Pollution Characteristics And Health Risk Assessment Of Fine Particulate Matter And Road Dust In Traffic Environment In Lanzhou

In recent years,rising vehicles ownership has contributed enormously to air pollution in Lanzhou,while few research were conducted upon fine particulate matter(PM_2.5)and road dust of traffic environment in Lanzhou.In this study,eleven main roads were selected to collect PM_2.5and road dust samples,then the characteristics of 9 water-soluble ions and 7 heavy metal elements were analyzed,and the health risks of heavy metals to the general population,traffic police and sanitation workers were assessed.Several conclusions are listed below:?1?The PM_2.5 pollution is particularly serious in heating period,exceeding the secondary ambient air quality standard of China.The total mass concentration of water soluble ions in PM_2.5accounted for 34.70%and 28.90%and heavy metals in PM_2.5.5 accounted for 1.49%and 4.55%of PM_2.5 in heating and the non-heating period respectively.SO₄^2-?NO₃^-and NH₄⁺were the main water-soluble ions of PM_2.5 in heating period,the sums of which accounted for 75.50%of PM_2.5;SO₄^2-?and Ca²⁺were the main water-soluble ions of PM_2.5 in non-heating period,the sums of which accounted for 64.85%of PM_2.5.Zn and Mn were main heavy metals in PM_2.5,which accounted for71.29%and 74.22%of PM_2.5 respectively in heating and non-heating period.?2?Ca²⁺was the main water-soluble ions in the road dust accounting for 42.06%and 66.12%of the total of water-soluble ions in the road dust in heating and non-heating period respectively.Mn and Zn were the main heavy metals in the road dust accounting for 70.62%and 77.93%of the total heavy metal elements of road dust in heating and non-heating period.?3?The sources of water-soluble ions and heavy metal in PM_2.5 from Lanzhou traffic environment mainly come from vehicle emissions.Water soluble ions of road dust mainly come from coal,construction dust and dust from the ground,and heavy metals may come from vehicle emissions,coal burning and industrial source.NO₃^-/SO₄^2-of PM_2.5 were 1.17 and 0.34 in heating and non-heating period respectively,indicating that PM_2.5 pollution mainly derived from the flow sources and stationary sources in heating and non-heating period respectively.?4?In Lanzhou's traffic environment,Mn in PM_2.5 of different periods has non-carcinogenic risk to traffic police and sanitation workers,while Cr in PM_2.5.5 of heating period has non-carcinogenic risk to sanitation workers.In different periods of Cr in PM_2.5 has a carcinogenic risk to sanitation workers;Cr in non-heating periods PM_2.5 has a carcinogenic risk to traffic police.Heavy metals in road dust don't have a non-carcinogenic or carcinogenic risks to different populations.In conclusion,PM_2.5 pollution is much more serious in heating period.SO₄^2-,N0₃^-and NH₄⁺were main water-soluble ions of PM_2.5.5 in heating period;SO₄^2-and Ca²⁺were main water-soluble ions of PM_2.5.5 in non-heating period.Ca²⁺was the main water-soluble ion of road dust.Zn and Mn were the main heavy metals in PM_2.5 and road dust.Compared with the general population,heavy metals have greater health risks to sanitation workers and traffic police,and there are carcinogenic and non-carcinogenic risks.