为了解北京城市街区PM10浓度日变化特征及其影响因素,利用2003年10月BECAPEX(Beijing City Air Pollution Experiment)街道、街区及周边小区4个测点PM10浓度的对比观测试验资料和同期街道机动车流量、采样点附近自动气象站风速及探空资...为了解北京城市街区PM10浓度日变化特征及其影响因素,利用2003年10月BECAPEX(Beijing City Air Pollution Experiment)街道、街区及周边小区4个测点PM10浓度的对比观测试验资料和同期街道机动车流量、采样点附近自动气象站风速及探空资料进行了综合对比分析。通过天气诊断和统计学分析相结合,初步分析了北京市城区街道大气污染物PM10浓度日变化特征及机动车排放污染、气象条件对PM10浓度日变化的影响。结果表明,试验期间北京市城区街道PM10浓度日变化特征存在明显差异,交通源污染物PM10浓度日变化具有单峰与双峰型差异的特殊性。工作日PM10浓度日变化出现双峰,周末PM10浓度日变化仅有单峰出现;交通污染源和气象条件对城市街区PM10浓度日变化特征的影响程度存在空间差异。离交通污染源较近的街区PM10浓度日变化受机动车排放污染的影响程度较大,而离交通源较远的小区PM10浓度受机动车排放污染的影响相对较小;不稳定天气条件下交通污染源影响范围较小,在特定天气条件下,气象条件的影响强度可显著超过交通污染源的影响。展开更多
A traditional wedding procession escorts the groom to the bride＇s house through the streets of Beijing, adding a splash of red delight to an otherwise grey urban setting. These processions are becoming a rare sight a...A traditional wedding procession escorts the groom to the bride＇s house through the streets of Beijing, adding a splash of red delight to an otherwise grey urban setting. These processions are becoming a rare sight as modern life engulfs many ancient cultural events.展开更多
Environmental magnetic measurements were carried out on the samples of street dust and topsoil,which were collected along the roadway in the urban and suburb of Beijing,including magnetic sus-ceptibility(χ),anhystere...Environmental magnetic measurements were carried out on the samples of street dust and topsoil,which were collected along the roadway in the urban and suburb of Beijing,including magnetic sus-ceptibility(χ),anhysteretic remanent magnetization(ARM),isothermal remanent magnetization(IRM)of all samples and temperature-dependence of magnetic susceptibilities and magnetic hysteresis pa-rameters of representative samples.Obvious differences exist between the samples of street dust and those of topsoil.Compared with topsoil samples,the concentration of magnetic particles and high-coercivity components in street dust samples are higher,and the magnetic grains are coarser.Both dust and topsoil samples are dominated by ferrimagnetic minerals,and iron particles are only detected in some dust samples.These results suggest that street dust samples reflect the characteris-tic of particles produced by industrial and traffic activities,and the magnetic property of topsoil sam-ples represents the characteristic of particles from both anthropogenic and natural sources.The dis-tribution of magnetic parameters is influenced by the environment where the samples are collected,like industry,traffic density and other road conditions.Hard isothermal remanent magnetization(HIRM)may be used as an indicator of particles produced by traffic activity.Dust storm samples collected on 17 and 18 April,2006 have different magnetic properties from street dust and natural particles,like loess and paleosol,which indicate that the dust storm might be mixed with anthropogenic particulates during transport and falling.展开更多
The distribution and the concentrations of various chemical elements in street sediments were investigated along a rural-urban boundary in Beijing, China. The statistical factor analysis of the data concerned identifi...The distribution and the concentrations of various chemical elements in street sediments were investigated along a rural-urban boundary in Beijing, China. The statistical factor analysis of the data concerned identifies two anthropogenic sources responsible for the contamination of Beijing air. The first source is a steel factory in the western part of Beijing. From this source, Mn, Fe and Ti were emitted into the atmosphere through chimneys and by wind from coal heaps used as the primary energy source for the factory. The second source is a combination of traffic, domestic heating and some small factories in the center of Beijing urban area discharging Cu, Pb, Zn and Sn. Grain-size analyses show that most of the metals in the road dust have higher concentrations in the small grain-size fraction <0.125 mm, which is the severest case because these small particles with larger specific surface area and high heavy metal contents fly up easily and float in the air for a long time. Besides the anthropogenic contamination, such elements as Y, Zr, Nb, Ce and Rb are derived mainly both from natural soils and from the deserts. This is supported by mineral-phase analysis, which shows a clear imprint of materials in road dusts coming from the west China deserts. Our results clearly show that the chemical compositions of the urban road dusts can be used to identify distinctive sources responsible for the contamination mentioned above. The study shows that the chemistry of road dusts is an important monitor to assess the contamination in the urban environment.展开更多
A good skylight environment in urban residential areas is an important component of a healthy city,and has always been highly valued.With the rapid development of new-type urbanization,the density of buildings continu...A good skylight environment in urban residential areas is an important component of a healthy city,and has always been highly valued.With the rapid development of new-type urbanization,the density of buildings continues to increase,and megacities have entered the stage of stock transformation.An effective method for evaluating the skylight environment of large-scale urban residential areas is urgently needed.However,there is still a lack of empirical research methods and cases of large-scale residential skylight environment.In this regard,this article takes the megacity Beijing as the research object,and proposes an efficient analysis method of residential skylight environment that integrates multiple real-world data at city scale.In terms of data,it collects and integrates 3D data of urban-scale building space and residential boundary data;in terms of algorithm,Sky View Factor(SVF)is used as the evaluation index of residential skylight environment,and an efficient analysis method of urban-scale skylight environment based on cloud parallel simulation is realized.Through analysis,it is found that:(1)the average SVF value of Beijing residential area is 61%,which means that its skylight quality is in general level;(2)the skylight environment of Beijing residential area is distributed in a circle,and there are 4 types of skylight environment quality residential areas;(3)The skylight environment of Beijing residential area is relatively weakly related to the distance from the residential area to the city center and the average height of the residential buildings,and is closely related to the plot volume ratio,the residential building density and the shading from surrounding buildings.The highlight of this study lies in the empirical research on the skylight environment of mega-city residential areas that incorporates multiple real data for the first time,which can promote the study of skylight environment on a city scale and provide a reference for the updating of Beijing’s residential daylight environment.展开更多
文摘为了解北京城市街区PM10浓度日变化特征及其影响因素,利用2003年10月BECAPEX(Beijing City Air Pollution Experiment)街道、街区及周边小区4个测点PM10浓度的对比观测试验资料和同期街道机动车流量、采样点附近自动气象站风速及探空资料进行了综合对比分析。通过天气诊断和统计学分析相结合,初步分析了北京市城区街道大气污染物PM10浓度日变化特征及机动车排放污染、气象条件对PM10浓度日变化的影响。结果表明,试验期间北京市城区街道PM10浓度日变化特征存在明显差异,交通源污染物PM10浓度日变化具有单峰与双峰型差异的特殊性。工作日PM10浓度日变化出现双峰,周末PM10浓度日变化仅有单峰出现;交通污染源和气象条件对城市街区PM10浓度日变化特征的影响程度存在空间差异。离交通污染源较近的街区PM10浓度日变化受机动车排放污染的影响程度较大,而离交通源较远的小区PM10浓度受机动车排放污染的影响相对较小;不稳定天气条件下交通污染源影响范围较小,在特定天气条件下,气象条件的影响强度可显著超过交通污染源的影响。
文摘A traditional wedding procession escorts the groom to the bride＇s house through the streets of Beijing, adding a splash of red delight to an otherwise grey urban setting. These processions are becoming a rare sight as modern life engulfs many ancient cultural events.
基金Ministry of Education of China(Grant No.NCET-04-0727)the National Natural Science Foundation of China(Grant No.40032010B)111 Project(Grant No.B07011)
文摘Environmental magnetic measurements were carried out on the samples of street dust and topsoil,which were collected along the roadway in the urban and suburb of Beijing,including magnetic sus-ceptibility(χ),anhysteretic remanent magnetization(ARM),isothermal remanent magnetization(IRM)of all samples and temperature-dependence of magnetic susceptibilities and magnetic hysteresis pa-rameters of representative samples.Obvious differences exist between the samples of street dust and those of topsoil.Compared with topsoil samples,the concentration of magnetic particles and high-coercivity components in street dust samples are higher,and the magnetic grains are coarser.Both dust and topsoil samples are dominated by ferrimagnetic minerals,and iron particles are only detected in some dust samples.These results suggest that street dust samples reflect the characteris-tic of particles produced by industrial and traffic activities,and the magnetic property of topsoil sam-ples represents the characteristic of particles from both anthropogenic and natural sources.The dis-tribution of magnetic parameters is influenced by the environment where the samples are collected,like industry,traffic density and other road conditions.Hard isothermal remanent magnetization(HIRM)may be used as an indicator of particles produced by traffic activity.Dust storm samples collected on 17 and 18 April,2006 have different magnetic properties from street dust and natural particles,like loess and paleosol,which indicate that the dust storm might be mixed with anthropogenic particulates during transport and falling.
文摘The distribution and the concentrations of various chemical elements in street sediments were investigated along a rural-urban boundary in Beijing, China. The statistical factor analysis of the data concerned identifies two anthropogenic sources responsible for the contamination of Beijing air. The first source is a steel factory in the western part of Beijing. From this source, Mn, Fe and Ti were emitted into the atmosphere through chimneys and by wind from coal heaps used as the primary energy source for the factory. The second source is a combination of traffic, domestic heating and some small factories in the center of Beijing urban area discharging Cu, Pb, Zn and Sn. Grain-size analyses show that most of the metals in the road dust have higher concentrations in the small grain-size fraction <0.125 mm, which is the severest case because these small particles with larger specific surface area and high heavy metal contents fly up easily and float in the air for a long time. Besides the anthropogenic contamination, such elements as Y, Zr, Nb, Ce and Rb are derived mainly both from natural soils and from the deserts. This is supported by mineral-phase analysis, which shows a clear imprint of materials in road dusts coming from the west China deserts. Our results clearly show that the chemical compositions of the urban road dusts can be used to identify distinctive sources responsible for the contamination mentioned above. The study shows that the chemistry of road dusts is an important monitor to assess the contamination in the urban environment.
基金This research is supported by Outstanding Youth Program of the National Natural Science Foundation of China(No.51825802)General Program of the National Natural Science Foundation of China(No.51578302).
文摘A good skylight environment in urban residential areas is an important component of a healthy city,and has always been highly valued.With the rapid development of new-type urbanization,the density of buildings continues to increase,and megacities have entered the stage of stock transformation.An effective method for evaluating the skylight environment of large-scale urban residential areas is urgently needed.However,there is still a lack of empirical research methods and cases of large-scale residential skylight environment.In this regard,this article takes the megacity Beijing as the research object,and proposes an efficient analysis method of residential skylight environment that integrates multiple real-world data at city scale.In terms of data,it collects and integrates 3D data of urban-scale building space and residential boundary data;in terms of algorithm,Sky View Factor(SVF)is used as the evaluation index of residential skylight environment,and an efficient analysis method of urban-scale skylight environment based on cloud parallel simulation is realized.Through analysis,it is found that:(1)the average SVF value of Beijing residential area is 61%,which means that its skylight quality is in general level;(2)the skylight environment of Beijing residential area is distributed in a circle,and there are 4 types of skylight environment quality residential areas;(3)The skylight environment of Beijing residential area is relatively weakly related to the distance from the residential area to the city center and the average height of the residential buildings,and is closely related to the plot volume ratio,the residential building density and the shading from surrounding buildings.The highlight of this study lies in the empirical research on the skylight environment of mega-city residential areas that incorporates multiple real data for the first time,which can promote the study of skylight environment on a city scale and provide a reference for the updating of Beijing’s residential daylight environment.
