Majority of carbon emissions originate from fossil energy consumption,thus necessitating calculation and monitoring of carbon emissions from energy consumption.In this study,we utilized energy consumption data from Si...Majority of carbon emissions originate from fossil energy consumption,thus necessitating calculation and monitoring of carbon emissions from energy consumption.In this study,we utilized energy consumption data from Sichuan Province and Chongqing Municipality for the years 2000 to 2019 to estimate their statistical carbon emissions.We then employed nighttime light data to downscale and infer the spatial distribution of carbon emissions at the county level within the Chengdu-Chongqing urban agglomeration.Furthermore,we analyzed the spatial pattern of carbon emissions at the county level using the coefficient of variation and spatial autocorrelation,and we used the Geographically and Temporally Weighted Regression(GTWR)model to analyze the influencing factors of carbon emissions at this scale.The results of this study are as follows:(1)from 2000 to 2019,the overall carbon emissions in the Chengdu-Chongqing urban agglomeration showed an increasing trend followed by a decrease,with an average annual growth rate of 4.24%.However,in recent years,it has stabilized,and 2012 was the peak year for carbon emissions in the Chengdu-Chongqing urban agglomeration;(2)carbon emissions exhibited significant spatial clustering,with high-high clustering observed in the core urban areas of Chengdu and Chongqing and low-low clustering in the southern counties of the Chengdu-Chongqing urban agglomeration;(3)factors such as GDP,population(Pop),urbanization rate(Ur),and industrialization structure(Ic)all showed a significant influence on carbon emissions;(4)the spatial heterogeneity of each influencing factor was evident.展开更多
This paper focuses on Chengdu and Chongqing’s positioning as important economic center in western China and their evolving into an economic center of national influence.On the one hand,it uses the synthetic differenc...This paper focuses on Chengdu and Chongqing’s positioning as important economic center in western China and their evolving into an economic center of national influence.On the one hand,it uses the synthetic difference-in-differences(SDID)method to analyze the impact of policies since 2011 designed to build Chengdu and Chongqing into an important economic center in western China.On the other hand,it employs the entropy-weighted TOPSIS method to comprehensively evaluate the influences of ten core Chinese cities as economic centers within four major urban agglomerations,as well as conduct an analytical assessment of the Chengdu-Chongqing economic circle from key perspectives such as its capacity to lead,capacity to agglomerate,and capacity to radiate.From a longitudinal historical perspective,both Chengdu and Chongqing have benefited significantly from policies designed to build an important economic center in western China,and which laid a foundation for building an economic center of national influence.From a horizontal regional comparison,among the ten core cities evaluated as economic centers within the four major urban agglomerations,Chengdu and Chongqing ranked in the middle,possessing a moderate but not yet outstanding influence.Consequently,to evolve into an economic center of national influence,the Chengdu-Chongqing economic circle should leverage its relative advantages in connectivity,market size,value chain division of labor,policy attractiveness,and industry development.It can enhance its influence by strengthening the complementarity of its economic resources,overcoming the administrative inertia,accelerating the establishment of a regional innovation system,broadening the scope of its economic radiation,and promoting its comprehensive and all-dimensional opening-up.展开更多
Chengdu,a city rich in history and culture,is a beacon of China’s storied past embracing a distinct postmodern vibe.As an important hub along the ancient Silk Road,it has long been a meeting point for di!erent civili...Chengdu,a city rich in history and culture,is a beacon of China’s storied past embracing a distinct postmodern vibe.As an important hub along the ancient Silk Road,it has long been a meeting point for di!erent civilizations,where ideas and cultures have exchanged and thrived.Driven by the vision of a community with a shared future for mankind in recent years,Chengdu scholars and media have opened their arms to the world,engaging in multilingual storytelling.These efforts share the warmth and goodwill of a city consistently ranked one of the happiest in China.Through consistent efforts,new insights have emerged—ideas and aspirations intended to be shared with readers both at home and abroad.展开更多
As a key mode of transportation, urban metro networks have significantly enhanced urban traffic environments and travel efficiency, making the identification of critical stations within these networks increasingly ess...As a key mode of transportation, urban metro networks have significantly enhanced urban traffic environments and travel efficiency, making the identification of critical stations within these networks increasingly essential. This study presents a novel integrated topological-functional(ITF) algorithm for identifying critical nodes, combining topological metrics such as K-shell decomposition, node information entropy, and neighbor overlapping interaction with the functional attributes of passenger flow operations, while also considering the coupling effects between metro and bus networks. Using the Chengdu metro network as a case study, the effectiveness of the algorithm under different conditions is validated.The results indicate significant differences in passenger flow patterns between working and non-working days, leading to varying sets of critical nodes across these scenarios. Moreover, the ITF algorithm demonstrates a marked improvement in the accuracy of critical node identification compared to existing methods. This conclusion is supported by the analysis of changes in the overall network structure and relative global operational efficiency following targeted attacks on the identified critical nodes. The findings provide valuable insight into urban transportation planning, offering theoretical and practical guidance for improving metro network safety and resilience.展开更多
To investigate the seasonal characteristics in air pollution in Chengdu,a single particle aerosol mass spectrometry was used to continuously observe atmospheric fine particulate matter during one-month periods in summ...To investigate the seasonal characteristics in air pollution in Chengdu,a single particle aerosol mass spectrometry was used to continuously observe atmospheric fine particulate matter during one-month periods in summer and winter,respectively.The results showed that,apart from O_(3),the concentrations of other pollutants(CO,NO_(2),SO_(2),PM_(2.5)and PM_(10))were significantly higher in winter than in summer.All single particle aerosols were divided into seven categories:biomass burning(BB),coal combustion(CC),Dust,vehicle emission(VE),K mixedwith nitrate(K-NO_(3)),Kmixed with sulfate and nitrate(K-SN),and K mixedwith sulfate(K-SO_(4))particles.The highest contributions in both seasons were VE particles(24%).The higher contributions of K-SO_(4)(16%)and K-NO_(3)(10%)particles occurred in summer and winter,respectively,as a result of their different formation mechanisms.S-containing(KSO_(4)and K-SN),VE,and BB particles caused the evolution of pollution in both seasons,and they can be considered as targets for future pollution reduction.The mixing of primary sources particles(VE,Dust,CC,and BB)with secondary components was stronger in winter than in summer.In summer,as pollution worsens,the mixing of primary sources particles with 62[NO_(3)]−weakened,but themixing with 97[HSO_(4)]−increased.However,in winter,the mixing state of particles did not exhibit an obvious evolution rules.The potential source areas in summer were mainly distributed in the southern region of Sichuan,while in winter,besides the southern region,the contribution of the western region cannot be ignored.展开更多
Mainstream media play a crucial role in constructing the cultural memory of a city.This study used 319 short videos released by“Hi Chengdu,”a new media product of Chengdu Radio and Television,as samples.Based on the...Mainstream media play a crucial role in constructing the cultural memory of a city.This study used 319 short videos released by“Hi Chengdu,”a new media product of Chengdu Radio and Television,as samples.Based on the grounded theory,a research framework encompassing“content,technology,and discourse”was established to explore the paths through which mainstream media construct the cultural memory.Regarding content,this paper emphasized temporal and spatial contexts and urban spaces,delving deep into the themes of the cultural memory and vehicles for it.In terms of technology,this paper discussed the practice of leveraging audio/visual-mode discourse to stitch together the impressions of a city and evoke emotional resonance to create a“flow”of memory.As for discourse,this paper looked at the performance of a communication ritual to frame concepts and shape urban identity.It is essential to break free from conventional thinking and leverage local culture as the primary driving force to further boost a city’s productivity,in order to excel in cultural communication.展开更多
Urban-suburban-rural(U-S-R)zones exhibit distinctive transitional characteristics in interaction between human and nature.U-S-R transition zones(U-S-RTZ)are also highlighting the function diversity and landscape heter...Urban-suburban-rural(U-S-R)zones exhibit distinctive transitional characteristics in interaction between human and nature.U-S-R transition zones(U-S-RTZ)are also highlighting the function diversity and landscape heterogeneity across territorial spaces.As a super megacity in western China,Chengdu’s rapid urbanization has driven the evolution of U-S-R spaces,resulting in a sequential structure.To promote the high-quality spatial development of urban-rural region in a structured and efficient manner,it is essential to con-duct a scientific examination of the multidimensional interconnection within the U-S-RTZ framework.By proposing a novel identifica-tion method of U-S-RTZ and taking Chengdu,China as a case study,grounded in a blender of natural and humanistic factors,this study quantitatively delineated and explored the spatial evolutions of U-S-RTZ and stated the optimization orientation and sustainable devel-opment strategies of the production-living-ecological spaces along the U-S-R gradients.The results show that:1)it is suitable for the quantitative analysis of U-S-RTZ by established three-dimensional identification system in this study.2)In 1990-2020,the urban-sub-urban transition zones(U-STZ)in Chengdu have continuously undergone a substantial increase,and the scale of the suburban-rural transition zones(S-RTZ)has continued to expand slightly,while the space of rural-ecological transition zones(R-ETZ)has noticeably compressed.3)The landuse dynamics within U-S-RTZ has gradually increased in 1990-2020.The main direction of landuse transition was from farmland to construction land or woodlands,with the expansion of construction land being the most significant.4)R-ETZ primarily focus on ecological functions,and there is a trade-off relationship between the production-ecological function within the S-RTZ,and in the U-STZ,production-living composite functions are prioritized.This study emphasizes the importance of elastic planning and precise governance within the U-S-RTZ in a rapid urbanization region,particularly highlighting the role of suburbs as landscape corridors and service hubs in urban-rural integration.It elucidates to the practical implications for achieving high-quality development of integrated U-S-R territorial spaces.展开更多
Single-particle aerosol mass spectrometry was used to study the characteristics of Fecontaining particles during winter in Chengdu,southwest China.The mass concentrations of PM_(2.5)and PM_(10)during the study period ...Single-particle aerosol mass spectrometry was used to study the characteristics of Fecontaining particles during winter in Chengdu,southwest China.The mass concentrations of PM_(2.5)and PM_(10)during the study period were 64±38 and 89±49μg/m~3,respectively,and NO_(2)and particulate matter were high compared with most other regions of China.The Fecontaining particles were divided into seven categories with different mass spectra,sources and aging characteristics.The highest contribution was from Fe mixed with carbonaceous components(Fe-C,23.1%)particles.Fe was more mixed with sulfate than nitrate and therefore the contribution of Fe mixed with sulfate(Fe-S,20.7%)particles was higher than that of Fe mixed with nitrate(Fe-N,12.5%)particles.The contributions from Fe-containing particles related to primary combustion were high in the small particle size range,whereas aged Fecontaining particles and dust-related particles were mostly found in the coarse particle size range.The air masses mainly originated from the west and east of Chengdu,and the corresponding PM_(2.5)concentrations were 79±36 and 55±36μg/m~3,respectively.The west and east air masses showed stronger contributions of Fe-containing particles related to biomass burning(Fe-B)and fossil fuel combustion(Fe-C and Fe-S)particles,respectively.The southwest area contributed the most Fe-containing particles.Future assessments of the effects of Fe-containing particles during heavy pollution period should pay more attention to Fe-C and Fe-S particles.Emission-reduction of Fe-containing particles should consider both local emissions and short-distance transmission from the surrounding areas.展开更多
The air quality in China has improved significantly in the last decade and,correspondingly,the characteristics of PM_(2.5)have also changed.We studied the interannual variation of PM_(2.5)in Chengdu,one of the most he...The air quality in China has improved significantly in the last decade and,correspondingly,the characteristics of PM_(2.5)have also changed.We studied the interannual variation of PM_(2.5)in Chengdu,one of the most heavily polluted megacities in southwest China,during the most polluted season(winter).Our results show that the mass concentrations of PM_(2.5)decreased significantly year-by-year,from 195.8±91.0μg/m~3in winter 2016 to 96.1±39.3μg/m^(3)in winter 2020.The mass concentrations of organic matter(OM),SO_()4^(2-),NH_(4)^(+)and NO_(3)^(-)decreased by 49.6%,57.1%,49.7% and 28.7%,respectively.The differential reduction in the concentrations of chemical components increased the contributions from secondary organic carbon and NO_(3)^(-)and there was a larger contribution from mobile sources.The contribution of OM and NO_(3)^(-)not only increased with increasing levels of pollution,but also increased year-by-year at the same level of pollution.Four sources of PM_(2.5)were identified:combustion sources,vehicular emissions,dust and secondary aerosols.Secondary aerosols made the highest contribution and increased year-by-year,from 40.6%in winter 2016 to 46.3% in winter 2020.By contrast,the contribution from combustion sources decreased from 14.4% to 8.7%.Our results show the effectiveness of earlier pollution reduction policies and emphasizes that priority should be given to key pollutants(e.g.,OM and NO_(3)^(-))and sources(secondary aerosols and vehicular emissions)in future policies for the reduction of pollution in Chengdu during the winter months.展开更多
This paper developed a comprehensive evaluation system that was able to quantify the levels of high-quality development across the cities within the Chengdu-Chongqing economic circle,and investigate the impact that di...This paper developed a comprehensive evaluation system that was able to quantify the levels of high-quality development across the cities within the Chengdu-Chongqing economic circle,and investigate the impact that digital finance had on the cities’high-quality development and the underlying mechanisms through which it achieved this.This comprehensive evaluation system was constructed using statistical data from these cities for the period 2014 to 2020 while also taking China’s high-quality development philosophy into account.The key findings revealed that:(a)Digital finance was able to significantly promote high-quality development in the Chengdu-Chongqing economic circle;(b)Digital finance had a significant positive effect in promoting innovative,coordinated,green,open,and shared development;(c)Digital finance was able to stimulate the high-quality development in the Chengdu-Chongqing economic circle by boosting entrepreneurial dynamism;(d)Digital finance had a significant impact on the high-quality development of the axis areas,while its impact was less discernible in non-axis areas.The insights from this research offer a deeper understanding of the factors that drive high-quality development,the role digital finance plays,and the mechanisms through which digital finance is able to propel high-quality development at the city cluster scale.展开更多
Significant epidemiological research has revealed that exposure to air pollution is substantially associated with numerous detrimental health consequences^([1-3]).The negative health effects of individual air pollutan...Significant epidemiological research has revealed that exposure to air pollution is substantially associated with numerous detrimental health consequences^([1-3]).The negative health effects of individual air pollutants(e.g.,fine particulate matter:PM_(2.5);nitrogen dioxide:NO_(2);carbon monoxide,CO;or ozone:O_(3))have been widely explored^([4]).However,humans are constantly exposed to multipollutant mixtures in real life,and biological responses to inhaled pollutants are likely to depend on the interplay of pollutant mixtures.Therefore,it is critical and imperative to explore the joint effects of multipollutant mixtures on human beings.展开更多
The Chengdu community security funds refer to the special security funds for urban and rural community development and governance in Chengdu.At present,there are some problems in the use of community security funds,su...The Chengdu community security funds refer to the special security funds for urban and rural community development and governance in Chengdu.At present,there are some problems in the use of community security funds,such as low participation of residents,and low efficiency of fund use.Taking the exploration of standardization of community security fund management in Wuhou district,Chengdu city,as an example,this paper suggests further strengthening the use and management of community security funds by means of standardization,ensuring the democratic,open,and transparent use of funds,and effectively enhancing the supporting role of community security funds in community governance.展开更多
Surface ozone(O_(3))has become a critical pollutant impeding air quality improvement in many Chinese megacities.Chengdu is a megacity located in Sichuan Basin in southwest China,where O_(3)pollution occurs frequently ...Surface ozone(O_(3))has become a critical pollutant impeding air quality improvement in many Chinese megacities.Chengdu is a megacity located in Sichuan Basin in southwest China,where O_(3)pollution occurs frequently in both spring and summer.In order to understand the elevated O_(3)during spring in Chengdu,we conducted sampling campaign at three sites during O_(3)pollution episodes in April.Volatile organic compounds(VOCs)compositions at each site were similar,and oxygenated VOCs(OVOCs)concentrations accounted for the highest proportion(35%-45%),followed by alkanes,alkens(including acetylene),halohydrocarbons,and aromatics.The sensitivity of O_(3)to its precursors was analyzed using an observation based box model.The relative incremental reactivity of OVOCs was larger than other precursors,suggesting that they also played the dominant role in O_(3)formation.Furthermore,the positive matrix factorization model was used to identify the dominant emission sources and to evaluate their contribution to VOCs in the city.The main sources of VOCs in spring were from combustion(27.75%),industrial manufacturing(24.17%),vehicle exhaust(20.35%),and solvent utilization(18.35%).Discussions on VOCs and NO_(x)reduction schemes suggested that Chengdu was typical in the VOC-limited regime,and VOC emission reduction would help to prevent and control O_(3).The analysis of emission reduction scenarios based on VOCs sources showed that the emission reduction ratio of VOCs to NO_(2)needs to reach more than 3 in order to achieve O_(3)prevention.Emission reduction from vehicular exhaust source and solvent utilization source may be more effective.展开更多
Soil bulk density is a basic but important physic soil property related to soil porosity,soil moisture and hydraulic conductivity,which is crucial to soil quality assessment and land use management.In this study,we ev...Soil bulk density is a basic but important physic soil property related to soil porosity,soil moisture and hydraulic conductivity,which is crucial to soil quality assessment and land use management.In this study,we evaluated the spatial variability of soil bulk density in the 0–20,20–40,40–60 and 60–100 cm layers as well as its affecting factors in Southwest China’s agricultural intensive area.Results indicated the mean value of surface soil bulk density(0–20 cm)was 1.26 g cm^(–3),significantly lower than that of subsoil(20–100 cm).No statistical difference existed among the subsoil with a mean soil bulk density of 1.54 g cm^(–3).Spatially,soil bulk density played a similar spatial pattern in soil profile,whereas obvious differences were found in details.The nugget effects for soil bulk density in the 0–20 and 20–40 cm layers were 27.22 and27.02%while 12.06 and 3.46%in the 40–60 and 60–100 cm layers,respectively,gradually decreasing in the soil profile,indicating that the spatial variability of soil bulk density above 40 cm was affected by structural and random factors while dominated by structural factors under 40 cm.Soil organic matter was the controlling factor on the spatial variability of soil bulk density in each layer.Land use and elevation were another two dominated factor controlling the spatial variability of soil bulk density in the 0–20 and 40–60 cm layers,respectively.Soil genus was one of the dominated factors controlling the spatial variability of soil bulk below 40 cm.展开更多
[Objective] The aim was to analyze one cold wave weather process in Chengdu in March in 2010.[Method] Based on the NCEP 1°×1° 6 h interval reanalysis data and daily observation data,using synoptic analy...[Objective] The aim was to analyze one cold wave weather process in Chengdu in March in 2010.[Method] Based on the NCEP 1°×1° 6 h interval reanalysis data and daily observation data,using synoptic analysis and diagnosis methods,and combining with the cold wave forecast index in spring of Sichuan,a cold wave event covering the whole region between March 21 and 24,2010 was analyzed from the aspects of circulation background,influencing weather systems and weather causation.[Result] Results showed that the 500 high-altitude cold vortex,700-850 hPa low layer shear,and ground cold front were the main systems that influenced this cold wave;there was a ridge from Lake Balkhash across Lake Baikal at 500 hPa.The early stage of the process was controlled by the high pressure ridge and the temperature was increasing obviously.The daily mean temperature was high.The range of cold high pressure was large and the central intensity was 1 043.0 hPa;the cold air was strong and deep which was in accordance with the strong surface temperature reduction center.The strong north airstream of Lake Balkhash to Lake Baikal,ground cold high pressure center intensity changes,north and south ocean pressure and temperature differences,850 hPa temperature changes,cold advection movement route and intensity were considered as reference factors for the forecast of cold wave intensity.[Conclusion] The study provided theoretical basis for improving the forecast ability of cold wave weather.展开更多
To study the emission characteristics of typical construction machinery in Chengdu,12 construction machinery (excavators,bulldozers,loaders,and forklifts) under idling mode,moving mode,and working mode,were tested usi...To study the emission characteristics of typical construction machinery in Chengdu,12 construction machinery (excavators,bulldozers,loaders,and forklifts) under idling mode,moving mode,and working mode,were tested using a portable emission measurement system(PEMS).Under three operating modes,the typical construction machinery in the working mode was higher in the fuel-based average emission factors of PM_(2.5)and NOx,while the fuel-based average emission factors of HC and CO were higher in idling mode.Integrated the results of investigation on ownership and activity levels of construction machinery,an exhaust emission inventory of typical construction machinery of Chengdu in 2018 was established according to the recommendation method.The annual emission of PM_(2.5),NOx,HC,and CO were 1.67×106,1.61×108,3.83×106,and 1.26×107kg,respectively,and the excavator contributed the maximum emissions,accounting for an average proportion of 43.95%.The emission of construction machinery in Chengdu exhibited a clear monthly trend,with the highest from April to October and the lowest from November to March.In addition,the exhaust emissions presented an obvious spot-like characteristics,and the high-value areas were mainly concentrated in the surrounding suburban counties such as Shuangliu Wenjiang etc.To reduce pollution from construction machinery and improve the quality of the atmospheric environment,more effective measures on housing construction and municipal construction should be taken in those districts in Chengdu.展开更多
The rice and wheat cropping pattern is one of the main cropping systems in the world. A large number of research results showed that successive cropping of rice and wheat resulted in a series of problems such as hinde...The rice and wheat cropping pattern is one of the main cropping systems in the world. A large number of research results showed that successive cropping of rice and wheat resulted in a series of problems such as hindering nutrition absorption, gradual degeneration of soil fertility, decline of soil organic matter, and increased incidence of diseases and pests. In China, especially in the Chengdu plain where rice-wheat cropping system is practiced, productivity and soil fertility was enhanced and sustained. This paper reviews the relevant data and experiences on rice-wheat cropping in the Chengdu Plain from 1977 to 2006. The principal sustainable strategies used for rice-wheat cropping systems in Chengdu Plain included： 1） creating a favorable environment and viable rotations; 2） balanced fertilization for maintenance of sustainable soil productivity; 3） improvement of crop management for higher efficiency; and 4） use the newest cultivars and cultivation techniques to upgrade the production level. Future research is also discussed in the paper as： 1） the constant topic： a highly productive and efficient rice-wheat cropping system for sustainable growth; 2） the future trend： simplified cultivation techniques for the rice-wheat cropping system; 3） the foundation： basic research for continuous innovation needed for intensive cropping. It is concluded that in the rice-wheat cropping system, a scientific and reasonable tillage/cultivation method can not only avoid the degradation of soil productivity, but also maintain sustainable growth in the long run.展开更多
A Gram-negative, aerobic, non-motile, rod-shaped bacterial strain, designated 25-1T, was isolated from the air inside giant panda enclosures at the Chengdu Research Base of Giant Panda Breeding, China. Strain 25-1T gr...A Gram-negative, aerobic, non-motile, rod-shaped bacterial strain, designated 25-1T, was isolated from the air inside giant panda enclosures at the Chengdu Research Base of Giant Panda Breeding, China. Strain 25-1T grew optimally at pH 7.0-8.0, at 28-30 ℃ and in the presence of NaCI concentrations from 0.0% to 0.5%. 16S rRNA gene sequence analysis indicated that strain 25-1m belongs to the genus Chryseobacterium within the family Flavo- bacteriaceae and is related most closely to C. camis G81m （96.4% similarity）, C. lathyri RBA2-6T （95.8% similarity）, and C. zeae JM1085T （95.8% similarity）. Its genomic DNA G＋C molar composition was 36.2%. The major cellular fatty acids were iso-C15：0 （44.0%）, iso-C17：0 3OH （19.8%） and C16：1 ω7c/16：1 ω6c （12.7%）. The only isoprenoid quinone was menaquinone 6 （MK-6）. The major polar lipids were phosphatidylethanolamine, two unidentified amino lipids and two unidentified lipids. The DNA-DNA relatedness between strain 25-1m and C. lathyri RBA2-6T was 38%. Phenotypic, genotypic, and phylogenetic characteristics indicated that strain 25-1T is a novel member of the genus Chryseobacterium, for which the name C. chengduensis sp. nov. is proposed. The type strain is 25-1T （ccmoc AB2015133T=DSM 100396T）.展开更多
With the advancement of urbanization,the urban heat island effect and ozone pollution have become hot issues in urban research.The urban heat island effect can impact ozone conversion,but its mechanism of action is un...With the advancement of urbanization,the urban heat island effect and ozone pollution have become hot issues in urban research.The urban heat island effect can impact ozone conversion,but its mechanism of action is unclear.In this study,the effects of the urban heat island effect on ozone concentration in Chengdu City,China,were investigated by comparing the ozone concentration under different heat island levels with ozone data from March 2020 to February 2021 and the temperature and wind field data of ERA5-Land during the same period.The results showed that:1)regarding the distribution characteristics,the ozone concentration in Chengdu presented a‘high in summer and low in winter’distribution.The ozone concentration in summer(189.54µg/m^(3))was nearly twice that in winter(91.99µg/m^(3)),and the ozone diurnal variation presented a‘single peak and single valley’distribution,with a peak at 16:00.2)For the characteristics of the heat island effect,the heat island intensity in Chengdu was obviously higher in spring than in other seasons,and the diurnal variation showed a‘single peak and single valley’distribution,with the peak and trough values appearing at 9:00 and 17:00,respectively.Spatially,the eastern part of Chengdu was a heat island,while the western and northwestern parts were mostly cold island.3)The correlation analysis between heat island intensity and ozone concentration showed a significant positive correlation but with a 7–8 h time lag.Ambient air temperature was not the main factor affecting ozone concentration.The heat island effect impacts the ozone concentration in two ways:changing the local heat budget to promote ozone generation and forming local urban wind,which promotes ozone diffusion or accumulation and forms different areas of low and high ozone values.展开更多
Traditional rural homegarden agroforestry system in the Chengdu Plain of China,called“Linpan”in Chinese,integrates the ecological functions of the landscape with human production activities.Studying the driving mech...Traditional rural homegarden agroforestry system in the Chengdu Plain of China,called“Linpan”in Chinese,integrates the ecological functions of the landscape with human production activities.Studying the driving mechanisms of rural landscape changes in the Chengdu Plain is of great significance from stakeholders’perspective.Taking the Pidu Linpan Farming System(PLFS)in the suburban area of Chengdu(designated as one of China-Nationally Important Agricultural Heritage Systems in 2020)as a case,this study combined remote sensing image analysis,oral history interviews,and focus group interviews to elucidate the driving forces of landscape changes in the PLFS.The results show that tourism development,traffic accessibility,economic demand,and agricultural heritage protection measure are the main driving forces promoting the stability and maintenance of the traditional homegardens.In contrast,population ageing,land circulation,centralized residence,climate change,and living and recreational need are the forces leading to adverse changes in the traditional homegardens.In addition,these driving forces have led to the gradual abandonment of traditional agricultural activities and critical issues related to rural landscape planning and management.The current research indicates that infrastructure construction and increased traditional agricultural income are considered as the best practices of local stakeholders,promoting the development of the protected homegardens of heritage sites and tourist destinations.Finally,we put forward some suggestions to improve and maintain the traditional rural landscape:(1)establishing a benefit-sharing mechanism;(2)establishing a training system with traditional technology and culture;(3)strengthening infrastructure construction;(4)promoting the development of the agricultural industry;(5)improving the cultural quality of farmers;and(6)establishing a management system with legal effects.This research can provide a basis for the formulation of rural landscape planning and the orderly and healthy development of agricultural heritage in Chengdu Plain.展开更多
基金supported by the Humanities and Social Sciences Project of the Ministry of Education of the Peoples Republic(No.21YJCZH099)the National Natural Science Foundation of China(Nos.41401089 and 41741014)the Science and Technology Project of Sichuan Province(No.2023NSFSC1979).
文摘Majority of carbon emissions originate from fossil energy consumption,thus necessitating calculation and monitoring of carbon emissions from energy consumption.In this study,we utilized energy consumption data from Sichuan Province and Chongqing Municipality for the years 2000 to 2019 to estimate their statistical carbon emissions.We then employed nighttime light data to downscale and infer the spatial distribution of carbon emissions at the county level within the Chengdu-Chongqing urban agglomeration.Furthermore,we analyzed the spatial pattern of carbon emissions at the county level using the coefficient of variation and spatial autocorrelation,and we used the Geographically and Temporally Weighted Regression(GTWR)model to analyze the influencing factors of carbon emissions at this scale.The results of this study are as follows:(1)from 2000 to 2019,the overall carbon emissions in the Chengdu-Chongqing urban agglomeration showed an increasing trend followed by a decrease,with an average annual growth rate of 4.24%.However,in recent years,it has stabilized,and 2012 was the peak year for carbon emissions in the Chengdu-Chongqing urban agglomeration;(2)carbon emissions exhibited significant spatial clustering,with high-high clustering observed in the core urban areas of Chengdu and Chongqing and low-low clustering in the southern counties of the Chengdu-Chongqing urban agglomeration;(3)factors such as GDP,population(Pop),urbanization rate(Ur),and industrialization structure(Ic)all showed a significant influence on carbon emissions;(4)the spatial heterogeneity of each influencing factor was evident.
文摘This paper focuses on Chengdu and Chongqing’s positioning as important economic center in western China and their evolving into an economic center of national influence.On the one hand,it uses the synthetic difference-in-differences(SDID)method to analyze the impact of policies since 2011 designed to build Chengdu and Chongqing into an important economic center in western China.On the other hand,it employs the entropy-weighted TOPSIS method to comprehensively evaluate the influences of ten core Chinese cities as economic centers within four major urban agglomerations,as well as conduct an analytical assessment of the Chengdu-Chongqing economic circle from key perspectives such as its capacity to lead,capacity to agglomerate,and capacity to radiate.From a longitudinal historical perspective,both Chengdu and Chongqing have benefited significantly from policies designed to build an important economic center in western China,and which laid a foundation for building an economic center of national influence.From a horizontal regional comparison,among the ten core cities evaluated as economic centers within the four major urban agglomerations,Chengdu and Chongqing ranked in the middle,possessing a moderate but not yet outstanding influence.Consequently,to evolve into an economic center of national influence,the Chengdu-Chongqing economic circle should leverage its relative advantages in connectivity,market size,value chain division of labor,policy attractiveness,and industry development.It can enhance its influence by strengthening the complementarity of its economic resources,overcoming the administrative inertia,accelerating the establishment of a regional innovation system,broadening the scope of its economic radiation,and promoting its comprehensive and all-dimensional opening-up.
文摘Chengdu,a city rich in history and culture,is a beacon of China’s storied past embracing a distinct postmodern vibe.As an important hub along the ancient Silk Road,it has long been a meeting point for di!erent civilizations,where ideas and cultures have exchanged and thrived.Driven by the vision of a community with a shared future for mankind in recent years,Chengdu scholars and media have opened their arms to the world,engaging in multilingual storytelling.These efforts share the warmth and goodwill of a city consistently ranked one of the happiest in China.Through consistent efforts,new insights have emerged—ideas and aspirations intended to be shared with readers both at home and abroad.
基金Project supported by the National Natural Science Foundation of China (Grant No. 71971150)the Project of Research Center for System Sciences and Enterprise Development (Grant No. Xq16B05)the Fundamental Research Funds for the Central Universities of China (Grant No. SXYPY202313)。
文摘As a key mode of transportation, urban metro networks have significantly enhanced urban traffic environments and travel efficiency, making the identification of critical stations within these networks increasingly essential. This study presents a novel integrated topological-functional(ITF) algorithm for identifying critical nodes, combining topological metrics such as K-shell decomposition, node information entropy, and neighbor overlapping interaction with the functional attributes of passenger flow operations, while also considering the coupling effects between metro and bus networks. Using the Chengdu metro network as a case study, the effectiveness of the algorithm under different conditions is validated.The results indicate significant differences in passenger flow patterns between working and non-working days, leading to varying sets of critical nodes across these scenarios. Moreover, the ITF algorithm demonstrates a marked improvement in the accuracy of critical node identification compared to existing methods. This conclusion is supported by the analysis of changes in the overall network structure and relative global operational efficiency following targeted attacks on the identified critical nodes. The findings provide valuable insight into urban transportation planning, offering theoretical and practical guidance for improving metro network safety and resilience.
基金supported by the Basic Research Cultivation Support Plan of Southwest Jiaotong University(No.2682023ZTPY016)the Natural Science Foundation of Sichuan Province(No.2022NSFSC0982)the National Natural Science Foundation of China(Nos.U23A2030,42205100,and 41805095).
文摘To investigate the seasonal characteristics in air pollution in Chengdu,a single particle aerosol mass spectrometry was used to continuously observe atmospheric fine particulate matter during one-month periods in summer and winter,respectively.The results showed that,apart from O_(3),the concentrations of other pollutants(CO,NO_(2),SO_(2),PM_(2.5)and PM_(10))were significantly higher in winter than in summer.All single particle aerosols were divided into seven categories:biomass burning(BB),coal combustion(CC),Dust,vehicle emission(VE),K mixedwith nitrate(K-NO_(3)),Kmixed with sulfate and nitrate(K-SN),and K mixedwith sulfate(K-SO_(4))particles.The highest contributions in both seasons were VE particles(24%).The higher contributions of K-SO_(4)(16%)and K-NO_(3)(10%)particles occurred in summer and winter,respectively,as a result of their different formation mechanisms.S-containing(KSO_(4)and K-SN),VE,and BB particles caused the evolution of pollution in both seasons,and they can be considered as targets for future pollution reduction.The mixing of primary sources particles(VE,Dust,CC,and BB)with secondary components was stronger in winter than in summer.In summer,as pollution worsens,the mixing of primary sources particles with 62[NO_(3)]−weakened,but themixing with 97[HSO_(4)]−increased.However,in winter,the mixing state of particles did not exhibit an obvious evolution rules.The potential source areas in summer were mainly distributed in the southern region of Sichuan,while in winter,besides the southern region,the contribution of the western region cannot be ignored.
文摘Mainstream media play a crucial role in constructing the cultural memory of a city.This study used 319 short videos released by“Hi Chengdu,”a new media product of Chengdu Radio and Television,as samples.Based on the grounded theory,a research framework encompassing“content,technology,and discourse”was established to explore the paths through which mainstream media construct the cultural memory.Regarding content,this paper emphasized temporal and spatial contexts and urban spaces,delving deep into the themes of the cultural memory and vehicles for it.In terms of technology,this paper discussed the practice of leveraging audio/visual-mode discourse to stitch together the impressions of a city and evoke emotional resonance to create a“flow”of memory.As for discourse,this paper looked at the performance of a communication ritual to frame concepts and shape urban identity.It is essential to break free from conventional thinking and leverage local culture as the primary driving force to further boost a city’s productivity,in order to excel in cultural communication.
基金Under the auspices of National Natural Science Foundation of China(No.41930651)Sichuan Science and Technology Program(No.2023NSFSC1979)。
文摘Urban-suburban-rural(U-S-R)zones exhibit distinctive transitional characteristics in interaction between human and nature.U-S-R transition zones(U-S-RTZ)are also highlighting the function diversity and landscape heterogeneity across territorial spaces.As a super megacity in western China,Chengdu’s rapid urbanization has driven the evolution of U-S-R spaces,resulting in a sequential structure.To promote the high-quality spatial development of urban-rural region in a structured and efficient manner,it is essential to con-duct a scientific examination of the multidimensional interconnection within the U-S-RTZ framework.By proposing a novel identifica-tion method of U-S-RTZ and taking Chengdu,China as a case study,grounded in a blender of natural and humanistic factors,this study quantitatively delineated and explored the spatial evolutions of U-S-RTZ and stated the optimization orientation and sustainable devel-opment strategies of the production-living-ecological spaces along the U-S-R gradients.The results show that:1)it is suitable for the quantitative analysis of U-S-RTZ by established three-dimensional identification system in this study.2)In 1990-2020,the urban-sub-urban transition zones(U-STZ)in Chengdu have continuously undergone a substantial increase,and the scale of the suburban-rural transition zones(S-RTZ)has continued to expand slightly,while the space of rural-ecological transition zones(R-ETZ)has noticeably compressed.3)The landuse dynamics within U-S-RTZ has gradually increased in 1990-2020.The main direction of landuse transition was from farmland to construction land or woodlands,with the expansion of construction land being the most significant.4)R-ETZ primarily focus on ecological functions,and there is a trade-off relationship between the production-ecological function within the S-RTZ,and in the U-STZ,production-living composite functions are prioritized.This study emphasizes the importance of elastic planning and precise governance within the U-S-RTZ in a rapid urbanization region,particularly highlighting the role of suburbs as landscape corridors and service hubs in urban-rural integration.It elucidates to the practical implications for achieving high-quality development of integrated U-S-R territorial spaces.
基金supported by the Scientific Research Project (No.17ZB0484)of Sichuan Provincial Department of EducationScientific Research Project (No.2021ZKQN004)of Southwest Medical University+1 种基金National Natural Science Foundation of China (No.41805095)Sichuan Science and Technology Program (No.2019YFS0476)。
文摘Single-particle aerosol mass spectrometry was used to study the characteristics of Fecontaining particles during winter in Chengdu,southwest China.The mass concentrations of PM_(2.5)and PM_(10)during the study period were 64±38 and 89±49μg/m~3,respectively,and NO_(2)and particulate matter were high compared with most other regions of China.The Fecontaining particles were divided into seven categories with different mass spectra,sources and aging characteristics.The highest contribution was from Fe mixed with carbonaceous components(Fe-C,23.1%)particles.Fe was more mixed with sulfate than nitrate and therefore the contribution of Fe mixed with sulfate(Fe-S,20.7%)particles was higher than that of Fe mixed with nitrate(Fe-N,12.5%)particles.The contributions from Fe-containing particles related to primary combustion were high in the small particle size range,whereas aged Fecontaining particles and dust-related particles were mostly found in the coarse particle size range.The air masses mainly originated from the west and east of Chengdu,and the corresponding PM_(2.5)concentrations were 79±36 and 55±36μg/m~3,respectively.The west and east air masses showed stronger contributions of Fe-containing particles related to biomass burning(Fe-B)and fossil fuel combustion(Fe-C and Fe-S)particles,respectively.The southwest area contributed the most Fe-containing particles.Future assessments of the effects of Fe-containing particles during heavy pollution period should pay more attention to Fe-C and Fe-S particles.Emission-reduction of Fe-containing particles should consider both local emissions and short-distance transmission from the surrounding areas.
基金supported by the National Natural Science Foundation of China(Nos.42205100 and 41805095)the Sichuan Science and Technology Program(Nos.2019YFS0476and 2022NSFSC0982)support from the Sichuan comprehensive monitoring station for environmental air quality。
文摘The air quality in China has improved significantly in the last decade and,correspondingly,the characteristics of PM_(2.5)have also changed.We studied the interannual variation of PM_(2.5)in Chengdu,one of the most heavily polluted megacities in southwest China,during the most polluted season(winter).Our results show that the mass concentrations of PM_(2.5)decreased significantly year-by-year,from 195.8±91.0μg/m~3in winter 2016 to 96.1±39.3μg/m^(3)in winter 2020.The mass concentrations of organic matter(OM),SO_()4^(2-),NH_(4)^(+)and NO_(3)^(-)decreased by 49.6%,57.1%,49.7% and 28.7%,respectively.The differential reduction in the concentrations of chemical components increased the contributions from secondary organic carbon and NO_(3)^(-)and there was a larger contribution from mobile sources.The contribution of OM and NO_(3)^(-)not only increased with increasing levels of pollution,but also increased year-by-year at the same level of pollution.Four sources of PM_(2.5)were identified:combustion sources,vehicular emissions,dust and secondary aerosols.Secondary aerosols made the highest contribution and increased year-by-year,from 40.6%in winter 2016 to 46.3% in winter 2020.By contrast,the contribution from combustion sources decreased from 14.4% to 8.7%.Our results show the effectiveness of earlier pollution reduction policies and emphasizes that priority should be given to key pollutants(e.g.,OM and NO_(3)^(-))and sources(secondary aerosols and vehicular emissions)in future policies for the reduction of pollution in Chengdu during the winter months.
文摘This paper developed a comprehensive evaluation system that was able to quantify the levels of high-quality development across the cities within the Chengdu-Chongqing economic circle,and investigate the impact that digital finance had on the cities’high-quality development and the underlying mechanisms through which it achieved this.This comprehensive evaluation system was constructed using statistical data from these cities for the period 2014 to 2020 while also taking China’s high-quality development philosophy into account.The key findings revealed that:(a)Digital finance was able to significantly promote high-quality development in the Chengdu-Chongqing economic circle;(b)Digital finance had a significant positive effect in promoting innovative,coordinated,green,open,and shared development;(c)Digital finance was able to stimulate the high-quality development in the Chengdu-Chongqing economic circle by boosting entrepreneurial dynamism;(d)Digital finance had a significant impact on the high-quality development of the axis areas,while its impact was less discernible in non-axis areas.The insights from this research offer a deeper understanding of the factors that drive high-quality development,the role digital finance plays,and the mechanisms through which digital finance is able to propel high-quality development at the city cluster scale.
基金supported by the National Nature Science Foundation of China(42005136)Innovation Team Fund of Southwest Regional Meteorological Center+3 种基金China Meteorological Administration(XNQYCXTD-202203)China Postdoctoral Science(2020M670419)Key Research and Development program for Social Development in Yunnan Provincial(in China)(202203AC100006,202203AC100005)National Key Research and Development Program of China(2016YFA0602004)。
文摘Significant epidemiological research has revealed that exposure to air pollution is substantially associated with numerous detrimental health consequences^([1-3]).The negative health effects of individual air pollutants(e.g.,fine particulate matter:PM_(2.5);nitrogen dioxide:NO_(2);carbon monoxide,CO;or ozone:O_(3))have been widely explored^([4]).However,humans are constantly exposed to multipollutant mixtures in real life,and biological responses to inhaled pollutants are likely to depend on the interplay of pollutant mixtures.Therefore,it is critical and imperative to explore the joint effects of multipollutant mixtures on human beings.
文摘The Chengdu community security funds refer to the special security funds for urban and rural community development and governance in Chengdu.At present,there are some problems in the use of community security funds,such as low participation of residents,and low efficiency of fund use.Taking the exploration of standardization of community security fund management in Wuhou district,Chengdu city,as an example,this paper suggests further strengthening the use and management of community security funds by means of standardization,ensuring the democratic,open,and transparent use of funds,and effectively enhancing the supporting role of community security funds in community governance.
基金supported by the National Natural Science Foundation of China(No.21906108)the Fundamental Research Funds for the Central Universities(No.YJ201937)Chengdu Science and Technology Bureau(No.2020-YF09-00051-SN)
文摘Surface ozone(O_(3))has become a critical pollutant impeding air quality improvement in many Chinese megacities.Chengdu is a megacity located in Sichuan Basin in southwest China,where O_(3)pollution occurs frequently in both spring and summer.In order to understand the elevated O_(3)during spring in Chengdu,we conducted sampling campaign at three sites during O_(3)pollution episodes in April.Volatile organic compounds(VOCs)compositions at each site were similar,and oxygenated VOCs(OVOCs)concentrations accounted for the highest proportion(35%-45%),followed by alkanes,alkens(including acetylene),halohydrocarbons,and aromatics.The sensitivity of O_(3)to its precursors was analyzed using an observation based box model.The relative incremental reactivity of OVOCs was larger than other precursors,suggesting that they also played the dominant role in O_(3)formation.Furthermore,the positive matrix factorization model was used to identify the dominant emission sources and to evaluate their contribution to VOCs in the city.The main sources of VOCs in spring were from combustion(27.75%),industrial manufacturing(24.17%),vehicle exhaust(20.35%),and solvent utilization(18.35%).Discussions on VOCs and NO_(x)reduction schemes suggested that Chengdu was typical in the VOC-limited regime,and VOC emission reduction would help to prevent and control O_(3).The analysis of emission reduction scenarios based on VOCs sources showed that the emission reduction ratio of VOCs to NO_(2)needs to reach more than 3 in order to achieve O_(3)prevention.Emission reduction from vehicular exhaust source and solvent utilization source may be more effective.
基金supported by the National Natural Science Foundation of China (4120124)the Science Fund of the Education Department of Sichuan Province, China (16ZB0048)
文摘Soil bulk density is a basic but important physic soil property related to soil porosity,soil moisture and hydraulic conductivity,which is crucial to soil quality assessment and land use management.In this study,we evaluated the spatial variability of soil bulk density in the 0–20,20–40,40–60 and 60–100 cm layers as well as its affecting factors in Southwest China’s agricultural intensive area.Results indicated the mean value of surface soil bulk density(0–20 cm)was 1.26 g cm^(–3),significantly lower than that of subsoil(20–100 cm).No statistical difference existed among the subsoil with a mean soil bulk density of 1.54 g cm^(–3).Spatially,soil bulk density played a similar spatial pattern in soil profile,whereas obvious differences were found in details.The nugget effects for soil bulk density in the 0–20 and 20–40 cm layers were 27.22 and27.02%while 12.06 and 3.46%in the 40–60 and 60–100 cm layers,respectively,gradually decreasing in the soil profile,indicating that the spatial variability of soil bulk density above 40 cm was affected by structural and random factors while dominated by structural factors under 40 cm.Soil organic matter was the controlling factor on the spatial variability of soil bulk density in each layer.Land use and elevation were another two dominated factor controlling the spatial variability of soil bulk density in the 0–20 and 40–60 cm layers,respectively.Soil genus was one of the dominated factors controlling the spatial variability of soil bulk below 40 cm.
文摘[Objective] The aim was to analyze one cold wave weather process in Chengdu in March in 2010.[Method] Based on the NCEP 1°×1° 6 h interval reanalysis data and daily observation data,using synoptic analysis and diagnosis methods,and combining with the cold wave forecast index in spring of Sichuan,a cold wave event covering the whole region between March 21 and 24,2010 was analyzed from the aspects of circulation background,influencing weather systems and weather causation.[Result] Results showed that the 500 high-altitude cold vortex,700-850 hPa low layer shear,and ground cold front were the main systems that influenced this cold wave;there was a ridge from Lake Balkhash across Lake Baikal at 500 hPa.The early stage of the process was controlled by the high pressure ridge and the temperature was increasing obviously.The daily mean temperature was high.The range of cold high pressure was large and the central intensity was 1 043.0 hPa;the cold air was strong and deep which was in accordance with the strong surface temperature reduction center.The strong north airstream of Lake Balkhash to Lake Baikal,ground cold high pressure center intensity changes,north and south ocean pressure and temperature differences,850 hPa temperature changes,cold advection movement route and intensity were considered as reference factors for the forecast of cold wave intensity.[Conclusion] The study provided theoretical basis for improving the forecast ability of cold wave weather.
基金supported by the Public Environmental Service Project of the Ministry of Ecology and Environmental of the PRC (No. 201409012)。
文摘To study the emission characteristics of typical construction machinery in Chengdu,12 construction machinery (excavators,bulldozers,loaders,and forklifts) under idling mode,moving mode,and working mode,were tested using a portable emission measurement system(PEMS).Under three operating modes,the typical construction machinery in the working mode was higher in the fuel-based average emission factors of PM_(2.5)and NOx,while the fuel-based average emission factors of HC and CO were higher in idling mode.Integrated the results of investigation on ownership and activity levels of construction machinery,an exhaust emission inventory of typical construction machinery of Chengdu in 2018 was established according to the recommendation method.The annual emission of PM_(2.5),NOx,HC,and CO were 1.67×106,1.61×108,3.83×106,and 1.26×107kg,respectively,and the excavator contributed the maximum emissions,accounting for an average proportion of 43.95%.The emission of construction machinery in Chengdu exhibited a clear monthly trend,with the highest from April to October and the lowest from November to March.In addition,the exhaust emissions presented an obvious spot-like characteristics,and the high-value areas were mainly concentrated in the surrounding suburban counties such as Shuangliu Wenjiang etc.To reduce pollution from construction machinery and improve the quality of the atmospheric environment,more effective measures on housing construction and municipal construction should be taken in those districts in Chengdu.
基金funded by the National Key Technologies Research and Development Program of China(2006BAD02A05)the Science and Technology Project for Public (Agriculture)the Ministry of Agriculture, China (200903050-4)
文摘The rice and wheat cropping pattern is one of the main cropping systems in the world. A large number of research results showed that successive cropping of rice and wheat resulted in a series of problems such as hindering nutrition absorption, gradual degeneration of soil fertility, decline of soil organic matter, and increased incidence of diseases and pests. In China, especially in the Chengdu plain where rice-wheat cropping system is practiced, productivity and soil fertility was enhanced and sustained. This paper reviews the relevant data and experiences on rice-wheat cropping in the Chengdu Plain from 1977 to 2006. The principal sustainable strategies used for rice-wheat cropping systems in Chengdu Plain included： 1） creating a favorable environment and viable rotations; 2） balanced fertilization for maintenance of sustainable soil productivity; 3） improvement of crop management for higher efficiency; and 4） use the newest cultivars and cultivation techniques to upgrade the production level. Future research is also discussed in the paper as： 1） the constant topic： a highly productive and efficient rice-wheat cropping system for sustainable growth; 2） the future trend： simplified cultivation techniques for the rice-wheat cropping system; 3） the foundation： basic research for continuous innovation needed for intensive cropping. It is concluded that in the rice-wheat cropping system, a scientific and reasonable tillage/cultivation method can not only avoid the degradation of soil productivity, but also maintain sustainable growth in the long run.
基金supported by the Chengdu Giant Panda Breeding Research Foundation(No.CPF2010-06)the National Key Technology R&D Program of China(No.2012BAC01B06)
文摘A Gram-negative, aerobic, non-motile, rod-shaped bacterial strain, designated 25-1T, was isolated from the air inside giant panda enclosures at the Chengdu Research Base of Giant Panda Breeding, China. Strain 25-1T grew optimally at pH 7.0-8.0, at 28-30 ℃ and in the presence of NaCI concentrations from 0.0% to 0.5%. 16S rRNA gene sequence analysis indicated that strain 25-1m belongs to the genus Chryseobacterium within the family Flavo- bacteriaceae and is related most closely to C. camis G81m （96.4% similarity）, C. lathyri RBA2-6T （95.8% similarity）, and C. zeae JM1085T （95.8% similarity）. Its genomic DNA G＋C molar composition was 36.2%. The major cellular fatty acids were iso-C15：0 （44.0%）, iso-C17：0 3OH （19.8%） and C16：1 ω7c/16：1 ω6c （12.7%）. The only isoprenoid quinone was menaquinone 6 （MK-6）. The major polar lipids were phosphatidylethanolamine, two unidentified amino lipids and two unidentified lipids. The DNA-DNA relatedness between strain 25-1m and C. lathyri RBA2-6T was 38%. Phenotypic, genotypic, and phylogenetic characteristics indicated that strain 25-1T is a novel member of the genus Chryseobacterium, for which the name C. chengduensis sp. nov. is proposed. The type strain is 25-1T （ccmoc AB2015133T=DSM 100396T）.
基金Under the auspices of the National Science Foundation of Sichuan Province(No.2022NSFSC1006)Science and Technology Innovation Capability Improvement Plan Project of Chengdu University of Information Technology in 2022(No.KYQN202215)the National Science Foundation of China(No.41505122)。
文摘With the advancement of urbanization,the urban heat island effect and ozone pollution have become hot issues in urban research.The urban heat island effect can impact ozone conversion,but its mechanism of action is unclear.In this study,the effects of the urban heat island effect on ozone concentration in Chengdu City,China,were investigated by comparing the ozone concentration under different heat island levels with ozone data from March 2020 to February 2021 and the temperature and wind field data of ERA5-Land during the same period.The results showed that:1)regarding the distribution characteristics,the ozone concentration in Chengdu presented a‘high in summer and low in winter’distribution.The ozone concentration in summer(189.54µg/m^(3))was nearly twice that in winter(91.99µg/m^(3)),and the ozone diurnal variation presented a‘single peak and single valley’distribution,with a peak at 16:00.2)For the characteristics of the heat island effect,the heat island intensity in Chengdu was obviously higher in spring than in other seasons,and the diurnal variation showed a‘single peak and single valley’distribution,with the peak and trough values appearing at 9:00 and 17:00,respectively.Spatially,the eastern part of Chengdu was a heat island,while the western and northwestern parts were mostly cold island.3)The correlation analysis between heat island intensity and ozone concentration showed a significant positive correlation but with a 7–8 h time lag.Ambient air temperature was not the main factor affecting ozone concentration.The heat island effect impacts the ozone concentration in two ways:changing the local heat budget to promote ozone generation and forming local urban wind,which promotes ozone diffusion or accumulation and forms different areas of low and high ozone values.
基金funded by the National Natural Science Foundation of China(52008278)。
文摘Traditional rural homegarden agroforestry system in the Chengdu Plain of China,called“Linpan”in Chinese,integrates the ecological functions of the landscape with human production activities.Studying the driving mechanisms of rural landscape changes in the Chengdu Plain is of great significance from stakeholders’perspective.Taking the Pidu Linpan Farming System(PLFS)in the suburban area of Chengdu(designated as one of China-Nationally Important Agricultural Heritage Systems in 2020)as a case,this study combined remote sensing image analysis,oral history interviews,and focus group interviews to elucidate the driving forces of landscape changes in the PLFS.The results show that tourism development,traffic accessibility,economic demand,and agricultural heritage protection measure are the main driving forces promoting the stability and maintenance of the traditional homegardens.In contrast,population ageing,land circulation,centralized residence,climate change,and living and recreational need are the forces leading to adverse changes in the traditional homegardens.In addition,these driving forces have led to the gradual abandonment of traditional agricultural activities and critical issues related to rural landscape planning and management.The current research indicates that infrastructure construction and increased traditional agricultural income are considered as the best practices of local stakeholders,promoting the development of the protected homegardens of heritage sites and tourist destinations.Finally,we put forward some suggestions to improve and maintain the traditional rural landscape:(1)establishing a benefit-sharing mechanism;(2)establishing a training system with traditional technology and culture;(3)strengthening infrastructure construction;(4)promoting the development of the agricultural industry;(5)improving the cultural quality of farmers;and(6)establishing a management system with legal effects.This research can provide a basis for the formulation of rural landscape planning and the orderly and healthy development of agricultural heritage in Chengdu Plain.
