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Keywords = China’s coastal zone

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16 pages, 4272 KiB  
Article
Prediction Analysis of Integrative Quality Zones for Corydalis yanhusuo W. T. Wang Under Climate Change: A Rare Medicinal Plant Endemic to China
by Huiming Wang, Bin Huang, Lei Xu and Ting Chen
Biology 2025, 14(8), 972; https://doi.org/10.3390/biology14080972 (registering DOI) - 1 Aug 2025
Viewed by 216
Abstract
Corydalis yanhusuo W. T. Wang, commonly known as Yanhusuo, is an important and rare medicinal plant resource in China. Its habitat integrity is facing severe challenges due to climate change and human activities. Establishing an integrative quality zoning system for this species is [...] Read more.
Corydalis yanhusuo W. T. Wang, commonly known as Yanhusuo, is an important and rare medicinal plant resource in China. Its habitat integrity is facing severe challenges due to climate change and human activities. Establishing an integrative quality zoning system for this species is of significant practical importance for resource conservation and adaptive management. This study integrates multiple data sources, including 121 valid distribution points, 37 environmental factors, future climate scenarios (SSP126 and SSP585 pathways for the 2050s and 2090s), and measured content of tetrahydropalmatine (THP) from 22 sampling sites. A predictive framework for habitat suitability and spatial distribution of effective components was constructed using a multi-model coupling approach (MaxEnt, ArcGIS spatial analysis, and co-kriging method). The results indicate that the MaxEnt model exhibits high prediction accuracy (AUC > 0.9), with the dominant environmental factors being the precipitation of the wettest quarter (404.8~654.5 mm) and the annual average temperature (11.8~17.4 °C). Under current climatic conditions, areas of high suitability are concentrated in parts of Central and Eastern China, including the Sichuan Basin, the middle–lower Yangtze plains, and coastal areas of Shandong and Liaoning. In future climate scenarios, the center of suitable areas is predicted to shift northwestward. The content of THP is significantly correlated with the mean diurnal temperature range, temperature seasonality, and the mean temperature of the wettest quarter (p < 0.01). A comprehensive assessment identifies the Yangtze River Delta region, Central China, and parts of the Loess Plateau as the optimal integrative quality zones. This research provides a scientific basis and decision-making support for the sustainable utilization of C. yanhusuo and other rare medicinal plants in China. Full article
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32 pages, 2291 KiB  
Article
Impact of Green Financial Reform on Urban Economic Resilience—A Quasi-Natural Experiment Based on Green Financial Reform and Innovation Pilot Zones
by Yahui Chen, Yi An, Zixun Nie, Yuanying Chi and Xinyue Jia
Sustainability 2025, 17(15), 6969; https://doi.org/10.3390/su17156969 - 31 Jul 2025
Viewed by 349
Abstract
As a key engine driving China’s green financial transformation, the Green Financial Reform and Innovation Pilot Zones have demonstrated significant achievements in enhancing the capacity of financial services to support green real economies, preventing and mitigating green financial risks, and bolstering national and [...] Read more.
As a key engine driving China’s green financial transformation, the Green Financial Reform and Innovation Pilot Zones have demonstrated significant achievements in enhancing the capacity of financial services to support green real economies, preventing and mitigating green financial risks, and bolstering national and urban economic resilience. On this basis, a spatial Markov chain model is applied to further analyze the economic toughness of prefecture-level cities. This study treats the establishment of these pilot zones as a quasi-natural experiment, using panel data from 269 prefecture-level cities in China from 2013 to 2023 and employing a multi-period difference-in-differences (DID) model to empirically examine the impact of green financial reform on urban economic resilience and its underlying mechanisms. The results reveal that the establishment of these pilot zones significantly enhances urban economic resilience. Specifically, green financial reforms primarily improve urban economic resilience by increasing credit accessibility and capital allocation efficiency in the pilot cities. Furthermore, the policy effects are more pronounced in large cities and resource-dependent cities compared to small and medium-sized cities and non-resource-dependent cities, with stronger impacts observed in southern and coastal regions than in northern inland areas. Additionally, the policy effects are significantly greater in environmentally prioritized cities than in non-prioritized cities. By integrating green financial reforms and urban economic resilience into a unified analytical framework, this study provides valuable insights for policymakers to refine green financial strategies and design resilience-enhancing policies. Full article
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20 pages, 753 KiB  
Article
Has the Free Trade Zone Enhanced the Regional Economic Resilience? Evidence from China
by Henglong Zhang and Congying Tian
Sustainability 2025, 17(15), 6951; https://doi.org/10.3390/su17156951 - 31 Jul 2025
Viewed by 247
Abstract
This study examines the impact of free trade zone (FTZ) establishment on regional economic resilience (RER) in China, using provincial-level panel data spanning from 2010 to 2022 and a multi-period difference-in-differences (DID) approach. The empirical results indicate that FTZ implementation significantly enhances regional [...] Read more.
This study examines the impact of free trade zone (FTZ) establishment on regional economic resilience (RER) in China, using provincial-level panel data spanning from 2010 to 2022 and a multi-period difference-in-differences (DID) approach. The empirical results indicate that FTZ implementation significantly enhances regional economic resilience by 3.46%, with the development of green finance acting as a key moderating mechanism that amplifies this positive effect. Heterogeneity analysis uncovers notable disparities across policy cohorts and geographical regions: the first wave of FTZs demonstrates the most pronounced resilience-enhancing impact, whereas later cohorts exhibit weaker or even adverse effects. Coastal regions experience substantial benefits from FTZ policies, in contrast to statistically insignificant outcomes observed in inland areas. These findings suggest that strategically expanding the FTZ network, when paired with tailored implementation mechanisms and the integration of green finance, could serve as a powerful policy tool for post-COVID economic recovery. Importantly, by strengthening economic resilience through institutional openness and green investment, this study offers valuable insights into balancing economic growth with environmental sustainability. It provides empirical evidence to support the optimization of FTZ spatial governance and institutional innovation pathways, thereby contributing to the pursuit of sustainable regional development. Full article
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19 pages, 8699 KiB  
Article
Study on the Spatio-Temporal Characteristics and Driving Factors of PM2.5 in the Inter-Provincial Border Region of Eastern China (Jiangsu, Anhui, Shandong, Henan) from 2022 to 2024
by Xiaoli Xia, Shangpeng Sun, Xinru Wang and Feifei Shen
Atmosphere 2025, 16(8), 895; https://doi.org/10.3390/atmos16080895 - 22 Jul 2025
Viewed by 256
Abstract
The inter-provincial border region in eastern China, encompassing the junction of Jiangsu, Anhui, Shandong, and Henan provinces, serves as a crucial zone that connects the important economic zones of Beijing–Tianjin–Hebei and the Yangtze River Delta. It is of great significance to study the [...] Read more.
The inter-provincial border region in eastern China, encompassing the junction of Jiangsu, Anhui, Shandong, and Henan provinces, serves as a crucial zone that connects the important economic zones of Beijing–Tianjin–Hebei and the Yangtze River Delta. It is of great significance to study the temporal variation characteristics, spatial distribution patterns, and driving factors of PM2.5 concentrations in this region. Based on the PM2.5 concentration observation data, ground meteorological data, environmental data, and socio-economic data from 2022 to 2024, this study conducted in-depth and systematic research by using advanced methods, such as spatial autocorrelation analysis and geographical detectors. The research results show that the concentration of PM2.5 rose from 2022 to 2023, but decreased from 2023 to 2024. From the perspective of seasonal variations, the concentration of PM2.5 shows a distinct characteristic of being “high in winter and low in summer”. The monthly variation shows a “U”-shaped distribution pattern. In terms of spatial changes, the PM2.5 concentration in the inter-provincial border region of eastern China (Jiangsu, Anhui, Shandong, Henan) forms a gradient difference of “higher in the west and lower in the east”. The high-concentration agglomeration areas are mainly concentrated in the Henan part of the study region, while the low-concentration agglomeration areas are distributed in the eastern coastal parts of the study region. The analysis of the driving factors of the PM2.5 concentration based on geographical detectors reveals that the average temperature is the main factor affecting the PM2.5 concentration. The interaction among the factors contributing to the spatial differentiation of the PM2.5 concentration is very obvious. Temperature and population density (q = 0.92), temperature and precipitation (q = 0.95), slope and precipitation (q = 0.97), as well as DEM and population density (q = 0.96), are the main combinations of factors that have continuously affected the spatial differentiation of the PM2.5 concentration for many years. The research results from this study provide a scientific basis and decision support for the prevention, control, and governance of PM2.5 pollution. Full article
(This article belongs to the Special Issue Atmospheric Pollution Dynamics in China)
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16 pages, 3297 KiB  
Article
Predicting the Potential Geographical Distribution of Scolytus scolytus in China Using a Biomod2-Based Ensemble Model
by Wei Yu, Dongrui Sun, Jiayi Ma, Xinyuan Gao, Yu Fang, Huidong Pan, Huiru Wang and Juan Shi
Insects 2025, 16(7), 742; https://doi.org/10.3390/insects16070742 - 21 Jul 2025
Viewed by 431
Abstract
Dutch elm disease is one of the most devastating plant diseases, primarily spread through bark beetles. Scolytus scolytus is a key vector of this disease. In this study, distribution data of S. scolytus were collected and filtered. Combined with environmental and climatic variables, [...] Read more.
Dutch elm disease is one of the most devastating plant diseases, primarily spread through bark beetles. Scolytus scolytus is a key vector of this disease. In this study, distribution data of S. scolytus were collected and filtered. Combined with environmental and climatic variables, an ensemble model was developed using the Biomod2 platform to predict its potential geographical distribution in China. The selection of climate variables was critical for accurate prediction. Eight bioclimatic factors with high importance were selected from 19 candidate variables. Among these, the three most important factors are the minimum temperature of the coldest month (bio6), precipitation seasonality (bio15), and precipitation in the driest quarter (bio17). Under current climate conditions, suitable habitats for S. scolytus are mainly located in the temperate regions between 30° and 60° N latitude. These include parts of Europe, East Asia, eastern and northwestern North America, and southern and northeastern South America. In China, the low-suitability area was estimated at 37,883.39 km2, and the medium-suitability area at 251.14 km2. No high-suitability regions were identified. However, low-suitability zones were widespread across multiple provinces. Under future climate scenarios, low-suitability areas are still projected across China. Medium-suitability areas are expected to increase under SSP370 and SSP585, particularly along the eastern coastal regions, peaking between 2041 and 2060. High-suitability zones may also emerge under these two scenarios, again concentrated in coastal areas. These findings provide a theoretical basis for entry quarantine measures and early warning systems aimed at controlling the spread of S. scolytus in China. Full article
(This article belongs to the Section Insect Pest and Vector Management)
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23 pages, 48857 KiB  
Article
A 36-Year Assessment of Mangrove Ecosystem Dynamics in China Using Kernel-Based Vegetation Index
by Yiqing Pan, Mingju Huang, Yang Chen, Baoqi Chen, Lixia Ma, Wenhui Zhao and Dongyang Fu
Forests 2025, 16(7), 1143; https://doi.org/10.3390/f16071143 - 11 Jul 2025
Viewed by 317
Abstract
Mangrove forests serve as critical ecological barriers in coastal zones and play a vital role in global blue carbon sequestration strategies. In recent decades, China’s mangrove ecosystems have experienced complex interactions between degradation and restoration under intense coastal urbanization and systematic conservation efforts. [...] Read more.
Mangrove forests serve as critical ecological barriers in coastal zones and play a vital role in global blue carbon sequestration strategies. In recent decades, China’s mangrove ecosystems have experienced complex interactions between degradation and restoration under intense coastal urbanization and systematic conservation efforts. However, the long-term spatiotemporal patterns and driving mechanisms of mangrove ecosystem health changes remain insufficiently quantified. This study developed a multi-temporal analytical framework using Landsat imagery (1986–2021) to derive kernel normalized difference vegetation index (kNDVI) time series—an advanced phenological indicator with enhanced sensitivity to vegetation dynamics. We systematically characterized mangrove growth patterns along China’s southeastern coast through integrated Theil–Sen slope estimation, Mann–Kendall trend analysis, and Hurst exponent forecasting. A Deep Forest regression model was subsequently applied to quantify the relative contributions of environmental drivers (mean annual sea surface temperature, precipitation, air temperature, tropical cyclone frequency, and relative sea-level rise rate) and anthropogenic pressures (nighttime light index). The results showed the following: (1) a nationally significant improvement in mangrove vitality (p < 0.05), with mean annual kNDVI increasing by 0.0072/yr during 1986–2021; (2) spatially divergent trajectories, with 58.68% of mangroves exhibiting significant improvement (p < 0.05), which was 2.89 times higher than the proportion of degraded areas (15.10%); (3) Hurst persistence analysis (H = 0.896) indicating that 74.97% of the mangrove regions were likely to maintain their growth trends, while 15.07% of the coastal zones faced potential degradation risks; and (4) Deep Forest regression id the relative rate of sea-level rise (importance = 0.91) and anthropogenic (nighttime light index, importance = 0.81) as dominant drivers, surpassing climatic factors. This study provides the first national-scale, 30 m resolution assessment of mangrove growth dynamics using kNDVI, offering a scientific basis for adaptive management and blue carbon strategies in subtropical coastal ecosystems. Full article
(This article belongs to the Section Forest Inventory, Modeling and Remote Sensing)
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21 pages, 1545 KiB  
Article
Balancing Industrialization with Pollution: Evidence from the Marine Ecological Civilization Demonstration Zone Program in China
by Jinxuan Ling and Yi Jin
Sustainability 2025, 17(14), 6352; https://doi.org/10.3390/su17146352 - 11 Jul 2025
Viewed by 288
Abstract
This study provides empirical evidence on how the Marine Ecological Civilization Demonstration Zone program, a policy integrating industrial upgrading with ecological protection, achieves dual objectives in a developing economy context. Theoretically, we uncover three key mechanisms, including green technology innovation, productivity gains, and [...] Read more.
This study provides empirical evidence on how the Marine Ecological Civilization Demonstration Zone program, a policy integrating industrial upgrading with ecological protection, achieves dual objectives in a developing economy context. Theoretically, we uncover three key mechanisms, including green technology innovation, productivity gains, and government intervention, that explain the program’s impacts, offering a framework for reconciling industrialization with environmental sustainability. Our novel findings demonstrate that the program significantly boosts industrial structure upgrading and coastal water quality, with pronounced effects in the Pearl River Delta. We highlight the need for regionally tailored measures, expanded green R&D support, and strategic zone expansion insights critical for China and other developing nations navigating similar trade-offs. By bridging the gap between environmental regulation and industrial transformation, this work contributes to the debates on sustainable development in coastal regions. Full article
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19 pages, 3235 KiB  
Article
Characteristics and Evaluation of Living Shorelines: A Case Study from Fujian, China
by Xingfan Li, Shihui Lin, Libing Qian, Zhe Wang, Chao Cao, Qi Gao and Jiwen Cai
J. Mar. Sci. Eng. 2025, 13(7), 1307; https://doi.org/10.3390/jmse13071307 - 5 Jul 2025
Viewed by 325
Abstract
Under the context of global climate change, sea-level rise and frequent storm surge events pose significant challenges to coastal areas. Protecting coastlines from erosion, mitigating socio-economic losses, and maintaining ecosystem balance are critical for the sustainable development of coastal zones. The concept of [...] Read more.
Under the context of global climate change, sea-level rise and frequent storm surge events pose significant challenges to coastal areas. Protecting coastlines from erosion, mitigating socio-economic losses, and maintaining ecosystem balance are critical for the sustainable development of coastal zones. The concept of “living shorelines” based on Nature-based Solutions (NbS) employs near-natural ecological restoration and protection measures. In low-energy coastal segments, natural materials are prioritized, while high-energy segments are supplemented with artificial structures. This approach not only enhances disaster resilience but also preserves coastal ecosystem stability and ecological functionality. This study constructs a coastal vitality evaluation system for Fujian Province, China, using the entropy weight method, integrating three dimensions: protective safety, ecological resilience, and economic vitality. Data from 2010 and 2020 were analyzed to assess the spatiotemporal evolution of coastal vitality. Results indicate that coastal vitality initially exhibited a spatial pattern of “low in the north, high in the center, and low in the south,” with vitality values ranging from 0.20 to 0.67 (higher values indicate stronger vitality). Over the past decade, ecological restoration projects have significantly improved coastal vitality, particularly in central and southern regions, where high-vitality segments increased markedly. Key factors influencing coastal vitality include water quality, cyclone intensity, biological shoreline length, and wetland area. NbS-aligned coastal management strategies and soft revetment practices have generated substantial ecological and economic benefits. To further enhance coastal vitality, region-specific approaches are recommended, emphasizing rational resource utilization, optimization of ecological and economic values, and the establishment of a sustainable evaluation framework. This study provides scientific insights for improving coastal protection capacity, ecological resilience, and economic potential. Full article
(This article belongs to the Special Issue Coastal Geochemistry: The Processes of Water–Sediment Interaction)
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20 pages, 4992 KiB  
Article
Spatial Heterogeneity and Controlling Factors of Heavy Metals in Groundwater in a Typical Industrial Area in Southern China
by Jiaxu Du, Fu Liao, Ziwen Zhang, Aoao Du and Jiale Qian
Water 2025, 17(13), 2012; https://doi.org/10.3390/w17132012 - 4 Jul 2025
Viewed by 576
Abstract
Heavy metal contamination in groundwater has emerged as a significant environmental issue, driven by rapid industrialization and intensified human activities, particularly in southern China. Heavy metal pollution in groundwater often presents complex spatial patterns and multiple sources; understanding the spatial heterogeneity and controlling [...] Read more.
Heavy metal contamination in groundwater has emerged as a significant environmental issue, driven by rapid industrialization and intensified human activities, particularly in southern China. Heavy metal pollution in groundwater often presents complex spatial patterns and multiple sources; understanding the spatial heterogeneity and controlling factors of heavy metals is crucial for pollution prevention and water resource management in industrial regions. This study applied spatial autocorrelation analysis and self-organizing maps (SOM) coupled with K-means clustering to investigate the spatial distribution and key influencing factors of nine heavy metals (Cr, Fe, Mn, Ni, Cu, Zn, As, Ba, and Pb) in a typical industrial area in southern China. Heavy metals show significant spatial heterogeneity in concentrations. Cr, Mn, Fe, and Cu form local hotspots near urban and peripheral zones; Ni and As present downstream enrichment along the river pathway with longitudinal increase trends; Zn, Ba, and Pb exhibit a fluctuating pattern from west to east in the piedmont region. Local Moran’s I analysis further revealed spatial clustering in the northwest, riverine zones, and coastal outlet areas, providing insight into potential source regions. SOM clustering identified three types of groundwater: Cluster 1 (characterized by Cr, Mn, Fe, and Ni) is primarily influenced by industrial pollution and present spatially scattered distribution; Cluster 2 (dominated by As, NO3, Ca2+, and K+) is associated with domestic sewage and distributes following river flow; Cluster 3 (enriched in Zn, Ba, Pb, and NO3) is shaped by agricultural activities and natural mineral dissolution, with a lateral distribution along the piedmont zone. The findings of this study provide a scientific foundation for groundwater pollution prevention and environmental management in industrialized areas. Full article
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16 pages, 24903 KiB  
Technical Note
A Shipborne Doppler Lidar Investigation of the Winter Marine Atmospheric Boundary Layer over Southeastern China’s Coastal Waters
by Xiaoquan Song, Wenchao Lian, Fuyou Wang, Ping Jiang and Jie Wang
Remote Sens. 2025, 17(13), 2161; https://doi.org/10.3390/rs17132161 - 24 Jun 2025
Viewed by 379
Abstract
The Marine Atmospheric Boundary Layer (MABL), as a critical component of Earth’s climate system, governs the exchange of matter and energy between the ocean surface and the lower atmosphere. This study presents shipborne Doppler lidar observations conducted during 12 January to 3 February [...] Read more.
The Marine Atmospheric Boundary Layer (MABL), as a critical component of Earth’s climate system, governs the exchange of matter and energy between the ocean surface and the lower atmosphere. This study presents shipborne Doppler lidar observations conducted during 12 January to 3 February 2024, along the southeastern Chinese coast. Employing a Coherent Doppler Wind Lidar (CDWL) system onboard the R/V “Yuezhanyu” research vessel, we investigated the spatiotemporal variability of MABL characteristics through integration with ERA5 reanalysis data. The key findings reveal a significant positive correlation between MABL height and surface sensible heat flux in winter, underscoring the dominant role of sensible heat flux in boundary layer development. Through the Empirical Orthogonal Function (EOF) analysis of the ERA5 regional boundary layer height, sensible heat flux, and sea level pressure, we demonstrate MABL height over the coastal seas typically exceeds the corresponding terrestrial atmospheric boundary layer height and exhibits weak diurnal variation. The CDWL observations highlight complex wind field dynamics influenced by synoptic conditions and maritime zones. Compared to onshore regions, the MABL over offshore areas further away from land has lower wind shear changes and a more uniform wind field. Notably, the terrain of Taiwan, China, induces significant low-level jet formations within the MABL. Low-level jets and low boundary layer height promote the pollution episode observed by CDWL. This research provides new insights into MABL dynamics over East Asian marginal seas, with implications for improving boundary layer parameterization in regional climate models and advancing our understanding of coastal meteorological processes. Full article
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16 pages, 2983 KiB  
Article
Birds as Biodiversity Beacons: Identifying Conservation Priority Areas Through Multi-Dimensional Diversity in China
by Fei Duan, Shuyi Zhu, Xiaoyun Shi, Xiaoli Shen and Sheng Li
Diversity 2025, 17(7), 442; https://doi.org/10.3390/d17070442 - 21 Jun 2025
Viewed by 374
Abstract
Biodiversity conservation plays a pivotal role in achieving sustainable development and fostering harmonious coexistence between humans and nature. This study identifies avian conservation priority areas across China by analyzing multi-dimensional biodiversity, incorporating species diversity, functional diversity, and phylogenetic diversity. Through systematic conservation planning [...] Read more.
Biodiversity conservation plays a pivotal role in achieving sustainable development and fostering harmonious coexistence between humans and nature. This study identifies avian conservation priority areas across China by analyzing multi-dimensional biodiversity, incorporating species diversity, functional diversity, and phylogenetic diversity. Through systematic conservation planning using Zonation version 4 software, we delineated priority areas across these diversity dimensions. Our results demonstrate a distinct south-to-north diversity gradient in China’s avifauna, with functional and phylogenetic diversity hotspots concentrated in Yunnan Province, the Hengduan Mountains, Hainan Island, Taiwan Island, and southeastern coastal regions. The identified priority conservation areas cover 14.6% of China’s terrestrial territory, protecting 89.8% of the country’s bird species—including 93.5% of endemic species and 88.9% of critically endangered species. Notably, existing nature reserves encompass merely 8.1% of these priority areas, revealing substantial conservation gaps within the current protection framework. Building upon China’s 3C Zoning Framework (Cities and farms, Shared landscapes, and Large wild areas), we propose zone-specific conservation strategies, with particular emphasis on strengthening protected area networks in the eastern coastal regions and the middle-lower Yangtze River basin, where urbanization pressures are most acute. These findings highlight the critical importance of incorporating multi-dimensional diversity in conservation planning and offer novel perspectives for optimizing China’s protected area system. Full article
(This article belongs to the Section Biodiversity Conservation)
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33 pages, 9948 KiB  
Article
Research on Port Competitiveness Dynamics in China Under the Background of Free Trade Zone and Port Integration
by Hongchu Yu, Zheng Guo and Lei Xu
Sustainability 2025, 17(12), 5502; https://doi.org/10.3390/su17125502 - 14 Jun 2025
Viewed by 425
Abstract
Free trade zone (FTZ) policies and port integration play critical roles in advancing international shipping and port development. While Free trade zones (FTZs) promote trade liberalization and attract investment to support port infrastructure, port integration helps alleviate excessive competition, reduce redundant labor, and [...] Read more.
Free trade zone (FTZ) policies and port integration play critical roles in advancing international shipping and port development. While Free trade zones (FTZs) promote trade liberalization and attract investment to support port infrastructure, port integration helps alleviate excessive competition, reduce redundant labor, and minimize resource inefficiencies. Given these dynamics, it is important to examine how FTZs and port integration differentially shape shipping capacity and port competitiveness across China’s coastal provinces. To this end, this study introduces a comprehensive evaluation framework for port competitiveness, which considers both port operation–related factors and the external environment. The framework employs a combination of principal component analysis and the entropy weight method to assess port competitiveness in coastal regions. The findings reveal that comprehensive port service capacity and management efficiency capacity have the most significant influence on port competitiveness, outweighing the impact of other evaluated indicators. It also reveals that the development of China’s coastal ports is regionally unbalanced, with strong competitiveness in the Yangtze River Delta, Pearl River Delta, and Bohai Rim clusters, moderate development in the southeastern cluster, and relatively weak performance in the Beibu Gulf cluster. Both FTZ and port integration policies can promote port competitiveness to some extent, especially for professional technical support and services, digital management, and overall management efficiency. The dynamics of port competitiveness under the FTZs are higher than those under port integration. The research results deepen the understanding of the roles of FTZ and port integration policies in promoting the competitiveness of ports in various regions and provide insights for ports to seize opportunities and enhance development. The reinforcement of industrial synergies with neighboring regions and the formation of complementary development patterns enhance their overall competitiveness. Exploring new modes aligned with the advancement of FTZs and port integration can further stimulate regional economic development and support national opening-up strategies. Full article
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18 pages, 4783 KiB  
Article
Land Use Change and Mangrove Restoration Modulate Heavy Metal Accumulation in Tropical Coastal Sediments: A Nearly Decade-Long Study from Hainan, China
by Tingting Si, Penghua Qiu, Lei Li, Wenqian Zhou, Chuanzhao Chen, Qidong Shi, Meihuijuan Jiang and Yanli Yang
Land 2025, 14(6), 1259; https://doi.org/10.3390/land14061259 - 12 Jun 2025
Viewed by 833
Abstract
Mangrove forests, vital coastal ecosystems that provide critical biodiversity habitats and carbon sequestration services, face increasing heavy metal pollution that threatens their ecological functions through bioaccumulation and toxicity to marine organisms. However, existing studies lack dynamic insights into temporal and spatial variations of [...] Read more.
Mangrove forests, vital coastal ecosystems that provide critical biodiversity habitats and carbon sequestration services, face increasing heavy metal pollution that threatens their ecological functions through bioaccumulation and toxicity to marine organisms. However, existing studies lack dynamic insights into temporal and spatial variations of heavy metals in mangrove sediments. This study systematically analyzed two mangrove reserves in Hainan Island, China (Hainan Dongzhaigang National Nature Reserve [DZG] and Hainan Qinglan Provincial Nature Reserve [QL]), by collecting sediment samples in 2014 and 2022, analyzing metals (Cr, Cu, Zn, As, Cd, and Pb) via ICP-MS, and applying the geo-accumulation index, potential ecological risk index, Markov transition matrix, and statistical analyses. Results showed that DZG exhibited rising Cu and Zn levels but declining Cr, As, Cd, and Pb, with Cd showing the most significant decrease (66.83%). In contrast, QL saw only a 42.7% reduction in Cd, while other heavy metals increased. Spatial heterogeneity linked higher concentrations to anthropogenic hotspots, DZG’s southeast (industrial/aquaculture inputs), and QL’s northwest (urban/industrial discharges). Although ecological risks were generally low, Cd in QL reached a moderate risk level (ECd = 46.44, 40 ≤ Ei < 80). The large-scale pond-to-mangrove conversion significantly increased vegetation cover, which enhanced sedimentation rates and exerted a “dilution effect” on sediment heavy metals. These findings underscore anthropogenic activities as the dominant driver of heavy metal contamination. We recommend (1) stringent wastewater control near QL, (2) enhanced shipping regulation, and (3) the establishment of mangrove buffers in heavy metal accumulation zones to improve ecological status. Full article
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19 pages, 2243 KiB  
Article
Divergent Response of Blue Carbon Components and Microbial Communities in Sediments to Different Shellfish Zones of Geligang, Liaodong Bay, China
by Qingbiao Hu, Bingyu Li, Yongan Bai, Fangliang Zheng, Muzhan Sun, Ruiqi Zeng, Xuetong Wang, Xiaodong Li and Chunyu Zhu
Water 2025, 17(12), 1728; https://doi.org/10.3390/w17121728 - 7 Jun 2025
Viewed by 559
Abstract
Coastal wetlands are critical components of blue carbon ecosystems, yet the functional roles of benthic shellfish species in regulating sediment carbon dynamics are not yet fully elucidated. To address this knowledge gap, we investigated the effects of different shellfish zones—gastropods (Bullacta exarata [...] Read more.
Coastal wetlands are critical components of blue carbon ecosystems, yet the functional roles of benthic shellfish species in regulating sediment carbon dynamics are not yet fully elucidated. To address this knowledge gap, we investigated the effects of different shellfish zones—gastropods (Bullacta exarata, Umbonium thomasi) and bivalves (Mactra veneriformis, Meretrix meretrix, Potamocorbula laevis)—on sediment carbon fractions and microbial communities in representative intertidal wetlands of Liaodong Bay, China. We analyzed dissolved organic carbon (DOC), particulate organic carbon (POC), microbial biomass carbon (MBC), enzyme activities, and microbial genomic profiles, with particular emphasis on carbon fixation gene abundance within the top 0–10 cm of sediment. The results showed that POC and MBC levels in gastropod zones were 56.11% and 99.83% higher, respectively, than in bivalve zones, while carbon fixation gene abundance was 14.54% lower. Structural equation modeling (SEM) further revealed that shellfish type had a significant direct effect on MBC (λ = 0.824, p < 0.001). This study provides novel evidence that shellfish community composition regulates blue carbon storage through both biogeochemical and microbial pathways, highlighting the importance of species-specific management in shellfish aquaculture to enhance carbon sequestration. These findings offer a theoretical foundation for future assessments of coastal wetland carbon sinks and ecosystem service valuation. Full article
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18 pages, 5357 KiB  
Article
Multi-Scale Validation of Suspended Sediment Retrievals in Dynamic Estuaries: Integrating Geostationary and Low-Earth-Orbiting Optical Imagery for Hangzhou Bay
by Yi Dai, Jiangfei Wang, Bin Zhou, Wangbing Liu, Ben Wang, C. K. Shum, Xiaohong Yuan and Zhifeng Yu
Remote Sens. 2025, 17(12), 1975; https://doi.org/10.3390/rs17121975 - 6 Jun 2025
Viewed by 408
Abstract
Water color remote sensing is vital for the monitoring and quantification of marine suspended sediment dynamics and their distributions. Yet validations of these observables in coastal regions and deltaic estuaries, including the Hangzhou Bay in the East China Sea, remain challenging, primarily due [...] Read more.
Water color remote sensing is vital for the monitoring and quantification of marine suspended sediment dynamics and their distributions. Yet validations of these observables in coastal regions and deltaic estuaries, including the Hangzhou Bay in the East China Sea, remain challenging, primarily due to the pronounced complex oceanic dynamics that exhibit high spatiotemporal variability in the signals of the suspended sediment concentration (SSC) in the ocean. Here, we integrate satellite images from the sun-synchronous satellites, China’s Huanjing (Chinese for environmental, HJ)-1A/B (charged couple device) CCD (30 m), and from Korea’s Geostationary Ocean Color Imager GOCI (500 m) to the spatiotemporal scale effects to validate SSC remote sensing-retrieved data products. A multi-scale validation framework based on coefficient of variation (CV)-based zoning was developed, where high-resolution HJ CCD SSC data were resampled to the GOCI scale (500 m), and spatial variability was quantified using CV values within corresponding HJ CCD windows. Traditional validation, comparing in situ point measurements directly with GOCI pixel-averaged data, introduces significant uncertainties due to pixel heterogeneity. The results indicate that in regions with high spatial heterogeneity (CV > 0.10), using central pixel values significantly weakens correlations and increases errors, with performance declining further in highly heterogeneous areas (CV > 0.15), underscoring the critical role of spatial averaging in mitigating scale-related biases. This study enhances the quantitative assessment of uncertainties in validating medium-to-low-resolution water color products, providing a robust approach for high-dynamic oceanic environment estuaries and bays. Full article
(This article belongs to the Special Issue Remote Sensing Band Ratios for the Assessment of Water Quality)
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