Coastal China Research Articles

The Impact of China's Coast Guard on Indo‐Pacific Security from the Perspective of a Maritime Power

In 2024, the China Coast Guard (CCG) invoked China Coast Guard Regulation No. 3 to detain Taiwanese fishing boats twice in disputed waters. The positive actions of the CCG can be looked back to 2019. The CCG entered the waters of the Diaoyu islands in Japan twelve times and carried out cruises on the Diaoyu islands. It is necessary to study the follow-up actions of the CCG and their impact on Indo-Pacific security. This study examines the effect of the CCG's maritime rights protection on the security of the Indo-Pacific region when the People's Republic of China (China) becomes a maritime power. It was changed to the Maritime Police Corps of the Chinese People's Armed Police Force to integrate the business of marine surveillance, fishery administration, customs, border defense, and other units. The reason for the gradual expansion of powers and the impact of its strong protection of maritime rights and interests on neighboring countries. The research results can help us understand the current situation of the CCG and further evaluate China's ability to achieve maritime power. This paper finds that China intends to implement regular patrols in disputed waters by increasing the tonnage of coast guard ships, strengthening rights protection, and militarizing organizations to demonstrate maritime power. On the other hand, this move triggered a maritime police competition among neighboring countries, and even a naval and air force arms race, intensified disputes between China and neighboring countries, especially the East China Sea and South China Sea issues, and made the security of the Indo-Pacific region more turbulent and complicated.

Hydrodynamic mechanisms of topographic evolution in straight sandy beach: a case study of Wanpingkou beach, China

Stricter controls on destructive human activities in recent years have improved the protection and management of sandy coasts in China. Marine-driven geomorphic changes have become the predominant process influencing future beach evolution. However, in the complex geomorphic conditions of mixed artificial and natural coastlines, the mechanisms and contributions of various marine-driven factors to beach changes remain unclear. Using methods of field observations and numerical simulations by FVCOM model, this study reveals the sedimentary dynamic mechanism of straight sandy beach in the southern Shandong Peninsula (Wanpingkou beach, WPK beach). From 2005 to 2016, the northern section of WPK Beach eroded at a rate of approximately 2-3 m/year, the middle section at about 0.5-1.5 m/year, and the southern section accrued at an average rate of about 1-2 m/year, demonstrating an overall pattern of “northern erosion and southern accretion.” During winter, the average grain size of beach sediments is about 0.5 mm with minimal variations, indicating an onshore transport trend; in summer, the average grain size is about 0.7 mm with larger variations, indicating an offshore transport trend. Offshore sediment transport correlates mainly with seasonal changes in wind direction, while alongshore sediment transport is influenced by tidal currents, wind-induced currents, and wave-induced currents. Wave-induced currents are the primary force in alongshore sediment transport with a velocity of 0.1-0.3 m/s toward southwest. Followed by tidal currents with a velocity of 0.05-0.1 m/s, and wind-induced currents with a velocity of 0-0.1 m/s, which have a relatively minor impact. Therefore, seasonal changes in beach morphology are primarily controlled by waves, while interannual variations is mainly influenced by a combination of wave-induced currents and tidal currents. With increasing efforts in beach maintenance and coastal ecological restoration in recent years, understanding the sedimentary dynamics of beaches remains of vital theoretical and practical value.

An Overview of Tidal Power in China

Abstract. Tidal energy is a renewable, clean and non-polluting renewable energy source with huge reserves, which is of great significance to alleviate the energy tension in coastal areas. The eastern coast of China is dotted with many economically developed cities such as Shanghai, Shenzhen, Hong Kong, etc. The energy consumption of these cities is very high and growing at a very high rate year by year. Although China has constructed the "West-East Electricity Transmission" project to alleviate the problem of electricity tension in the eastern coastal cities, it cannot fundamentally reduce the dependence on traditional fossil energy. Therefore, on the basis of extensive data collation, this paper further explores the possibility of utilizing tidal energy for power generation in China by studying China's tidal energy reserves, and analyzes the difficulties in developing tidal energy in China as well as puts forward suggestions for the future development of tidal energy.

Genomics-Informed Range Predictions Under Global Warming Reveal Reduced Adaptive Diversity Whilst Buffering Range Shifts for a Marine Snail.

Understanding the genetic basis of local adaptation in thermal performance is useful for predicting species distribution shifts under anthropogenic climate change. Many species are distributed across multiple biogeographic regions, and the uniquely adapted populations in each region may respond to future ocean warming with distinct distribution changes. In the present study, we investigated phylogeographic patterns, thermal sensitivity, and genetic differentiation in the intertidal snail Littorina brevicula along China's coast. Whole-genome sequencing results based on a newly assembled chromosome-level genome revealed two genetic lineages, with a north-south divergence that is linked to the thermal environment. Within each lineage, individuals could be further subdivided into genetic subgroups that differ at key genomic loci underpinning differences in upper heat tolerance. Heat stress drives adaptive divergence across multiple levels of organization, from the individual to the biogeographic level. Taking into account genetic diversity associated with variation in heat tolerance, a physiological species distribution model (pSDM) was applied to predict the distributions of the different genetic subgroups in response to climate change. Both northern and southern lineages were predicted to experience declines in habitat suitability under a 4°C future warming scenario, and that a genotypic subset of snails from the southern lineage may even be driven to extinction. These findings illustrate that even when a species' range is maintained, it can nonetheless experience a significant decrease in adaptive diversity as a result of climate change. The integrated approach presented here, which considered both physiological and adaptive genetic variation at the level of individuals within a biogeographical context, provided new insights into how marine species can respond to global warming.

Crustal silica content of East China: A seismological perspective and its significance

East China has experienced multiple periods of tectonic movements, which have contributed to the composition and rheological properties of its present crust. Estimating the composition of the crust is crucial for understanding the tectonic processes. Based on the teleseismic receiver functions with data from the National Seismic Network of China, we applied the H-κ-c method to obtain the crustal bulk VP/VS ratio and to constrain the SiO2 content in the crust. We estimated the SiO2 content to range from 50.89 wt% to 73.51 wt%, with an average value of 65.87 wt%, indicating a predominant felsic composition of the East China's crust. Our study suggests that the North-South Gravity Lineament (NSGL) is an approximate delimitator of the felsic and mafic crust in East China, hinting at a widespread deficiency of mafic lower crust in the east of the NSGL. The mafic crust is extensively distributed in the Taihang orogenic region (TSR) and WuLingshan gravity gradient belts (WLG), particularly in the Datong volcanic area, which manifests the mantle materials intraplating. The scatteredly distributed mafic crust at the east of the NSGL is mainly concentrated in the southeast coast of China and in the intersection region of the Tanlu Fault (TLF) and Sulu region. In Sulu region, the TLF may primarily provide a channel for the thermal intrusion from the underlying mantle lithosphere, which has increased the mafic content. The Pacific/Philippine Sea plate subduction has triggered a significant amount of crust-mantle material exchange below southeast China that resulted in a high degree of mafic crustal composition.

Multiple Genotypes and Reassortants of Severe Fever With Thrombocytopenia Syndrome Virus Co-Circulating in Hangzhou in Southeastern China, 2013-2023.

Severe fever with thrombocytopenia syndrome (SFTS), a tick-borne infectious disease caused by the SFTS virus (SFTSV), is becoming a significant public health threat due to its high mortality rate. Knowledge of SFTSV in southeastern coastal China is limited. The whole genomes of 66 SFTSV strains collected from 2013 to 2023 in Hangzhou, a coastal city in China, were amplified and sequenced to elucidate the geography-related genetic and pathogenic diversity. Hangzhou SFTSVs could be classified into five pure genotype groups (A, B-2, D, E, and F); genotype A was dominant, and genotype E was significantly associated with SFTS fatality. An unclassified sublineage of the L segment was proposed as a novel B-4 subgenotype. Seven types of genetic reassortants (abbreviated as B-3B-3B-1, CCA, B-2AB-2, B-2CB-2, DFD, B-4FF, and B-4B-2B-1 for the L, M, and S segments) were identified, including three novel forms. Six recombination events and ten amino acid substitutions were identified in the Hangzhou viruses. Collectively, our results demonstrated that all known SFTSV genotypes co-circulated in Hangzhou, leading to a gradual increase in genetic diversity and the generation of novel reassortants. Increased surveillance is urgently needed in Hangzhou, a critical region for SFTSV genetic exchange.

Genome-Wide Genetic Diversity and Population Structure of Charybdis feriata (Crustacea, Decapoda, and Portunidae) Along the Southeast Coast of China Inferred from Genotyping-by-Sequencing (GBS) Approach

Genome-Wide Genetic Diversity and Population Structure of Charybdis feriata (Crustacea, Decapoda, and Portunidae) Along the Southeast Coast of China Inferred from Genotyping-by-Sequencing (GBS) Approach

The Geopolitics of Water Infrastructure on the Kinmen Islands

ABSTRACT This paper examines the bordering and debordering deployment of water infrastructures on the Islands of Kinmen. Located less than 5 km off the coast of China, yet 200 km from their governing authority, Taiwan, Kinmen holds a critical position in cross-strait relations, and its water infrastructures have carried opposite political intentions. The 2018 Fujian-Kinmen water transfer pipeline serves as a debordering tool as it showcases that the People’s Republic of China could offer benefits to the people on the islands. In contrast, Kinmen’s existing water infrastructure, established during the Cold War, served as part of the bordering campaign to counter Communist China, as it represented progress and modern living under the government of the Republic of China (Taiwan). However, rather than assuming the successful deployment of infrastructure or a passive role of the islands, this paper highlights that the planning and construction of Kinmen’s water infrastructures were influenced by conditions of militarisation, shifting cross-strait relations, the islands’ socio-material constraints and their relationships with Taiwan and China. The case of Kinmen illustrates the capacity of water infrastructure to serve bordering and debordering purposes, as well as how other factors disrupt or facilitate these processes.

Impacts of tropical cyclone–heat wave compound events on surface ozone in eastern China: comparison between the Yangtze River and Pearl River deltas

Abstract. China has implemented some air pollution management measures in recent years, yet severe ozone pollution remains a significant issue. The southeastern coast of China (SECC) is often influenced by hot extremes and tropical cyclones (TCs), and the two can occur simultaneously (TC–HDs). The compound TC–HDs show a rising trend in the summers of 2014–2019, potentially affecting ozone pollution. Here, we found that surface ozone concentrations over the SECC are more elevated during extremely hot days than the summer climatology. However, compared to extremely hot days alone (AHDs), the maximum 8 h average ozone (MDA8 O3) concentration increases by an average of 6.8 µg m−3 in the Pearl River Delta (PRD) and decreases by 13.2 µg m−3 in the Yangtze River Delta (YRD) during the compound TC–HDs. The meteorological conditions during AHDs favor the chemical production of ozone over the SECC, exhibiting increased temperature and solar radiation and decreased relative humidity. Relative to AHDs, strong northeasterly winds prevail in the SECC during TC–HDs, suggesting the potential of ozone cross-regional transport between YRD and PRD. The process analysis in the chemical transport model (GEOS-Chem) suggests that relative to AHDs, the chemical production of ozone is enhanced in YRD during TC–HDs, while horizontal transport alleviates ozone pollution in YRD but worsens it in PRD through cross-regional transport. The results highlight the significant effects of cross-regional transport in modulating ozone pollution in the two megacity clusters during hot extremes accompanied by TC activities, giving insight into future ozone control measures over the SECC under global warming.

Acoustic Target Strength Measurement of Larmichthys crocea Based on the Kirchhoff-Ray Mode Model

Larmichthys crocea (L. crocea) is an economically important fish species mainly distributed off the coast of China. In this study, 11 L. crocea samples of different body lengths were collected from aquaculture cages in the East China Sea to measure the acoustic target strength (TS). Using the Kirchhoff-Ray mode (KRM) model, the directional TS of L. crocea was measured at frequencies of 70 kHz, 120 kHz, and 200 kHz. Furthermore, the relationships between TS and body length were determined using the least squares method and the standard b20 equation. The results showed that the TS of L. crocea varied with tilt angle, frequency, and body length. For tilt angles ranging from (−5°, 15°), the equation for fitting TS and body length using the least squares method were TS = 32.99·log10L − 87.36 (70 kHz), TS = 33.26·log10L − 87.77 (120 kHz), and TS = 39.46·log10L − 95.51 (200 kHz). They were expressed in the standard b20 equation as TS = 20·log10L − 71.16 (70 kHz), TS = 20·log10L − 71.23 (120 kHz), and TS = 20·log10L − 71.24 (200 kHz). For tilt angles ranging from (0°, 10°), the equation for fitting TS and body length using the least squares method is TS = 28.69·log10L − 81.71 (70 kHz), TS = 32.30·log10L − 86.44 (120 kHz), and TS = 45.87·log10L − 103.73 (200 kHz). They were expressed in the standard b20 equation as TS = 20·log10L − 70.88 (70 kHz), TS = 20·log10L − 71.10 (120 kHz), and TS = 20·log10L − 71.48 (200 kHz). Moreover, the 18–300 kHz spectral curve showed a decreasing trend in the frequency range from 18 kHz to 30 kHz, while maintaining relatively stable fluctuations in the other frequency ranges. These findings offer a comprehensive understanding of the scattering characteristics of L. crocea and provide a reliable reference of TS for the fishery acoustic assessment of L. crocea.

Water content drives distinct evolution trajectory of Early Cretaceous granitoids in inland and coastal southeast China

Water plays a crucial role in determining the crystallization sequence of magma, which subsequently influences the chemical compositions of magmatic rocks across different tectonic settings. In this study, we compared the evolutionary features of granitic rocks along the coast and inland areas of southeast China, aiming to identify the key factors influencing their evolution. Our work indicates that multiple granitic intrusions formed between 126 and 142 Ma in the coastal region of southeastern China, which is consistent with the formation ages of large-scale granitoids in the inland Gan-Hang Belt. Isotopic characteristics suggest that the granitic rocks in southern Fujian originated from the melting of juvenile crust, while those in northern Fujian and eastern Zhejiang were formed from the partial melting of ancient crustal rocks, incorporating mafic magma evolved from the mantle. Most of the granitoids from the coastal region of southeastern China exhibit low zircon saturation temperatures (680–800 °C) and Zr/Sr ratios (<1), suggesting their origin from a cold, wet magma reservoir. The porphyritic quartz diorite and porphyritic monzogranite represent the residual cumulate rocks of this hydrous magma reservoir, whereas the granitic porphyry and high-silica equigranular alkali feldspar granite evolved from the felsic melts extracted from the same reservoir. In contrast, most of the Early Cretaceous granitoids in the Gan-Hang Belt, located in the inland areas of southeast China, display high zircon saturation temperatures (800–900 °C) and Zr/Sr ratios (>1), indicating their origin from hot, water-poor magma reservoirs. The porphyritic granites in this region represent residual cumulate rocks formed in water-poor magma reservoirs, whereas the high-silica equigranular granites evolved from hot felsic melts extracted from similar magma reservoirs. In the Early Cretaceous, the coastal region of southeastern China was closer to the Late Mesozoic paleo-Pacific subduction zone, where crystal-melt segregation within cold, wet magma reservoirs predominantly influenced magma evolution. Conversely, the granitoids in the Gan-Hang Belt in the inland region, located farther from the Late Mesozoic paleo-Pacific subduction zone, were associated with a rift tectonic setting and formed through crystal-melt segregation within hot, water-poor magma reservoirs. Our study underscores the critical role of water content in magma reservoirs in shaping the chemical composition of granitic rocks through crystal-melt segregation, thereby deepening our understanding of crustal formation processes across diverse tectonic environments.

Shift from legacy to emerging per- and polyfluoroalkyl substances for watershed management along the coast of China

Per- and polyfluoroalkyl substances and their short-chain alternatives have attracted world-wide attention due to their widespread presence and persistence in the environment. However, the sources, environmental fate, and driving forces of PFAS in coastal ecosystems remain poorly understood. In this study, the spatial distribution, source apportionment, and driving mechanisms of PFAS were investigated through a comprehensive analysis of water samples collected along the China's coastline. The concentrations of Σ25PFAS in water samples followed a general pattern, with higher levels observed in northern coastal zones of China than the south, ranging from 0.72 to 1872.21 ng L−1. PFOA and PFBA were dominant. Emerging short-chain PFAS, such as PFBS, PFBA, F-53B and GenX, were frequently detected, with detection rates of 97%, 99%, 95% and 77%, respectively. This indicated a shift in coastal PFAS contamination from legacy compounds to emerging short-chain alternatives. Source apportionment using the Positive Matrix Factorization model identified key contributors to PFAS pollution, including textile production, volatile precursors, precious metal industries, aqueous film-forming foam, metal-plating, electrochemical fluorination, and fluoropolymer manufacturing. Additionally, PFAS concentrations were significantly positively correlated with cultivated land, urban area, and wastewater discharge, while negatively correlated with annual precipitation and woodland coverage (p < 0.05). Socio-economic development was identified as a major driver of PFAS emissions, while the hydrological factors and vegetation coverage can significantly enhance watershed resilience against PFAS pollution.

Research on regional "dual carbon" targets and path planning based on mathematical modeling methods: a case study of southeast coastal China

Research on regional "dual carbon" targets and path planning based on mathematical modeling methods: a case study of southeast coastal China

Substantial reduction in population exposure to sea level changes along the Chinese mainland coast through emission mitigation

Abstract Rising sea level increases the exposure to flooding and related damage in coastal areas with high population density and substantial economic activity. As global temperatures continue to rise due to climate change, sea levels have been consistently increasing and are projected to continue this upward trend. This study assesses the future exposure at provincial and city levels populations coastal mainland China coast to local sea level changes under five greenhouse gas (GHG) emission scenarios from IPCC-AR6, as well as two low-confidence scenarios accounting for the potential impact of uncertain ice sheet processes with low- and high-GHG emissions. We incorporate spatial heterogeneity into regional sea level projections and population projections from 2020 to 2100, extreme sea levels (ESLs) of 10-, 50-, and 100 year return periods (RP), and local coastal protection standards. Our findings indicate that the inundated areas expand continuously within the century with heightened exposure under higher emission scenarios. Although the coastal population is projected to decline, the fraction of the coastal population exposed to flooding increases across all scenarios, with accelerated growth under higher GHG emissions and higher ESLs. Zhejiang and Jiangsu emerge as the provinces most exposed to sea-level rise, whereas Taizhou, Nantong, Wuxi, Panjin, and Huzhou are identified as the top five cities with the highest population exposure to local sea level rise (SLR). Transitioning towards a sustainable scenario (i.e. SSP1-2.6) rather than a fossil fuel-intensive one (i.e. SSP5-8.5) can reduce the local SLR and substantially mitigate these exposures. Compared to the median projections under SSP5-8.5, aligning GHG emissions with SSP1-2.6 could reduce population exposure substantially in all coastal provinces, especially in Jiangsu, where population exposure to 100 year RP coastal floods would be reduced by ∼1.6 M in 2050 and by ∼5.4 M in 2100.

Spatial and Temporal Variations in Offshore Crude Oil Transportation: Insights From China's Coastal Ports

ABSTRACTAnalyzing the spatial and temporal variations of offshore crude oil transportation at China's coastal ports is critical for the country's energy security. The automatic identification system provides high‐resolution real‐time data on China's offshore crude oil transportation, offering more precise spatial and temporal insights than existing statistical studies. In this study, we propose a novel method for calculating offshore crude oil transportation volumes by considering the operational status of crude oil tankers as “empty” or “full.” This approach enhances reliability and provides detailed port‐level transport data. Our findings reveal notable similarities between the centrality measures of maritime oil transportation and oil tanker networks, but significant differences in community divisions. Specifically, in the tanker networks, Chinese ports are categorized into three regions, with one region being dominant and the other two regions containing only four ports. In contrast, the oil flow networks show China divided into two major regions and two minor ones. This study offers valuable contributions to strengthening energy security in China and supports informed policy development and implementation.

Ecological Effects of the Huge Invasive Species Removal Project in Coastal China.

Saltmarsh wetlands are recognized as some of the most ecologically valuable yet vulnerable ecosystems globally. However, since the 1970s, saltmarsh wetlands in coastal China have been seriously threatened by the invasive Spartina alterniflora. Although the Chinese government has initiated a nationwide S.alterniflora removal project, the potential benefits and risks of this project remain unknown. Here, we focus on the Yangtze River Estuary Saltmarsh Wetland (YRESW) and simulate its future ecosystem structure, function, and quality under three scenarios based on remote sensing and field investigation data. The simulation scenarios include the absence of a removal project, natural regeneration postproject (NRP), and planted restoration postproject. The results show that the removal project will reverse the escalating invasion trend of S.alterniflora in the YRESW. Compared to the baseline year of 2022, there is a remarkable increase in ecosystem structure (composition: +107%, configuration: +27%) and ecosystem quality (+10.5%) under the NRP scenario. Although blue carbon storage sharply decreases under both scenarios involving project implementation, planted restoration can restore YRESW's carbon sequestration capacity to 0.19 Tg C per year, achieving 87% of the carbon storage present before the project. This study underscores the necessity of comprehensive and detailed risk assessments in ecological projects, particularly when dominant species are involved. Our findings hold significant implications for stabilizing coastal wetland ecosystems and promoting sustainable development in coastal areas.

Soil carbon pools and microbial network stability depletion associated with wetland conversion into aquaculture ponds in Southeast China

Wetlands, which are ecosystems with the highest soil surface carbon density, have been severely degraded and replaced by artificial reclamation for fish and shrimp ponds in recent years. This transformation is causing intricate shifts in soil carbon pools and microbial stability. In this study, we examined natural wetlands and reclaimed aquaculture ponds in Southeast China to analyze the structure and network stability of soil microbial communities following the reclamation of estuarine wetlands and to elucidate the microbial-mediated mechanisms for regulating soil organic carbon (SOC). The aquaculture ponds presented significantly less average SOC content than the natural wetlands (p < 0.05). ACE, Chao1, and Shannon's indices of bacteria and fungi were decreased in aquaculture ponds. Less numbers of nodes and edge links in the co-occurrence network of soil fungi and bacteria in aquaculture ponds. This suggests reduced correlation and stability within the microbial network of aquaculture ponds. Decomposers in soil fungi (e.g. Dung Saprotroph) reduced. Reduced proportions of key phyla Ascomycota, Basidiomycota and Rozellomycota in the soil fungal network. Reduced proportions of key phyla Proteobacteria, Chloroflexi and Desulfobacterota in the soil bacterial network. In conclusion, our results suggest that converting wetland paddocks to intensive aquaculture ponds results in carbon pool loss and reduces soil microbial network stability. The results highlight the importance of protecting or moderately restoring mangrove wetlands along the coast of southeastern China. It is also predicted that such measures may enhance the storage capacity of soil carbon pools and improve the stability of carbon sequestration by soil microorganisms, thus offering a potential solution for mitigating global climate change.

Using detrital zircon U[sbnd]Pb geochronology to track the provenance of Miocene sediments in the northern Pearl River Mouth Basin, South China Sea

The Late Cenozoic provenance study of the Pearl River Mouth Basin (PRMB) holds significant implications for understanding the tectonic-climatic interactions, drainage evolution, and oceanic circulation in the northern South China Sea. However, the Miocene sediment routing system remains poorly understood due to the paucity of zircon geochronological data and the effects of sediment mixing and homogenization. This study reconstructs the ancient source-to-sink system by means of detrital zircon analyses from the northern PRMB and zircon age-based mixture modeling of well-defined provenance end-members. The results disclose varied and complex source-to-sink scenarios since the Early Miocene, involving three primary contributors: the Pearl River drainage system, coastal SE China, and Taiwan Island. In combination with seismic facies and climatic proxies, the intensive addition of Precambrian zircons suggests that, during the Middle and Late Miocene, progressive drainage expansion within the Yangtze Block likely contributed to the increasing sediment supply from the western Pearl River drainage system. Furthermore, the provenance shift in the northern PRMB, as indicated by the Mesozoic ages, may reflect a response to the activation of oceanic circulation and intensification of the East Asian monsoon. Additionally, though less significant, contributions from the Hainan and Luzon Island are also observed, indicating the input of the branch of the Kuroshio Current during the Late Miocene.

Microplastics in the atmospheric of the eastern coast of China: different function areas reflecting various sources and transport.

Suspended atmospheric microplastics (SAMPs) display varying occurrence characteristics on different underlying surfaces in urban areas. This study investigated the occurrence characteristics, source apportionment, and transportation patterns of SAMPs in two typical underlying surfaces: the downtown area (Site T) and the industrial area (Site C) of a coastal city in China. In the spring of 2023, a total of 32 types comprising 1325 SAMPs were detected. The average MP abundances were found to be 3.74 ± 2.86n/m3 in Site T and 2.67 ± 1.68n/m3 in Site C. In Site T, SAMPs attributed to living source constituted 78.05%, while industry was the main source in Site C with a proportion reaching 42.89%, consistent with the functional zoning of the underlying surface. Furthermore, HYSPLIT analysis revealed that there was no significant difference between these two sites in long-distance horizontal transport affected by external airflow regardless of altitude; conversely, PCA indicated a notable correlation between vertical velocity and both abundance and species diversity. According to the hourly average wind speeds, the maximum transmission distance was computed as 350km for updraft and the minimum transmission distances was as low as 32m for downdraft. Subsequently, the coincidence between the source proportion of SAMPs on random day and meteorological parameters confirmed the synergistic impact on SAMPs transport influenced by functional zoning, geographic environment, and vertical velocity.

Sediment source-to-sink patterns along the southeast China coast during the late Quaternary: New insights from sediment geochemistry and OSL ages in Ningde Bay

The geomorphology and environmental conditions of the southeast China coast are significantly influenced by sediment discharge from the Yangtze River, a major river located to the north. Nonetheless, the extent to which the Yangtze River affects sediment transport processes from source to sink along the southeast coast remains unclear. Our recent findings in coastal/marine deposits from the late Quaternary period (MIS5e, MIS3, and MIS1) in Ningde Bay offer new perspectives on this issue. Provenance discrimination of the late Quaternary boreholes was carried out using sediment geochemical analysis and OSL dating of fine- and medium-grained quartz. The results indicate varying provenances during sea-level fluctuation, with distal Yangtze River origins during MIS5e, MIS3, and MIS1, and a local source during MIS4. The findings also suggest that the southward transport of Yangtze sediments along the southeast China coast has occurred since MIS5e. However, OSL ages of the fine-grained quartz in the MIS3 deposit range from approximately 90 to 140 kyr, notably older than those of medium-grained quartz (40–80 kyr). This remarkable age discrepancy indicates that Yangtze-derived sediments previously deposited on the shelf of the East China Sea during MIS5 were reworked and transported southward in MIS3. This phenomenon can be elucidated by the insufficient supply of Yangtze sediments during MIS3, which could be linked to the weakened East Asian monsoon. This new source-to-sink pattern for the southeast China coast is characterized by a compensating mechanism of inner shelf old sediment in response to the inadequate supply of Yangtze sediments. This study contributes to a better understanding of the significant impacts of reduced Yangtze sediment input on its distal sedimentary systems over time.