| Aerosol particle is the solid or liquid particle substance distrubuted in the air and it is one important factor of influencing air quality in the city. According to the related research,the fine particles in the air link with the human health closely.The poisonous and harmful composition enriched on the particles endanger not only to the air quality,but also to the ecological environment and human health.And the heavy metal is one of the main pollutants,being permanent pollutant once entering into the environment system.So it is necessary to understand the spartial and timely distrubution feature and spread mechanism of particles in the environment of surface ground.Research on the regulation of accumulation and transfer of heavy metal element enriched in the aerosol particle is significant for the related department take measures to prevent the parcticle and heavy metal pollution,enhance the city living environment and protect the residents'health.This essay elects the Putuo campus and Minhang campus of East China Normal University and the Xianghuaqiao station of water conservancy technology in Qingpu district as the sampling sites of aerosol particles,standing for the residential region,industrial region and agriculture region.It analyses the spartial and timely feature of particles(PM2.5,PM10,TSP) of the surface ground in Shanghai as well as the chemistrial feature of heavy metal in them and it discusses the change of particles in Shanghai under the speacial weather condition,such as the sand storm.It also makes primary judgement of the source where the particles come from with the CMB model and Scanning Electron Microscope with EDX.The conclusion it makes are as follows:(1) The concentration of TSP in Shanghai in the year of 2009-2010 is under the air quality standard limit ofâ…¡district. The concentration of PM10 and PM 2.5 decreases compared with that of the year between 2001 and 2005,implying the measures to prevent the aerosol particle pollution is effective.The concentration of particles in winter and spring is much higher than that in summer and fall,which is the result of the special weather system in winter and the influence of sand storm weather in spring.(2)The heavy metal concentration of aerosol paricles such as Cu,Zn,Pb in Shanghai is not as high as the measurement result of other cities,which means the man-made pollution is relatively less in Shanghai.The annual concentration of Pb in the year of 2009-2010 decreases remarkably.That is because since Shanghai prohibited the petrol with Pb in 1997,the Pb emission in the air has been well controlled.(3)The concentration of the elements in PM2.5,PM10 and TSP in winter is the highest,that is because the special weather condition leads to the pollutants can't diffuse easily.The lowest concentration of most heavy metal appears in the summer and fall because of the abundant rainfall,which can decrease the element concentration with the mechnism of brush and rain remove.The concentration of Ca,K,Fe,Mn,Al and Mg is a little higher in the spring.That is because with the influence of sand storm in the north in spring,the storm in Shanghai is strong,bringing much crustal elements.However,its effect to the man-made elements is relatively small.(4)The enrichment factor of Cu,Mn,Cr,Ni,Zn,Pb in PM2.5>PM10>TSP,implying the effective of enrichment is more evident in the fine particle.The enrichment of Ni,Zn,Pb in the PM2.5,PM10 TSP is larger than 10, which means the enrichment has happened.(5)The first component of three sampling sites mainly comes from Zn,Cu,K,Fe,Mn,Cr,Pb, most of which is atmophile element from the emission of man-made pollution.The second component comes from Mg,Ca,Al,standing for lithophile element from the nature source.(6) According to the judgement result of aerosol particles in Shanghai with CMB model,The first three emission sources of PM2.5,PM10 are coal burning,cement emission and soil dust and they are cement emission, soil dust and car gas in the case of TSP.The source judgement of three sites is similar but different with each other,implying the aerosol particles in Shanghai are effected both regionally and locally. (7)According to the observation with SEM(EDX),there are several classes of aerosol particles in Shanghai:(1)coal burning dust; (2) soot aggregation in the shape of chain; (3) soot aggregation in the shape of loose agglomerate; (4)mineral particle in regular shape; (5)mineral particle in irregular shape; (6)salt particle; (7)unknown particle with special shape. With the analysis of EDX,coal burning belongs to one of the common pollution sources in Shanghai and soil dust is another important emission source.The EDX result also reveals it exists the elemnet of S in the aerosol particles in Shanghai,which maybe linked with the high concentration of SO2 in the air.(8)The analysis of backward trajectories during the period of sandstorm weather in Shanghai reveals that air pollution in Shanghai was effected by the sandstorm in the north to large extent in late March. While the air pollution in Shanghai during the sandstorm weather in late April also comes from the sea besides the influence of sandstorm in the innner land. |
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