Sea-Level Rise (SLR) directly changes the hydrology and salinity of estuarine tidal wetlands and is one of the primary drivers of global change that significantly impacts ecosystem processes. Herein, various methodologies and experimental facilities (marsh organs, weirs, and flow-through mesocosms) for manipulating SLR are systematically reviewed. This study provides a comprehensive summary of the effects and mechanisms associated with SLR regarding the fluxes and production rates of CH4 and CO2, and the pathways and rates of soil organic carbon mineralization from the perspectives of SLR-saltwater intrusion and inundation increase. Saltwater intrusion due to SLR notably decreases CH4 production rates and fluxes. It induces a shift in the pathways of soil organic carbon mineralization, transitioning from CH4 production to microbial SO
The global Ocean General Circulation Model (OGCM) is a critical component of Earth system modeling and plays an essential role in climate projections and marine environmental forecasting. Herein, the history of global OGCM models is systematically reviewed and significant scientific and recent technological advancements are summarized. This review covers three topics involving the core technology of OGCMs: the dynamical core, physics or physical parameterization, and soft-hardware configuration. In the dynamic core, the latest developments in horizontal discretization methods, vertical coordinate schemes, and multi-resolution strategies are explored. Regarding physics, the focus has been on the progress of mesoscale, sub-mesoscale, and boundary-layer mixing parameterizations. In the soft-hardware configuration section, the current status and prospects for the application of heterogeneous computing architectures and artificial intelligence technology in global OGCMs are discussed. The advancement of the LASG/IAP Climate System Ocean Model, a fully autonomous Chinese global OGCM, is also highlighted. Based on key trends and novel ideas in the field of global OGCMs, suggestions are provided for Chinese researchers and relevant policymakers to comprehensively advance R&D strategies and long-term planning for fully autonomous global OGCMs.
Tree-ring latewood maximum density is a well-known proxy for temperature during and at the end of the growing season. Utilizing the DENDRO2003 tree ring density analysis system, density data were obtained from tree increment cores of Picea brachytyla var. complanata, collected from northwestern Yunnan Province. Each tree-ring latewood maximum density series was fitted with a 67-year cubic smoothing spline to remove non-climatic trends, and the latewood maximum density chronology was developed using the ARSTAN program spanning 1253-2017 AD for our study area. Correlation analyses were conducted between the latewood maximum density chronology and climatic elements recorded at Deqin meteorological station. The results indicated that the strongest correlation (r = 0.495, p <0.01) was found between the average September-October maximum temperature and the latewood maximum density chronology, and a stronger correlation (r = 0.763, p <0.01) was found for the first-difference data of the same variables. Furthermore, the results of a 31-year moving correlation analysis indicated that the correlation between maximum density chronology and average September-October maximum temperatures weakened during 1955-2017, whereas it exhibited a stronger correlation and further increased after the first difference during the same period. These results suggest that it would be better if the tree-ring latewood maximum density served as a proxy for inter-annual temperature variation. However, such a conclusion requires further validation for the northwestern Yunnan Province.
Pyrite, a significant heavy mineral in shale, aids in the comprehension of shale depositional environments. Referencing the Wufeng-Long1 subsection Formation of the Luzhou Block in Sichuan Basin, a network model for pyrite SEM image segmentation was established via core mineral experiments, SEM observations, network model refinement, and feature parameter analysis. The model assesses the sedimentary environment of the study block using pyrite framboid parameters.
Coprophilous fungal spores, “Non-Pollen Palynomorph” parts of pollen analysis, are mainly used to reconstruct past changes in the population sizes of herbivores and intensity of pastoral activities. By systematically summarizing research examples of modern processes and paleoecological applications of coprophilous fungal spores at home and abroad, this study identified that foreign research has focused on the diversity, influencing factors, and dissemination, transportation, and deposition processes of coprophilous fungal spores. Sporormiella-type, Sordaria spp., and Podospora sp. have emerged as reliable indicators of herbivore activity; in particular Sporormiella-type coprophilous fungal spores have found widespread applications in different study areas. A strong correlation between coprophilous fungal spores and grazing activity has been found in the northeastern Qinghai-Tibetan Plateau. International paleoecological studies have demonstrated that Sporormiella-type fungal spores effectively indicate the extinction of large herbivores and fluctuations in grazing intensity. Domestic studies have identified the suppression of human hunting activities by herbivores during the Early and Middle Holocene. Key transitional periods were identified, such as the beginning of grazing activity about 5.6 ka, an increase after approximately 4.0 ka, and a significant increase during the historical period. In future research, it will be necessary to enhance the modern processes of coprophilous fungal spores investigation to understand the production, transmission, deposition, and preservation of coprophilous fungal spores and the mechanisms involved. Additionally, to explore the relationship between coprophilous fungal spores and herbivore population sizes, vegetation status, sedimentary environment, and transport dynamics to provide valuable information for the accurate interpretation of fossil coprophilous fungal spore records of natural sedimentary strata by combining multiple indicators and employing interdisciplinary evidence. Therefore, further research regarding the modern processes and applications of coprophilous fungal spores is of great significance in understanding the histories of past human activities and their interactions with environmental changes.
Global lake systems have been facing ubiquitous aquatic environmental challenges since 1950. The baseline and changing history of lake aquatic environments can be reconstructed by quantitative transfer functions, which aids in the assessment of the degree of human impact on lake ecosystems and in setting practical targets for ecological restoration. The basic processes of developing and applying quantitative transfer functions are first introduced. Then, typical case studies from various lake catchments are comprehensively summarized to elaborate on the application of quantitative transfer functions based on sedimentary subfossils to reconstruct lake aquatic environmental parameters. These parameters include water pH, total phosphorus, dissolved oxygen, transparency, water level, salinity, and temperature. The rate and magnitude of deviation from natural baselines due to anthropogenic disturbances, changing trajectories, and underlying mechanisms in typical lake environments in the Anthropocene were examined from multiple perspectives. Finally, constraints and prospects for lake transfer functions are discussed from the following aspects: developing new indicators and a multi-proxy approach, improving training sets with larger sample sizes and machine learning, improving modern ecological studies of biological indicators, and combining transfer functions with ecosystem modeling to further improve the quality of transfer functions and enlarge application fields to provide scientific references and guidance for future research.
There exist three sets of quality shale that developed in the Dalong, Wujiangping, and Maokou Formations during the mid-upper Permian, which are important replacements for marine shale gas exploration or the Wufeng Formation-Longmaxi Formation. Based on the relationships between important geological events built on an isochronous stratigraphic framework, sedimentary structures, paleoenvironments, and ancient living organisms, the influence of major geological events, such as middle-late Permian upwelling and volcanic activity, on the development of organic-rich shale in northeastern Sichuan was studied.
The Miocene SQ21.0 sequence of the Zhujiang Formation in the Baiyun Depression, Pearl River Mouth Basin, developed large-scale deep-water fan sandstone stratigraphic reservoirs related to a mixed-source deep-water canyon system. Based on the 3-dimensional high-resolution sequence stratigraphy method constrained by drilling data, this study details the morphology, filling evolution, and main controlling factors of a mixed-source deep-water canyon system of clastic and carbonate rocks in the SQ21.0 sequence during the Miocene in the Baiyun Depression, Pearl River Mouth Basin. Our findings show that the mixed-source canyon system extends >150 km from the continental shelf break to the southern slope and is distributed in a SN direction in the eastern area of the Baiyun Depression, which presents a characteristic three-segment pattern, such as the head of the upper slope canyon system, Baiyun East Depression on the middle slope, and Yunli Low Uplift Liwan Depression on the lower slope. The profile topology has evolved from a V-shaped upper slope to a U-W-shaped middle and lower slope, and in the plane, it has evolved from multiple divergent canyons into a large canyon system. The development and distribution of the mixed-source canyon system of the Zhujiang Formation were controlled by the evolution of the dual source of the Paleo-Pearl River Delta-Dongsha Uplift platform, relative sea-level changes, shelf breaks, and restricted slope landforms. During the early forced regression of relative sea-level decline, a sand-rich canyon channel system supplied by the coastline system of the Paleo-Pearl River Delta and Dongsha Uplift developed, with significant erosion to the shelf-break-outer shelf and restricted slope change areas. Conversely, during transgression to the highstand period of relative sea level rise, with the retreat of the Paleo-Pearl River Delta source and rapid growth of reefs on the Dongsha Uplift platform, a large-scale canyon channel system supplied by argillaceous/carbonate detritus developed, with intense incision erosion occurring in the upper-middle section of the strongly restricted steep slope filled with relatively rich mud or lime debris. Canyon channel systems were filled with mud or lime debris, with a near-NS-oriented distribution, cutting across the nose-shaped structural belts and underlying early deep-water sand fan bodies in the near EW direction, forming large-scale stratigraphic trap groups which serve as key breakthrough areas for the recent exploration of stratigraphic traps in Baiyun deep-water areas.