Study On Pollution Of Heavy Metals And Polycyclic Aromatic Hydrocarbons In Road Dust In Datong Urban Area In Spring And Summer

In this study,the road dust in spring and summer in Datong urban area was taken as the research object.The contents of V,Cr,Mn,Co,Ni,Cu,Zn and Pb in the samples were determined by X-ray fluorescence spectrometer.The contents of polycyclic aromatic hydrocarbons(PAHs)in spring and summer road dust in Datong urban area were analyzed by HPLC.The spatial interpolation method of ArcGIS was used to reveal the spatial and temporal variation characteristics of heavy metals and polycyclic aromatic hydrocarbons in spring and summer.Correlation analysis,principal component analysis,cluster analysis,feature ratio method and positive definite matrix factor method were used to clarify the sources of heavy metals and PAHs in road dust in Datong city.Using the enrichment factor method,the pollution load index method,and the potential ecological risk index method,the environmental and ecological risks of heavy metals in road dust in spring and summer in Datong city could be evaluated.The single factor pollution index method,nemero comprehensive pollution index method and ecological risk assessment method were used to evaluate the environmental and ecological risks of PAHs pollution.It provides scientific theoretical basis for the environmental risk assessment of heavy metals in road dust and PAHs pollution in Datong urban area and the establishment of urban environmental quality standards.The main research results are as follows:(1)The first mode of the road dust particle size in spring and summer in Datong urban area is 100?250 ?m.The frequency susceptibility of road dust in spring is between 0.10%and 13.64%,with an average value of 5.32%.The frequency susceptibility of road dust in summer is between 0.10%and 4.32%,with an average value of 1.34%.The content of LOI in road dust in spring ranges from 0.87%to 30.99%,with an average of 7.58%.The content of LOI in road dust in summer ranges from 0.55%to 19.41%,with an average of 3.49%.The physical and chemical indicators of road dust in Datong urban area show a certain spatial and temporal distribution difference:in summer,the magnetic susceptibility and LOI of road dust in Datong city are lower than those in spring.And the magnetic susceptibility and LOI of road dust in the west of city are greater than those in the east of city.(2)The determination results of the contents of V,Cr,Mn,Co,Ni,Cu,Zn and Pb in road dust of Datong urban area in spring and summer show that the contents of Cr,Co,Zn and Pb in road dust in spring and summer are higher than those of soil elements in Shanxi background value,and the average content of eight heavy metals in summer dust samples was less than that in spring dust samples.(3)The content of PAHs in the road dust of Datong urban area in spring ranges from 1.84 to 58.37 mg/kg,with an average of 14.80 mg/kg.The content of PAHs in summer road dust ranges from 0.68 to 45.11 mg/kg,with an average of 5.38 mg/kg.The average value of the 16 PAHs monomers except Acy in summer dust samples is lower than that in spring dust samples.The three-ring PAHs contributes the most in spring and summer.(4)The content of V,Cr,Mn,Co,Ni,Cu,Zn and Pb in spring road dust samples of Datong urban area is higher than that in summer.The high-value regions of V,Pb,Ni,and Zn in spring and summer road dust samples in Datong urban area are almost unchanged;the high-value regions of Co and Cr begin to become concentrated.The average content of PAHs in spring is higher than that in summer.The high value area of PAHs in summer is lower than that in spring.The general trend of the total change of PAHs is higher in the central part of Datong city,and lower PAHs content of road dust in other surrounding areas.(5)There are different sources of heavy metals in spring and summer road dust in Datong urban area.V,Mn,and Ni in road dust in spring and summer are mainly affected by natural factors.Pb,Cu,and Zn in spring and summer road dust are mainly from pollution sources of automobile traffic.Co and Cr in spring road dust are mainly from mixed sources of industry and traffic.Cr in summer road dust comes from living sources,and Co mainly comes from industrial activities.Heavy metals pollution from road dust in Datong in spring and summer mainly comes from automobile traffic activities.Contributions to pollution sources in the content of PAHs in road dust of Datong urban area in spring are traffic pollution sources(71.30%),oil spill sources,and coal-fired mixed sources(28.70%),respectively.The contribution of each pollution source in the content of PAHs in road dust of Datong urban area in summer are traffic pollution source(27.60%),diesel combustion source(25.50%),oil leakage source(27.00%),and coal burning source(19.80%).(6)There is no enrichment of Mn and Ni in spring road dust in Datong urban area.V,Cr,Cu,Zn and Pb are all slightly enriched,and Co shows significant enrichment.In summer road dust,V,Cr,Mn,Ni,Cu,Zn,and Pb all show no or slight enrichment,and Co shows significant enrichment.Pollution load index analysis shows that heavy metals in road dust in Datong urban area are moderately polluted in spring,and moderately polluted in summer.The comprehensive potential ecological risk of heavy metals in spring road dust in Datong urban area indicates that there is a strong ecological risk.The single potential ecological risk of heavy metals indicates that the pollution level of Co is serious,V,Cr,Cu,Zn,and Pb are medium pollution levels,and Mn and Ni are low pollution levels.The comprehensive potential ecological risk of heavy metals in summer road dust in Datong urban area is medium comprehensive ecological risk.The single potential ecological risk of heavy metals shows that Co is seriously polluted,V,Cr,Cu,Zn,and Pb are medium pollution levels,and Mn and Ni are low pollution levels.The risk level is higher in spring than in summer.(7)The content of PAHs in road dust in Datong urban area in the spring reaches a high pollution,and the content of PAHs in road dust in summer reaches a high pollution.The analysis of ERL and ERM show that PAHs had frequent poisoning effects in road dust in spring,and occasional poisoning effects in road dust in summer.Potential ecological risk analysis shows that the potential ecological risk of PAHs in road dust in Datong urban area in spring is higher than that in summer.(8)There is a certain correlation between the contents of LMW,HMW,and?PAHs and the contents of V,Mn,Ni,Cu,Zn,and Pb in spring road dust in Datong urban area.There is a strong positive correlation between Cu and Mn and 3 to 6-ring PAHs monomers in road dust in summer.Zn and Pb in summer road dust have a positive impact on ?PAHs.There is a positive correlation between Ni and PAHs monomers of 2 and 3 rings in road dust in summer.