Typical City Research Articles

The research on narrow-valley city flood control mode based on hydrodynamic-hydrological coupling model

The flood processes and control methods in narrow-valley cities exhibit significant differences compared to other regions. Therefore, precise modeling and simulation of their flood processes is crucial. This study focuses on a typical narrow-valley city located in the Loess Plateau of northern China. A hydrodynamic-hydrological coupling model was constructed to simulate the floods, analyzing flood disaster characteristics as well as the effects and differences of various flood control measures in the narrow-valley city. The results indicate: (1) The hydrodynamic-hydrological coupling model proposed in this paper is highly appropriate for accurately simulating floods in narrow-valley cities. A hydrological model was used to generalize the hydrological process in hilly mountainous areas. While a hydrodynamic model was employed to conduct a detailed simulation of the river terrace, where the main urban area is located. After validation through two actual flood events, the model demonstrated satisfactory simulation performance. (2) The flood characteristics of narrow-valley cities differ from those of plain regions mainly because the terrain restricts the spread of floods once they surpass the embankments. This limitation leads to potentially greater inundation risks in such topographical features. Additionally, the elongated distribution of cities in these areas creates spatial disparities in flooding between upstream and downstream areas. (3) There are significant variations in the effectiveness of different flood control measures. Various flood control approaches were modeled and simulated in this paper. Their flood control capabilities were ranked in descending order as: reservoirs, flood diversion channels, and river channel dredging. (4) The combined flood control effect of multiple measures is notably superior to that of individual measures. Among them, the combination of reservoirs and flood diversion channels is optimal, as it regulates the inflow from a large upstream area. The conclusions drawn in this paper can provide a certain degree of reference and basis for the construction of flood models and flood control systems in narrow-valley cities.

The relationship between air pollutants and preterm birth and blood routine changes in typical river valley city

ObjectiveTo collect maternal maternity information on preterm births in two tertiary hospitals in the urban area of Baota District, Yan'an City, from January 2018 to December 2020, to explore the long-term and short-term effects of air pollutants (PM2.5, PM10, SO2, NO2, CO and O3) and preterm births, and to explore changes in blood cell counts due to air pollutants.MethodsDaily average mass concentration data of six air pollutants in the urban area of Yan'an City from January 1, 2017 to December 31, 2020 were collected from the monitoring station in Baota District, Yan'an City. Meteorological information was obtained from the Meteorological Bureau of Yan'an City, including temperature,relative humidity and wind speed for the time period. The mass concentration of air pollutants in each exposure window of pregnant women was assessed by the nearest monitoring station method, and conditional logistic regression was used to analyze the relationship between air pollutants and preterm births, as well as the lagged and cumulative effects of air pollutants. Multiple linear regression was used to explore the relationship between air pollutants and blood tests after stepwise linear regression was used to determine confounders for each blood test.ResultsThe long-term effects of pollutants showed that PM2.5, PM10, SO2, NO2and CO were risk factors for preterm birth. In the two-pollutant model, PM2.5, PM10, SO2 and NO2 mixed with other pollutants were associated with preterm birth. The lagged effect showed that PM2.5, PM10, SO2, NO, and CO were associated with preterm birth; the cumulative effect showed that other air pollutants except O3 were associated with preterm birth. The correlation study between air pollutants and blood indicators showed that air pollutants were correlated with leukocytes, monocytes, basophils, erythrocytes, hs-CRPand not with CRP.ConclusionExposure to air pollutants is a risk factor for preterm birth. Exposure to air pollutants was associated with changes in leukocytes, monocytes, basophils and erythrocytes and hs-CRP.

Evaluation of Nocturnal Aerosol Optical Depth Determining From a Lunar Photometry in Lanzhou of Northwest China

AbstractA Cimel Sun‐sky‐lunar photometer (CE318‐T) is designed to perform daytime and nighttime photometric measurements and calculate diurnal cycle of aerosol optical depth (AOD). Nevertheless, the determination of nocturnal AOD from CE318‐T requires a precise knowledge of extraterrestrial lunar irradiance, which significantly changes with moon's phase angle (MPA) and lunar libration in a single night. This study evaluated the 1‐year nocturnal AODs at Lanzhou by using three different methods, which were validated by collocated measurements of DIAL Lidar (as a reference) and Cimel software (as a proxy). The results indicated that three independent approaches could implement a similar performance to compute nocturnal AOD near full moon phase (i.e., MPA = 0°) under moderate aerosol loading. The spectral AOD values at nighttime calculated by ROLO Lunar Langley (Robotic Lunar Observatory model) and Sun‐moon Gain Factor (SMGF) methods are significantly underestimated under low moon's illumination or high MPA (MPA < −47° or MPA > 47°) and distinctly dependent on MPA. The RIMO correction factor (RCF) (ROLO Implementation for Moon photometry Observation correction factor) method could compensate the underestimated extraterrestrial lunar irradiances of ROLO model for about 6.76%–9.78%, and thus greatly improve the calculation accuracy of nighttime AOD. The day/night coherence transition test has demonstrated that we would obtain a good diurnal variation of AODs at Lanzhou after RCF correction. The overall averages of nocturnal AOD440nm differences between Cimel software and ROLO model and SMGF method are 0.064 ± 0.024 and 0.052 ± 0.022, respectively, while the corresponding difference of RCF is less than 0.021 ± 0.014 for all wavelengths, falling within uncertainty range of AERONET AOD products (∼±0.02). The diurnal variations of AODs determined from RCF method agree well with synchronous results of DIAL Lidar, with total mean AOD532nm differences of 0.038 ± 0.024 and 0.023 ± 0.017 in daytime and nighttime, respectively. The spectral AODs computed from RCF method are well consistent with Cimel software, although there are some discrepancies under low AOD cases (AOD440nm < 0.30), and the overall average of AOD440nm differences are less than −0.0053 ± 0.002 and −0.0185 ± 0.013 in daytime and nighttime, respectively. Our results confirmed that the CE318‐T photometer can be reasonably calculated nighttime AOD and Ångström exponent (AE440–870nm) at urban Lanzhou by using three independent methods, although the former two need to be greatly improved under low moon's illumination. The RCF method was proved to reliably calculate nocturnal AOD from moonlight irradiance, which didn't rely on MPA. A more accurate lunar irradiance model needs to be developed to improve the underestimation of current ROLO model. Long‐term climatological information of nocturnal AOD is crucial for comprehensively characterizing the diurnal variations of aerosol optical properties and atmospheric boundary layer structure during the winter at typical northern city of China, which deserves to be further investigated in the future.

System dynamics-multiple the objective optimization model for the coordinated development of urban economy-energy-carbon system

The deepening conflict between human societal progress and efforts to combat climate change necessitates immediate coordination among the Economy-Energy-Carbon (EEC) management. The study applies IPCC accounting methods to compute the historical carbon emissions in the Chengdu-Chongqing economic circle from 2005 to 2021. It assesses the developmental efficiency of various subsystems in the EEC system by employing the rank-sum ratio. Taking a typical city in the region (Chongqing) as a case study, this study integrates System Dynamics (SD) with NSGAIII to develop an EEC multi-objective optimization model. It utilizes the VIKOR model to select the optimal solution. Based on this, the analysis explores the coupled and coordinated state of the EEC system from 2022 to 2030 under the optimal solution mode. Research findings indicate that: (1) The overall carbon emissions exhibit a slight increase, where carbon sources surpass the carbon sink created by land use. (2) Compared to results from other preference-based scenarios, in the scenario where subsystem efficiencies are all optimal, the minimum cumulative carbon emissions amount to 1520.52 million tons, with the economy maintaining a favorable status. Moreover, the overall coupling coordination of the EEC is in a relatively favorable state, and it tends to improve annually. (3) To attain the coordinated development of the EEC system by 2030, the energy structure of the representative city must decrease coal consumption by 26.17%, maintain the construction land ratio below 3.7%, and guarantee forest coverage exceeds 57.77%. This study, utilizing complex system simulations and optimization analyses across various scenarios, offers pertinent recommendations for attaining urban low-carbon development while upholding societal advancement.

Research on the Spatial Structure of the Beijing–Tianjin–Hebei Urban Agglomeration Based on POI and Impervious Surface Coverage

Exploring urban spatial structures through spatial coupling analysis methods is an important method to provide theoretical support for the construction of sustainable urban structures. In order to make up for the neglect of POI species differences in previous studies, information entropy was introduced to calculate POI confusion, and a comprehensive POI index was constructed by combining kernel density and the entropy weight method; impervious surface coverage was extracted based on land cover data. The spatial distribution of the Beijing–Tianjin–Hebei urban agglomeration and some typical cities was analyzed by coupling two types of data using the dual-factor mapping method. The research indicates the following: (1). The spatial distribution of the two sets of data in the Beijing–Tianjin–Hebei region is highly consistent, indicating a state of high spatial coupling; Beijing has the highest proportion of coupling in the same region at the city level (73.39%). (2). The areas with different coupling of the two types of data are mainly distributed in the urban fringe areas transitioning from the city center to the suburbs, as well as in large-scale areas with single functionality such as airports, scenic spots, and ports. This study shows that analysis combining the POI comprehensive index and impervious surface coverage can effectively characterize urban spatial structure characteristics, providing a new perspective for the study of the spatial structure of the Beijing–Tianjin–Hebei urban agglomeration. It is of great significance for a deeper understanding of the laws of urban agglomeration spatial structures and guiding the coordinated development of the Beijing–Tianjin–Hebei urban agglomeration.

Identification and seasonal variation of specific particulate bound (halogenated) polycyclic aromatic hydrocarbons in air from different metal industrial parks in Northwest China.

During the process of industrial heating, a large amount of polycyclic aromatic hydrocarbons (PAHs) and their halogenated compounds (Cl/Br-PAHs) can be formed. However, there is still limited understanding of the chemicals from different metal smelting industrial parks. This study evaluated the seasonal variations, composition profiles, and source allocations of the atmospheric particulate-bound PAHs and Cl/Br-PAHs in different metal industrial parks in a typical industrial city in northwest China. The results showed that the main PAHs produced by metal smelting were low molecular weight isomers, and the concentrations of Cl-PAHs were lower compared to Br-PAHs. The main Br-PAHs were 1-Br-Pyr and 4-Br-Pyr, while 9-Cl-Fle, 1-Cl-Pyr, and 6-Cl-BaP were the dominated Cl-PAH isomers. No significant difference was found in the concentrations among the sites, whereas the levels of the target chemicals were higher during cold months compared to warm months. The main source of PAHs was coal combustion and gasoline vehicle emission during metal smelting, and that of Cl/Br-PAHs was also industrial coal burning. In addition to the primary source, the secondary chlorination of parent PAHs was also a significant source of Cl-PAHs in the production of high purity aluminum. This study suggests that Cl-PAHs and Br-PAHs may behave differently in the atmosphere.

Spatial and Temporal Distribution of Antibiotic Resistance Genes in Different River Sediments in Typical Cities: A Case Study of Shijiazhuang

Rivers are important reservoirs of antibiotic resistance genes (ARGs). However, most current studies have focused on the temporal and spatial distribution, and data on the differences in the species and abundance of ARGs between urban and rural rivers is still lacking for certain areas. In view of this, two rural rivers and three urban rivers were selected in Shijiazhuang City. In both December 2020 and April 2021, sediments were collected at 15 sampling sites. Metagenomic sequencing technology was used to compare the differences in temporal-spatial variation for ARGs in sediments. The results showed that:① 162 and 79 ARGs were detected in urban (4 776 ±4 452) and rural rivers (1 043 ±632), respectively. The abundance and species of ARGs in urban rivers were higher than those in rural rivers. ② The relative abundances of sulfonamide (SAs,27 %), aminoglycoside (AGs,26 %), and multidrug (MDs,15 %) ARGs had the highest abundance in urban rivers, whereas the relative abundance of MDs ARGs was highest in rural rivers (65 %). On the whole, the complexity of ARGs in urban rivers was higher than that in rural rivers. ③ There was a significant positive correlation between SAs, AGs, MDs, tetracycline, phenicol, macrolides-lincosamids-streptogramins (MLS), β-lactams, and diaminopyrimidine ARGs in urban rivers (P < 0.01); however, there was a significant negative correlation between glycopeptide ARGs and all types of ARGs (P < 0.05 and P < 0.01). There was a significant positive correlation between MDs and SAs ARGs in rural rivers (P < 0.05), but there was a significant negative correlation between amino aminocoumarin, peptide, rifamycin, and fosfomycin ARGs (P < 0.05 and P < 0.01). ④ For the temporal variation in urban rivers, 162 ARGs (4 776 ±4 452) and 148 ARGs (5 673 ±5 626) were detected in December and April, respectively. For the temporal variation in rural rivers, 79 species (1 043 ±632) and 46 species (467 ±183) were detected in December and April, respectively. ⑤ RDA analysis results showed that the spatial-temporal distributions of ARGs in urban and rural rivers were different. Correlation analysis showed that the ARGs in urban rivers were significantly correlated with the number of industrial enterprises, whereas the ARGs in rural rivers were significantly correlated with the output value of animal husbandry. In general, this study identified the main influencing factors for ARGs in different rivers and provided data support for ARGs risk management in different rivers.

Permeate gap thermo-osmotic system for simultaneous freshwater production, energy storage, and power generation

The emerging thermo-osmotic system enables harvesting low-grade thermal energy below 100 °C for the simultaneous production of fresh water and electricity. Considering the fluctuation of low-grade heat sources, a novel permeate gap thermo-osmotic system without pump pressurization was proposed in this study, which also allows for energy storage. A lab-scale setup with a 32 cm2 membrane area was built, by which a 2 W light bulb was successfully illuminated through the thermal energy-potential energy-electricity conversion process. In the pressurization process of the permeate side, the hydrophobic membranes with non-woven support exhibit higher pressure resistance, capable of withstanding pressures exceeding 200 kPa. Through experimental and theoretical analyses, the influences of different operation conditions and membrane properties on system performance were studied. Furthermore, utilizing solar energy as the heat source, a case study was conducted based on real meteorological data from a typical coastal city over a consecutive 72-hour period. In the solar-driven PGTO system with a power capacity of approximately 150 kW, the exergy efficiency can achieve 1.04 %, with a power density surpassing 0.1 W m−2, and an average daily freshwater production of over 70000 t. The energy storage function enables stable power generation within the 72 h, and it can sustain steady operation for nearly 7 h thereafter in the absence of sunlight. This study demonstrated the potential of the proposed PGTO system to efficiently utilize fluctuating low-grade thermal energy.

Spatial Vulnerability Assessment for Mountain Cities Based on the GA-BP Neural Network: A Case Study in Linzhou, Henan, China

Mountain cities with complex topographies have always been highly vulnerable areas to global environmental change, prone to geological hazards, climate change, and human activities. Exploring and analyzing the vulnerability of coupling systems in mountain cities is highly important for improving regional resilience and promoting sustainable regional development. Therefore, a comprehensive framework for assessing the spatial vulnerability of mountain cities is proposed. A vulnerability assessment index system is constructed using three functional systems, ecological protection, agricultural production, and urban construction. Subsequently, the BP neural network and the genetic algorithm (GA) are combined to establish a vulnerability assessment model, and geographically weighted regression (GWR) is introduced to analyze the spatial influence of one-dimensional systems on the coupling system. Linzhou, a typical mountain city at the boundary between China’s second- and third-step terrains, was selected as a case study to demonstrate the feasibility of the framework. The results showed that the vulnerability of the ecological protection system was highly aggregated in the east–central region, that of the agricultural production system was high in the west, and that of the urban construction system was low in the central region and high in the northwestern region. The coupling system vulnerability was characterized by multispatial distribution. The complex topography and geomorphology and the resulting natural hazards are the underlying causes of the vulnerability results. The impact of ecological and urban systems on the coupling system vulnerability is more prominent. The proposed framework can serve as a reference for vulnerability assessments of other similar mountain cities with stepped topographies to support the formulation of sustainable development strategies.

Anthropogenic-driven changes in concentrations and sources of winter volatile organic compounds in an urban environment in the Yangtze River Delta of China between 2013 and 2021

Volatile organic compounds (VOCs) serve as crucial precursors to surface ozone and secondary organic aerosols (SOA). In response to severe air pollution challenges, China has implemented key air quality control policies from 2013 to 2021. Despite these efforts, a comprehensive understanding of the chemical composition and sources of urban atmospheric VOCs and their responses to emission reduction measures remains limited. Our study focuses on analyzing VOCs composition and concentrations during the winters of 2013 and 2021 through online field observations in urban Nanjing, a typical city in the Yangtze River Delta region of China. Using a machine learning approach, we found a notable reduction in total VOCs concentration from 52.4 ± 30.4 ppb to 33.9 ± 21.6 ppb between the two years, with dominant contributions (approximately 94.3 %) associated with anthropogenic emission control. Furthermore, alkanes emerged as the major contributors (48.6 %) to such anthropogenic-driven decline. The total SOA formation potential decreased by approximately 27.4 %, with aromatics identified as the major contributing species. Positive matrix factorization analysis identified six sources. In 2013, prominent contributors were solid fuel combustion (43.6 %), vehicle emission (16.7 %), and paint and solvent use (12.8 %). By 2021, major sources shifted to solid fuel combustion (31.9 %), liquefied petroleum gas and natural gas (26.8 %), and vehicle emission (25.5 %). Solid fuel combustion emerged as the primary driver for total VOCs reduction. The lifetime carcinogenic risk in 2021 decreased by 72.6 % relative to 2013, emphasizing the need to address liquefied petroleum gas and natural gas source, and vehicle emissions for improved human health. Our findings contribute critical insights for policymakers working on effective air quality management.

Evaluating the Development Levels of Green Urban Transportation Systems

To promote the green and resilient development of urban transportation and the sustainable development of cities, we developed a technique that can be used to evaluate the level of urban green transportation development. First, the toughness evaluation indexes were integrated according to the connotation requirements of green transportation development, and the evaluation index system was constructed using the hierarchical analysis method. Second, subjective and objective weighting methods, such as the G1, entropy weighting, and “addition” integration methods, which provide a simple and easy-to-use evaluation method that can improve evaluation accuracy, were adopted. Finally, Harbin, a typical city in the north, was chosen as a representative city to verify the method effectiveness. The study findings can be used to evaluate the current level of green development of a city as well as for future planning, providing a basis for formulating sustainable urban transportation development strategies. We will continue to conduct comparative studies on different evaluation methods and cities to improve the generalizability of the method.

The various synergistic impacts of precursor emission reduction on PM2.5 and O3 in a typical industrial city with complex distributions of emissions

The synergistic responses of O3 and PM2.5 to their common precursors remain unclear within industrial cities with complex emissions. In this study, hundreds of scenarios of jointly reduced local NOx and VOCs emissions were designed along with the source apportionment techniques embedded in the Comprehensive Air quality Model with extensions (CAMx) system to explore the locally formed O3 and PM2.5 sensitivities to the reduced emissions of NOx and VOCs. The results indicate that locally formed O3 and PM2.5 are more connected to local emissions, resulting in unique formation sensitivities. Local O3 formation is usually in a transitional regime and transferred to VOC-limited condition under O3-polluted conditions due to high VOC emissions. Locally formed O3 and PM2.5 vary largely in different functional regions due to different emission feature and meteorological condition. When reducing VOCs emissions alone, an increase in PM2.5 formation could be observed due to the increase in the formation of nitrate resulting from reduced competition of NOx in O3 formation. To reduce PM2.5 and O3 concentrations simultaneously, specific ratios of NOx reduction percentage to VOC reduction percentage should be considered to different functional regions under different pollution levels. This research highlights the importance to conduct targeted sensitivity tests for emission reduction in different functional zones with complex emission features for the coordinated control of O3 and PM2.5 pollution in typical industrialized cities.

Unsupervised Domain Adaptation with Contrastive Learning-Based Discriminative Feature Augmentation for RS Image Classification

High- and very high-resolution (HR, VHR) remote sensing (RS) images can provide comprehensive and intricate spatial information for land cover classification, which is particularly crucial when analyzing complex built-up environments. However, the application of HR and VHR images to large-scale and detailed land cover mapping is always constrained by the intricacy of land cover classification models, the exorbitant cost of collecting training samples, and geographical changes or acquisition conditions. To overcome this limitation, we propose an unsupervised domain adaptation (UDA) with contrastive learning-based discriminative feature augmentation (CLDFA) for RS image classification. In detail, our method first utilizes contrastive learning (CL) through a memory bank in order to memorize sample features and improve model performance, where the approach employs an end-to-end Siamese network and incorporates dynamic pseudo-label assignment and class-balancing strategies for adaptive domain joint learning. By transferring classification models trained on a source domain (SD) to an unlabeled target domain (TD), our proposed UDA method enables large-scale land cover mapping. We conducted experiments using a massive five billion-pixels dataset as the SD and tested the HR and VHR RS images of five typical Chinese cities as the TD and applied the method on the completely unlabeled world view 3 (WV3) image of Urumqi city. The experimental results demonstrate that our method excels in large-scale HR and VHR RS image classification tasks, highlighting the advantages of semantic segmentation based on end-to-end deep convolutional neural networks (DCNNs).

Hydrogen peroxide serves as pivotal fountainhead for aerosol aqueous sulfate formation from a global perspective

Traditional atmospheric chemistry posits that sulfur dioxide (SO2) can be oxidized to sulfate (SO42–) through aqueous-phase reactions in clouds and gas-phase oxidation. Despite adequate knowledge of traditional mechanisms, several studies have highlighted the potential for SO2 oxidation within aerosol water. Given the widespread presence of tropospheric aerosols, SO42− production through aqueous-phase oxidation in aerosol water could have a pervasive global impact. Here, we quantify the potential contributions of aerosol aqueous pathways to global sulfate formation based on the GEOS-Chem simulations and subsequent theoretical calculations. Hydrogen peroxide (H2O2) oxidation significantly influences continental regions both horizontally and vertically. Over the past two decades, shifts in the formation pathways within typical cities reveal an intriguing trend: despite reductions in SO2 emissions, the increased atmospheric oxidation capacities, like rising H2O2 levels, prevent a steady decline in SO42− concentrations. Abating oxidants would facilitate the benefit of SO2 reduction and the positive feedback in sulfate mitigation.

Challenges for monitoring artificial turf expansion with satellite remote sensing.

Urban green spaces are central components of urban ecosystems, providing refuge for wildlife while helping 'future proof' cities against climate change. Conversion of urban green spaces to artificial turf has become increasingly popular in various developed countries, such as the UK, leading to reduced urban ecosystem services delivery. To date, there is no established satellite remote sensing method for reliably detecting and mapping artificial turf expansion at scale. We here assess the combined use of very high-resolution multispectral satellite imagery and classical, open source, supervised classification approaches to map artificial lawns in a typical British city. Both object-based and pixel-based classifications struggled to reliably detect artificial turf, with large patches of artificial turf not being any more reliably identified than small patches of artificial turf. As urban ecosystems are increasingly recognised for their key contributions to human wellbeing and health, the poor performance of these standard methods highlights the urgency of developing and applying new, easily accessible approaches for the monitoring of these important ecosystems.

Study on the Urban Expansion of Typical Tibetan Plateau Valley Cities and Changes in Their Ecological Service Value: A Case Study of Xining, China

The accelerated urbanization process drives urban spatial expansion, making it essential to clarify the driving factors of this expansion and the corresponding ecosystem service value (ESV) response for effective regional urban planning. We selected Xining City, a typical plateau valley city with a spatial layout constrained by mountainous and riverine topography, as our study area. We analyzed land changes in Xining City over the past 20 years using the land transfer matrix and the PLUS model, and predicted land use changes under different scenarios for 2030. By combining these analyses with the improved unit area equivalent factor method, we quantitatively assessed the drivers of urban expansion in the main urban area of Xining City from 2000 to 2030 and estimated the ESV. The results showed that: (1) Over the past two decades, Xining City has experienced notable urban expansion, particularly along the Huangshui River, Beichuan River, and Nanchuan River. The urban construction land is mainly converted from cropland and grassland, and the simulation results under different scenarios in the future of 2030 show that the area of cropland and grassland continues to decrease. (2) The spatial expansion of urban areas in Xining City is primarily influenced by topographical factors, with urban transportation planning exerting a secondary influence. Distinct levels of roads exhibit varying degrees of impact on the expansion of constructed areas, with tertiary roads demonstrating the most widespread and substantial influence. Conversely, factors such as population density, GDP, and proximity to government have lesser influence on urban expansion. (3) The ecosystem service value (ESV) of Xining City exhibits a general decline from 2000 to 2030, marked by a significant loss of arable land and grassland and substantial shifts in ESV. Simulated ESV outcomes under diverse scenarios for 2030 consistently underscore that, irrespective of policy orientations, urban expansion and development, despite guarantees for urban, cropland, and ecological preservation, inevitably engender diminishing ecosystem service functionalities.

Monitoring public perceptions of contaminated sites based on social media

Contaminated sites have a negative impact on human health and the ecological environment, which can potentially lead to major pollution incidents, and frequently receive complaints and reports from the public. Therefore, monitoring public perceptions of contaminated sites is crucial for risk management. However, methods based on traditional questionnaire surveys are limited in terms of time, cost, and target audience size. The purpose of this study was to establish a method using social media to monitor public perceptions of contaminated sites in the Yangtze River Delta urban agglomeration. Thus, 6802 public opinions were collected from social media (mainly microblogs in China) and topic modeling and pollution and spatial mining techniques were employed. The topic modeling results indicated that public perceptions of contaminated sites mainly focused on the construction of prevention and control systems, law enforcement work, developments and challenges applicable to the coal industry, environmental public interest litigation (pertaining to pollution), pollution inspection and rectification, and green development and ecological governance, with intensities of 7.9%, 7.8%, 7.1%, 6.1%, 5.9%, and 4.8%, respectively. Three communities resulting from public opinions in the study area included “environment and pollution,” “enterprises,” and “environmental protection,” with proportions of 37.68%, 34.78%, and 27.54%, respectively. The field investigation results indicated that approximately 90% of the tweets in three typical cities (i.e., Taizhou City in Zhejiang Province and Wuxi and Changzhou Cities in Jiangsu Province) involved key industrial enterprises or contaminated sites located within 1 km of the surrounding areas. The emotional analysis indicated that >3401 tweets dealt with a pollution probability (i.e., the possibility of potentially contaminated sites mentioned in social media becoming contaminated sites) exceeding 0.90 for the period 2011–2021. This finding suggests that the pollution probability for the sites involved in these tweets was high. Our study provides methodological references for monitoring public perceptions of contaminated sites for large-scale, long-term, and high-resolution studies.

The Interaction Mechanism of Real Estate Market of Typical Cities in China: Analysis Based on VAR Model

As an important part of the national economy, the real estate market is closely related to macro policies, investor confidence, etc., and at the same time shows regional heterogeneity. This study explores the real estate market in four typical cities in China (Beijing, Xi'an, Xiamen, and Chengdu) and analyzes the correlation between real estate prices, sales area, real estate development investment, market investor confidence, and money supply. Through analysis based on the VAR model, it is found that the real estate markets in different cities present their own specific interactive influence patterns. The various factors in Beijing are more closely related and have a continuous impact; other cities have similar characteristics, and the impact of each factor is somewhat different. Therefore, when formulating real estate macro-management policies, it is necessary to consider the market characteristics of different cities and the comprehensive impact of external factors to formulate more targeted strategies and mitigate the potential impact of market fluctuations on the economy.

Impact of Meteorological Conditions on PM2.5 Pollution in Changchun and Associated Health Risks Analysis

The escalating concern regarding increasing air pollution and its impact on the health risks associated with PM2.5 in developing countries necessitates attention. Thus, this study utilizes the WRF-CMAQ model to simulate the effects of meteorological conditions on PM2.5 levels in Changchun, a typical city in China, during January 2017 and January 2020. Additionally, it introduces a novel health risk-based air quality index (NHAQI) to assess the influence of meteorological parameters and associated health risks. The findings indicate that in January 2020, the 2-m temperature (T2), 10-m wind speed (WS10), and planetary boundary layer height (PBLH) were lower compared to those in 2017, while air pressure exhibited a slight increase. These meteorological parameters, characterized by reduced wind speed, heightened air pressure, and lower boundary layer height—factors unfavorable for pollutant dispersion—collectively contribute to the accumulation of PM2.5 in the atmosphere. Moreover, the NHAQI proves to be more effective in evaluating health risks compared to the air quality index (AQI). The annual average decrease in NHAQI across six municipal districts from 2017 to 2020 amounts to 18.05%. Notably, the highest health risks are observed during the winter among the four seasons, particularly in densely populated areas. The pollutants contributing the most to the total excess risk (ERtotal) are PM2.5 (45.46%), PM10 (33.30%), and O3 (13.57%) in 2017, and PM2.5 (67.41%), PM10 (22.32%), and O3 (8.41%) in 2020. These results underscore the ongoing necessity for PM2.5 emission control measures while emphasizing the importance of considering meteorological parameters in the development of PM2.5 reduction strategies.

Neutralizing the sacred space: pre-election messages in a typical Indonesian city

AbstractDespite frequent claims that religion serves as a motivator of political behavior in Muslim-majority contexts, empirical evidence of political messaging in sacred spaces is scant. Building on earlier studies on political messaging in both churches and mosques, we examine the presence and nature of political messages across Muslim and Christian religious contexts in a typical Indonesian city, Yogyakarta. Through an analysis of 71 sermons that took place in mosques and churches prior to elections in 2017 and 2019, we analyze the frequency, style, tone, and consistency of political content. We find that political messages within individual houses of worship were often inconsistent from week to week, reducing their potential as a mobilizing force for political action. We also find that houses of worship frequently sought to present themselves as politically neutral spaces in an electoral context in which religious themes are politicized.