| With the modernization of cities,the implementation of rapid traffic and the continuous advancement of industrialization,the amount of urban dustfall and heavy metals content have increased gradually,and the problem of urban air environmental pollution is imminent.The pollutants gathered in the dry subsidence not only cause inconvenience to the residents’ daily life,but its wet subsidence process also cause certain pollution to the urban receiving water body.The study on heavy metal pollution characteristics of dry deposition in atmospheric environment is conducive to understand the pollution status of cities under current conditions,and lay a foundation for the study on the pollution mechanism of urban surface runoff in the later period,which is of great significance to improve the quality of urban water environment.In this paper,based on the National Natural Science Foundation of China,named"Pollution Mechanism of Heavy Metals from Dry and Wet Atmospheric Sedimentation in Typical Uran Areas on Surface Runoff"(51879242),taking Zhengzhou as the study area,dust samples from roads and high-rise buildings in urban different functional areas were investigated.The pollution characteristics of heavy metals in the samples were analyzed,the pollution levels were assessed,the contamination sources of metal elements in urban dust were identified,the contribution rates of each source were calculated,and the potential ecological risk,non-carcinogenic and carcinogenic risk of heavy metals to human were evaluated.The main research work and achievements are as follows:(1)The pollution characteristics of heavy metals in urban road dust from different functional areas were analyzed,and the content of each heavy elements in high-rise and road dust samples were compared to explore the pollution mechanism of air dry deposition.According to the geoaccumulation index(Igeo),pollution index(PI),and pollution load index(PLI),the heavy metal pollution level in the study area was evaluated.The results showed that the order of metal concentration values in road dust samples was as follows:Zn>Pb>Cr>Cu>Ni>As>Hg>Cd;the total average elements concentration of each functional area was:CA>RA>IA>EA>PA;the order of each metal concentation value in the high-rise dust sample is the same as that in the road dust,showing a certain consistency.(2)Identify heavy metal sources in dust samples.Pearson correlation coefficient was selected to preliminarily analyze the relationship between elements.On this basis,the receptor model methods of principal component analysis-multiple linear regression and positive definite matrix factorization were applied to identify the pollution sources of eight heavy elements in collected road dust samples and the contribution rates of each contamination source to each metal were calculated.The results indicate that the main sources of heavy metals in road dust are automobile exhaust and urban traffic facilities,followed by agricultural non-point sources and natural background values.(3)Assess human health risk.The human health risk assessment model was applied to evaluate the carcinogenic and non-carcinogenic risks of urban residents exposed to the studied metal elements through different exposure paths in different functional areas of Zhengzhou.Results displayed that the non-carcinogenic risk of Cu,Zn and Pb for children was one order of magnitude higher than that for adults.The carcinogenic risk of human exposure is higher in industrial sampling sites,which needs further study. |
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