Pollution Charateristics And Chemical Speciation Study Of Heavy Metals In Urban Street Dust Of Nanchang

Urban street dust which is a sort of pollutant as well as carrier of heavy metals belongs to the research scope of urban environmental study. Concentration of heavy metals in urban street dust is mainly affected by human related activities as traffic, transportation, industrial production and urban construction. Urban street dust is detrimental to human health by respiration and skin touch. Therefore, it is of profound scientific and practical significance to study on pollution characteristics of heavy metals(Pb,Cu,Cr,Mn,Ni,Cd,Zn) in Nanchang street dust.Physicochemical characteristics, total concentration and chemical forms of heavy metals are analyzed in order to investigate its'distribution features, sources, pollution condition, accumulation degree and potential ecological hazard. The main conclusions of this study can be summed up as follows:The overall level of heavy metals in street dust of Nanchang maintains high. The average contents of Pb,Cu,Cr,Mn,Ni,Cd,Zn are 1.59,8.15,2.9,2.37,2.21, 3.17,39.36 times in compared with soil background value of Nachang. The most polluted area is Bayi road with heavy traffic and high vehical flow; secondly, the Zhongshan road commercial area and Nanjing-Beijing road. In comparison with other street dust in other cities in and abroad, it is obviously that the situation of heavy metals pollution in Nanchang is not optimistic. Except from Pb,Mn,Ni, the concentration of Cu,Cr,Cd,Zn are more than the average level in domestic, amongst which Zn is the highest and Pb is the lowest. Assess the pollution degree by using enrichment factor method. It shows that:Zn is the most accumulated, followed with Cu and Cd. Pb, Cr, Mn which are moderately accumulated. Ni accumulated the least. Choose the most 4 seriously accumulated heavy metals Cu,Cr,Cd,Zn for pontential ecological hazard assessment. It come to the conclusion that except that Cr is at relatively higher contamination level, the rest 3 heavy metals are all at high contamination level, especially Cd,Zn.The selective sequential extraction procedures BCR was used to study chemical speciation of heavy metals in urban street dust in Nangchang. The results show that Gr,Zn,Pb,Ni and Mn are present mainly in the residual fraction which are relatively stable in urban street dust. Cu and Cd existed mainly in the oxidizable fraction which confirm that Cu,Cd are more active and had potential influence on the environment. The order of bioavailability of heavy metals in urban street dust is as followed:Mn,Zn,Cd,Ni,Pb,Cu,Cr. The order of heavy metal activity:Cd,Cu,Mn,Ni,Pb,Zn,Cr is figured out according to the concentration of non-residual fraction...