Environmental inequality is a prevalent issue in developing countries undergoing urban expansion.Urban expansion induces the formation and evolution of environmental inequality by creating environmental and structural...Environmental inequality is a prevalent issue in developing countries undergoing urban expansion.Urban expansion induces the formation and evolution of environmental inequality by creating environmental and structural conditions that lead to the spatial relocation of environmental hazards and the socio-spatial segregation of different groups in developing countries.This study investigated the spatial patterns and temporal trends of environmental inequality under urban expansion in Guangzhou,a megacity in China.It considered how environmental disparities and socio-demographic attributes interact in terms of industrial pollution exposure using additive semiparametric quantile regression,combined with spatial visualisation,on the basis of the economic and population census data from 1990 to 2020.This study revealed that urban expansion sparked the spatial displacement of environmental risks and the social-spatial differentiation,exposing the peripheral regions and disadvantaged groups to higher environmental risks.A reciprocal transformation occurred between central and peripheral regions,as well as a process of redistributing environmental risks across social space.In the context of urban expansion in developing countries,the causes of environmental inequality shifted from individual socio-economic differences to structural factors,such as industrial layout and social division of labour in cities,leading to the spatial displacement and concealment of environmental inequality.This study provides insights and guidance for policymakers to address the issue of environmental inequality in the context of urban expansion.展开更多
The accessibility and fairness of public service facilities are important manifestations of the convenience and equality of urban public service resource allocation.Optimizing the layout of urban public service facili...The accessibility and fairness of public service facilities are important manifestations of the convenience and equality of urban public service resource allocation.Optimizing the layout of urban public service facilities is an inevitable requirement for promoting the construction of people centered cities.This paper takes the old urban area of Guangzhou as the research area,measures the accessibility of multiple types of public service facilities based on an improved two-step floating catchment method,and combines Palma Ratio and location quotient methods to explore the fairness of urban public service facilities from two dimensions:social equity and spatial equity,with supply and demand relationship analysis as the main line.Research has shown that:①there is a significant spatial difference in the accessibility of public service facilities in the old urban areas of Guangzhou,and the comprehensive accessibility is generally higher in the central and southeastern regions of the old urban areas with fewer residential populations;②from the perspective of social equity,the resource allocation of public service facilities in the old urban areas of Guangzhou is in a seriously unfair state(with a fairness index of 2.99),and there are also varying degrees of unfairness within the streets;③from the perspective of spatial equity,the location quotient of public service facilities in the old urban areas of Guangzhou shows a pattern of multil center circles decreasing,indicating a significant spatial mismatch between the accessibility supply side of public service facilities and the demand side of the residential population.The research conclusion will provide scientific basis for optimizing the allocation of urban public service facilities and ensuring the equalization of public services.展开更多
Thermal comfort evaluations for Yuexiu Park,Lushan Park,and Baiyun Lake Park in Guangzhou were conducted using field meteorological data collection,visitor questionnaires,and literature reviews.It analyzed the impact ...Thermal comfort evaluations for Yuexiu Park,Lushan Park,and Baiyun Lake Park in Guangzhou were conducted using field meteorological data collection,visitor questionnaires,and literature reviews.It analyzed the impact of green coverage,water body layout,and facility configuration on thermal comfort.The results showed that good green and water body design effectively lowered the temperature in the park and improved the thermal comfort of visitors,but the insufficient facility configuration in some open areas affected the experience.The visitor’s experience is closely related to the natural environment and facility layout of the park.Therefore,in the future,park design should pay more attention to the rational configuration of shading,ventilation,and cooling facilities to improve thermal comfort,and encourage citizens to participate in the construction and management of parks to improve ecological quality and user experience.This study provides a reference for the improvement of thermal comfort in urban parks in Guangzhou and aims to promote the sustainable and human-oriented development of urban park design.展开更多
The chemical characteristics（water-soluble ions and carbonaceous species） of PM2.5 in Guangzhou were measured during a typical haze episode.Most of the chemical species in PM2.5 showed significant difference between...The chemical characteristics（water-soluble ions and carbonaceous species） of PM2.5 in Guangzhou were measured during a typical haze episode.Most of the chemical species in PM2.5 showed significant difference between normal and haze days.The highest contributors to PM2.5 were organic carbon（OC）,nitrate,and sulfate in haze days and were OC,sulfate,and elemental carbon（EC） in normal days.The concentrations of secondary species such as,NO3^-,SO4^2-,and NH4^＋ in haze days were 6.5,3.9,and 5.3 times higher than those in normal days,respectively,while primary species（EC,Ca^2＋,K^＋） show similar increase from normal to haze days by a factor about 2.2-2.4.OC/EC ratio ranged from 2.8 to 6.2 with an average of 4.7 and the estimation on a minimum OC/EC ratio showed that SOC（secondary organic carbon） accounted more than 36.6% for the total organic carbon in haze days.The significantly increase in the secondary species（SOC,NO3^-,SO4^2-,and NH4^＋）,especially in NO3^-,caused the worst air quality in this region.Simultaneously,the result illustrated that the serious air pollution in haze episodes was strongly correlated with the meteorological conditions.During the sampling periods,air pollution and visibility had a good relationship with the air mass transport distance;the shorter air masses transport distance,the worse air quality and visibility in Guangzhou,indicating the strong domination of local sources contributing to haze formation.High concentration of the secondary aerosol in haze episodes was likely due to the higher oxidation rates of sulfur and nitrogen species.展开更多
Urbanization has boon the most important process that changed land cover landscape in Guangzhou since reformation, especially since 1990. It is essential for monitoring and assessing ecological consequences of urbaniz...Urbanization has boon the most important process that changed land cover landscape in Guangzhou since reformation, especially since 1990. It is essential for monitoring and assessing ecological consequences of urbanization to understand landscape quantitative characteristics and its changes. Based on four land-cover type maps interpreted from remote sensing TM images of 1990, 1995, 2000 and 2005, combining gradient analysis with landscape metrics, the quantified spatial pattern and its dynamics of urbanization in Guangzhou was got. Three landscape metrics were computed within different regional areas including the whole study area, two transects along two highways （one N-S and the other W-E） and radiation zones with equal distance outwards the city center were set. Buffer zones for transects N-S and W-E were outlined along highways. The following questions should be answered in this paper： What responses were implied with changing spatial grain size or extent for landscape pattern analysis？ Could gradient progress of urbanization be characterized by landscape pattern analysis？ Did landscape metrics reveal urban expanding gradually？ Were there directional differences in land cover landscape pattern during urbanizing development？ The results gave some affirmative answers. Landscape pattern exhibited obviously scale-dependent to grain size and extent. The landscape metrics with gradient analysis could quantitatively approach spatial pattern of urbanization. A precise location for urbanized area, like city center and sub-center, could be identified by multiple landscape metrics. Multiple adjunctive centers occurred as indicated by analysis of radiation zones around the city center. Directional differences of landscape pattern along the two transects （N-S and W-E） came into being. For example, fragmentation of landscape in the transect W-E was obviously higher than that in the transect N-S. All in all, some interesting and important ecological implications were revealed under landscape patterns of two transects or radiation zones, and that was the important step to link pattern with processes in urban ecological studies and the basis to improve urban environment.展开更多
The plant biomass and net primary production(NPP) of urban vegetation in Guangzhou were estimated by dimension analysis, tree truck volume, and harvest methods as well as relationship between biomass and NPP and so on...The plant biomass and net primary production(NPP) of urban vegetation in Guangzhou were estimated by dimension analysis, tree truck volume, and harvest methods as well as relationship between biomass and NPP and so on. The biomass and NPP were respectively 2875150t and 1058122 t/a. They were respectively 392495t and 64948 t/a in the built-up area and 2482655t and 993147 t/a in the unbuilt-up area. It would make plant biomass, especially NPP decline obviously, if the unbuilt-up area were changed to the built-up area. The carbon content of plant was 1328649 for the total and 13.78 t/hm 2 for the mean, and amounts of carbon fixed and oxygen made by urban vegetation were respectively 4.80 t/(hm 2·a) and 12.79 t/(hm 2·a) for the mean and 462624 t/a and 1232430 t/a for the total, which were equal to 1.45 times and 1.04 times of those by human breathing. However, they were only equal to 7.61% and 4.97% of amount of carbon released and oxygen consumption in urban Guangzhou. The biomass and NPP of urban vegetation in Guangzhou only corresponded to 7.8% and 47.3% of those of southern subtropical evergreen broad-leaf forest in Dinghu Mountain. Therefore, the roles of Guangzhou urban vegetation in balance of carbon and oxygen would be increased greatly if it could be conserved and improved in some way.展开更多
On the basis of the reported air quality index （API） and air pollutant monitoring data provided by the Guangzhou Environment Monitoring Stations over the last twenty-five years, the characteristics of air quality, p...On the basis of the reported air quality index （API） and air pollutant monitoring data provided by the Guangzhou Environment Monitoring Stations over the last twenty-five years, the characteristics of air quality, prominent pollutants, and variation of the average annual concentrations of SOE, NOE, total suspended particulate （TSP）, fine particulates （PM10）, CO and dustfall in Guangzhou City were analyzed. Results showed that TSP was the prominent pollutant in the ambient air environment of Guangzhou City. Of the prominent pollutants, TSP accounted for nearly 62%, SOE 12.3%, and NOx 6.4%, respectively. The average API of Guangzhou over 6 years was higher than that of Beijing, Tianjin, Nanjing, Hangzhou, Suzhou and Shanghai, and lower than that of Shenzhen, Zhuhai and Shantou. Concentrations of air pollutants have shown a downward trend in recent years, but they are generally worse than ambient air quality standards for USA, Hong Kong and EU. SOE and NOx pollution were still serious, impling that waste gas pollution from all kinds of vehicles had become a significant problem for environmental protection in Guangzhou. The possible causes of worsening air quality were also discussed in this paper.展开更多
基金Under the auspices of the National Natural Science Foundation of China(No.42271181,41871111)。
文摘Environmental inequality is a prevalent issue in developing countries undergoing urban expansion.Urban expansion induces the formation and evolution of environmental inequality by creating environmental and structural conditions that lead to the spatial relocation of environmental hazards and the socio-spatial segregation of different groups in developing countries.This study investigated the spatial patterns and temporal trends of environmental inequality under urban expansion in Guangzhou,a megacity in China.It considered how environmental disparities and socio-demographic attributes interact in terms of industrial pollution exposure using additive semiparametric quantile regression,combined with spatial visualisation,on the basis of the economic and population census data from 1990 to 2020.This study revealed that urban expansion sparked the spatial displacement of environmental risks and the social-spatial differentiation,exposing the peripheral regions and disadvantaged groups to higher environmental risks.A reciprocal transformation occurred between central and peripheral regions,as well as a process of redistributing environmental risks across social space.In the context of urban expansion in developing countries,the causes of environmental inequality shifted from individual socio-economic differences to structural factors,such as industrial layout and social division of labour in cities,leading to the spatial displacement and concealment of environmental inequality.This study provides insights and guidance for policymakers to address the issue of environmental inequality in the context of urban expansion.
文摘The accessibility and fairness of public service facilities are important manifestations of the convenience and equality of urban public service resource allocation.Optimizing the layout of urban public service facilities is an inevitable requirement for promoting the construction of people centered cities.This paper takes the old urban area of Guangzhou as the research area,measures the accessibility of multiple types of public service facilities based on an improved two-step floating catchment method,and combines Palma Ratio and location quotient methods to explore the fairness of urban public service facilities from two dimensions:social equity and spatial equity,with supply and demand relationship analysis as the main line.Research has shown that:①there is a significant spatial difference in the accessibility of public service facilities in the old urban areas of Guangzhou,and the comprehensive accessibility is generally higher in the central and southeastern regions of the old urban areas with fewer residential populations;②from the perspective of social equity,the resource allocation of public service facilities in the old urban areas of Guangzhou is in a seriously unfair state(with a fairness index of 2.99),and there are also varying degrees of unfairness within the streets;③from the perspective of spatial equity,the location quotient of public service facilities in the old urban areas of Guangzhou shows a pattern of multil center circles decreasing,indicating a significant spatial mismatch between the accessibility supply side of public service facilities and the demand side of the residential population.The research conclusion will provide scientific basis for optimizing the allocation of urban public service facilities and ensuring the equalization of public services.
文摘Thermal comfort evaluations for Yuexiu Park,Lushan Park,and Baiyun Lake Park in Guangzhou were conducted using field meteorological data collection,visitor questionnaires,and literature reviews.It analyzed the impact of green coverage,water body layout,and facility configuration on thermal comfort.The results showed that good green and water body design effectively lowered the temperature in the park and improved the thermal comfort of visitors,but the insufficient facility configuration in some open areas affected the experience.The visitor’s experience is closely related to the natural environment and facility layout of the park.Therefore,in the future,park design should pay more attention to the rational configuration of shading,ventilation,and cooling facilities to improve thermal comfort,and encourage citizens to participate in the construction and management of parks to improve ecological quality and user experience.This study provides a reference for the improvement of thermal comfort in urban parks in Guangzhou and aims to promote the sustainable and human-oriented development of urban park design.
基金supported by the National Excellent Youth Foundation of China (No. 20625722)the China Postdoctoral Science Foundation (No. 20080430396)
文摘The chemical characteristics（water-soluble ions and carbonaceous species） of PM2.5 in Guangzhou were measured during a typical haze episode.Most of the chemical species in PM2.5 showed significant difference between normal and haze days.The highest contributors to PM2.5 were organic carbon（OC）,nitrate,and sulfate in haze days and were OC,sulfate,and elemental carbon（EC） in normal days.The concentrations of secondary species such as,NO3^-,SO4^2-,and NH4^＋ in haze days were 6.5,3.9,and 5.3 times higher than those in normal days,respectively,while primary species（EC,Ca^2＋,K^＋） show similar increase from normal to haze days by a factor about 2.2-2.4.OC/EC ratio ranged from 2.8 to 6.2 with an average of 4.7 and the estimation on a minimum OC/EC ratio showed that SOC（secondary organic carbon） accounted more than 36.6% for the total organic carbon in haze days.The significantly increase in the secondary species（SOC,NO3^-,SO4^2-,and NH4^＋）,especially in NO3^-,caused the worst air quality in this region.Simultaneously,the result illustrated that the serious air pollution in haze episodes was strongly correlated with the meteorological conditions.During the sampling periods,air pollution and visibility had a good relationship with the air mass transport distance;the shorter air masses transport distance,the worse air quality and visibility in Guangzhou,indicating the strong domination of local sources contributing to haze formation.High concentration of the secondary aerosol in haze episodes was likely due to the higher oxidation rates of sulfur and nitrogen species.
基金National Natural Science Foundation of China,No.40635029Guangzhou Science & Technology Program,No.08C027
文摘Urbanization has boon the most important process that changed land cover landscape in Guangzhou since reformation, especially since 1990. It is essential for monitoring and assessing ecological consequences of urbanization to understand landscape quantitative characteristics and its changes. Based on four land-cover type maps interpreted from remote sensing TM images of 1990, 1995, 2000 and 2005, combining gradient analysis with landscape metrics, the quantified spatial pattern and its dynamics of urbanization in Guangzhou was got. Three landscape metrics were computed within different regional areas including the whole study area, two transects along two highways （one N-S and the other W-E） and radiation zones with equal distance outwards the city center were set. Buffer zones for transects N-S and W-E were outlined along highways. The following questions should be answered in this paper： What responses were implied with changing spatial grain size or extent for landscape pattern analysis？ Could gradient progress of urbanization be characterized by landscape pattern analysis？ Did landscape metrics reveal urban expanding gradually？ Were there directional differences in land cover landscape pattern during urbanizing development？ The results gave some affirmative answers. Landscape pattern exhibited obviously scale-dependent to grain size and extent. The landscape metrics with gradient analysis could quantitatively approach spatial pattern of urbanization. A precise location for urbanized area, like city center and sub-center, could be identified by multiple landscape metrics. Multiple adjunctive centers occurred as indicated by analysis of radiation zones around the city center. Directional differences of landscape pattern along the two transects （N-S and W-E） came into being. For example, fragmentation of landscape in the transect W-E was obviously higher than that in the transect N-S. All in all, some interesting and important ecological implications were revealed under landscape patterns of two transects or radiation zones, and that was the important step to link pattern with processes in urban ecological studies and the basis to improve urban environment.
基金TheNationalNaturalScienceFoundationofChina(No .495 710 64 )andGuangdongEnvironmentalProtectionBureau (No .1999 15 )
文摘The plant biomass and net primary production(NPP) of urban vegetation in Guangzhou were estimated by dimension analysis, tree truck volume, and harvest methods as well as relationship between biomass and NPP and so on. The biomass and NPP were respectively 2875150t and 1058122 t/a. They were respectively 392495t and 64948 t/a in the built-up area and 2482655t and 993147 t/a in the unbuilt-up area. It would make plant biomass, especially NPP decline obviously, if the unbuilt-up area were changed to the built-up area. The carbon content of plant was 1328649 for the total and 13.78 t/hm 2 for the mean, and amounts of carbon fixed and oxygen made by urban vegetation were respectively 4.80 t/(hm 2·a) and 12.79 t/(hm 2·a) for the mean and 462624 t/a and 1232430 t/a for the total, which were equal to 1.45 times and 1.04 times of those by human breathing. However, they were only equal to 7.61% and 4.97% of amount of carbon released and oxygen consumption in urban Guangzhou. The biomass and NPP of urban vegetation in Guangzhou only corresponded to 7.8% and 47.3% of those of southern subtropical evergreen broad-leaf forest in Dinghu Mountain. Therefore, the roles of Guangzhou urban vegetation in balance of carbon and oxygen would be increased greatly if it could be conserved and improved in some way.
基金Project supported by the National Natural Science Foundation of China (No. 30270282)the Key Project of Chinese Education Ministry (No. 704037)the Special Invited Professor Foundation of Guangdong Province.
文摘On the basis of the reported air quality index （API） and air pollutant monitoring data provided by the Guangzhou Environment Monitoring Stations over the last twenty-five years, the characteristics of air quality, prominent pollutants, and variation of the average annual concentrations of SOE, NOE, total suspended particulate （TSP）, fine particulates （PM10）, CO and dustfall in Guangzhou City were analyzed. Results showed that TSP was the prominent pollutant in the ambient air environment of Guangzhou City. Of the prominent pollutants, TSP accounted for nearly 62%, SOE 12.3%, and NOx 6.4%, respectively. The average API of Guangzhou over 6 years was higher than that of Beijing, Tianjin, Nanjing, Hangzhou, Suzhou and Shanghai, and lower than that of Shenzhen, Zhuhai and Shantou. Concentrations of air pollutants have shown a downward trend in recent years, but they are generally worse than ambient air quality standards for USA, Hong Kong and EU. SOE and NOx pollution were still serious, impling that waste gas pollution from all kinds of vehicles had become a significant problem for environmental protection in Guangzhou. The possible causes of worsening air quality were also discussed in this paper.
