecological vulnerability. The ecological environment condition in the ecologically fragile areas of China and Mongolia restricts the sustainable development of regional ecology and social economy, and is crucial to the ecological security of China and Mongolia. Thus, it is urgently necessary to thoroughly explore the characteristics of ecologically fragile ecosystems in China and Mongolia and their response mechanisms to global changes, which can provide a scientific basis for regional ecological environmental restoration. Based on the carbon and nitrogen cycles of fragile ecosystems affected by global change, this study presents and summarizes the following key research topics: fragile ecosystem carbon and nitrogen cycles and coupling mechanisms, the influence of global change on fragile ecosystems, fragile ecosystem safety threshold identification and risk assessment under the background of global change, and the adaptive management of fragile ecosystems to global change. In view of the national major needs of ecological safety, researches in the following aspects are urgently needed: analyzing the annual, seasonal, and diurnal characteristics of nitrogen turnover pathways, transformation form, and flux in water-soil-gas-biomass systematically to reveal the carbon and nitrogen cycling process, spatio-temporal law, and coupling mechanism of fragile ecosystems and determine the primary mechanism of the carbon and nitrogen sink function in fragile ecosystems. Building a carbon and nitrogen coupling model in fragile ecosystems, quantifying the influence strength of different intensities of climate change on fragile ecosystem safety and the influence of human disturbance on the carbon and nitrogen cycle and its ecological system, assessing the effect of fragile ecological systems on the carbon and nitrogen cycle in the Earth system and its carbon and nitrogen source-sink effect, and proposing management countermeasures and measures of fragile ecosystems to global change.
The global operational ocean forecasting system is a comprehensive application with numerical ocean models as the key， ocean observation as the basis， and supercomputer comprehensive application capabilities as the tool， providing a full range of forecast services for ocean disaster reduction and prevention， navigation safety， ecosystem protection， search and rescue， etc. It briefly introduces the countries/organizations implementing marine operational forecasting services and their atmospheric forecasting systems. Sea surface winds are the source of driving waves； therefore， wave forecasting is generally carried out in conjunction with the atmosphere. The parameter configurations of the global ocean wave forecasting system were constructed based on WW3 （WAVEWATCH III?） and WAM （Wave Model） numerical ocean wave models. It focuses on the composition and parameter configurations of the global ocean circulation forecasting system based on HYCOM （HYbrid Coordinate Ocean Model）， NEMO （Nucleus for European Modelling of the Ocean）， and MOM（Modular Ocean Model）. An overview of the operational sea ice forecasting system based on the CICE（Community Ice CodE） and LIM sea ice models coupled with the ocean circulation forecast system is provided. Finally， the conclusions and development directions of the global operational ocean forecasting system are summarized.
The negative impact of global climate change on resources, ecology, and the environment is becoming increasingly apparent. Hence, reducing the atmospheric carbon dioxide (CO2) concentration has become a global concern. Intertidal wetlands (e.g., mangroves and salt marshes) have strong carbon sink functions that can reduce the CO2 concentration, thus mitigating global climate change. Mangroves and salt marshes are important coastal blue carbon ecosystems characterized by high soil carbon storage. Porewater exchange and associated carbon exchange driven by tides and rainfall in mangroves and salt marshes are challenging issues when estimating the effects of coastal blue carbon sinks. Large amounts of porewater-derived sediment carbon outwellings remain in the ocean and may represent an important carbon sink; however, they are poorly understood, despite being potentially significant components of the salt marsh carbon budget. This review aims to quantify the porewater exchange rate and related carbon fluxes, analyze their driving mechanisms, and reassess the carbon budgets and carbon sink potentials of mangroves and salt marshes. This study promotes understanding the carbon balance and cycle processes associated with mangrove and salt marsh ecosystems, and provides a scientific basis for the construction, protection, and sustainable development of coastal blue carbon sinks in the context of global climate change.
Considering the close genetic connection between South and North China， the Tibetan Plateau and the northward subduction zones of the Australian and Indian Ocean plates， all are included in the Southeast Asian tectonic region. The larger Southeast Asian tectonic domain is divided into the Tethys， mountain and arc， extrusion escape， Sundaland， eastern marginal sea， and the Philippine Arc tectonic domains. Overall， research in Southeast Asia is insufficient due to geographical and historical issues， and there are still many unsolved geoscience-related issues. Among them， the splitting and collage of the Tethys block from Gondwanaland， the existence and extinction of the proto-South China Sea， the formation mechanism of the present South China Sea， the attributes of the Philippine Arc active zone and the New Guinea Arc， and the relationship with the proto-South China Sea， are scientific issues worthy of attention in future geoscience research in Southeast Asia.
Clarifying the stability of salt marsh soil organic carbon sinks is of great significance when scientifically evaluating the carbon sink potential of “blue carbon” in coastal zones. The chemical structure and composition of Soil Organic Matter (SOM) are closely related to the stability of soil organic carbon sinks. This study focused on four reclamation areas with different construction times in the eastern part of Chongming Island, China. Solid-state 13C Nuclear Magnetic Resonance (13C NMR) was used to investigate the characteristics of SOM chemical structures in buried salt marsh samples obtained by drilling and topsoil samples acquired from woods around the drilling cores (CM2, CM4, CM5, and CM6). The purpose of this study was to elucidate the variations in the chemical structure of SOM during its turnover. The results showed that
the variations in soil organic carbon functional groups from the surface to the deep layers exhibited similar trends for the four reclamation areas, despite different construction times. The alkyl carbon and aromatic carbon proportions showed an increasing trend whereas those of alkoxy carbon and carbonyl carbon showed a decreasing trend from the topsoil samples to the buried soil samples. The alkyl carbon/alkoxy carbon, aromaticity, and hydrophobic carbon/hydrophilic carbon of the buried salt marsh soil samples were greater than those of the topsoil samples in the woods around the drilling cores. The stability of the SOM chemical structure increased with burial depth.
From west to east, alkyl carbon/alkoxy carbon, aromaticity, and hydrophobic carbon/hydrophilic carbon were all less than 1 and showed a gradually increasing trend, but aliphatic carbon/aromatic carbon gradually decreased in the topsoil samples in the woods around the drilling cores. The overall decomposition degree of organic matter in topsoil samples from the woods was low and showed a gradually increasing trend from west to east, which meant that SOM stability gradually improved. This was because the planting time for trees gradually became earlier and the development time for topsoil became longer in the woods from west to east.
From east to west, the proportions and ratios of organic carbon functional groups in buried salt marsh samples showed that SOM stability increased with reclamation time. In summary, along with soil development, the decomposition degree of salt marsh SOM continued to improve, with an increasing proportion of refractory SOM components and a decreasing proportion of labile SOM components. In addition, SOM stability continued to increase. The changes in the chemical structure and composition of SOM in the reclamation areas, constructed in different years along the Yangtze River estuary, were studied using solid-state 13C NMR and the results improve understanding about the temporal trend and chemical mechanism underlying soil carbon sink stability.
The vulnerability of mountain ecosystems and community residents makes them a key area for the research and implementation of the United Nations Sustainable Development Goals (SDGs). The sustainable development of underdeveloped mountainous areas is related to the development process and the effectiveness of the United Nations SDGs. Based on the bibliometric method, which focuses on the development goals associated with SDGs related to mountainous areas, the main countries and research produced by scientific institutions associated with the sustainable development of underdeveloped mountainous areas across the globe were analyzed. Five key research areas for sustainable development in underdeveloped mountainous areas: sustainable livelihoods, the health and well-being of residents, water supply and sanitation, ecosystem protection, and climate change and response, which are closely related to SDGs, were selected and research progress and policy measures in each area are described. At the same time, this study investigated ways of improving the evaluation system to promote the systematization of SDGs evaluation in underdeveloped mountainous areas; used big Earth data to remove the data bottleneck associated with SDGs monitoring in underdeveloped mountainous areas; researched the relationship between SDGs to promote their coordinated implementation in underdeveloped mountainous areas; and carried out an SDGs realization path demonstration to help underdeveloped mountainous areas. In terms of the implementation of SDGs policies in developed mountainous areas, this study analyzed the challenges and countermeasures affecting the realization of SDGs in underdeveloped mountainous areas and provides a useful reference for sustainable development research in underdeveloped mountainous areas.
Gully erosion is an important type of soil erosion and is considered the dominant sediment source in small watersheds. Accurately predicting the spatial distribution of gully erosion and spatiotemporal variation of erosion intensity is critical for optimizing soil and water conservation measures in small watersheds, promoting regional food production, and maintaining regional ecological security. Topographic threshold models, susceptibility assessments, morphological features, erosion prediction models, and landscape evolution models are the main techniques for the location prediction of gully initiation, probability evaluation of gully erosion, and estimation of gully erosion intensity. Based on the fundamentals and principles of these methods, the findings of related studies are systematically compared and reviewed, and the advantages and disadvantages of each method are determined. Future research should focus on the optimization of gully measurements and the accumulation of monitoring data, the processes of gully erosion and the comparability of related data, the selection of prediction models and their applicable regions, the development of empirical models and variability of related parameters among various regions, and the gully erosion mechanisms and the development of process-based gully erosion models. Therefore, the proposed research provides technical foundations for mitigating gully erosion and insurance for sustainable development of regional society and economics.
Potash is an important strategic mineral resource to ensure national food security. From the perspective of national security, we have constructed a security assessment and early warning index system for potash resources, evaluating the security of potash resources from 2001 to 2020 using constant weight and variable weight evaluation models. Based on this, we also conducted an early warning analysis from 2021 to 2030. The results show that from 2001 to 2007, potash resources have a high degree of security risk and are in a state of insecurity due to low reserve-production ratio and reserve index and high import dependence and concentration. With an increase in the reserve-production ratio and the decrease in import dependence and concentration, the degree of security risk of potash resources decreased slightly and is in the safe state from 2008 to 2020. The security early warning assessment value of potash resources is within the range of 5.08~6.28 from 2021 to 2030, and the early warning level shows a changing trend from blue to yellow and then to blue. From the perspective of risk warning, the public risk factors affecting the security of potash resources are the reserve index, import dependence, and concentration, which should be prevented.
Sea ice leads are linear fracture zones in Arctic pack ice caused by divergent sea ice motion driven by wind and ocean currents. In winter， leads that are the main factories of ice formation and brine rejection， serve as the prime window for heat and material exchange between the Arctic Ocean and atmosphere. Spring onward， solar shortwave radiation transmitted through leads promotes the bloom of ice algae and plankton and subsequently sustains a habitat for wildlife in the Arctic. In summer， meltwater from sea ice floats on the ocean surface and usually converges to a reservoir of leads. In practice， the ocean surface in open leads is a crucial reference for satellite altimetry because it provides pathways for surface vessels and migration corridors for marine animals. Leads can be detected in optical， thermal， and microwave remote sensing images utilizing the contrast in their albedo， surface temperature， emissivity， and roughness from the surrounding pack ice. Various satellite and airborne images with moderate and high ground resolution have been used to evaluate the presence of leads. The products of lead distribution in the Arctic have been generated using different satellite remote sensing techniques. As sea ice in the Arctic becomes thinner and retreats earlier in the melt season， changes in the spatial and temporal distributions of leads can be expected. A recent study using MODIS thermal images has confirmed the continuous rise of spring lead areas in the Beaufort Sea since 2001， although for the entire Arctic， the results are still inconclusive. In the context of declining sea ice， the energy budget in leads must be parameterized based on comprehensive observations. The contribution of both open and refreezing leads to a regional energy and mass balance of sea ice， and its role in the changing Arctic climate and marine system， remains to be recognized.
Hydrological models are efficient and economical tools for conducting scientific studies. They are not only useful in validating scientific theories and guiding the deployment of observation networks, but they also play an indispensable role in facilitating decision-making within socioeconomic spheres such disaster prevention and mitigation. Distributed hydrological modelling via numerical methods entail the application of hydrological equations to express the spatial heterogeneity of hydrological parameters at a fine-scale. This fine-scale analysis allows for a detailed characterization of hydrological processes, which is a critical step within the context of developing robust hydrological models. The SHUD model adopts the finite volume method to resolve integrated surface-subsurface hydrological processes. The model uses an irregular triangular network, which can rapidly realize an ultra-high-resolution numerical simulation (i.e., from meters to kilometers). The AutoSHUD automated hydrological simulation system, which consists of the SHUD model, rSHUD tool, and global essential terrestrial data, can facilitate pre- and post-processing of the model and has been applied to several research projects; hence, the validity and applicability of the model have been verified. At present, the exploration, development, and application of distributed hydrological models by numerical methods are limited in our hydrological community, and there is an urgent need for more original research in this field. The global development of new models as well as the validation, promotion, and improvement of existing models is a worthwhile goal.
Marine sediments contain large amounts of alkanes， mainly consisting of methane （CH4）， ethane （C2H6）， and propane （C3H6）. Similar to methane， ethane and propane are also important greenhouse gases. The decomposition of hydrates and oil/gas seeps can cause the release of ethane and propane into seawater and the atmosphere， significantly impacting the marine ecosystems and global climate change. The microbial oxidation of alkanes， in marine environments， effectively reduces the emission flux of these gases. The latest research progresses on the distribution and biotransformation of ethane and propane in marine environment were reviewed with the following highlights：
The distribution of ethane and propane in seawater exhibited clear patterns， which are largely influenced by hydrological， chemical， and biological factors；
Biological sources of ethane and propane in marine environments include phytoplankton production in seawater and anaerobic production by microorganisms in sediments. Methanogens can produce ethane and propane using a variety of substrates， and
aerobic oxidation of ethane to propane is performed by hydrocarbon-degrading bacteria， and this process is accompanied by carbon and hydrogen isotope fractionation.
Anaerobic oxidation of ethane and propane in sediments is usually coupled with sulfate reduction. Sulfate-reducing bacteria can oxidize ethane and propane， and a possible mechanism for this process has been proposed. This review summarizes the source， distribution， and microbial metabolism of ethane and propane in marine environments and provides a scientific basis for further understanding the biogeochemical cycle of hydrocarbons.
Mountain glacier ecosystems contain diverse habitats, including ice, snow, meltwater, cryoconite, sediment, debris, and soil. These habitats harbor unique biomes that are dominated by cold-tolerant microbes. Mountain glaciers have responded strongly to climate change and have considerably shrunk in size over recent decades. Mountain glacier ecosystem was divided into supraglacial zone, englacial zone, subglacial zone, and proglacial zone, according to the vertical stratifications, horizontal locations, environmental characteristics, and trophic types of colonized microbes. This study reviewed research focused on the physiological characteristics, community composition, and diversity of the microbial community and ecological factors driving their distributions in these four zones. The studies (2010-2022) about the microbial communities in mountain glacier ecosystems that were reviewed mainly investigated the following:
isolation and culture of psychrotrophs and psychrophiles;
characteristics of microbial community composition and diversity;
microbial community assemblage and succession processes;
biogeochemical cycles driven by the microbes; and
interactions between ecological factors and the microbial community. Most of the studies were conducted in the proglacial and supraglacial zones and mainly focused on the composition and diversity of the bacterial community. In future studies, all zones should be considered as an integrated system to conduct long-term monitoring and investigation of multiple microbial communities in different habitats. They should also focus on microbial interactions and functions. This study improves understanding about the ecological processes mediated by microbes and their ecological roles in extreme environments, both of which have implications for maintaining the stability of glaciers and surrounding ecosystems.
The remediation and utilization of salt-affected soil through the application of green and sustainable technologies are important for cultivating healthy soil, ensuring global food security, and mitigating global climate change. Biochar has the potential to improve soil health and increase crop yield because of its multiple advantages, such as excellent pore structure, abundant surface functional groups, and high carbon stability. Recent research focusing on the improvement of salt-affected soils via biochar application has garnered increasing interest. However, the effect of biochar on salt-affected soil is extremely complex and diverse, resulting in a lack of critical mechanisms responsible for biochar performance in salt-affected soils. This greatly limits the application of biochar technology for the improvement of salt-affected soils and the industrialization of biochar. Therefore, this review comprehensively analyzed the impact of biochar on the physical, chemical, and biological properties of salt-affected soils. Specific focus areas included the relationship and critical mechanism between biochar properties and salt-affected soils and the deficiencies in areas that need to be strengthened. We emphasize the importance and urgency of comprehensively evaluating the effects of biochar application in the remediation of salt-affected soils from the perspective of soil health. In this study, we aimed to provide a theoretical basis for the application and popularization of biochar, as well as technical assurance for the green development of salt-affected soils.
The period of the late Miocene Tortonian （11.61~7.25 Ma） was warmer and wetter than today， with atmospheric partial pressure of carbon dioxide （pCO2） near the preindustrial level. Greenhouse climate under low pCO2 was rare throughout the Cenozoic and understanding its mechanisms will help to better forecast the future climate. We summarized two hypotheses to elucidate this mechanism. One is the late Miocene climate-pCO2 "decoupling hypothesis" based on geological records， and the other is "synergistic effects hypothesis" based on climate modeling. Geological records indicate that the late Miocene climate may not have been affected by pCO2， that is， climate and pCO2 were decoupled. Climate modeling results indicate that different vegetation and tectonic conditions in the late Miocene may have contributed to the global temperature increase. However， realistically， it is difficult to fully simulate the amplitude and pattern of the late Miocene warmth. Future work should focus on reconstructing pCO2 records with high accuracy and resolution. Vegetation， clouds， water vapor feedback， and soil properties may be the dominant factors contributing to the late Miocene greenhouse climate， which should also be considered in future simulation work.
Redox Sensitive Trace Elements （RSE）， such as Re， Mo， and U， are often autogenetically enriched in sediments because of their different solubilities and/or affinities for particulates under various redox states at the time of sediment deposition when diffusing through the sediment-water interface. The enrichment of Re is primarily in a suboxic depositional environment but that of Mo is in an euxinic environment. In contrast， U has a relatively large depositional depth range in sediments. The special geochemical behavior of the RSEs makes it possible to indicate the redox state， as the autogenetic enrichment degrees in sediments have a good correlation with the redox conditions of marine sedimentary environments. Lower enrichments were recorded from sediments deposited in oxic （Re/Al<1.3×10-7， Mo/Al<0.4×10-4） and beneath seasonal oxygen minimum zone environments， while higher enrichments were recorded from sediments deposited within the perennial oxygen minimum zone （U/Al>5×10-4， Mo/Al>5×10-4） and euxinic （Mo/Al>5×10-4） environments. In addition to the relative enrichment degree， the paleoredox proxies of the enrichment coefficient （TMEF<1 means depletion； TMEF>1 means enrichment； TMEF>3 means obvious enrichment； TMEF>10 means significant enrichment）， trace elements ratios （Re/Mo≤0.3×10-3 indicates an oxic environment； Re/Mo≈10×10-3~30×10-3 indicates an anoxic environment； Re/Mo≈0.7×10-3~0.8×10-3 indicates an euxinic environment）， the trace elements covariant system （MoEF/UEF≈0.1×modern seawater value~0.3×modern seawater value indicates an oxic-suboxic environment； MoEF/UEF>1×modern seawater value indicates an anoxic environment； MoEF/UEF≈3×modern seawater value~10×modern seawater value indicates an euxinic environment）， and isotope values （δ98/95Mo≈-0.7‰ in an oxic environment； δ98/95Mo≈-0.5‰~+1.3‰ in a suboxic environment； δ98/95Mo≈+1.6‰ in an anoxic environment； δ98/95Mo≈+2.2‰~+2.5‰ in an euxinic environment） could also be utilized to comprehensively unravel the history of depositional environments. It should be noted that the migration and transformation mechanisms under the different redox conditions of Re， Mo， and U are imperfect， and related datasets in modern marine systems are limited. The highly variable enrichment degrees of Re， Mo， and U reflect obvious regional differentiation， which is yet to be examined. In future， more observations and research in modern marine systems are needed to improve the indicative utility of RSEs combined with the paleo-marine system.
The atmospheric boundary layer connects the land surface to the atmosphere through the turbulent exchange of heat, momentum, and trace gases. In addition, it plays an important role in the formation and evolution of weather and climate. The characteristics and formation mechanisms of the deep atmospheric boundary layer have been key focus areas in atmospheric boundary layer research. Focusing on extremely arid regions and special geographical locations, the observational facts and influencing factors of the deep atmospheric boundary layer were reviewed and summarized. Furthermore, a physical description of turbulent motion in the development of the deep atmospheric boundary layer was provided. Using the Taklimakan Desert as an example, the effects of the interactions between the deep atmospheric boundary layer and dust stagnation on weather and climate were discussed. In order to provide a roadmap for future research, this study identified and outlined four key scientific problems related to deep atmospheric boundary layer research.
The Timor Trough is located at the boundary of the Eurasian and the Australian plates， in the outer Banda Arc between the Banda Sea in Southeast Asia and the Timor Sea in northwest Australia. Since the Neogene， especially from the Late Miocene to the Late Pliocene， the collision between the Australian continent and the Banda Arc caused the uplift of Timor Island and the deformation of the Timor Trough， which affected the regional tectonic activities. A series of normal faults developed at the margin of the Australian Northwest shelf， which mainly controls the platform， horst， and graben features. The northern Timor Trough formed a series of thrust faults under the dual effect of the uplift of Timor Island and subsidence of the Timor Trough caused by arc continental collision. The NE-SW thrust fault at the bottom of the Timor Trough is the deformation front that controls the shape of the trough. The characteristics of tectonics and earthquakes indicate that the Banda subduction zone between the Australian Plate and Banda Arc is located in the Ombai Strait， which is between Timor Island and the inner Banda Arc， subducting at an average high angle of approximately 62° at a depth of more than 600 km. The subduction angle in the south is larger than that in the north， which is related to the compression of the Indian Ocean subduction plate. The front oceanic crust subducted below the northwest Banda Sea showed a horizontal trend below 500 km. There is an obvious discontinuity in the earthquakes between the deep and upper focus zones. The subduction of the Australian Plate beneath the Southeast Asian Plate may have gradually slowed down and stopped； however， the deformation of Timor Island and the Timor Trough caused by arc continental collision continues. The inner Banda Arc is deforming along the Banda Sea. Under the background of relatively balanced subduction， the subduction of the Australian Plate beneath the Southeast Asian Plate may have transformed into an orogeny. In the future， the inner Banda Arc may be uplifted to form an inner and outer Banda Arc double orogenic belt.
The mineralization process of elution-deposited Rare Earth Element (REE) deposits is closely related to chemical weathering. Elution-deposited REE deposits in South China are an extremely important type of rare resource, with large reserves, a wide distribution, and a high content of Heavy REEs (HREE). In recent years, the migration and enrichment mechanism of earth elements during the chemical weathering process and the ore-forming mechanism of elution-deposited REE deposits has garnered great research interest. This subject has become one of the central issues in geoscience research. Multiple aspects, such as the metallogenic characteristics and processes of elution-deposited REE deposits, structural characteristics of granite weathering crust, distribution characteristics of REEs, occurrence and migration modes of REEs, main factors affecting the migration and enrichment of REEs, and the characteristics of Eu and Ce anomalies are systematically summarized in this paper. The purpose of this study is to comprehensively summarize knowledge centered on the behavior of REEs in the process of supergene weathering, to provide novel directions for future research. Non-traditional stable isotope tracing of chemical weathering is novel and effective; specifically, stable isotope analysis methods for Ce and Nd have been successfully established. Therefore, future research should explore earth elements through the lens of isotopic methods, as this approach could provide important insights for tracing chemical weathering, revealing the mineralization process of REE deposits, and studying environmental evolution.
The China National Key Research and Development Program of China “The experiment of a multi-platform collaborative field campaign on offshore typhoon (2018YFC1506400)” was established to meet the needs of the country for typhoon prevention and disaster reduction. Additionally, the project aims to solve the lack of direct typhoon observation data, which restricts the development of typhoon science and the improvement of operational forecasting ability in China. Since the establishment of the project in December 2018, field observation-diagnosis and theoretical analysis based on observational data-numerical simulation and data verification have been used to adapt and transform new typhoon detection equipment independently developed by China in recent years. This included high-altitude unmanned aerial vehicles and stratospheric airships and the complete design of the “land-ocean-air-sky” three-dimensional collaborative observation scheme for offshore typhoons. Furthermore, multi-platform collaborative field observation experiments were implemented for 16 offshore target typhoons and the parameterization scheme of the physical process of the typhoon model based on the analysis of multi-source direct observation data was modified and applied to the national-level typhoon operational numerical prediction model. This significantly improved the performance and forecast accuracy of the track and intensity of the typhoon operational numerical prediction model and precipitation forecast by 5% and 3%~5%, respectively. Here, the progress of the program is summarized and associated scientific issues are discussed. The typhoon multi-platform observation system and collaborative observation scheme constructed by the project will lay the foundation for the construction of operational direct typhoon observation in offshore areas of China and is expected to realize the progress from the current “follow-up” to “parallel” and partial “lead.”
We investigated the development of soil aggregates on temporal and spatial scales. By analyzing the time of publication， countries and regions of publication， and keywords， we can grasp the research direction， hotspots， and trends of soil aggregates. In the last decade， the main research directions in soil aggregates have focused on the mechanisms of soil organic carbon on the stability of soil aggregates in the context of climate change and the role of soil aggregates in mitigating soil erosion， wind erosion， and heavy metal pollution. Hot topics in research on soil aggregates are the mechanisms by which different land management regimes or land use practices affect the stability of soil aggregates and the role of soil aggregates in the carbon cycle. Meanwhile， research on soil aggregates has been highly concentrated at low and middle latitudes and altitudes， with insufficient attention being paid to high latitudes and altitudes. Future research on soil aggregates must be conducted in the context of climate change. First， we studied the mechanism of interaction between soil aggregates and soil organic carbon to give full play to the carbon sequestration potential of soil aggregates. Second， its relationship with soil moisture was studied and its impact on the water cycle at different scales was explored. Third， we conducted further deep and extensive research at high latitudes and altitudes.
Compound-specific D/H ratios of lipid biomarkers contain valuable environmental information. The δD values of biomarkers represented by long-chain alkenones， dinosterols， and fatty acids have been increasingly applied to reconstruct paleo-Sea-Surface Salinity （SSS）. However， studies over the past two decades have shown that the δD of marine algae biomarkers is sensitive to many factors， such as salinity， species， temperature， and light intensity. Here， we focused on the impact of SSS on the δD of marine algae lipids and summarized the relationships between lipid δD and salinity from culture experiments and field studies. Then， based on the successful reconstruction of paleo-salinity with lipid δD， we put forward the problems that need to be addressed when applying it as a paleo-SSS proxy. It is hoped tha t this study will help us better understand the application potential of lipid δD and provide more accurate and detailed information for δD research.
A systematic analysis of runoff changes in the Yellow River is important for ecological protection and the maintenance of high-quality standards within the Yellow River basin. Based on the measured runoff data at 11 hydrological stations and meteorological data from 19 meteorological stations from 1956 to 2020 above the Lanzhou hydrological station， including the Daxia， Tao， Huangshui， and Datong Rivers， linear regression and Mann-Kendall tests were used to analyze the variability of runoff series and the influence of driving factors on runoff change. The results showed that the runoff changes at representative hydrological stations in the study area increased and decreased from 1956 to 2020. The source region and northwest rivers showed slight increases in runoff， whereas the southeast rivers showed a decrease. Overall， the non-source rivers showed a decreasing trend. There was an abrupt runoff change at each station around 1990， with the runoff in the 1990s exhibiting the lowest values. A gradual increase was then observed， with the runoff reaching or exceeding the previous maximum value around the year 2020. Contrary to the trend of annual runoff， the winter runoff at all stations in the study area showed increases， except for the Daxia River， which was mostly influenced by anthropogenic activities. Changes in precipitation and snowmelt water were the main causes of runoff change in the source region， whereas the increase in regional water use and water consumption resulted in a decrease in runoff in non-source areas. Snow cover played a key role in increasing runoff after 2010 and alleviating drought in the 1990s， while permafrost degradation was the main reason for the change in the annual runoff processes slowing down throughout the year， except in winter.
Clarifying the occurrence, form, content, and distribution of water in shale is conducive to further understanding the internal relationship between “oil (gas)-water-rock”. This line of research has implications in guiding the generation, storage, migration, exploration, and development of shale oil and gas. Considering that the current classification of different waters in shale is complex and inconsistent, a classification approach based on the occurrence state of water is proposed combined with existing classification methods. Specifically, it categorizes water into free-state movable water, volume-filled capillary-bound water, surface-adsorbed bound water film, and structured water of ionic state. Irreducible water is the “competitor” of the storage space and an “obstacle” in the transportation channel for oil (gas). The bound water film occupies the effective adsorption sites of shale oil and gas, and the capillary-bound water blocks small pores and throats. Simultaneously, the occurrence state of water changes with changes in the minerals and organic matter, thus affecting the wettability of the reservoir and the exploration and development of shale oil and gas. In addition, the influence of minerals, organic matter, and pore characteristics on the occurrence-related mechanisms of water in shale were discussed, and thermal analysis and nuclear magnetic resonance detection methods were applied to understand the content, location, and microscopic distribution characteristics of different occurrences of water. This was done to provide a theoretical basis for the efficient development of shale oil and gas.
Kalimantan Island is located in central Southeast Asia. Since the Cenozoic， the most significant tectonic feature of Kalimantan Island has been that it experienced counter-clockwise rotation as a result of plate tectonic movement in Southeast Asia. This study focuses on the regional tectonic-sedimentary response characteristics of large-scale tectonic events in Southeast Asia during the Miocene. Based on a systematic review of the characteristics of the Miocene delta sedimentary system in the Kutei Basin （Southeast Kalimantan Island）， and the analysis of the characteristics of the Miocene semi-deep bathyal slope and basin floor sedimentary system in the East Java Basin （South Kalimantan Island）， this paper comprehensively discusses the characteristics and sedimentary response to the Miocene regional tectonic inversion in the southern margin of Kalimantan Island. Approximately 15 Ma during the Middle Miocene， a large-scale Mahakan progressive delta depositional system was formed. According to the drilling and seismic data constraints， the initial development time of the Miocene semi-deep bathyal slope and basin-floor sedimentary system in the East Java Basin is approximately 16-15 Ma. The initial development times of the two sedimentary systems were similar. The paper holds that the large-scale tectonic inversion events during the Middle Miocene in Southeast Asia are the main controlling factors for the development of the two sedimentary systems in the southern margin of Kalimantan Island. In the same period， the open deep-water environment of the Kutei Basin and the East-West narrow extended semi-deep bathyal environment of the East Java Basin created sufficient space for the development of a large-scale progradational delta sedimentary system in the Kutei Basin and semi-deep bathyal turbidite in the East Java Basin.
Rock materials in an orogen are usually large-scale denuded and transferred to their surrounding basins during the post-collisional stage. Therefore, studies on sedimentary rocks in these basins are helpful for better understanding the evolutionary history of the orogen. The Hefei Basin, located north of the Dabie Orogen, was filled with clastic materials from the orogen, recording key information on its uplift and denudation history. In this study, sandstones of the Lower Cretaceous Zhuxiang Formation and siltstones of the Paleogene Dingyuan Formation in the central Hefei Basin were selected for detailed detrital zircon LA-ICP-MS U-Pb dating. The detrital zircon age frequencies in the Zhuxiang Formation show Triassic and middle Neoproterozoic age clusters, whereas the Dingyuan Formation has a predominant middle Neoproterozoic age cluster, with secondary age clusters in the Paleoproterozoic and the Archean. All the samples lacked or contained few Early Cretaceous zircon ages. Combined with the results of previous studies, it can be concluded that the provenance of the Zhuxiang Formation is mainly the Dabie Orogen and that its formation age corresponds to the late stage of the Fenghuangtai Formation in the southern Hefei Basin. Different detrital zircon age frequencies in different samples correspond to the process in which the high-pressure and ultrahigh-pressure rocks were gradually denuded in the Dabie Orogen during the Early Cretaceous. In the Paleogene, the Hefei Basin was surrounded by a series of uplifts, which greatly reduced the diversity of clastic material sources of the Paleogene Dingyuan Formation. Because the detrital zircon age frequencies of the Dingyuan Formation are consistent with those of the Sinian strata in the South China Block, it can be inferred that the source materials of the Dingyuan Formation mainly come from the Sinian of the Zhangbaling Uplift. The provenance of sedimentary rocks in the Hefei Basin changed from the Dabie Orogen to the Zhangbaling Uplift at the end of the Late Cretaceous or the beginning of the Paleogene.
Silicon is the second most abundant element in the earth’s crust and plays an important role in soil formation, growth, and evolution of terrestrial higher plants, aquatic phytoplankton, and the carbon cycle. Studying the silicon biogeochemical cycle has become increasingly important under current accelerated climate change. In recent years, studies on the silicon cycle in terrestrial and oceanic systems have been relatively thorough, whereas those in atmospheric systems are lacking. Aerosols are important carriers of active components and geochemical cycles of elements in the atmosphere. To date, the compositions and sources of silicon in aerosols and the importance of silicon sedimentation load in some regions are not well understood. This restricts our understanding of the silicon cycle in the surface earth system. Based on the current research, this study summarizes the compositions of aerosol silicon and its coupling with other elements, reviews the application of emerging silicon isotopes in atmospheric particulate matter tracing, and discusses the ecological effects of long-distance transportation of silicon in coastal areas and the impacts of silicon nanoparticles on human health. Generally, silicon exists in aerosols mainly in the form of inorganic silicon, and the deposition of aerosol silicon in some offshore waters has a controlling effect on phytoplankton growth. Further research should focus on the generation and transformation mechanisms of aerosol silicon, silicon deposition, its influence on key processes of biogeochemical cycles, and the toxicological effects of silicon nanoparticles.
The North Irian Basin is located at the convergence and compression edges of the Australian and Pacific plates. Since the Late Cretaceous， the Australian Plate has been moving northward， and collision with the Pacific Plate has occurred several times， forming a complex area of tectonic activity. This provides a foundation for the formation of extensive landslides on the seafloor in the northern margin of the basin. By analyzing the high precision 2D seismic data in the north of the basin， the characteristics of submarine landslides are described in detail. Three structural units of a submarine landslide， namely the headwall domain， translation domain， and toe domain， are identified， which have their typical seismic characteristics. Submarine landslides are widespread in this area and can be divided into four types： continental slope/shelf， channel wall， valley， and Mass Transport Deposits （MTDs）. Combined with the regional geological background of the basin， it is considered that the tectonic movement of subduction and collision between plates plays a major role in controlling submarine landslides， which is induced by the combined action of external factors such as the submarine terrain slope as the internal cause， the sediment supply rate， sea-level change， and seismic activity.
Recently， the proportion of deep-water incremental reserves has increased gradually each year. This proportion has exceeded 50% since 2010. Deepwater environments have become a key area of future oil and gas exploration. As one of the main reservoirs for deep-water oil and gas exploration， deep-water channels have attracted increasingly more attention. Based on high-resolution （40 Hz） 3D seismic data， this study carried out a detailed description of an aggradational channel-levee complex in the study area. The centerlines of the different channels in the complex were recognized from bottom to top. The overall width of this channel-levee complex is 25~30 km. The width of the single-channel is about 300 m， and the thickness is estimated to be 12 m. The channel morphology of this complex shows an organized evolution. The channel was relatively straight with low curvature at the beginning of aggradation， and the curvature gradually increases over time. During aggradation， the deep-water channels not only swing but also sweep downstream. Predecessors believed that downstream sweep is very rare in deep-water channels； however， our research shows that this phenomenon may be common under some special conditions.
Because of the development of nanotechnology in recent years， various novel functional nanomaterials have been used in the remediation of water pollution. As the most studied two-dimensional transition metal dichalcogenide nanomaterial， molybdenum disulfide （MoS2） has unique structures and excellent physicochemical properties， leading to promising environmental capabilities in the field of water-environment remediation. MoS2 and MoS2-based nanocomposites are characterized by a large specific surface area， multiple active sites and strong photocatalytic activity， which can effectively remove heavy metal ions （e.g.， Co2+， Cd2+， Cu2+， Pb2+， Hg+， and Cr3+） and organic pollutants （e.g.， oils， organic dyes， and antibiotics） in a water environment through adsorption， redox and photocatalytic degradation. They have become a hot topic in water pollution remediation research. In this review， the effects of morphology， surface modification， phase， and surface defects of MoS2 on the removal performance of water pollutants are described. In addition， various synthesis methods and structural characteristics of MoS2 and MoS2-based binary and ternary nanocomposites are summarized. The adsorption， catalytic， and redox mechanisms of MoS2 and MoS2-based nanocomposites for the removal of heavy metals and organic pollutants， as well as the main influencing factors and mechanisms， are discussed. In addition， the environmental risk assessment of MoS2 and its oxidation products and the methods for recycling MoS2 and its nanocomposites are reviewed. Finally， the research direction and application potential of MoS2 and MoS2-based nanocomposites are discussed， which lays a theoretical foundation for the further study of MoS2 in water-environment remediation. Further research should focus on a more facile and low-cost method for the synthesis of MoS2 nanocomposites with good stability， high-efficiency performance and good environmental sustainability. Meanwhile， the long-term environmental transformations， as well as the impact of MoS2 and MoS2-based nanocomposites on the ecological system and human health， must be thoroughly investigated before large-scale industrial applications in water-environment remediation.
Using the daily precipitation data of 2 510 meteorological stations in China from 1961 to 2019 and the precipitation simulation data of 12 coupling models of CMIP6 from 2030 to 2100 under the SSP2-4.5 future scenario， the values of three annual rainstorm elements （annual rainstorm days， annual rainstorm rainfall， and annual rainstorm intensity） in the historical and future scenarios were calculated based on the kernel density function under four return periods （5，10，20，50 years）. Based on this， the future hazard change of rainstorms in China was assessed. The main conclusions are as follows：
From a national perspective， the number of rainstorm days and rainfall amount are estimated to increase in the future， and the annual rainstorm intensity is estimated to change differently in different return periods. Under the four return periods， the mean change of annual rainstorm days in China is expected to be 0.36， 0.57， 0.73 and 0.92 days； the mean change of annual rainstorm rainfall is expected to be 22.30， 36.24， 46.92 and 60.12 mm； and the mean change of annual rainstorm intensity is expected to be 2.43， 0.27， -1.95 and -4.86 mm/d.
From the perspective of different climatic zones， the annual rainstorm rainfall and rainstorm days showed an increasing trend in the Qinghai-Tibet Plateau， Eastern arid zone， Northeast China， North China， and Southwest China， and a decreasing trend in the western arid （semi-arid） zone， Central China， and South China. The annual rainstorm intensity is expected to increase in the Qinghai-Tibet Plateau and decrease in most other regions under the four return periods.
The hot spot analysis shows that the southeastern and southern Qinghai-Tibet Plateau are expected to be the areas with the most significant increases in rainstorm hazards. The areas with reduced annual rainstorm days and annual rainstorm rainfall are expected to be concentrated in the middle of Southwest China， the middle and south of Central China and South China. Finally， the areas with reduced annual rainstorm intensities are expected to be concentrated in the middle of the eastern arid zone， the west of Southwest China， and the north and south of North China.
Precipitation is the main source of surface freshwater. The temporal and spatial heterogeneity of precipitation distribution brings great uncertainty to the study of the surface water cycle. The study of spatial heterogeneity and the factors influencing precipitation has always been the focus of water cycle research. To explore the relationship between the spatial distribution of precipitation and terrain factors， 351 precipitation observation stations in eastern China with abundant observational data were used according to the Ordinary Least Squares regression （OLS）， Geographically Weighted Regression model （GWR）， and Multi-scale Geographically Weighted Regression model （MGWR）. The results show that OLS cannot show the influence of terrain factors on the spatial heterogeneity of precipitation distribution， while GWR and MGWR achieved a better goodness of fit and stronger interpretability （Goodness of fit R2>0.7）. Furthermore， the MGWR can reflect the scale effects of terrain factors on the spatial distribution of precipitation based on bandwidths， and local influencing factors with smaller bandwidths have a stronger influence on the spatial heterogeneity of precipitation. For the annual average precipitation， the terrain elevation and terrain relief are the main terrain factors that affect the spatial heterogeneity of precipitation， while the terrain slope and Prevailing Wind-direction Effect Index （PWEI） have no significant impact on precipitation. However， seasonally， the influence of different terrain factors on the spatial distribution of precipitation is different. Specifically， in summer， terrain elevation is more important than other factors； in spring and autumn， the distance from the coast plays an important role in the mountain regions， and in winter local influencing factors such as terrain relief mainly affect the spatial distribution of precipitation. Clarifying the relationship between precipitation and terrain factors can help us understand the contribution of complex terrain factors （in all seasons） to precipitation and provide support for model simulation and improvement in regions with a complex topography.
Anthropogenic heat flux is an important term of urban energy budget. Estimation of the anthropogenic heat flux is critical for the study of urban climate and heat island effect. Therefore, the anthropogenic heat flux of Hefei from 2013 to 2020 was estimated based on the energy balance equation method using Landsat 8 satellite data and ERA5 reanalysis data. Land surface characteristic parameters and each component of the energy balance equation was quantitatively validated against in-situ measurements, then the spatiotemporal distribution of anthropogenic heat flux was analyzed. The results showed that:
The retrieval algorithm of surface temperature and the estimation scheme of downwelling long-wave radiation suitable for urban are established. The root mean square errors of surface temperature and downwelling long-wave radiation are 2.33 K and 9.26 W/m2, respectively.
The estimated net radiation flux, sensible heat flux, latent heat flux and anthropogenic heat flux are in good agreement with the in-situ observations, and the root mean square errors are 82.00 W/m2, 69.51 W/m2, 55.19 W/m2 and 75.47 W/m2, respectively.
The spatial distribution of anthropogenic heat flux is relatively concentrated, and anthropogenic heat flux in urban areas is much higher than that over the natural underlying surface; the industrial area in the main urban area is the largest anthropogenic heat flux emission area throughout the year; the anthropogenic heat flux has distinct seasonal variation, with the largest in summer, the second in spring and the smallest in autumn and winter; there are obvious differences in anthropogenic heat flux on different surface cover types, the urban area is the largest, followed by farmland, and the forest and water body are small, the seasonal average of the urban area in spring, summer, autumn and winter are as follows: 280 W/m2, 321 W/m2, 203 W/m2 and 131 W/m2, respectively. The research results have important scientific significance and application value for evaluating the energy emissions, development status, layout planning and urban regional climate of large and medium-sized cities.
Talus slopes are widely developed hillslope landforms accumulated by debris at the foot of escarpments. As the key area for understanding the alpine sediment cascade in basin-mountain systems, talus slopes contain abundant information on regional rock weathering rates and climate change. Based on geomorphological research of talus slopes in alpine periglacial areas worldwide, we summarized the developmental environment, geomorphic types, morphological characteristics, and sedimentary structures and rates. The key to understanding the geomorphological evolution of talus slopes lies in accurately judging their morphological characteristics and sedimentary processes. The deposition rate of talus slopes obtained by measuring key factors such as its thickness and volume using advanced technology allows to ascertain the weathering rate of regional alpine escarpments and deduce the evidence of regional paleoclimate changes. Future research on talus slopes in the dry denudated mountains in China needs to be conducted systematically and thoroughly with modern technology in terms of their type and distribution, sedimentary structure and evolution, and chronology to provide key evidence for determining the temporal and spatial variation characteristics of regional mountain weathering rates and paleoclimate changes in Asia.
The Tibetan Plateau, known as the “Asian Water Tower”, is the source of many major rivers in Asia. Its energy and water cycle processes have important impacts on regional and global climate change. Understanding the water vapor transport process and the contribution of water vapor sources is crucial for clarifying the water vapor budget of the plateau. In this study, we analyze the advantages and disadvantages of the research methods used to study the transport and sources of water vapor on the Tibetan Plateau. The classical Euler method was used to study the qualitative features of water vapor transport by calculating the water vapor flux. In addition, Lagrangian trajectory models are essential tools for studying the quantitative characteristics of water vapor transport by simulating the trajectories of humid air parcels. Eulerian tracer methods can be run in parallel with climate models or a posteriori with reanalysis data to track the water vapor transport process. Physical water vapor tracers are powerful tools for studying the water vapor sources of precipitation by measuring stable water isotopes. This study primarily focused on reviewing relevant research on water vapor transport and sources over the Tibetan Plateau and adjacent areas. Based on these studies, the main water vapor channels and characteristics of water vapor transport over the Tibetan Plateau were summarized. The review concluded with a summary of the challenges of current research and a forecast of future research directions.
The entire flood process consists of multiple characteristic variables， including the flood peak and flood volume， for different durations. There is a positive correlation between these variables， and multivariate joint analysis should be performed for flood frequency analysis. However， the multi-dimensional joint distribution has greater sampling uncertainty with increasing variables using limited measurable samples. This could improve the accuracy of the marginal distribution of each characteristic variable and the correlation parameters of the Copula function using historical flood information that predated the period of systematic gauging for extending observation records in the multi-dimensional joint frequency analysis. Based on the hierarchical Archimedean Copulas function， a multi-dimensional joint flood frequency analysis hierarchical model， considering the uncertainty of historical flood events， was constructed and decomposed into several cascaded multi-level forms of two-dimensional Copula functions. Combined with the maximum likelihood method， the parameters of the nested multi-level Copula function and the marginal distribution of the characteristic variables are effectively estimated using a genetic algorithm. The Yichang hydrological station， located in the main stream of the Yangtze River， was selected as a case study， including systematic gauge records and historical flood data. The results show that it can completely describe the entire flood process and consider the correlation between the characteristic variables of the flood process with the multi-dimensional joint flood frequency analysis hierarchical model. This could improve the representativeness of the values of the marginal distribution parameters. Meanwhile， it could effectively use historical floods and improve the representativeness of the samples， and the correlation parameters of the Copula function were more consistent with the correlation between the measured data.