The Pb-monitoring program was extended for 6 years from 2002 to 2007 at 17 representative urban sites (6 traffic, 5 industrial, and 6 residential sites), and 3 suburban sites to assess the lead pollution in fine particulate matter (PM2.5) after phasing out leaded gasoline in Shanghai. Compared with Pb levels reported in other places, the Pb pollution in Shanghai is still serious after phasing out leaded gasoline, which remains at high concentration range (213–176 ng/m3) in PM2.5 in winter. Significant spatial variation of Pb concentrations and strong seasonal variation of higher Pb concentration in winter than that in summer were detected. The size distribution of Pb in particulate matter has a unimodal mode that peaks at approximately 0.154–1.59 μm particle diameter, indicating that Pb is mainly concentrated in fine fraction. Lead in the fine fraction is enriched by a factor of 103–104 relative to Pb abundance in crust. Eight categories of Pb pollution sources were identified in the PM2.5 in the winter of 2007 in Shanghai. The important emission sources among them are vehicle exhaust derived from combustion of unleaded gasoline, metallurgic industry emission, and coal combustion emission.
LI XiaolinZHANG YuanxunTAN MingguangLIU JiangfengBAO LiangmanZHANG GuilinLI YanIIDA Atsuo
In order to further understand the sources of PM2.5 in Shanghai air, the synchrotron X-ray fluores-cence microprobe at the BL-4A Beamline of Photon Factory of High Energy Accelerator Research Organization, Japan, was applied to analyze the individual PM2.5 particles collected from Shanghai air in the winter of 2007.Eight categories of emission sources were recognized in these individual particles.The source identification shows that most of the analyzed PM2.5 particles are derived from vehicle exhaust and metallurgical emissions.This suggests that the important emission sources of PM2.5 in Shanghai air would be vehicle exhaust and metallurgical activities.
In this study,vehicle exhaust particles were collected three locations (the middle,entrance and outside) of the Dapu Road tunnel in downtown Shanghai,and the particle samples were characterized using SEM,XAFS,ICP-MS and M?ssbauer spectrometry,and the oxidative damage was assessed by plasmid DNA.Most iron-containing particles are found from vehicle exhaust,and iron oxide is the major species in all samples.Its concentration in the particles inside the tunnel is higher than that the outside particles.The iron particles inside the tunnel have higher proportion of water-soluble fraction in hydrous iron sulfate form or smaller size.ZnCl2 is the main soluble fraction in zinc-containing particles,while higher percentage of insoluble fraction existed in the particles outside of tunnel.Major species of lead-containing particles are PbSO4,Pb3(PO4)2 and PbCO3.In addition,the soluble fraction of other transition metallic elements as Ti and V is higher in the particles inside the tunnel than that outside the tunnel.The plasmid DNA assay results indicate that the particles from vehicle exhaust have a stronger oxidative damage and inflammation than that from outside of the tunnel.
JIN ChanFAN XiaoyanLI YanLIANG FengLI YulanZOU YangYANG YongjiXIE Yaning
More than 20 hair strands obtained from several people are analyzed by non-invasive micro-proton induced X-ray emission (PIXE) for probing calcium and sulfur distribution and pattern. The sulfur con- tent in woman’s hair along the longitudinal axis shows a monthly rhythm whereas the level of Ca is much higher in the medulla core and exhibits a daily rhythm both in male and female hair. The Ca content gradually decreases from the tip to the root position in the shedding process and more Ca can be found in black hair compared to white hair.
In this paper,the impact of the viaduct on flow and traffic exhausting particles dispersion within urban street canyons was nu-merically simulated using a computational fluid dynamics(CFD) model.Two-dimensional flow and dispersion of particles from traffic exhausts were modeled using the standard k-? turbulence model.The street canyons with a viaduct at different widths and different heights above the ground are simulated.The results show that the airflow in street canyon is evidently in-fluenced by the viaduct:The position of the main vortex center is changed,especially there are two strong vortexes when the viaduct is placed at 10 m height above the ground.It is found based on the study of the particles number concentrations(PNCs) that the viaduct may mitigate the pollution level in the street canyon sometimes.The impact of the viaduct width on PNCs is stronger than that of the height.The study of PNDs reveals that the mean PNCs at the wall of upwind building increase when a viaduct is placed in street canyon.In addition,it is found based on the study of mean particles residence time(PRT) that the removal of the particles strongly correlates to the mean PNCs.The results indicate that the viaduct is an important factor to in-fluence the flow patterns and particles dispersion in street canyons.
ZHANG ChuanFuWEN MouZENG JianRongZHANG GuiLinFANG HaiPingLI Yan
