Urban environmental problems are of increasing concern. Lanzhou is a large industrial city in North-west China. Street dust samples representing different temporal and spatial scales were collected for magnetic proper...Urban environmental problems are of increasing concern. Lanzhou is a large industrial city in North-west China. Street dust samples representing different temporal and spatial scales were collected for magnetic properties study. Magnetic measurements indicate a high concentration of magnetic minerals in Lanzhou street dust, dominated by pseudo-single domain (PSD) magnetite. The concentration of magnetic materials is distinctly high in winter and spring, low in autumn. Similarly, higher concentra-tions associated with heavy industry, concentrated residential development, and vehicular traffic sug-gest mixed contributions of magnetic material from both anthropogenic and natural sources. χ_lf and SOFT% are effective magnetic parameters that denote seasonal differences among magnetic proper-ties in street dust, convenient and economical methods for monitoring street dust pollution.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
基金the National Natural Science Foundation of China (Grant Nos.40571147 and 40401064)
文摘Urban environmental problems are of increasing concern. Lanzhou is a large industrial city in North-west China. Street dust samples representing different temporal and spatial scales were collected for magnetic properties study. Magnetic measurements indicate a high concentration of magnetic minerals in Lanzhou street dust, dominated by pseudo-single domain (PSD) magnetite. The concentration of magnetic materials is distinctly high in winter and spring, low in autumn. Similarly, higher concentra-tions associated with heavy industry, concentrated residential development, and vehicular traffic sug-gest mixed contributions of magnetic material from both anthropogenic and natural sources. χ_lf and SOFT% are effective magnetic parameters that denote seasonal differences among magnetic proper-ties in street dust, convenient and economical methods for monitoring street dust pollution.
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.
