| Air quality has significant impact on human life and production,and PM2.5 has a very important effect on environment and health of people.To know the characteristics of PM2.5 in Kunshan and provide the basis for the government,the samples of PM2.5 at different season and seven region were be anaylised to learned physical properties and chemical composition.The main results as follows:(1)The daily average concentration of PM2.5 in Kunshan in 2013 was in the range of 4-366 ?g/m,and the annual average of 57?g/m3,which was more than 63%standard.The mass concentration of regional difference was very small,and the seasonal variation characteristics was obviously.The concentration in the winter significantly higher and lower in summer,The value of spring and autumn was almost equal.Daily average concentrations of PM2.5 were characteristics,gentle in the summer and volatile in the winter.PM2.5 and PM1O had the same pollution sources in most of the year.(2)The total number concentration of particle size of 0.3?lO?m was 587#/cm3.Particle size in 0.3-2.5 microns particle number concentration were accounted for 99.7%of total number of particles,accounted for about 50%of quality,surface area accounted for more than 85%.(3)The concentation of water soluble ions SO2-4,NO3-,CI-,NH4+,F-in PM2.5 was 7.60?g/m3,4.13?g/m3,2.79?g/m3,2.30?g/m3 and 0.06?g/m3,the quality of PM2.5 accounted for 26.9%.Soluble ions had seasonal characteristics of higher in the spring and fall,lower in the summer and winter.The regional difference was not big.(NH4)2 SO4 was the major form of ammonium salt in PM2.5 in Kunshan.(4)The average concentration of OC in PM2.5 in 2013 was 13.7?g/m3 and EC was 2.97?g/m3,TC accounted for 28.3%of the quality of PM2.5.The average of OC/EC was 4.71,the characteristics of secondary organic carbon is obvious.The possibility of OC and EC in PM2.5 had the same sources was very high in these three seasons spring,autumn and winter in Kunshan.(5)The average concentration of 22 kinds of inorganic elements in PM2.5 were between 3.02?1113 ng/m3,total account for 5.22%of PM2.5.The concentration was high in the spring and fall,low in the summer and winter,there had the peak pollution in the spring.Cd,T1 and Ag,Se,Sb and Sn enrichment of trace elements such as very high.(6)Forty-three kinds of organic compounds were found in PM2 5 in Kunshan,and most in the fall,PAHs was checked out the specific material of organic matter type.The autumn was the highest season of ?PAHs,annual average 12.7 ng/m3.The highest two regions was the second water plant and Zhenchuan middle school.PAHs of 4,5 and 6 ring were the heaviest in all the rings.Vehicle exhaust is becoming a very important source of atmospheric pollution in Kunshan according to Characteristic values.(7)The total quality contribution rate of SO2-4,NO3-,C1-,NH4+,F-,OM,EC and 22 kinds of inorganic elements to PM2.5 was 75.8%.OM in the spring,summer and autumn had highest levels,and other components had in the winter.(8)PM2.5/PM10 reached 0.791,number concentration of PM0.3?10,water soluble ions,OC/EC,22 kinds of element all rised in heavy haze weather in December 2013.NO3-and inorganic elements increased significantly,OM and Cl" reduced,the haze was more affected by the outside.(9)The source of atmospheric PM2.5 in Kunshan was analysised through factor analysis,the results showed that motor vehicle exhaust and industrial emissions,dust,secondary reaction and waste incineration,combustion of biomass and soil dust on the contribution rate of PM2.5were 29.5%,19.1%,16.7%,19.1%,other reasons accounted for 22.5%. |
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