Search Results (133)

The remote sensing monitoring of land use changes and future scenario simulation hold crucial significance for accurately characterizing urban expansion patterns, optimizing urban land use configurations, and thereby promoting coordinated regional development. Through the integration of multi-source data, this study systematically analyzes the spatiotemporal trajectories and driving forces of land use changes in the Pearl River Delta urban agglomeration (PRD) from 1990 to 2020 and further simulates the spatial patterns of urban land use under diverse development scenarios from 2025 to 2035. The results indicate the following: (1) During 1990–2020, urban expansion in the Pearl River Delta urban agglomeration exhibited a “stepwise growth” pattern, with an annual expansion rate of 3.7%. Regional land use remained dominated by forest (accounting for over 50%), while construction land surged from 6.5% to 21.8% of total land cover. The gravity center trajectory shifted southeastward. Concurrently, cropland fragmentation has intensified, accompanied by deteriorating connectivity of ecological lands. (2) Urban expansion in the PRD arises from synergistic interactions between natural and socioeconomic drivers. The Geographically and Temporally Weighted Regression (GTWR) model revealed that natural constraints—elevation (regression coefficients ranging −0.35 to −0.05) and river network density (−0.47 to −0.15)—exhibited significant spatial heterogeneity. Socioeconomic drivers dominated by year-end paved road area (0.26–0.28) and foreign direct investment (0.03–0.11) emerged as core expansion catalysts. Geographic detector analysis demonstrated pronounced interaction effects: all factor pairs exhibited either two-factor enhancement or nonlinear enhancement effects, with interaction explanatory power surpassing individual factors. (3) Validation of the Patch-generating Land Use Simulation (PLUS) model showed high reliability (Kappa coefficient = 0.9205, overall accuracy = 95.9%). Under the Natural Development Scenario, construction land would exceed the ecological security baseline, causing 408.60 km² of ecological space loss; Under the Ecological Protection Scenario, mandatory control boundaries could reduce cropland and forest loss by 3.04%, albeit with unused land development intensity rising to 24.09%; Under the Economic Development Scenario, cross-city contiguous development zones along the Pearl River Estuary would emerge, with land development intensity peaking in Guangzhou–Foshan and Shenzhen–Dongguan border areas. This study deciphers the spatiotemporal dynamics, driving mechanisms, and scenario outcomes of urban agglomeration expansion, providing critical insights for formulating regionally differentiated policies. Full article

The Requisition–Compensation Balance of Cropland (RCBC) policy is important for ensuring food security. Previous studies have mainly focused on the quantity and quality of cropland when assessing the impacts of this policy. In terms of morphology, previous studies have primarily relied on landscape indicators. Therefore, this study aims to thoroughly analyze the impacts of the RCBC policy on the quality and morphology of cropland (especially morphological spatial pattern analysis, MSPA) in the Pearl River Delta (PRD) during 1996–2021. To this end, we constructed a comprehensive evaluation index system by combining MSPA, landscape indicators, and field research. The results show that the cropland quality in the PRD has exhibited a consistent improvement trend. High-quality cropland is spreading from central cities to the periphery, and the spatial distribution is becoming more even. Nonetheless, MSPA reveals an increasing trend of cropland fragmentation. The results indicate a decline in the area of the “core”, an increase in the area of the “island”, and a decrease in the connectivity of the cropland. Our field research confirms that the RCBC policy has indirectly exacerbated cropland fragmentation. In many regions of the PRD, the fragmentation of cropland hinders the application of agricultural mechanization and increases the cost of cultivation, resulting in severe cropland abandonment. Therefore, local governments should implement rigorous planning and prioritize cropland morphology when compensating cropland. Our findings are expected to provide empirical evidence for improving the RCBC policy and protecting cropland. Full article

Air quality in Guangdong Province has improved in recent years, but progress varies across different provincial sub-regions, particularly between Pearl River Delta (PRD) and non-PRD (NPRD) regions. To unveil possible causes of this, this study established a high-resolution gridded emission inventory for Guangdong (2006–2020) by integrating multi-year Point of Interest (POI) data and road network information. The spatiotemporal evolutions of anthropogenic sulfur dioxide (SO₂), nitrous oxide (NO_X), and particulate matter (PM₁₀ and PM_2.5) emissions were analyzed, with a focus on their impacts on PM_2.5 pollution using the CMAQ model. Spatial shifts in emission sources were quantified using spatial statistical methods, including the average nearest neighbor index (ANNI), kernel density analysis (KDA), standard deviational ellipse (SDE), and mean center (MC). From 2006 to 2020, emissions decreased significantly for SO₂ (88%), NO_X (26%), PM₁₀ (64%), and PM_2.5 (68%). Emission hotspots shifted toward NPRD regions, driven by stricter environmental policies and industrial restructuring, lowering PRD-to-NPRD emission ratios for SO₂ (from 1.25 to 0.87), NO_X (1.67–1.51), and PM₁₀ (0.94–0.89). The spatial evolution of emissions varied across sources. For example, the emission share of industrial sources in the PRD declined despite an increase in enterprises, whereas vehicle emissions remained concentrated in the PRD. CMAQ modeling results revealed that overall emission reductions from 2012 to 2020 lowered provincial PM_2.5 concentrations by 9.2–10.5 μg/m³. Accounting for spatial evolution further enhanced PM_2.5 reductions in the PRD by 1.4 μg/m³ (April) and 1.1 μg/m³ (October). Conversely, PM_2.5 improvements in NPRD regions weakened, with reductions declining by 0.2–3.2 μg/m³ (April) and 0.1–1.4 μg/m³ (October). These findings provide guidance for formulating region-specific strategies, aiming for more equitable air quality improvements across Guangdong. Full article

Background: The Pearl River Delta (PRD) region in Guangdong, China, is urbanized and economically significant. Rapid development has shaped diverse dietary habits. In this densely populated area, there is an urgent need to assess vitamin status and its impact on age-related diseases. Methods: A total of 2646 participants (age: 50.92 ± 9.30 years; male: 64.06%) were recruited from the Pearl River Delta (PRD) region. Participants were included from 1 December 2020 to 30 November 2021. Three restricted cubic spline logistic models, interaction terms, and mediated effects analyses were used to assess the association between vitamin A, B, E, B₁, B₂, B₃, B₅, B₆, and B₉ between five age-related diseases: cerebrovascular disease (CVD), coronary heart disease (CHD), hypertension (HTN), dyslipidemia (DYS), and type 2 diabetes mellitus (T2DM). Results: Blood concentrations of nine vitamins showed a right-skewed distribution. Significant correlations were found between vitamin levels and age-related diseases across nine groups (p < 0.05). A J-shaped relationship was observed between vitamin levels and the risk of age-related diseases, except for the Vitamin A-HTN/T2DM, which showed Maximum Effective Concentration (MEC). Specific thresholds included: Vitamin A: 1080 ng/mL (DYS); Vitamin B₁: 77 ng/mL (CVD), 75.5 ng/mL (HTN); Vitamin B₅: 900 ng/mL (CVD), 600 ng/mL (HTN), 690 ng/mL (DYS); Vitamin B₆: 82 ng/mL (CVD). The protective effect of vitamins against age-related diseases decreased with age, and higher levels of vitamins A and B₁ correlated with increased hypertension risk in older adults (P_interaction < 0.01). Low Body Resilience Index (BRI) and physical activity mediated the protective effects of vitamins A and B₅ on HTN and DYS, while no mediating effects were found for smoking and alcohol consumption. Conclusions: The effectiveness of multivitamin supplementation in preventing cardiovascular, cerebrovascular, and metabolic diseases may be limited in healthy aging populations. Health professionals should consider patients’ physiological conditions and blood vitamin levels to avoid overdose. More interventional studies are needed to establish causal relationships. Full article

The sustainable development of urban agglomerations depends on the effective coordination of water, energy, food, and ecology (WEFE) systems. However, disparities in resource endowments and socio-economic conditions create challenges for achieving a balanced WEFE system across urban regions. This study examines three urban agglomerations in China with distinct development gradients: the Pearl River Delta (PRD), the Hohhot–Baotou–Ordos–Yulin (HBOY) region, and the Central Jilin Province (CJP). A comprehensive evaluation index system is constructed to assess the coupling coordination degree (CCD) of the WEFE system from 2008 to 2022. Through the CCD model, spatiotemporal evolution trends are analyzed, while correlation analysis explores development patterns under varying gradient conditions. A back-propagation artificial neural network (BPANN) model identifies the primary driving factors influencing WEFE coordination. Key findings include the following: (1) the CCD of the PRD, HBOY, and CJP urban agglomerations has improved over time, with CCD values ranging between 0.4 and 0.6, 0.3 and 0.5, and 0.4 and 0.6, respectively. (2) The CCD exhibits a negative correlation with urbanization rates exceeding 70% and industrialization rates but shows a positive correlation with per capita GDP. (3) The dominant contributing subsystems vary; ecology in the PRD (28.76%), food in HBOY (28.83%), and food in CJP (29.32%). These findings underline the importance of tailored strategies for enhancing WEFE system coordination in urban agglomerations with diverse development gradients. Targeted policy recommendations are proposed based on regional characteristics and subsystem contributions. Full article

The ozone levels over eastern China show a distinct two-stage process, with an inter-seasonal low (ISL) between May and September, unlike other polluted northern low-to-mid-latitude regions. The timing and progression of this low from southern to northern China align with the East Asian summer monsoon (EASM). The EASM leads to a decrease (ΔISL1) during the first stage and an increase (ΔISL2) during the second stage. The response varies by region, with the ΔISL1 (25 to 60 ppbv) greater than the ΔISL2 (20 to 30 ppbv) in the North China Plain (NCP), and the ΔISL1 (20 to 35 ppbv) less than the ΔISL2 (35 to 55 ppbv) in the Pearl River Delta (PRD). The ozone levels are inversely related to the monsoon index (MI) during stage 1 (r = −0.69, p < 0.05), while during stage 2, the ozone levels are anticorrelated with the maximum MI in the NCP and PRD (r = −0.73 and −0.80, p < 0.05). And the average ozone levels are anticorrelated with the MI during stage 2 in the Yangtze River Delta (YRD) (r = −0.71, p < 0.05). The simulations using CMIP6 suggest that intensified EASM caused by greenhouse emissions may help reduce summertime ozone pollution. The results show that different regions require different pollution control policies during pre- and post-monsoon seasons. Full article

Urbanization challenges city sustainability by aggravating uneven population migration and land exploitation. Understanding the characteristics and dynamics of this imbalance is crucial for promoting sustainable development. With a focus on population-related land change, this study analyzes the urban–rural imbalance characterized by settlement expansion from 1985 to 2019, using nighttime light (NTL) remote sensing imagery and global settlement distribution data, with Guangdong province, China, as a case study. The key findings reveal significant spatiotemporal differences in settlement expansion between the urban and rural regions. The urban settlements experienced faster expansion from 1985 to 2005, which slowed post-2005, while the rural settlements maintained a stable growth rate throughout the study period. The economic and environmental conditions were identified as major drivers of expansion diversity, with economic factors playing a dominant role in the urban regions and both factors influencing the rural regions. A linear regression analysis highlighted the diverse quantity relationships between the urban and rural settlements across different spatial extents; the urban settlements dominated in quantity at the provincial level, primarily due to the contributions of the core Pearl River Delta (PRD) region. In contrast, the rural settlements outnumbered the urban ones in most of the other prefectures, a trend that continued to deepen across Guangdong province. The findings of this study provide deeper insights into the characteristics and evolvement of the urban–rural imbalance, policy implications and actionable strategies are offered for equitable and sustainable city development. Full article

Analyzing the electric power consumption (EPC) patterns of China’s mega urban agglomerations is crucial for promoting sustainable development both domestically and globally. Utilizing 2017–2021 NPP/VIIRS low-light remote sensing imagery to extract total nighttime light data, this study proposed an EPC prediction method based on the K-Means clustering algorithm combined with multiple indicators integrated with socio-economic factors. Combining IPAT theory, regional GDP and population density, the final EPC prediction models were developed. Using these models, the EPC distributions for Beijing-Tianjin-Hebei (BTH), Yangtze River Delta (YRD), and Pearl River Delta (PRD) urban agglomerations in 2017–2021 were generated at both the administrative district level and the 1 km × 1 km grid scale. The spatio-temporal dynamics of the EPC distribution in these urban agglomerations during this period were then analyzed, followed by EPC predictions for 2022. The models showed a significant improvement in prediction accuracy, with the average MARE decreasing from 30.52% to 7.60%, 25.61% to 11.08% and 18.24% to 12.85% for the three urban agglomerations, respectively; EPC clusters were identified in these areas, mainly concentrated in Langfang and Chengde, Shanghai and Suzhou, and Dongguan; from 2017 to 2021, the EPC values of the three urban agglomerations show a growth trend and the distribution patterns were consistent with their economic development and population density; the R² values and the statistical values for the 2022 EPC predictions using the improved classification EPC models reached 0.9692, 0.9903 and 0.9677, respectively, confirming that the proposed method can effectively predict the EPC of urban agglomerations and is applicable in various scenarios. This method provides a timely and accurate spatial update of EPC dynamics, offering fine-scale characterization of urban EPC patterns using night light images. Full article

Atmospheric nitrogen deposition is a vital component of the global nitrogen cycle, with significant implications for ecosystem health, pollution mitigation, and sustainable development. In the Pearl River Delta (PRD) region of China, high levels of ammonium (${\mathrm{NH}}_x$) wet deposition, driven by abundant precipitation and intensive anthropogenic activities, pose significant challenges to ecological balance and environmental sustainability. However, accurately estimating ${\mathrm{NH}}_x$ wet deposition flux is hindered by the complexity of nitrogen deposition processes and spatial heterogeneity in observational data. This study integrates machine learning and causal inference techniques to identify the spatial distribution patterns of ${\mathrm{NH}}_x$ wet deposition and key drivers of its spatial heterogeneity. Based on these findings, four machine learning models were developed to estimate ${\mathrm{NH}}_x$ wet deposition flux in the PRD region for the period 2012–2017. The results indicated that the integrated models significantly outperformed standard machine learning models (MSE = 0.486, R = 0.564), the FGCNN deep learning model (MSE = 0.454, R = 0.592), and the WRF-EMEP numerical model (MSE = 0.975, R = 0.334), achieving the highest average accuracy (MSE = 0.379, R = 0.610). This study emphasizes the importance of incorporating causal factors and spatial heterogeneity into estimation frameworks to improve the accuracy and stability of ${\mathrm{NH}}_x$ wet deposition flux estimates. The findings provide actionable insights for targeted mitigation strategies, contributing to sustainable ecosystem management and pollution reduction in rapidly urbanizing regions. Full article

This study investigates the spatiotemporal patterns of land development intensity and green economy development at the district and county level in nine cities within the Pearl River Delta (PRD). A comprehensive evaluation framework is developed using a coupling coordination degree model and panel vector autoregression (PVAR) model to explore the spatial and temporal evolution of their relationship. The research reveals several key findings. (1) In 2013–2023, land development intensity followed a pattern of “concentration in the east and south, and sparsity in the west and north”, highlighting significant regional imbalances. (2) In 2013–2023, high-intensity development areas tended to cluster together, forming high-value zones, while low-intensity areas were often located next to similarly underdeveloped regions, reflecting a “low-value connection” trend. (3) There is a long-term stable co-integration relationship between land development intensity and green economy development. This study fills a gap in research at the district and county scale and offers practical insights for optimizing regional growth strategies and fostering green economic development across different areas in 2013–2023. These findings contribute to the design of balanced and sustainable development policies in the PRD, addressing both economic growth and environmental sustainability. Full article

Rapid urbanization in China has profoundly transformed its urban systems, bringing about considerable ecological challenges and significant imbalances between urban growth and ecological health. The Pearl River Delta (PRD) urban agglomeration, as one of China’s most economically dynamic regions, exemplifies the complex interactions between rapid urbanization and environmental sustainability. This study examined these dynamics using statistical yearbook and geographic information data from 1999 to 2018. Through a multi-scale approach integrating panel entropy, coupled coordination analysis, and FLUS models, we evaluated the relationship between urbanization and ecology at both the agglomeration and city levels. The findings revealed that while the overall coordination between urbanization and ecology in the PRD has improved, it remains at a moderate level with pronounced core-periphery disparities. Core cities face increasing ecological pressures and inefficient land use patterns. Simulation results, under three distinct policy scenarios—“unconstrained”, “growth machine”, and “compact and intensive usage/urban renewal”—and validated through field research, indicate that urban renewal presents a viable strategy for optimizing land use and mitigating ecological pressures. The study provides both a comprehensive diagnostic framework for assessing urban health and sustainability and practical intervention pathways, particularly for regions experiencing similar rapid urbanization challenges. The insights gained are especially relevant to other developing countries, offering strategies to enhance urban resilience and ecological sustainability while addressing persistent regional inequalities. Full article

The mismatch between urban livability and population distribution can result in overcrowding and excessive pressure on ecosystem services if population growth surpasses urban capacity. Conversely, if urban expansion outpaces population needs, it can lead to underutilized infrastructure and inefficient land use. This study aims to assess the coordination between urban livability and population distribution in five major urban agglomerations in China: Beijing–Tianjin–Hebei (BTH), Yangtze River Delta (YRD), Pearl River Delta (PRD), Mid-Yangtze River (MYR), and Chengdu–Chongqing (CC). A comprehensive index for urban livability is established, from the aspects of social–economic development and ecosystem service. Additionally, a Coordination Distance Index (CDI) is developed to measure the relationship between urban livability and population distribution. Data from 2010, 2015, and 2020 are analyzed to evaluate the coordination levels and trends across the five urban agglomerations. The results show that from 2010 to 2020, most cities within these urban agglomerations experience improvements in their coordination levels, with the most notable advancements in the PRD and YRD regions. By 2020, the PRD and YRD were classified as having “high coordination”, while BTH, MYR, and CC were categorized as having “moderate coordination”. However, certain cities, such as Chengde in BTH, Shanghai in YRD, Ya’an in CC, and Zhuhai in PRD, still exhibited “low coordination”, highlighting areas requiring spatial planning adjustments. This study introduces a method for quantitatively assessing the coordination between urban livability and population distribution, providing essential insights for policymakers and urban planners to refine urbanization development strategies and population regulation policies in China’s major urban agglomerations. Full article

Understanding the spatial correlation of transportation carbon emissions and their influencing factors is significant in achieving an overall regional carbon emission reduction. This study analyzed the structure characteristics of the expressway carbon emission correlation network in Guangdong Province and examined its influencing factors with intercity expressway traffic flow data using social network analysis (SNA). The findings indicate that the correlation network of expressway carbon emissions in Guangdong Province exhibited a “core-edge” spatial pattern. The overall network demonstrated strong cohesion and stability, and a significant difference existed between the passenger vehicle and freight vehicle carbon emission networks. The positions and roles of different cities varied within the carbon emission network, with the Pearl River Delta (PRD) cities being in a dominant position in the carbon network. Cities such as Guangzhou, Foshan, and Dongguan play the role of “bridges” in the carbon network. The expansion of differences in GDP per capita, industrial structure, technological level, and transportation intensity facilitates the formation of a carbon emission network. At the same time, geographical distance between cities and policy factors inhibit them. This study provides references for developing regional collaborative carbon emission governance programs. Full article

To gain insights into the prevalence and antimicrobial resistance patterns of major bacterial pathogens affecting largemouth bass (Micropterus salmoides) in the Pearl River Delta (PRD) region, Guangdong, China, a study was conducted from August 2021 to July 2022. During this period, bacteria were isolated and identified from the internal organs of diseased largemouth bass within the PRD region. The antimicrobial resistance patterns of 11 antibiotics approved for use in aquaculture in China were analyzed in 80 strains of Edwardsiella piscicida using the microbroth dilution method. The results showed that 151 bacterial isolates were obtained from 532 samples, with E. piscicida (17.29%, 92/532), Aeromonas veronii (4.70%, 25/532), and Nocardia seriolae (2.26%, 12/532) being the main pathogens. Notably, E. piscicida accounted for the highest proportion of all isolated bacteria, reaching 60.92% (92/151), and mainly occurred from November to April, accounting for 68.48% (63/92) of the cases. The symptoms in largemouth bass infected with E. piscicida included ascites, enteritis, and hemorrhaging of tissues and organs. The drug sensitivity results showed that the resistance rates of all E. piscicida strains to ciprofloxacin, all sulfonamides, thiamphenicol, florfenicol, enrofloxacin, doxycycline, flumequine, and neomycin were 96.25%, 60–63%, 56.25%, 43.75%, 40%, 32.5%, 16.25%, and 1.25%, respectively. In addition, 76.25% (61/80) of these strains demonstrated resistance to more than two types of antibiotics. Cluster analysis revealed 23 antibiotic types (A–W) among the 80 isolates, which were clustered into two groups. Therefore, tailored antibiotic treatment based on regional antimicrobial resistance patterns is essential for effective disease management. The findings indicate that in the event of an Edwardsiella infection in largemouth bass, neomycin, doxycycline, and flumequine are viable treatment options. Alternatively, one may choose drugs that are effective as determined by clinical drug sensitivity testing. Full article

China aims to reduce its carbon emissions to achieve carbon peaking and neutrality. Measuring the carbon emission efficiency of three urban agglomerations in China, exploring their spatiotemporal characteristics, and investigating the main influencing factors are crucial for achieving regional sustainable development and dual carbon goals. Using the super-slack-based measurement (super-SBM) model, we calculated the carbon emission efficiency of the Beijing–Tianjin–Hebei (BTH), Yangtze River Delta (YRD), and Pearl River Delta (PRD) urban agglomerations from 2011 to 2021 and explored the spatiotemporal non-equilibrium characteristics of carbon emission efficiency and its influencing factors. The results indicated that: (1) Overall, the carbon emission efficiency showed an N-type trend, with the PRD having the highest average efficiency. Regional differences between the YRD and BTH regions gradually increased. (2) The efficiency hotspots shifted from the PRD to the YRD, whereas the cold spots were mainly concentrated in the BTH region. The variation in the standard deviation ellipse radius of carbon emission efficiency in the urban agglomerations was clear, and the spatial disequilibrium was significant. (3) Economic level and opening up had positive impacts on carbon emission efficiency, whereas energy intensity and industrial structure had negative impacts. The effects of population size, government intervention, and technological level varied among the regions. Full article