Search Results (26)

Mitigating traffic-related carbon emissions is pivotal for achieving carbon peaking targets and advancing sustainable urban development. This study employs spatial autocorrelation and high-low clustering analyses to analyze the spatial correlation and clustering patterns of urban road traffic carbon emissions in Shaanxi Province. The spatiotemporal evolution and structural impacts of emissions are quantified through a systematic framework, while the GTWR (Geographically Weighted Temporal Regression) model uncovers the multidimensional and heterogeneous driving mechanisms underlying carbon emissions. Findings reveal that road traffic CO₂ emissions in Shaanxi exhibit an upward trajectory, with a temporal evolution marked by distinct phases: “stable growth—rapid increase—gradual decline”. Emission dynamics vary significantly across transport modes: private vehicles emerge as the primary emission source, taxi/motorcycle emissions remain relatively stable, and bus/electric vehicle emissions persist at low levels. Spatially, the province demonstrates a pronounced high-carbon spillover effect, with persistent high-value clusters concentrated in central Shaanxi and the northern region of Yan’an City, exhibiting spillover effects on adjacent urban areas. Notably, the spatial distribution of CO₂ emissions has evolved significantly: a relatively balanced pattern across cities in 2010 transitioned to a pronounced “M”-shaped gradient along the north–south axis by 2015, stabilizing by 2020. The central urban cluster (Yan’an, Tongchuan, Xianyang, Baoji) initially formed a secondary low-carbon core, which later integrated into the regional emission gradient. By focusing on the micro-level dynamics of urban road traffic and its internal structural complexities—while incorporating built environment factors such as network layout, travel behavior, and infrastructure endowments—this study contributes novel insights to the transportation carbon emission literature, offering a robust framework for regional emission mitigation strategies. Full article

Background: In recent years, enzootic nasal tumor virus 2 (ENTV-2) has become prevalent in China, resulting in substantial economic losses for the goat industry. In order to enrich the availability of detection methods for ENTV-2, this study developed an expedited and accurate reverse-transcription quantitative real-time polymerase chain reaction (RT-qPCR) assay to facilitate the detection and quantification of ENTV-2. Methods: Specifically, a pair of primers and a TaqMan probe targeting conserved regions of the pro gene were designed to allow the specific amplification and detection of viral RNA in clinical samples. Moreover, modifying the method for use in a quantitative real-time PCR (qPCR) assay enables the detection of proviral DNA in tumor specimens. Results: Both methods exhibited a detection limit for the ENTV-2 standard plasmid at 10⁰ copies/µL. The detection methods we established exhibited high specificity and sensitivity to ENTV-2, without cross-reactivity with other pathogens causing respiratory diseases or endogenous retroviruses (EBRVs). We performed an ENTV-2 analysis of clinical samples in goats via RT-qPCR using nasal swab samples (n = 558) collected from three geographically distinct flocks in Lingyou County, Baoji City, Shaanxi Province, China, and 58 positive samples were detected for a positivity rate of 10.4%. After euthanasia, the autopsy report showed nasal cavity masses. Histopathological analysis demonstrated an epithelial neoplasm, in compliance with the features of enzootic nasal adenocarcinoma (ENA). Three full-length genomes were sequenced to assess genomic sequence conservation and variation. Multiple-sequence alignment demonstrated the existence of sequence variations among strains. Phylogenetic analysis of the nucleotide sequences revealed that the ENTV-2 SX1~3 isolates were phylogenetically related to the Chinese ENTV-2 isolates, especially the JY strain. Furthermore, recombination analysis suggested that both ENTV-2 SX1 and ENTV-2 SX2 might be recombinant variants. Conclusions: In conclusion, both methods are highly specific for the pro gene of ENTV-2, and the development of this assay has been deemed crucial to the early identification and subsequent control of this viral infection. Our results provide valuable information for further research on the genetic variation and evolution of ENTV-2 in China. Full article

The experiment of loess crack development under dry–wet cycle conditions is of great significance for the study of groundwater preferential flow channels and the prevention and control of infrastructure engineering disasters in loess areas. The loess samples in Chencang District of Baoji City, Shaanxi Province, were taken as the samples in the test. The multiple humidification and dehumidification tests were used to simulate multiple rainfall evaporation, and the moisture content changes in the loess samples during the dry–wet cycle were calculated. With the help of digital image technology, the fracture parameters of the loess samples were extracted, and the variation law of crack parameters was analyzed by combining fractal dimension, Bayesian factor, and Pearson correlation coefficient. The findings indicate that variations in soil moisture content and the number of dry and wet cycles contribute to fluctuations in soil evaporation rates, resulting in varying degrees of soil cracking development. The increase in the number of dry and wet cycles leads to evident soil shrinkage, an accelerated water evaporation process, pronounced surface deterioration, and a higher degree of crack development. The rate of crack propagation varies at different locations, with a higher rate observed in the horizontal plane compared to the vertical plane. The influence of temperature and humidity varies due to the different dimensions of cracks (horizontal and vertical). Horizontal crack development is primarily influenced by temperature, while vertical crack development is primarily influenced by humidity. Temperature and humidity inhibit each other. When one factor is dominant, the other indirectly affects crack development by influencing the dominant factor. The research findings can serve as a valuable reference for effectively mitigating and minimizing the impact of crack development-induced disasters. Full article

Background: Plovers (Charadriidae), within the order of Charadriiformes, a group of modern birds distributed worldwide, are a frequent subject of molecular phylogenetic studies. While research on mitochondrial genome (mitogenome) variation within the family Charadriidae, especially intraspecific variation, is limited. Additionally, the monophyly of Charadrius and the phylogenetic placement of Pluvialis remain contentious. Nevertheless, recent studies utilizing complete mitogenomes from available databases to construct phylogenetic trees for Charadriidae and Charadriiformes remain scarce. Methods: This study aims to explore mitogenome variation within Charadrius dubius and clarify the phylogenetic placement of Pluvialis fulva. We sequenced the complete mitogenome of six C. dubius and one P. fulva, and all additional available mitogenomes were integrated within Charadriiformes. The average complete mitogenome length of C. dubius is 16,889 bp, and P. fulva is 16,859 bp. Results: Our results support the suggestion that the monophyly of Charadrius and P. fulva is nested within Charadriidae. The phylogenetic analysis of Charadriiformes based on mitogenomes strongly supports the recognition of three major shorebird clades: Charadrii, Lari and Scolopaci, with Lari and Scolopaci identified as sister clades. Conclusions: Our study reinforces the credibility of the inferred evolutionary relationships within Charadriidae and Charadriiformes. Full article

In recent years, the increasing frequency of extreme weather events has exacerbated the severity of geological disasters. Therefore, it is important to understand the mechanisms of geological disasters under extreme rainfall conditions. From June to October 2021, Baoji City, Shanxi Province, China, experienced some extreme and continuous heavy rainfalls, which triggered more than 30 geological disasters. Those geo-disasters threatened the lives of 831 people and the safety of 195 houses. The field investigations found that most of these geological disasters were devastating collapses that occurred in the loess layer, primarily due to the cave dwelling construction. The shear strength, montmorillonite content, disintegration degree, and plasticity index of two typical loesses, namely the Sanmen Formation stiff clay and the Hipparion red clay, were analyzed, and their water sensitivities were evaluated. The failure mechanisms of the landslides, ground fissures, and collapses were analyzed and most of them were controlled by the cave dwelling construction and the strong water sensitivity of the loess. This study provides data for understanding shallow geological disasters induced by extreme rainfall in the loess area, which are more threatening than large geological disasters. We proposed an intensity–duration (I–D) rainfall threshold as I = 90 D^−0.92, which relates the rainfall intensity (I) to the rainfall event duration (D). The empirical threshold provides some useful information for the early warning of collapses or landslides in similar geological settings in the loess area. Full article

The Shaanxi section is the central region of the Loess Plateau. Its unique wetland environment plays an indispensable role in regional ecological environment security. Clarifying the characteristics of wetland changes in the region is an important prerequisite for wetland management and protection. This study, based on the remote sensing data of the Shaanxi section of the Loess Plateau, analyzed the changes in the wetland area and type transfer in this region in 1980, 1990, 2000, 2010 and 2020 using the wetland dynamic degree model, the Markov transfer matrix, the landscape pattern index, and centroid analysis. The results showed that, from 1980 to 2020, the total wetland area and natural wetland area in the Shaanxi section of the Loess Plateau continued to shrink, decreasing by 79.35 km² and 80.50 km², respectively, while the artificial wetland area increased by 1.14 km². Among the regions, Xi’an experienced the most significant reduction, with a total decrease of 83.04 km² over 40 years, followed by Xianyang City, where the wetland area decreased by 6.50 km². In contrast, the wetland areas of Yulin City, Weinan City, Yan’an City, Baoji City and Tongchuan City increased slightly. From 1980 to 2020, the change in the wetland types in the Shaanxi section of the Loess Plateau was mainly characterized by transfers between beach lands and river canals. River canals are the primary type of wetland in this region. The degree of fragmentation is the highest in reservoir potholes, while marshes have the largest clumpiness index. Over the same period, the centroid of the wetlands in the Shaanxi section of the Loess Plateau moved from south to north as a whole, although, between 1990 and 2000, the centroid position remained relatively stable. These results provide a theoretical basis and data support for wetland monitoring and protection in the Shaanxi section of the Loess Plateau and also provide a reference for the protection and sustainable development of other inland wetland resources in arid and semi-arid regions. Full article

The utilization of the Monte Carlo method in conjunction with probabilistic seismic hazard analysis (PSHA) constitutes a compelling avenue for exploration. This approach presents itself as an efficient and adaptable alternative to conventional PSHA, particularly when confronted with intricate factors such as parameter uncertainties and diverse earthquake source models. Leveraging the Monte Carlo method and drawing from the widely adopted Cornell-type seismicity model in engineering seismology and disaster mitigation, as well as a seismicity model capturing temporal, spatial, and magnitude inhomogeneity, we have derived a formula for the probability of earthquake intensity occurrence and the mean rate of intensity occurrence over a specified time period. This effort has culminated in the development of a MATLAB-based program named MCPSHA. To assess the model’s efficacy, we selected Baoji City, Shaanxi Province, China, as our research site. Our investigation delves into the disparity between occurrence probability and extreme probability (a surrogate commonly employed for occurrence probability) in the Baoji region over the next 50 years. The findings reveal that the Western region of Baoji exhibits a heightened hazard level, as depicted in the maps, which illustrate a 10% probability of exceedance within a 50-year timeframe. The probability of earthquake occurrence under various intensities (VI, VII, and VIII) over 50 years follows a declining trend from west to east. Furthermore, the likelihood of seismic intensity exceeding VI, VII, and VIII indicates the lowest exceeding probability in the northeast and the highest in the northwest. Notably, for intensities VI-VII, the difference between occurrence probability and extreme probability approaches twice, gradually diminishing with increasing intensity. This study underscores the MCPSHA model’s efficacy in providing robust technical support for mitigating earthquake risk and enhancing the precision of earthquake insurance premium rate calculations. Full article

An intensive field campaign was carried out from December 2022 to March 2023 at six different sites across five major cities (Xi’an, Baoji, Xianyang, Weinan, and Hancheng) in the Guanzhong Basin, China, covering most of the heating period there, which is characterized by high PM_2.5 pollution levels. During the campaign, the mean PM_2.5 concentrations at these sites exceeded the 24 h PM_2.5 standard (75 μg m⁻³), except the site at Hancheng, with mean PM_2.5 concentrations of 57.8 ± 32.3 μg m⁻³. The source apportionment of PM_2.5 varied significantly across sites, with vehicle exhaust being the dominant source at urban sites located in Xi’an and Baoji, coal combustion at suburban sites in Hancheng, and comparable contribution from coal combustion and industrial emissions at suburban sites in Xianyang and Weinan. Compared with clean condition, the contribution of vehicle exhaust and secondary inorganic sources (SIs) were largely enhanced during heavy PM_2.5 pollution periods, while the contribution from biomass burning (BB) and dust decreased significantly at all sites. Combined with an analysis of meteorological parameters, the study further found that higher contributions of SIs and heavy PM_2.5 pollution were generally associated with higher relative humidity (RH). In addition, higher PM_2.5 concentrations at suburban sites were related to lower wind speeds, which could be explained by the stagnant condition favoring the accumulation of local emissions as well as the formation of secondary pollutants. In contrast, at urban sites (e.g., Xianyang), higher PM_2.5 concentrations were more associated with the strong influence of vehicle exhaust at slightly higher wind speeds. Full article

In the new period of ups and downs in the international environment, it is necessary to seek a new endogenous impetus for the economic growth of urban agglomerations. Population agglomeration provides a new idea to explain the spatial differences in the economic growth of urban agglomerations. Thus, we ask the question, does population agglomeration affect the spatial differences in the economic growth of urban agglomerations, and how? This study first measured the spatial differences in district- and county-scale economic growth in China’s Guanzhong Plain urban agglomeration from 2005 to 2020 and then constructed an empirical formula to calculate the impact of population density on the urban agglomeration’s economic growth, taking into account the roles of both intra- and inter-district and county interactions. Thus, based on the population density data extracted from nighttime lighting data, we analyzed the impact of population density on economic growth within urban agglomerations, as well as the extent of the impact of population density on economic growth when incorporating spillover effects from neighboring districts and counties. The results indicate that, firstly, the Guanzhong Plain urban agglomeration in China has formed a “core-periphery” development pattern, with the main urban areas of Xi’an–Xianyang and Baoji as the core and the core area gradually spreading out to the neighboring districts and counties of their cities. Secondly, population density can significantly and steadily promote the economic growth of the districts and counties within the urban agglomeration, and the population agglomeration of districts and counties with railway stations can have a stronger effect on the economic growth of these districts and counties. Third, the agglomeration of economic and demographic factors in neighboring counties has a positive spillover effect on the local economy, while the positive impact of population density on economic growth remains unchanged when it is integrated into the spillover effect of neighboring counties. This study not only provides a theoretical basis for systematically exploring the influence of population density on the economic growth of urban agglomerations but also provides a reference for local governments to formulate policies related to regional economic development and spatial territorial planning. According to the research conclusion, this study suggests that local governments can continue to promote the regional development policy of spatial agglomeration and intensive land planning, strengthen the construction of the industrial chain and road network within the urban agglomeration, and deepen the network connection between districts and counties. Full article

The dynamic characteristics of a multi-span double-curved brick arch thin-shell factory of Changleyuan in Baoji City and the dynamic response to train vibration load were studied using field dynamic tests and finite-element numerical simulations, and a vibration evaluation of the thin-shell factory was carried out. The results showed that the first-order frequency of the thin-shell factory was 6.24 Hz in the horizontal direction (east–west) and 9.31 Hz in the vertical direction. Moreover, it was established that the horizontal vibration is the overall vibration of the factory, while the vertical vibration is the individual vibration of the double-curved brick arch. In addition, the self-oscillation frequency obtained from the numerical simulation results was greater compared with the field measurements, with a maximum error rate of 7.14%. Both in acceleration and velocity, the vertical vibration for each measurement point was larger than the horizontal vibration, and the farther away from the railroad, the smaller the vibration. The vibration of the velocity at the bottom of the arch was almost the same as that at the top of the arch, while the acceleration vibration at the bottom of the arch was significantly larger than that at the top of the arch, with an average amplitude of 40.64%. For every 20 km/h increase in train running speed, the average increase in vertical acceleration amplitude, vertical velocity amplitude, horizontal acceleration amplitude, and horizontal velocity amplitude for each measurement point of the thin-shell factory was 35.4%, 29.8%, 23.7%, and 12.5%, respectively. When v = 150 km/h, the maximum velocity amplitude for each measurement point of the thin-shell factory was 1.163 mm/s, which is less than the security specification limit of 2.5 mm/s, such that the security of the thin-shell factory meets the requirement, and the maximum horizontal velocity amplitude was 0.272 mm/s, which is close to the integrity specification limit of 0.27 mm/s, such that the integrity of the thin-shell factory just exceeds the requirement; so it is suggested that train running speeds should not exceed 150 km/h and that the thin-shell factory needs to strengthen the monitoring and protection of its integrity. Full article

Urban fugitive dust is a significant contributor to atmospheric PM_2.5 and a potential risk to humans. In 2019, both road dust and construction dust were collected from four cities, including Xi’an, Xianyang, Baoji, and Tongchuan, in Guanzhong Plain, China. Elements, water-soluble ions, and carbonaceous fractions were determined to establish the chemical source profile. High enrichment degrees of Se, Sc, Cl, and Zn in both road dust and construction dust indicated that the industrial system and energy consumption influenced Guanzhong Plain strongly. According to the coefficient of divergence, the two datasets within Xianyang and Tongchuan were similar. Combined with the chemical profile, road dust was affected by more stationary emission sources than construction dust in Xi’an, while biomass burning and vehicle exhaust contributed more to road dust than construction dust in Baoji. Moreover, the health risk of heavy metal was assessed, and corresponding influencing factors were identified. Road dust in all cities showed a non-negligible non-carcinogenic risk for children. Ingestion and inhalation were the main exposure pathways to which As and Co contributed the most, respectively. The land-use regression model revealed that the first-class road in a 100 m radius impacted all high-risk level metals, and the commercial building material and enterprises weakly influenced Co and Pb, respectively. Full article

With the continuous development of computer vision technology, more and more landslide identification detection tasks have started to shift from manual visual interpretation to automatic computer identification, and automatic landslide detection methods based on remote sensing satellite images and deep learning have been gradually developed. However, most existing algorithms often have the problem of low precision and weak generalization in landslide detection. Based on the Google Earth Engine platform, this study selected landslide image data from 24 study areas in China and established the DN landslide sample dataset, which contains a total of 1440 landslide samples. The original YOLOv7 algorithm model was improved and optimized by applying the SE squeezed attention mechanism and VariFocal loss function to construct the SE-YOLOv7 model to realize the automatic detection of landslides in remote sensing images. The experimental results show that the mAP, Precision value, Recall value, and F1-Score of the improved SE-YOLOv7 model for landslide identification are 91.15%, 93.35%, 94.54%, and 93.94%, respectively. At the same time, through a field investigation and verification study in Qianyang County, Baoji City, Shaanxi Province, comparing the detection results of SE-YOLOv7, it is concluded that the improved SE-YOLOv7 can locate the landslide location more accurately, detect the landslide range more accurately, and have fewer missed detections. The research results show that the algorithm model has strong detection accuracy for many types of landslide image data, which provides a technical reference for future research on landslide detection based on remote sensing images. Full article

Element flow has gradually become an important method for studying urban spatial structure. This study examined 11 prefectural cities in the Guanzhong Plain urban agglomeration; constructed a measurement model for information, traffic, migration, and composite networks; and analyzed the spatial structure of the urban network of the urban agglomeration through social network analysis and spatial visualization. The spatial structure of the composite flow network had Xi’an as the center and Xianyang, Baoji, Weinan and Tianshui as important nodes; Yuncheng, Linfen and Qingyang were the secondary nodes, radiating to the surrounding three cities. Element flow connection strength was unbalanced, and only three city pairs were in the first level of the composite flow network. Network density was low-middle, and the network connection was weak. Xi’an was the primary central city of the Guanzhong Plain urban agglomeration with the strongest agglomeration and radiation capabilities; it could communicate with other cities without intermediate cities and was a bridge for other cities. Tongchuan, Pingliang, Shangluo, and Qingyang were at the edge of the urban agglomeration and had weak agglomeration, radiation, and intermediary capabilities. The inner cities of cohesive subgroups were closely related with weak connections between subgroups. The single-polarization of the Guanzhong Plain urban agglomeration was serious, and the single-core spatial structure centered on Xi’an had limited impact on the urban agglomeration. Development of small and medium-sized cities should be strengthened in the future. Full article

Baoji is a medium-sized city in the Guanzhong Plain of northwest China. The compositions of three important organic groups, namely n-alkanes, polycyclic aromatic hydrocarbons (PAHs), and saccharides in atmospheric aerosol with different aerodynamic diameters in power were determined. Both seasonal and daily trends of the target organic chemical groups were demonstrated. The concentration levels of total quantified n-alkanes and saccharides in total suspended particles (TSP) in winter were 541 ± 39 and 651 ± 74 ng·m⁻³, respectively, much higher than those of the other three seasons. A high total quantified PAHs concentration level of 59.6 ± 6.4 ng·m⁻³ was also seen in wintertime. n-Alkanes showed a bimodal percent distribution in spring, autumn, and winter. Two peaks were found with the particle sizes of 0.7 μm < Dp < 2.1 μm and 3.3 μm < Dp < 4.7 μm, respectively. In summer, a unimodal was seen with a peak of 4.7 μm < Dp < 5.8 μm. Dehydrated saccharides and PAHs present a unimodal size distribution peaking at the aerodynamic diameters of 0.7 µm < Dp < 2.1 µm. In contrast to glucose and fructose, they mainly exist in the coarse mode particles and have the highest concentrations at aerodynamic diameters of 4.7 µm < Dp < 9.0 µm. The geometric mean diameters (GMD) of n-alkanes and saccharides of the fine particles in winter were higher than in the other seasons. Compared with the data in 2008, the fossil fuel-derived n-alkanes and PAHs in winter decreased by nearly an order of magnitude in 2017. Both the carbon preference index (CPI) of n-alkanes and the diagnostic ratios of PAHs suggest that coal combustion and vehicle exhaust were the major pollution sources of the organic groups in the two decades. It should be noted that the contribution of traffic emissions greatly increased from 2008 to 2017, consistently with a large raise of registered vehicles in Baoji city. The overall results confirm that the control measures conducted by the local government in the recent decade mitigated the air pollution in this city. Full article

Urban green spaces (UGSs) are indispensable for providing various ecosystem services (ESs) to society and city-dwellers. The equitable allocation of ESs provided by UGSs is a prerequisite for maintaining urban sustainability and human well-being. However, empirical studies have assessed the dynamics of UGS equity from ES facets, while neglecting to strengthen integrated evaluation indicators and coupled spatially explicit models. A framework was developed in this study to assess the spatio-temporal patterns of ESs provided by UGSs and their equity based on models of the Intelligent Urban Ecosystem Management System, location entropy, and the Gini coefficient. The results indicated that with urban spatial expansion, in each concentric circle, the values of three ES averages were generally the lowest in the megacity (Xi’an), and the values of carbon sequestration and the recreation averages in the medium-sized cities (Baoji and Xianyang) were also lower than in the small-sized city (Tongchuan). The inequity of ESs provided by UGSs was exacerbated from 2000 to 2020 in the Xi’an Metropolitan Area. The ES equity was the worst in Xi’an and the best in Tongchuan. Areas with extremely low CR location entropy occupied 67.01% in 2020. As cities spatially expanded, areas with extremely low ES location entropy generally increased in 2020. Additionally, the zero-value area of the ES Gini coefficient in Xi’an was the largest from 2000 to 2020. The ES Gini values mostly increased in the same concentric circle of each city in 2020, which demonstrates that equity declined. Spatial equity could be improved by diversifying UGS structures, promoting spatial matching between the ES supply and beneficiaries’ demands, and integrating UGSs into any available space in future UGS planning. The findings of the study could offer insights for optimizing the equitable provision of UGS resources and the targeted planning of urban greening. Full article