| The City is the center of human social, political, economic, cultural,scientific, education, facing with the pressure of huge resources andthe environment. With the growth trend of the economic, which bringsthe high emission of pollutants, the ecological environment of the cityfaces enormous pressure; the accelerated process of city, when thecity population increase, the rapid improvement of peoples livingstandards and consumption levels, bring greater pressure to thesupply of the ecological environment. Shanghai is located in theeastern coast of China, is one of Chinas largest cities and is economiccenter of China, also one of the world-famous metropolises.Because of developed economy and large population〠theintensity of human activities, environment pollution problem is moreserious. This paper intends to get samples of street dust from thedifferent functional areas of Shanghai, just like Xuhui District, BaoshanDistrict, Fengxian District.The magnetic characteristic of thecomprehensive analysis of dust samples by size, environmentalmagnetism, geochemical elements and relationship with heavy metalcontamination, the results show that: the magnetic studies show that:low-frequency the susceptibility χlf (×10-8/m3? kg-1) an average of824,range1from23.3to2014.2, the coefficient of variation was0.49,compared with other regions,the magnetic susceptibility of street dust,indicating that the dust magnetic mineral content is high, the pollutionis more serious. The main ferromagnetic in the samples is ferromagneticminerals, magnetic particle size is in PSD and MD. Spatial and temporalvariation of four seasons, χlf of samples in spring and summer are higher,the order is spring> winter> autumn>summer; χlf shows a decreasingtrend from the industrial area to a clean area; the trend of SIRM alsoshows similarity with χlf. Shanghai city street dust mean particle diameter and mediandiameter are73.2μm and37.7μm silt (<63μm) particles with averagecontent of73.9%; Shanghai street dust Particle size is mainly affected bythe conditions of wind power a variety of factors in the distcityce ofhuman activities (such as vehicles, manual cleaning) and endogenous(Source) control, non-normal distribution of particle size distributioncurve shows two peaks and multiple peaks; wind brought about bynatural sources of material superimposed in anthropogenic sources ofmaterial above the wind enhancements result in fine particles escaping,with an average particle size increases, sorting worse. The kineticenergy in the wind region, the dust mainly coarse particles;small area of the wind kinetic energy, while fine particulatematter-based. The spatial distribution of Shanghai street dust particlesize characteristics indicate that the dust samples of the clean areaand the District of Communications in Shanghai particle size of coarse,the business district and industrial zone, residential area is relatively small;particles larger than2μm sample of the total92%-99.5%, less than2μmparticles accounted for10percent, the Shanghai street dust particlesfrom soil dust and anthropogenic emissions of pollutants by thecommon contribution.Geochemical elements of the street dust samples indicate that:different functional areas of the street dust samples, Cr, Mn and Feelements the highest value in industrial areas; As, Ni, Sr., the highestvalue in the business district, respectively, Zn element values appear inthe traffic area, Sn, Ba and Pb are several elements of high-valueresidential areas, the rest of Cu, Rb, Zr, and other elements aredistributed evenly.Shanghai street dust samples by the influence of anthropogenicsources, including industrial emissions, transport, commercial and otheraspects. |
