Characteristic Analysis And Risk Assessment Of Typical Heavy Metal Pollutants In Urban Dust In Shenyang City

The city is an important place where people produce,live,study and entertain.The quality of urban dust will have an important impact on urban water,atmosphere,ecological environment and residents'health.In recent years,urban dust has become one of the research focuses of urban environmental problems.As a typical industrial city in northern China,Shenyang City has a large consumption of coal,rapid development of transportation industry,developed industry,dense population,and serious problems of heavy metal pollution.At present,there is less research on heavy metals in urban dust of Shenyang.So it is of great significance to carry out relevant research on heavy metal pollution in urban dust of Shenyang.In this paper,the heavy metal pollutants in the urban dust of Shenyang are taken as the research object,and the pollution characteristics,sources,chemical speciation concentration and bioavailability are analyzed.Based on this,the risk assessment is carried out.The conclusions are as follows:1.The average contents of Cu,Zn,Ni,Pb,Cr,Cd,Hg and As of urban dust in Shenyang were 41.19,149.82,38.21,38.47,60.66,0.49,0.04,6.51 mg·kg^-1,respectively.The order is Zn>Cr>Cu>Pb>Ni>As>Cd>Hg,the enrichment of Cd and Zn is relatively high,which are 3.07 and 2.50 times of the soil background value.The content of eight heavy metals in urban dust in the commercial area is relatively high,and the pollution level in the park area is relatively light;Moreover,the heavy metals are more easily enriched in the dust particles with smaller particle size.2.The spatial distribution of heavy metals in urban dust of Shenyang shows obvious heterogeneity.And heavy metal pollution remains in the former heavy industrial zone of Tiexi District.According to the source analysis,heavy metals in urban dust of Shenyang are mainly from the combined pollution of industry and transportation,and secondly by coal,urban garbage and daily life pollution.3.The chemical speciation of heavy metal elements in urban dust in different functional areas is similar to that in Shenyang.Cu is mainly composed of organic combined state and residual state.Zn and Pb are mainly composed of iron-manganese oxide and residual state.Cd has a certain amount of distribution in each speciation.Ni,Cr,Hg and As are mostly in residue state.Among them,Cd has the highest biological validity.4.According to the ecological risk assessment,the heavy metals of urban dust in Shenyang city are in moderate potential ecological hazard,the pollution degree and potential ecological risk of Cd are the highest.According to the human exposure risk assessment,the non-carcinogenic risk and carcinogenic risk of heavy metals in urban dust of Shenyang city are low,but children's exposure risk is greater than that of adults,which should be paid attention to.