The Chemical Speciation Of Heavy Metal And Risk Assessment Of Qingdao Urban Dust In Parks And Along Roads

This article studied the concentration and chemical speciation distribution of heavy metal in urban dust of eight parks in four districts and along ten roads of Qingdao. The risk assessment on heavy metal pollution in urban dust was further explored, and explore influencing factors on heavy metal sources in urban dust, At the same time, compared on the ability to accumulate and capture heavy metal of four common road trees in Qingdao. The results showed that:(1)The mean content of Cu in urban dust of parks was 109.27mg/kg, Zn was 326.88mg/kg, Pb was 126.02mg/kg, Cd was 1.79mg/kg. The content of Cu, Zn, Pb and Cd were respectively 8.28, 4.74, 4.07 and 13.77 times of the Qingdao soil background value. By using the method of geoaccumulation index to assess the heavy metal pollution in urban dust, the results showed: The overall pollution levels were expressed as Cd> Cu> Zn> Pb. The Hakanson's potential ecological risk assessment was used to assess the potential ecological risk of heavy metals in urban dust of different parks. And the ecological hazard indexs were Cd> Cu> Zn> Pb, Licang> Sifang> Shibei> Shinan. According to the speciation distribution of each heavy metal, the index of bioavailability of heavy metal is Zn> Cd> Pb> Cu.(2)The average content of Cu in urban dust along roads was 91.10mg/kg, Zn was 349.4mg/kg, Pb was 150.27mg/kg, Cd was 2.197mg/kg. The content of Cu, Zn, Pb and Cd were respectively 6.90, 5.06, 4.85 and 16.90 times of the Qingdao soil background value. By using the method of geoaccumulation index to assess the heavy metal pollution, the results showed: The overall pollution levels were expressed as Cd> Cu> Pb > Zn. The Hakanson's potential ecological risk assessment was used to assess the potential ecological risk of heavy metal, the ecological hazard indexs were Chongqing South Road> State Road 308> Haier Road> Chongqing Nouth Road> Yan'an Road> Hong Kong Midde Road> Shandong Road> Changsha Road> Siliu South Road> Tong'an Road. Traffic volume, road conditions, Car speed, green belt were important influence factors on heavy metal pollution in road dust. The non-residual fraction proportion of heavy metal in urban dust along roads from high to low were: Pb> Cu> Cd> Zn. The active fraction proportion of heavy metal in urban dust along roads from high to low were: Cd> Pb> Zn> Cu.(3)The abilities to accumulate heavy metal of road trees from high to low were: Ailanthus altissima> Fraxinus chinensis Roxb> Platanus orientalis L> Magnolia grandiflora linn. The abilities to capture heavy metal from high to low were: Magnolia grandiflora linn > Platanus orientalis L> Ailanthus altissima> Fraxinus chinensis Roxb.