The Characteristics Of Heavy Metals In Atmospheric Particulates Near Surface Along The Road In Shanghai

Heavy metal,pollution of Aerosol along the Highway near the surface is a research hotspot in recent years,and due to vehicle emissions and other factors,heavy metals of atmospheric particulates near the surface in the micro system along the urban road migrate,accumulate and transformate in the atmosphere near the ground,road dust,roadside soil,vegetables and the green belt with the atmospheric circulation.It has become a potential threat in the road ecological environment,and has become an important factor in the deterioration of the Earth's atmospheric environment.The pollution from heavy metals in the atmosphere,soil and water directly or indirectly endanger human health.This article seeks to follow the main line.Through the urban roads and highway intersection in the different height,different seasons and special meteorological,this article monitors and analyse atmospheric particulates and simultaneously investigates the surface of the soil,weather conditions and traffic flow. This article takes the study to aerosol near the surface heavy metal pollution in the course of highway constrution and operation in order to put forward some advices and to control the pollution,which has significantly realistic and scientific meaning.In this study,the points spatial location distribute the outer ring of Shanghai,Inner Ring,the Jinshajiang road through the outer and inner and the typical features zone such as:Baoshan Industrial Zone,schools sensitive areas.It is a total of 10 points representing large and medium-sized industrial zones,cultural and educational areas, commercial and heavy traffic areas,cleaning and other control characteristics of different functions.Samples for each point are atmospheric particulate,the surface soil of every corner of the crossroads of the Green Belt section,record data for the road traffic situation at a crossroads and local meteorological conditions,which is in 12-hour sampling.A near-surface atmospheric particulate matter sample is every three hours and the mode is dimensional arrangement sampling(two air sampler,spatial comparison);traffic is this three-hour time period on all types of vehicles(large cars,small cars and public Motor Vehicles);local meteorological conditions for one hour is temperature,humidity,wind direction and speed;at last which collected near-surface atmospheric particulate matter 77 samples,35 soil samples and 1300 record data field.The analysis was based on 2328 valid data and samples of various types of heavy metals Cd,Cr,Ni,Cu,Pb,Zn,As,Mn,Hg content and distribution characteristics and the urban environment along in near-surface atmospheric particulate pollution in heavy metals and ecological risk evaluation,which provides reliable sicentific basis of the enviroment pollution control,highway management and city planning. The main conclusions of this study can be summed up as follows:(1) The concentration of atmospheric particulates near the surface in Shanghai highway lines and intersections changes greatly,which are mainly due to weather conditions,traffic flow,and sampling of the surrounding environment etc.The general law is that the Concentration of the inner ring is higher than the outer ring;and for the same sampling point,near point was significantly higher than the far point,at the same time it show that the direct source of atmospheric particulate matter is from motor vehicles and traffic particulate matter.the Concentration of the sampling points is different in period of 12 hours a day,and a greater concentration generally appear in the first period of time 7:00-10:00 higher,and then in 10:00-13:00 and 13:00-16:00 reduced and 16:00-19:00 time period in the peak value.(2) The average content of heavy metals As,Cu,Fe,Mn,Ni,Pb, Zn in the sampling points in one day is higher in the intersection and lower along.Generally it is considered that the speed of vehicles traveling is a greater impact.The heavy metal contents of the sampling points are gradually increased from the outer to the inner region.In the same time period the atmospheric particulate matter sampling of near point was far more than the far point,but the content of heavy metal elements was significantly lower than the far point,the contents of heavy metal elements in a day change greatly which due to a variety of different conditions such as traffic flow.But it is due to weather conditions,the impacts are not the same,specifically,outer＞inner＞Central.In a sampling point,the content of far point's heavy metal elements is generally more than near point.(3) The contents of heavy metals Hg,Cr,Cu,Pb and Zn were 0.25, 4.02,78.20,113.64 and 419.65μg/g in Shanghai highway lines,which is for the environmental background values of 2.5,1.3,2.7,4.5 and 5 times. The spatial distribution of heavy metals content is great different and local pollution is serious.The soil concentration of heavy metal content in the intersection and highwaylines is higher in the road along and the central green.Through geoaccumulation index,pollutant load index and the potential ecological risk assessment method analyzing,it indicates that the vast majority were polluted,and in a few strong regional pollution. Seen from the three analytical methods,Hg high-level is a hazard.(4) From the analysis of traffic flow,it is great,and the speed of a moving vehicle is fast.So the particulate matter is more from the ground.And in the inner ring and the central intersection,vehicle speed is decelerate,Idling longer running,the engine combustion is not sufficient, a large quantity of emissioned.