Study On Composition Spectrum Of Dust Accumulation In Winter Pavement Roads In Shijiazhuang Based On Mobile Samping Method

PM_2.5.5 and PM₁₀0 have been known as hot topics in recent years,and road traffic dust has also attracted attention as one of the main sources of air pollution.In order to construct the characteristic spectrum of paved roads dust accumulation from Shijiazhuang,road dust samples from four types of roads were collected by using mobile sampling method,after pretreatment and composition analysis,the chemical composition,emission characteristics were analyzed and the composition spectrum were constructed by using enrichment factor method,ground accumulation index,etc.The chemical components in road dust PM_2.5.5 and PM₁₀0 were mainly OC,Ca²⁺,SO₄^2-and crust-like elements?Si,Al,Ca,Fe,Mg?,more chemical enrichment in road dust PM_2.5.The source of each component was related to factors such as vehicle exhaust emissions,vehicle material wear,deposition of airborne dust from coal combustion,biomass burning and dust entering road from green belts or carried by vehicles.The elemental composition of PM_2.5.5 and PM₁₀0 road dust samples from Shijiazhuang City was similar,The average contents of Mg,Ca,Cr,Cu,Ni,Zn,Pb,Sn,Sb,Mo and Cd were 1.2⁴0.5 times higher than that of local soil background value.Zn,Cu,Sn,Sb,Mo,Cr and Cd have higher enrichment factors than 10,which were caused by human pollution.Geo-accumulation index analysis showed that Cr,Sn(I_geo:4⁵)reached extremely high pollution level.Cd and Cu(I_geo:3⁴)achieved high pollution level.Sb,Mo,Zn(I_geo:2³)achieved medium-strong pollution level.Pb(I_geo:1²)reached moderate pollution level.The sum of 10 kinds water-soluble ions in road dust PM_2.5.5 was 15.31%,in PM₁₀was 11.15%,Ca²⁺and SO₄^2-in PM_2.5.5 and PM₁₀0 were more than 1%.The proportion of Ca²⁺was the highest,then SO₄^2-.The values of NO₃^-/SO₄^2-from PM_2.5.5 and PM₁₀0 were0.24 and 0.18.The particles were generally alkaline,and the alkaline of PM_2.5.5 was stronger than PM₁₀.There were different levels of secondary pollution in all types of road dust in Shijiazhuang.The percentage of OC3 was the highest among 8 carbon components,then OC4,while EC3 was the lowest.The divergence coefficient of road dust PM_2.5.5 composition spectrum and urban dust,soil dust,motor vehicle exhaust dust,building cement dust spectrum was 0.45,0.47,0.42,0.47.The divergence coefficient of road dust PM₁₀0 composition spectrum and soil dust,motor vehicle exhaust dust,urban dust composition spectrum was 0.48,0.36,0.31.All in maybe similar level at 0.2⁰.5.