Along with decrease of fine particulate matter(PM_(2.5))concentration in recent years in China,secondary species become increasingly important.This work focuses on characterizing secondary components,and a few importa...Along with decrease of fine particulate matter(PM_(2.5))concentration in recent years in China,secondary species become increasingly important.This work focuses on characterizing secondary components,and a few important groups of organics including organic nitrogen(ON),organonitrates(OrgN),organosulfates(OS)and polycyclic aromatic hydrocarbons(PAHs),via online measurement of submicron aerosols(PM_(1))in Nanjing,China,during 2022 summer.The average PM_(1) concentration was 15.39μg/m^(3),dominated by secondary components(69.1%),which were even more important at higher PM_(1) levels.The primary organic aerosols(POA)were from traffic,industry and cooking;the two secondary OA factors were both closely linked with photochemistry,with one(OOA1)being relatively fresh and important in early afternoon and another(OOA2)being aged and important in late afternoon.Sulfate formation was also governed by photochemistry but resembled that of OOA2 not OOA1;nitrate formation was associated strongly with heterogeneous hydrolysis and thermodynamic equilibrium.Results also reveal a possible photochemical reaction channel from POA to OOA1,then to OOA2.Case studies show that formations of secondary components responded differently to different weather conditions and governed summer PM_(1) pollution.The average ON,OrgN,OS and PAHs concentrations were determined to be 122.8,84.4,45.6 and 3.3 ng/m^(3),respectively.ON was dominated by primary sources(53.8%).OrgN varied similarly to nitrate.OS formation was linked with aqueous-phase reactions,which were insignificant therefore its level was low.PAHs was mainly from traffic,and photochemical oxidation might be its important sink during afternoon.展开更多
Urban lakes,situated in cities characterized by dense population and economic activities,are susceptible to eutrophication.This study focuses on the water ecological restoration project of Xuanwu Lake,assessing the ef...Urban lakes,situated in cities characterized by dense population and economic activities,are susceptible to eutrophication.This study focuses on the water ecological restoration project of Xuanwu Lake,assessing the efficacy of ecological management through laboratory analysis of water quality indicators.Furthermore,it delves into a comprehensive life cycle cost structure analysis,ecosystem service value accounting,and economic benefit evaluation.From an economic standpoint,the research examines the cost-effectiveness and external impacts of the clear-water ecosystem restoration project.Findings indicate that TP and TN levels in the treated area have decreased by over 50%,substantially reducing the eutrophication index.The cost-benefit ratio for each unit of treatment stands at 1:3.2(direct benefit).Notably,the restoration has markedly improved water quality and augmented the value of ecosystem services,demonstrating long-term cost sustainability and positive economic externalities.To ensure the sustained success of such restorations,it is imperative to optimize public resource allocation,incorporate market-based incentives,and furnish economic insights for managing urban lakes.展开更多
This study investigates community identity in Nanjing’s historic Hehuatang community during urban renewal,revealing tensions between heritage preservation and modernization.Through ethnographic research,three key fac...This study investigates community identity in Nanjing’s historic Hehuatang community during urban renewal,revealing tensions between heritage preservation and modernization.Through ethnographic research,three key factors are identified shaping identity:(i)material conditions including series of spatial conflicts around overcrowding,(ii)social tensions such as tenant-aborigine divides and generational misunderstanding,and(iii)institutional governance as top-down policies would exacerbate distrust.Despite 82%of residents expressing place attachment,67%desire relocation due to deteriorating liveability—a paradox highlighting the failure of China’s contemporary performative participation models.The adapted three-layer creativity model underscores the need to reconcile physical renewal with social equity.Findings advocate for co-design processes that integrate resident agency,offering lessons for sustainable urban renewal in rapidly developing contexts.展开更多
Aerosol hygroscopicity and liquid water content(ALWC)have important influences on the environmental and climate effect of aerosols.In this study,we measured the hygroscopic growth factors(GF)of particles with dry diam...Aerosol hygroscopicity and liquid water content(ALWC)have important influences on the environmental and climate effect of aerosols.In this study,we measured the hygroscopic growth factors(GF)of particles with dry diameters of 40,80,150,and 200 nm during the wintertime in Nanjing.Both the GF-derived hygroscopicity parameter(κ_(gf))and ALWC increased with particle size,but displayed differing diurnal variations,withκ_(gf)peaking around the midday,while ALWC peaking in the early morning.Nitrate,ammonium and oxygenated organic aerosols(OOA)were found as the chemical components mostly strongly correlated with ALWC.A closure study suggests that during midday photo-oxidation and nighttime high ALWC periods,theκof organic aerosols(κ_(org))was underestimated when using previous parameterizations.Accordingly,we re-constructed parameterizations forκ_(org)and the oxidation level of organics for these periods,which indicates a higher hygroscopicity of photochemically formed OOA than the aqueous OOA,yet both being much higher than the generally assumed OOA hygroscopicity.Additionally,in a typical high ALWC episode,concurrently increased ALWC,nitrate,OOA as well as aerosol surface area and mass concentrations were observed under elevated ambient RH.This strongly indicates a coupled effect that the hygroscopic secondary aerosols,in particular nitratewith strong hygroscopicity,led to large increase in ALWC,which in turn synergistically boosted nitrate and OOA formation by heterogeneous/aqueous reactions.Such interaction may represent an important mechanism contributing to enhanced formation of secondary aerosols and rapid growth of fine particulate matter under relatively high RH conditions.展开更多
The acceleration of global urbanization has caused habitat loss,fragmentation,and decrease of habitat quality,often leading to a decline in biodiversity.However,most previous urbanization studies focused on taxonomic ...The acceleration of global urbanization has caused habitat loss,fragmentation,and decrease of habitat quality,often leading to a decline in biodiversity.However,most previous urbanization studies focused on taxonomic diversity,with relatively less research on functional and phylogenetic diversity.In this study,we examined the phylogenetic and functional diversity and underlying influencing factors of bird communities in 37 urban parks in Nanjing,China.We conducted a systematic survey of bird communities in Nanjing urban parks and selected six park characteristics that are generally considered to affect bird diversity.Model selection based on corrected Akaike Information Criterion(AICc)and model averaging showed that park area,habitat diversity and building index(a proxy for the degree of urbanization)were significant factors affecting avian phylogenetic and functional diversity in Nanjing urban parks.Specifically,habitat diversity and park area were positively correlated with bird diversity,while the building index was negatively correlated with bird diversity.Moreover,the phylogenetic and functional structures of urban bird communities exhibited a clustered pattern,indicating that environmental filtering might play a role in shaping community composition.In addition,building index had certain impact on the construction of bird phylogenetic communities in urban parks.Our results suggest that expanding park areas,increasing habitat diversity and reducing building indexes may be effective measures to increase the avian phylogenetic and functional diversity in our system.展开更多
This study establishes a framework to assess greenspace supply-demand disparities related to thermal discomfort from the perspective of population mobility across urban functional zones(UFZs).High-resolution greenspac...This study establishes a framework to assess greenspace supply-demand disparities related to thermal discomfort from the perspective of population mobility across urban functional zones(UFZs).High-resolution greenspace maps and location-based service(LBS)datasets for Nanjing,China,were combined with Spearman correlation analyses and a four-quadrant model to elucidate associations and matching patterns between greenspace exposure and thermal comfort.The findings indicate that population fluctuations affect the availability of actual greenspace,with correlations to thermal discomfort showing significant temporal variations among different UFZs.During morning workday hours,commercial zones have a significantly higher representation in Quadrant Ⅱ(82.26%)compared to non-workdays(70.86%),which is characterized by high population density,low greenspace exposure,and pronounced thermal discomfort.In contrast,residential and public service zones maintain consistently high and stable proportions in Quadrant Ⅰ across all periods.This spatial mismatch is primarily caused by differences in available greenspace quantities and population mobility.Planning adjustments should focus on ensuring sufficient greenspace provision in key areas during peak population mobility periods to mitigate thermal discomfort.Minimizing residents'staying time in thermally uncomfortable zones,implementing time-specific greenspace access,and strategically increasing greenspace coverage are essential for improving the mismatch between greenspace supply and demand.展开更多
To understand the differences in the composition and sources of PM_(2.5) and PM_(10) caused by coarse particles,integrated PM_(2.5) and PM_(10) samples were synchronously collected in Nanjing,East China,in summer 2020...To understand the differences in the composition and sources of PM_(2.5) and PM_(10) caused by coarse particles,integrated PM_(2.5) and PM_(10) samples were synchronously collected in Nanjing,East China,in summer 2020 and winter 2020/2021.Bulk and molecular speciation and light absorption measurements of aerosol extractswere performed,followed by positivematrix factorization(PMF)based on the PM_(2.5) and PM_(10) data sets,respectively.The difference in average concentrations of total bulk species between PM_(2.5) and PM_(10) was mainly caused by the distribution of considerable NO_(3)^(–),SO42–,Ca^(2+),and organic carbon(OC)in coarse particles.Coarse PMinfluenced by abrasion products from tirewear and leaves contributed about half of the low-volatility n-alkanes in summer.The contribution of coarse PM to biomass burning tracers and water-soluble OC increased in winter when biomass combustion was excessively active.More than 70%of sugar polyols were attributable to coarse PM in summer,and biomass burning could be an important source in winter.The light-absorbing organic chromophores were almost entirely associated with PM_(2.5),but water-soluble organic carbon(WSOC)exhibited stronger light absorption in PM_(10) extracts than in PM_(2.5) extracts possibly due to the influence of coarse PMon pH.PMF analysis indicated that biomass burning,aqueous-phase reactions,and processed dust were the main contributors of organic matter and its light absorption in winter.Biogenic primary and secondary sources made discernable contributions only in summer.The differences between PM_(2.5) and PM_(10) were likely attributed to mixing of crustal dust,combustion particles,and surface reactions.展开更多
The institutional environment in China has quite evidently changed during modern socio-economic transitions.Driven both by local government and by marketing force,urban social space was redistributed after the reform ...The institutional environment in China has quite evidently changed during modern socio-economic transitions.Driven both by local government and by marketing force,urban social space was redistributed after the reform of urban land and real estate policies.Urban renewal makes for wide differential rent and therefore gentrification is occurring in China.This paper analyzes the background and institutional environment of gentrification in China,and further discusses the process,characteristics and evolutionary mechanisms in the case of Nanjing,through investigation of the attributes of 1075 residential communities built during the 1998-2008 at a macro level,and interviewing the residents and analyzing questionnaires in 6 different and typical communities at a micro level.As a socio-spatial course of two-way interaction,gentrification is divided into 3 stages of incubation,occurrence and fast development,according to the time of landmark events and policy reform on the leasehold of land in Nanjing during socio-economic transition.In terms of the socio-spatial characteristics of gentrification in Nanjing,the gentrification process under the trajectory of urban renewal makes urban social space present a new circle-layer structure;the rise of quite a number of gated communities results in the fragmentation of social space and privatization of public space;the management mode of modern communities and the change of life style have aggravated the indifference of neighborhood relationship of gentrified communities.Based on the empirical evidence of this study,this paper indicates that gentrification is quite different between China and western countries with respect to spatio-temporal order,dominant forces,paths of realization and spatial expression,and it further reveals the dynamic mechanism of gentrification developing in China at the present stage.展开更多
Particulate matter with diameters of 2.5 μm or smaller(PM_(2.5)) and ozone(O_3) are major pollutants in the urban atmosphere. PM_(2.5) can affect O_3 by altering the photolysis rate and heterogeneous reactions. Howev...Particulate matter with diameters of 2.5 μm or smaller(PM_(2.5)) and ozone(O_3) are major pollutants in the urban atmosphere. PM_(2.5) can affect O_3 by altering the photolysis rate and heterogeneous reactions. However, these two processes and their relative importance remain uncertain. In this paper, with Nanjing in China as the target city, we investigate the characteristics and mechanism of interactions between particles and O_3 based on ground observations and numerical modeling.In 2008, the average concentrations of PM_(2.5) and O_3 at Caochangmen station are 64.6 ± 47.4 μg m^(-3) and 24.6 ± 22.8 ppb,respectively, while at Pukou station they are 94.1 ± 63.4 μg m^(-3) and 16.9 ± 14.9 ppb. The correlation coefficient between PM_(2.5) and O_3 is -0.46. In order to understand the reaction between PM_(2.5) and O_3, we construct a box model, in which an aerosol optical property model, ultraviolet radiation model, gas phase chemistry model, and heterogeneous chemistry model,are coupled. The model is employed to investigate the relative contribution of the aforementioned two processes, which vary under different particle concentrations, scattering capability and VOCs/NOxratios(VOCs: volatile organic compounds;NOx: nitric oxide and nitrogen dioxide). Generally, photolysis rate effect can cause a greater O_3 reduction when the particle concentrations are higher, while heterogeneous reactions dominate O_3 reduction with low-level particle concentrations.Moreover, in typical VOC-sensitive regions, O_3 can even be increased by heterogeneous reactions. In Nanjing, both processes lead to O_3 reduction, and photolysis rate effect is dominant. Our study underscores the importance of photolysis rate effect and heterogeneous reactions for O_3, and such interaction processes should be fully considered in future atmospheric chemistry modeling.展开更多
Taking Nanjing as a case, the paper explains the spatial behavior differences existing in the information technology use among different groups of residents and households, by virtue of analyzing the survey data of ur...Taking Nanjing as a case, the paper explains the spatial behavior differences existing in the information technology use among different groups of residents and households, by virtue of analyzing the survey data of urban households in the 11 districts of Nanjing, from the social, spatial, life and other non-technical angles. Also it makes various analyses and evaluation quantitatively and qualitatively on the social and spatial effect of information technology. The results show that the new technology is changing the social spatial behaviors of urban residents. New behavioral spaces of urban family such as telecommuting, email and QQ have begun to emerge. With the help of Internet, the communication scope of families has expanded greatly, and more new forms of publicizing community information have begun to emerge. Telecommunication contact forms have been developing swiftly, and their frequencies of contact have been increasing dramatically.展开更多
Three groups of dynamic triaxial tests were performed for saturated Nanjing fine sand subjected to uniform cyclic loading. The tested curves of the excess pore water pressure （EPWP） ratio variation with the ratio of...Three groups of dynamic triaxial tests were performed for saturated Nanjing fine sand subjected to uniform cyclic loading. The tested curves of the excess pore water pressure （EPWP） ratio variation with the ratio of the number of cycles are provided. The concept of the EPWP increment ratio is introduced and two new concepts of the effective dynamic shear stress ratio and the log decrement of effective stress are defined. It is found that the development of the EPWP increment ratio can be divided into three stages： descending, stable and ascending. Furthermore, at the stable and ascending stages, a satisfactory linear relationship is obtained between the accumulative EPWP increment ratio and natural logarithm of the effective dynamic shear stress ratio. Accordingly, the EPWP increment ratio at the number of cycles N has been deduced that is proportional to the log decrement of effective stress at the cycle number N-l, but is independent of the cyclic stress amplitude. Based on the analysis, a new EPWP increment model for saturated Nanjing fine sand is developed from tested data fitting, which provides a better prediction of the curves of EPWP generation, the number of cycles required for initial liquefaction and the liquefaction resistance.展开更多
An extremely dense radiation fog event during 10-11 December 2007 was studied to understand its macro-micro-physics in relation to dynamic and thermodynamic structures of the boundary layer, as well as its structural ...An extremely dense radiation fog event during 10-11 December 2007 was studied to understand its macro-micro-physics in relation to dynamic and thermodynamic structures of the boundary layer, as well as its structural evolution in conjunction with the air-surface exchange of heat and water vapor. The findings are as follows. The extreme radiation fog process was divisible into formation, development, mature, and dissipation phases, depending on microstructure and visibility. This fog event was marked by rapid evolution that occurred after sunrise, when enhanced surface evaporation and cold air intrusion led to a three order of magnitude increase in liquid water content （LWC） in just 20 minutes. The maximum droplet diameter （MDD） increased four-fold during the same period. The fog structure was two-layered, with the top of both the surface-layer and upper-layer components characterized by strong temperature and humidity inversions, and low-level jets existed in the boundary layer above each fog layer. Turbulence intensity, turbulent kinetic energy, and friction velocity differed remarkably from phase to phase： these features increased gradually before the fog formation and decreased during the development phase; during the mature and dissipation phases these characteristics increased and then decreased again. In the development and mature stages, the mean kinetic energy of the lower-level winds decreased pronouncedly, both in the horizontal and vertical directions.展开更多
An increasing number of industrial, agricultural, and commercial chemicals in the aquatic environment leads to various deleterious effects on organisms, which is becoming an increasingly serious problem in China. In t...An increasing number of industrial, agricultural, and commercial chemicals in the aquatic environment leads to various deleterious effects on organisms, which is becoming an increasingly serious problem in China. In this study, the comet assay was conducted to investigate the genotoxicity to human body caused by organic concentrates in the drinking water sources of Nanjing City from Yangtze River of China, and health and ecology risk due to expose to these organic pollutants were evaluated with the multimedia environmental assessment system （MEAS）. For all the water samples, they were collected from four different locations in the drinking water sourcr samples, es of Nanjing City. The results of the comet assay showed that all the organic concentrates from the water samples could induce different levels DNA damages on human peripheral blood lymphocytes, and a statistically significant difference （p〈0.01） was observed compared with the solvent control, which demonstrated the genotoxicity was in existence. According to the ambient severity （AS） of individual compound, we had sorted out the main organic pollutants in the drinking water source of the four waterworks, and the results showed that there was some potential hazard to human body for all the source water, namely the total ambient severity （TAS） of health for each water source was more than 1. However, the TAS of ecology for each water source was less than 1, which indicated that it was safe to ecology. The results of this investigation demonstrate the application of the comet assay and the MEAS in aquatic environmental monitoring studies, and the comet assay found to be fast, sensitive, and suitable for genotoxicity monitoring programs of drinking water source.展开更多
Future or smart community, which mainly refers to the development of community information and communication technology(ICT) platforms or devices, has received considerable attention from urban governments and scholar...Future or smart community, which mainly refers to the development of community information and communication technology(ICT) platforms or devices, has received considerable attention from urban governments and scholars. However, only a few studies have been conducted to test the actual effects of using these community ICT platforms or devices on the community satisfaction of residents. Therefore, the present study conducts a survey in 40 communities in Nanjing, China and uses a mixed linear regression model to determine the relationship between community ICT usage and community satisfaction. Results indicate that residents with high-level community ICT usage are more satisfied with their community than those with low-level community ICT usage. Moreover, evident differences are observed regarding the influence of new commodity, old commodity and affordable housing communities in Nanjing. These findings are meaningful for the construction and development of future communities.展开更多
Laboratory tests on the large post-liquefaction deformation of saturated Nanjing fine sand were performed by using a hollow cylinder apparatus. The stress-strain responses and the characteristics of excess pore water ...Laboratory tests on the large post-liquefaction deformation of saturated Nanjing fine sand were performed by using a hollow cylinder apparatus. The stress-strain responses and the characteristics of excess pore water pressure after liquefaction were studied. It was found that the relationship between deviatoric stress and axial strain presented a sigmoid curve, and there was a good linearity relationship between normalized pore water pressure and deviatoric stress. On this basis, a constitutive model of stress-strain responses and a dissipation model of excess pore water pressure were established. It was found that the results predicted by the two models were in good agreement with the experimental data. The influence of relative densities and confining pressure on the characteristics of liquefied soil were studied, The results showed the relative densities and initial effective confining pressure all had an important influence on the stress-strain responses of liquefied saturated Nanjing fine sand. However, the dissipation model of excess pore water pressure after liquefaction was only affected by the confining pressure.展开更多
As a type of urban gentrification oriented by high-quality educational resources,jiaoyufication is a socio-spatial process that refers to the middle-class group that attaches importance to education realizes the agglo...As a type of urban gentrification oriented by high-quality educational resources,jiaoyufication is a socio-spatial process that refers to the middle-class group that attaches importance to education realizes the agglomeration in famous school districts by purchasing high-price school district houses.Based on the theoretical analysis of jiaoyufication conducted by Chinese and foreign scholars,this paper takes Nanjing as a case city,applies multi-source data like POIs(points of interest),real estate market data,mobile-phone user portraits and questionnaires,and develops a composite measurement of jiaoyufication to identify jiaoyufied school district,jiaoyufied group&its spatial characteristics,and discusses the causal mechanisms and effects of jiaoyufication.With the GIS-entropy-TOPSIS model,this paper evaluates the jiaoyufication level of public primary school districts in the main urban area of Nanjing.The result show that 218 primary school districts are categorized into four types,i.e.,high jiaoyufied school district,mid-high jiaoyufied school district,medium jiaoyufied school district,and low jiaoyufied school district.The high jiaoyufied school districts are closely associated with the institutional system.In the high jiaoyufied school districts,many middle-class families have abundant social,economic,and cultural capital.They purchase and move to houses with lower living quality in school districts to pursue high-quality education for their children.The strict school district system,soaring school district housing prices,and intense educational competition continuously solidify the jiaoyufication levels of famous school districts and lock the opportunities for high-quality education in specific school-district spaces and classes or groups.The phenomenon of this socio-spatial reconstruction process,which results from the unequal distribution of high-quality educational resources,tends to aggravate the rich-poor gap and social segregation in cities.It is suggested that equalization of compulsory education services should be effectively carried forward as soon as possible.展开更多
Based on the connotation of urban resilience and the main contradictions of China's urbanization,urban resilience is placed within the main daily activities contradictory scene of the urban man-land system to buil...Based on the connotation of urban resilience and the main contradictions of China's urbanization,urban resilience is placed within the main daily activities contradictory scene of the urban man-land system to build a theoretical framework of urban activity resilience.Relying on geographic big data,this study identifies the spatial characteristics of activity resilience,reveals the impact of activity environment on activity resilience in Nanjing,and proposes countermeasures.The main conclusions are as follows.1)Activity resilience presents a composite spatial structure of circles and clusters,and most areas are resilient but at a low level.2)There are significantly positive and negative global autocorrelation between activity resilience and activity scale,and activity stability.Simultaneously,there also exists a local spatial autocorrelation with the opposite positive and negative trends.3)Activity environment has a significant effect on activity resilience,and the degree and direction of influence among different dimensions and regions are heterogeneous.4)For activity resilience,it is necessary to increase the matching degree between the scale and stability of activities,and reduce the excessive concentration and flow of activities.For the activity environment,it is necessary to improve the accessibility of the ecological environment,strengthen the high-quality supply of the infrastructure environment,optimize the balance of the location environment,and promote the inclusiveness of the social environment.展开更多
The stratigraphical cross-sections of the Yangtze River incised-valley near the No.l, No.3 and No.4 Nanjing Yangtze River bridges were established with respective bore date and documents. By ^14C age analysis of the s...The stratigraphical cross-sections of the Yangtze River incised-valley near the No.l, No.3 and No.4 Nanjing Yangtze River bridges were established with respective bore date and documents. By ^14C age analysis of the samples of four drilling cores near the No.4 Bridge （to be built）, we can find that the time range of paleo-valley is dated in the LGM at a depth of-60 m to -90 m near Nanjing. It is also indicated that the deep incised-valley channel was narrow and the river flowed swiftly. The ancient Yangtze River deep channel presented partially and deeply incised features near the No.1 Bridge. According to previous publications, much research has been done on the main paleo-channel of the Yangtze River, but few results have been achieved on discharge estimation. In this paper, the incipient velocity and average veIocity of the LGM was calculated with Vc=4.60d^1/3h^1/6, Vc=1.281g（ 13.15. h /d95） √gd, V≈6.5u＊｜h/d90｜^1/6 etc., in terms of the river shape, sedimentary grain size and sequences near the No.3 and No.1 bridges. Moreover, the discharge in Nanjing reach of the Yangtze River during the LGM has been estimated to be around 12,000-16,000 m^3/s according to the relationship of discharge, velocity of flow and cross-section.展开更多
Urban carbon footprint reflects the impact and pressure of human activities on ur- ban environment. Based on city level, this paper estimated carbon emissions and carbon footprint of Nanjing city, analyzed urban carbo...Urban carbon footprint reflects the impact and pressure of human activities on ur- ban environment. Based on city level, this paper estimated carbon emissions and carbon footprint of Nanjing city, analyzed urban carbon footprint intensity and carbon cycle pressure and discussed the influencing factors of carbon footprint through LMDI decomposition model. The main conclusions are as follows： （1） The total carbon emissions of Nanjing increased rapidly since 2000, in which the carbon emission from the use of fossil energy was the largest Meanwhile, carbon sinks of Nanjing presented a declining trend since 2000, which caused the decrease of carbon compensation rate and the increase of urban carbon cycle pressure. （2） The total carbon footprint of Nanjing increased rapidly since 2000, and the carbon deficit was more than ten times of total land areas of Nanjing in 2009, which means Nanjing confronted high carbon cycle pressure. （3） Generally, carbon footprint intensity of Nanjing was on de- crease and the carbon footprint productivity was on increase. This indicated that energy utilization rate and carbon efficiency of Nanjing was improved since 2000, and the policy for energy conservation and emission reduction taken by Nanjing＇s government received better effects. （4） Economic development, population and industrial structure are promoting factors for the increase of carbon footprint of Nanjing, while the industrial carbon footprint intensity was inhibitory factor. （5） Several countermeasures should be taken to decrease urban carbon footprint and alleviate carbon cycle pressure, such as： improvement of the energy efficiency, industrial structure reconstruction, afforestation and environmental protection and land use control. Generally, transition to low-carbon economy is essential for Chinese cities to realize sustainable development in the future.展开更多
The existing researches on the influence of information and communication technology （ICT） are mainly focused on human activity, whilst with few efforts on urban space. In the e-society, the widespread adoption of 1...The existing researches on the influence of information and communication technology （ICT） are mainly focused on human activity, whilst with few efforts on urban space. In the e-society, the widespread adoption of 1CT devices not only affects almost every aspect of people＇s daily life and thereby reshapes the spatial development of regions and cities, but also generates a large amount of real-time activity data with location information. These georeferenced data, however, have relatively recently attracted attention from geographers. Adapted from Lynch＇s framework based on people＇s perceptions, this paper proposes a framework of urban spatial struc- ture based on people＇s actual activity, including five elements, namely activity path, activity node, central activity zone （CAZ）, activity district, and activity edge. In the empirical study, by using one week＇s check-in tweets （from February 25 to March 3 in 2013） collected in Nanjing City, the five elements are recognized and analyzed. Through the comparison between our results and urban spatial structure based on population （and land use）, we argue that ICT uses： 1） lead to polarize, rather than to smooth, the urban structural hierarchy, due to the dual role of distance; 2） enable a partial decoupling of activity and activity space node, which challenges our conventional under- standing of the role of home and the utility of travel; 3） blur the boundaries of activity districts and hence may play a positive role in enriching districts＇ functions, which should not be overlooked in the current urban transformation in China.展开更多
基金supported by the National Natural Science Foundation of China(Nos.22361162668 and 42021004)the National Key Research and Development Program of China(No.2023YFC3706203).
文摘Along with decrease of fine particulate matter(PM_(2.5))concentration in recent years in China,secondary species become increasingly important.This work focuses on characterizing secondary components,and a few important groups of organics including organic nitrogen(ON),organonitrates(OrgN),organosulfates(OS)and polycyclic aromatic hydrocarbons(PAHs),via online measurement of submicron aerosols(PM_(1))in Nanjing,China,during 2022 summer.The average PM_(1) concentration was 15.39μg/m^(3),dominated by secondary components(69.1%),which were even more important at higher PM_(1) levels.The primary organic aerosols(POA)were from traffic,industry and cooking;the two secondary OA factors were both closely linked with photochemistry,with one(OOA1)being relatively fresh and important in early afternoon and another(OOA2)being aged and important in late afternoon.Sulfate formation was also governed by photochemistry but resembled that of OOA2 not OOA1;nitrate formation was associated strongly with heterogeneous hydrolysis and thermodynamic equilibrium.Results also reveal a possible photochemical reaction channel from POA to OOA1,then to OOA2.Case studies show that formations of secondary components responded differently to different weather conditions and governed summer PM_(1) pollution.The average ON,OrgN,OS and PAHs concentrations were determined to be 122.8,84.4,45.6 and 3.3 ng/m^(3),respectively.ON was dominated by primary sources(53.8%).OrgN varied similarly to nitrate.OS formation was linked with aqueous-phase reactions,which were insignificant therefore its level was low.PAHs was mainly from traffic,and photochemical oxidation might be its important sink during afternoon.
文摘Urban lakes,situated in cities characterized by dense population and economic activities,are susceptible to eutrophication.This study focuses on the water ecological restoration project of Xuanwu Lake,assessing the efficacy of ecological management through laboratory analysis of water quality indicators.Furthermore,it delves into a comprehensive life cycle cost structure analysis,ecosystem service value accounting,and economic benefit evaluation.From an economic standpoint,the research examines the cost-effectiveness and external impacts of the clear-water ecosystem restoration project.Findings indicate that TP and TN levels in the treated area have decreased by over 50%,substantially reducing the eutrophication index.The cost-benefit ratio for each unit of treatment stands at 1:3.2(direct benefit).Notably,the restoration has markedly improved water quality and augmented the value of ecosystem services,demonstrating long-term cost sustainability and positive economic externalities.To ensure the sustained success of such restorations,it is imperative to optimize public resource allocation,incorporate market-based incentives,and furnish economic insights for managing urban lakes.
基金Sponsored by The National Social Science Fundation of China(24BGL216).
文摘This study investigates community identity in Nanjing’s historic Hehuatang community during urban renewal,revealing tensions between heritage preservation and modernization.Through ethnographic research,three key factors are identified shaping identity:(i)material conditions including series of spatial conflicts around overcrowding,(ii)social tensions such as tenant-aborigine divides and generational misunderstanding,and(iii)institutional governance as top-down policies would exacerbate distrust.Despite 82%of residents expressing place attachment,67%desire relocation due to deteriorating liveability—a paradox highlighting the failure of China’s contemporary performative participation models.The adapted three-layer creativity model underscores the need to reconcile physical renewal with social equity.Findings advocate for co-design processes that integrate resident agency,offering lessons for sustainable urban renewal in rapidly developing contexts.
基金supported by the National Natural Science Foundation of China(Nos.42275116 and 41975172).
文摘Aerosol hygroscopicity and liquid water content(ALWC)have important influences on the environmental and climate effect of aerosols.In this study,we measured the hygroscopic growth factors(GF)of particles with dry diameters of 40,80,150,and 200 nm during the wintertime in Nanjing.Both the GF-derived hygroscopicity parameter(κ_(gf))and ALWC increased with particle size,but displayed differing diurnal variations,withκ_(gf)peaking around the midday,while ALWC peaking in the early morning.Nitrate,ammonium and oxygenated organic aerosols(OOA)were found as the chemical components mostly strongly correlated with ALWC.A closure study suggests that during midday photo-oxidation and nighttime high ALWC periods,theκof organic aerosols(κ_(org))was underestimated when using previous parameterizations.Accordingly,we re-constructed parameterizations forκ_(org)and the oxidation level of organics for these periods,which indicates a higher hygroscopicity of photochemically formed OOA than the aqueous OOA,yet both being much higher than the generally assumed OOA hygroscopicity.Additionally,in a typical high ALWC episode,concurrently increased ALWC,nitrate,OOA as well as aerosol surface area and mass concentrations were observed under elevated ambient RH.This strongly indicates a coupled effect that the hygroscopic secondary aerosols,in particular nitratewith strong hygroscopicity,led to large increase in ALWC,which in turn synergistically boosted nitrate and OOA formation by heterogeneous/aqueous reactions.Such interaction may represent an important mechanism contributing to enhanced formation of secondary aerosols and rapid growth of fine particulate matter under relatively high RH conditions.
基金supported by the National Natural Science Foundation of China(No.32271734)。
文摘The acceleration of global urbanization has caused habitat loss,fragmentation,and decrease of habitat quality,often leading to a decline in biodiversity.However,most previous urbanization studies focused on taxonomic diversity,with relatively less research on functional and phylogenetic diversity.In this study,we examined the phylogenetic and functional diversity and underlying influencing factors of bird communities in 37 urban parks in Nanjing,China.We conducted a systematic survey of bird communities in Nanjing urban parks and selected six park characteristics that are generally considered to affect bird diversity.Model selection based on corrected Akaike Information Criterion(AICc)and model averaging showed that park area,habitat diversity and building index(a proxy for the degree of urbanization)were significant factors affecting avian phylogenetic and functional diversity in Nanjing urban parks.Specifically,habitat diversity and park area were positively correlated with bird diversity,while the building index was negatively correlated with bird diversity.Moreover,the phylogenetic and functional structures of urban bird communities exhibited a clustered pattern,indicating that environmental filtering might play a role in shaping community composition.In addition,building index had certain impact on the construction of bird phylogenetic communities in urban parks.Our results suggest that expanding park areas,increasing habitat diversity and reducing building indexes may be effective measures to increase the avian phylogenetic and functional diversity in our system.
基金National Natural Science Foundation of China,No.42371397The Key Laboratory of Lake and Watershed Science for Water Security,No.NKL2023-KP03。
文摘This study establishes a framework to assess greenspace supply-demand disparities related to thermal discomfort from the perspective of population mobility across urban functional zones(UFZs).High-resolution greenspace maps and location-based service(LBS)datasets for Nanjing,China,were combined with Spearman correlation analyses and a four-quadrant model to elucidate associations and matching patterns between greenspace exposure and thermal comfort.The findings indicate that population fluctuations affect the availability of actual greenspace,with correlations to thermal discomfort showing significant temporal variations among different UFZs.During morning workday hours,commercial zones have a significantly higher representation in Quadrant Ⅱ(82.26%)compared to non-workdays(70.86%),which is characterized by high population density,low greenspace exposure,and pronounced thermal discomfort.In contrast,residential and public service zones maintain consistently high and stable proportions in Quadrant Ⅰ across all periods.This spatial mismatch is primarily caused by differences in available greenspace quantities and population mobility.Planning adjustments should focus on ensuring sufficient greenspace provision in key areas during peak population mobility periods to mitigate thermal discomfort.Minimizing residents'staying time in thermally uncomfortable zones,implementing time-specific greenspace access,and strategically increasing greenspace coverage are essential for improving the mismatch between greenspace supply and demand.
基金supported by the National Natural Science Foundation of China(Nos.42007325 and 42177211).
文摘To understand the differences in the composition and sources of PM_(2.5) and PM_(10) caused by coarse particles,integrated PM_(2.5) and PM_(10) samples were synchronously collected in Nanjing,East China,in summer 2020 and winter 2020/2021.Bulk and molecular speciation and light absorption measurements of aerosol extractswere performed,followed by positivematrix factorization(PMF)based on the PM_(2.5) and PM_(10) data sets,respectively.The difference in average concentrations of total bulk species between PM_(2.5) and PM_(10) was mainly caused by the distribution of considerable NO_(3)^(–),SO42–,Ca^(2+),and organic carbon(OC)in coarse particles.Coarse PMinfluenced by abrasion products from tirewear and leaves contributed about half of the low-volatility n-alkanes in summer.The contribution of coarse PM to biomass burning tracers and water-soluble OC increased in winter when biomass combustion was excessively active.More than 70%of sugar polyols were attributable to coarse PM in summer,and biomass burning could be an important source in winter.The light-absorbing organic chromophores were almost entirely associated with PM_(2.5),but water-soluble organic carbon(WSOC)exhibited stronger light absorption in PM_(10) extracts than in PM_(2.5) extracts possibly due to the influence of coarse PMon pH.PMF analysis indicated that biomass burning,aqueous-phase reactions,and processed dust were the main contributors of organic matter and its light absorption in winter.Biogenic primary and secondary sources made discernable contributions only in summer.The differences between PM_(2.5) and PM_(10) were likely attributed to mixing of crustal dust,combustion particles,and surface reactions.
基金Under the auspices of European Commission under 7th Framework Programme (No ECUBS–230824)
文摘The institutional environment in China has quite evidently changed during modern socio-economic transitions.Driven both by local government and by marketing force,urban social space was redistributed after the reform of urban land and real estate policies.Urban renewal makes for wide differential rent and therefore gentrification is occurring in China.This paper analyzes the background and institutional environment of gentrification in China,and further discusses the process,characteristics and evolutionary mechanisms in the case of Nanjing,through investigation of the attributes of 1075 residential communities built during the 1998-2008 at a macro level,and interviewing the residents and analyzing questionnaires in 6 different and typical communities at a micro level.As a socio-spatial course of two-way interaction,gentrification is divided into 3 stages of incubation,occurrence and fast development,according to the time of landmark events and policy reform on the leasehold of land in Nanjing during socio-economic transition.In terms of the socio-spatial characteristics of gentrification in Nanjing,the gentrification process under the trajectory of urban renewal makes urban social space present a new circle-layer structure;the rise of quite a number of gated communities results in the fragmentation of social space and privatization of public space;the management mode of modern communities and the change of life style have aggravated the indifference of neighborhood relationship of gentrified communities.Based on the empirical evidence of this study,this paper indicates that gentrification is quite different between China and western countries with respect to spatio-temporal order,dominant forces,paths of realization and spatial expression,and it further reveals the dynamic mechanism of gentrification developing in China at the present stage.
基金supported by the National Key Basic Research & Development Program of China (Grant Nos. 2016YFC0203303, 2016YFC0208504 and 2014CB441203)the National Natural Science Foundation of China (Grant Nos. 91544230, 41575145 and 41621005)the EU 7th Framework Marie Curie Actions IRSES project: REQUA (Grant No. PIRSESGA-2013-612671)
文摘Particulate matter with diameters of 2.5 μm or smaller(PM_(2.5)) and ozone(O_3) are major pollutants in the urban atmosphere. PM_(2.5) can affect O_3 by altering the photolysis rate and heterogeneous reactions. However, these two processes and their relative importance remain uncertain. In this paper, with Nanjing in China as the target city, we investigate the characteristics and mechanism of interactions between particles and O_3 based on ground observations and numerical modeling.In 2008, the average concentrations of PM_(2.5) and O_3 at Caochangmen station are 64.6 ± 47.4 μg m^(-3) and 24.6 ± 22.8 ppb,respectively, while at Pukou station they are 94.1 ± 63.4 μg m^(-3) and 16.9 ± 14.9 ppb. The correlation coefficient between PM_(2.5) and O_3 is -0.46. In order to understand the reaction between PM_(2.5) and O_3, we construct a box model, in which an aerosol optical property model, ultraviolet radiation model, gas phase chemistry model, and heterogeneous chemistry model,are coupled. The model is employed to investigate the relative contribution of the aforementioned two processes, which vary under different particle concentrations, scattering capability and VOCs/NOxratios(VOCs: volatile organic compounds;NOx: nitric oxide and nitrogen dioxide). Generally, photolysis rate effect can cause a greater O_3 reduction when the particle concentrations are higher, while heterogeneous reactions dominate O_3 reduction with low-level particle concentrations.Moreover, in typical VOC-sensitive regions, O_3 can even be increased by heterogeneous reactions. In Nanjing, both processes lead to O_3 reduction, and photolysis rate effect is dominant. Our study underscores the importance of photolysis rate effect and heterogeneous reactions for O_3, and such interaction processes should be fully considered in future atmospheric chemistry modeling.
基金Under the auspices of Key Project of National Natural Science Foundation of China (No. 40435013, 40301014)
文摘Taking Nanjing as a case, the paper explains the spatial behavior differences existing in the information technology use among different groups of residents and households, by virtue of analyzing the survey data of urban households in the 11 districts of Nanjing, from the social, spatial, life and other non-technical angles. Also it makes various analyses and evaluation quantitatively and qualitatively on the social and spatial effect of information technology. The results show that the new technology is changing the social spatial behaviors of urban residents. New behavioral spaces of urban family such as telecommuting, email and QQ have begun to emerge. With the help of Internet, the communication scope of families has expanded greatly, and more new forms of publicizing community information have begun to emerge. Telecommunication contact forms have been developing swiftly, and their frequencies of contact have been increasing dramatically.
基金Key Research Project of National Natural Science Foundation of China Under Grant No.90715018National Basic Research Program of China Under Grant No.2007CB714200the Special Fund for the Commonweal Industry of China Under Grant No.200808022
文摘Three groups of dynamic triaxial tests were performed for saturated Nanjing fine sand subjected to uniform cyclic loading. The tested curves of the excess pore water pressure （EPWP） ratio variation with the ratio of the number of cycles are provided. The concept of the EPWP increment ratio is introduced and two new concepts of the effective dynamic shear stress ratio and the log decrement of effective stress are defined. It is found that the development of the EPWP increment ratio can be divided into three stages： descending, stable and ascending. Furthermore, at the stable and ascending stages, a satisfactory linear relationship is obtained between the accumulative EPWP increment ratio and natural logarithm of the effective dynamic shear stress ratio. Accordingly, the EPWP increment ratio at the number of cycles N has been deduced that is proportional to the log decrement of effective stress at the cycle number N-l, but is independent of the cyclic stress amplitude. Based on the analysis, a new EPWP increment model for saturated Nanjing fine sand is developed from tested data fitting, which provides a better prediction of the curves of EPWP generation, the number of cycles required for initial liquefaction and the liquefaction resistance.
基金supported jointly by the Key Project of Natural Science Foundation of Jiangsu Province under Grant No BK2007727the Scientific Project for Public Welfare specific to Meteo rologists (GYHY200706026, GYHY200906012)+1 种基金Qinglan Project "cloud fog precipitation and aerosol research innovation group"the National Natural Science Foundation of China (Grant Nos 40775012, 40975085, and 40775010)
文摘An extremely dense radiation fog event during 10-11 December 2007 was studied to understand its macro-micro-physics in relation to dynamic and thermodynamic structures of the boundary layer, as well as its structural evolution in conjunction with the air-surface exchange of heat and water vapor. The findings are as follows. The extreme radiation fog process was divisible into formation, development, mature, and dissipation phases, depending on microstructure and visibility. This fog event was marked by rapid evolution that occurred after sunrise, when enhanced surface evaporation and cold air intrusion led to a three order of magnitude increase in liquid water content （LWC） in just 20 minutes. The maximum droplet diameter （MDD） increased four-fold during the same period. The fog structure was two-layered, with the top of both the surface-layer and upper-layer components characterized by strong temperature and humidity inversions, and low-level jets existed in the boundary layer above each fog layer. Turbulence intensity, turbulent kinetic energy, and friction velocity differed remarkably from phase to phase： these features increased gradually before the fog formation and decreased during the development phase; during the mature and dissipation phases these characteristics increased and then decreased again. In the development and mature stages, the mean kinetic energy of the lower-level winds decreased pronouncedly, both in the horizontal and vertical directions.
基金The Society Development Foundation of Jiangsu Province (No. BS2001039)
文摘An increasing number of industrial, agricultural, and commercial chemicals in the aquatic environment leads to various deleterious effects on organisms, which is becoming an increasingly serious problem in China. In this study, the comet assay was conducted to investigate the genotoxicity to human body caused by organic concentrates in the drinking water sources of Nanjing City from Yangtze River of China, and health and ecology risk due to expose to these organic pollutants were evaluated with the multimedia environmental assessment system （MEAS）. For all the water samples, they were collected from four different locations in the drinking water sourcr samples, es of Nanjing City. The results of the comet assay showed that all the organic concentrates from the water samples could induce different levels DNA damages on human peripheral blood lymphocytes, and a statistically significant difference （p〈0.01） was observed compared with the solvent control, which demonstrated the genotoxicity was in existence. According to the ambient severity （AS） of individual compound, we had sorted out the main organic pollutants in the drinking water source of the four waterworks, and the results showed that there was some potential hazard to human body for all the source water, namely the total ambient severity （TAS） of health for each water source was more than 1. However, the TAS of ecology for each water source was less than 1, which indicated that it was safe to ecology. The results of this investigation demonstrate the application of the comet assay and the MEAS in aquatic environmental monitoring studies, and the comet assay found to be fast, sensitive, and suitable for genotoxicity monitoring programs of drinking water source.
基金Under the auspices of National Natural Science Foundation of China(No.41571146)National Natural Science Youth Foundation of China(No.51708276)Postdoctoral Science Foundation of China(No.2017M611781)
文摘Future or smart community, which mainly refers to the development of community information and communication technology(ICT) platforms or devices, has received considerable attention from urban governments and scholars. However, only a few studies have been conducted to test the actual effects of using these community ICT platforms or devices on the community satisfaction of residents. Therefore, the present study conducts a survey in 40 communities in Nanjing, China and uses a mixed linear regression model to determine the relationship between community ICT usage and community satisfaction. Results indicate that residents with high-level community ICT usage are more satisfied with their community than those with low-level community ICT usage. Moreover, evident differences are observed regarding the influence of new commodity, old commodity and affordable housing communities in Nanjing. These findings are meaningful for the construction and development of future communities.
文摘Laboratory tests on the large post-liquefaction deformation of saturated Nanjing fine sand were performed by using a hollow cylinder apparatus. The stress-strain responses and the characteristics of excess pore water pressure after liquefaction were studied. It was found that the relationship between deviatoric stress and axial strain presented a sigmoid curve, and there was a good linearity relationship between normalized pore water pressure and deviatoric stress. On this basis, a constitutive model of stress-strain responses and a dissipation model of excess pore water pressure were established. It was found that the results predicted by the two models were in good agreement with the experimental data. The influence of relative densities and confining pressure on the characteristics of liquefied soil were studied, The results showed the relative densities and initial effective confining pressure all had an important influence on the stress-strain responses of liquefied saturated Nanjing fine sand. However, the dissipation model of excess pore water pressure after liquefaction was only affected by the confining pressure.
基金National Natural Science Foundation of China,No.42171234,No.41901215,No.42271245。
文摘As a type of urban gentrification oriented by high-quality educational resources,jiaoyufication is a socio-spatial process that refers to the middle-class group that attaches importance to education realizes the agglomeration in famous school districts by purchasing high-price school district houses.Based on the theoretical analysis of jiaoyufication conducted by Chinese and foreign scholars,this paper takes Nanjing as a case city,applies multi-source data like POIs(points of interest),real estate market data,mobile-phone user portraits and questionnaires,and develops a composite measurement of jiaoyufication to identify jiaoyufied school district,jiaoyufied group&its spatial characteristics,and discusses the causal mechanisms and effects of jiaoyufication.With the GIS-entropy-TOPSIS model,this paper evaluates the jiaoyufication level of public primary school districts in the main urban area of Nanjing.The result show that 218 primary school districts are categorized into four types,i.e.,high jiaoyufied school district,mid-high jiaoyufied school district,medium jiaoyufied school district,and low jiaoyufied school district.The high jiaoyufied school districts are closely associated with the institutional system.In the high jiaoyufied school districts,many middle-class families have abundant social,economic,and cultural capital.They purchase and move to houses with lower living quality in school districts to pursue high-quality education for their children.The strict school district system,soaring school district housing prices,and intense educational competition continuously solidify the jiaoyufication levels of famous school districts and lock the opportunities for high-quality education in specific school-district spaces and classes or groups.The phenomenon of this socio-spatial reconstruction process,which results from the unequal distribution of high-quality educational resources,tends to aggravate the rich-poor gap and social segregation in cities.It is suggested that equalization of compulsory education services should be effectively carried forward as soon as possible.
基金Under the auspices of National Social Science Fund of China(No.20AZD040)the Program B for Outstanding PhD Candidate of Nanjing University(No.202002B103)。
文摘Based on the connotation of urban resilience and the main contradictions of China's urbanization,urban resilience is placed within the main daily activities contradictory scene of the urban man-land system to build a theoretical framework of urban activity resilience.Relying on geographic big data,this study identifies the spatial characteristics of activity resilience,reveals the impact of activity environment on activity resilience in Nanjing,and proposes countermeasures.The main conclusions are as follows.1)Activity resilience presents a composite spatial structure of circles and clusters,and most areas are resilient but at a low level.2)There are significantly positive and negative global autocorrelation between activity resilience and activity scale,and activity stability.Simultaneously,there also exists a local spatial autocorrelation with the opposite positive and negative trends.3)Activity environment has a significant effect on activity resilience,and the degree and direction of influence among different dimensions and regions are heterogeneous.4)For activity resilience,it is necessary to increase the matching degree between the scale and stability of activities,and reduce the excessive concentration and flow of activities.For the activity environment,it is necessary to improve the accessibility of the ecological environment,strengthen the high-quality supply of the infrastructure environment,optimize the balance of the location environment,and promote the inclusiveness of the social environment.
基金National Basic Research Program of China, No.2003CB415201-8 National Natural Science Foundation of China. No.40871010 Doctorate Foundation of Linyi Normal University, No.BS08021
文摘The stratigraphical cross-sections of the Yangtze River incised-valley near the No.l, No.3 and No.4 Nanjing Yangtze River bridges were established with respective bore date and documents. By ^14C age analysis of the samples of four drilling cores near the No.4 Bridge （to be built）, we can find that the time range of paleo-valley is dated in the LGM at a depth of-60 m to -90 m near Nanjing. It is also indicated that the deep incised-valley channel was narrow and the river flowed swiftly. The ancient Yangtze River deep channel presented partially and deeply incised features near the No.1 Bridge. According to previous publications, much research has been done on the main paleo-channel of the Yangtze River, but few results have been achieved on discharge estimation. In this paper, the incipient velocity and average veIocity of the LGM was calculated with Vc=4.60d^1/3h^1/6, Vc=1.281g（ 13.15. h /d95） √gd, V≈6.5u＊｜h/d90｜^1/6 etc., in terms of the river shape, sedimentary grain size and sequences near the No.3 and No.1 bridges. Moreover, the discharge in Nanjing reach of the Yangtze River during the LGM has been estimated to be around 12,000-16,000 m^3/s according to the relationship of discharge, velocity of flow and cross-section.
基金National Social Science Foundation of China, No. 10ZD＆030 National Natural Science Foundation of China, No.41301633+3 种基金 China Clean Development Mechanism Foundation, No.1214073 China Postdoctoral Science Foundation, No.2012M511243 No.2013 T60518 The Startup Project for High-level Talented Person of North China University of Water Resources and Electric Power, No.201164
文摘Urban carbon footprint reflects the impact and pressure of human activities on ur- ban environment. Based on city level, this paper estimated carbon emissions and carbon footprint of Nanjing city, analyzed urban carbon footprint intensity and carbon cycle pressure and discussed the influencing factors of carbon footprint through LMDI decomposition model. The main conclusions are as follows： （1） The total carbon emissions of Nanjing increased rapidly since 2000, in which the carbon emission from the use of fossil energy was the largest Meanwhile, carbon sinks of Nanjing presented a declining trend since 2000, which caused the decrease of carbon compensation rate and the increase of urban carbon cycle pressure. （2） The total carbon footprint of Nanjing increased rapidly since 2000, and the carbon deficit was more than ten times of total land areas of Nanjing in 2009, which means Nanjing confronted high carbon cycle pressure. （3） Generally, carbon footprint intensity of Nanjing was on de- crease and the carbon footprint productivity was on increase. This indicated that energy utilization rate and carbon efficiency of Nanjing was improved since 2000, and the policy for energy conservation and emission reduction taken by Nanjing＇s government received better effects. （4） Economic development, population and industrial structure are promoting factors for the increase of carbon footprint of Nanjing, while the industrial carbon footprint intensity was inhibitory factor. （5） Several countermeasures should be taken to decrease urban carbon footprint and alleviate carbon cycle pressure, such as： improvement of the energy efficiency, industrial structure reconstruction, afforestation and environmental protection and land use control. Generally, transition to low-carbon economy is essential for Chinese cities to realize sustainable development in the future.
基金National Natural Science Foundation of China(No.40971094)
文摘The existing researches on the influence of information and communication technology （ICT） are mainly focused on human activity, whilst with few efforts on urban space. In the e-society, the widespread adoption of 1CT devices not only affects almost every aspect of people＇s daily life and thereby reshapes the spatial development of regions and cities, but also generates a large amount of real-time activity data with location information. These georeferenced data, however, have relatively recently attracted attention from geographers. Adapted from Lynch＇s framework based on people＇s perceptions, this paper proposes a framework of urban spatial struc- ture based on people＇s actual activity, including five elements, namely activity path, activity node, central activity zone （CAZ）, activity district, and activity edge. In the empirical study, by using one week＇s check-in tweets （from February 25 to March 3 in 2013） collected in Nanjing City, the five elements are recognized and analyzed. Through the comparison between our results and urban spatial structure based on population （and land use）, we argue that ICT uses： 1） lead to polarize, rather than to smooth, the urban structural hierarchy, due to the dual role of distance; 2） enable a partial decoupling of activity and activity space node, which challenges our conventional under- standing of the role of home and the utility of travel; 3） blur the boundaries of activity districts and hence may play a positive role in enriching districts＇ functions, which should not be overlooked in the current urban transformation in China.
