A Chemically-speciated Study Based On The Tunnel Experiment Of Motor Vehicles In Zhengzhou,China

In order to obtain quantitative local mobile source profiles,studies need to be conducted under real-world driving conditions,but so far,no study has measured the chemical species on motor vehicle emissions in Zhengzhou.This study selected tunnel experiment,average mass and number concentrations of PM_2.5,organic carbon?OC?,elemental carbon?EC?,water soluble inorganic ions(Na⁺,NH₄⁺,K⁺,Mg2+,Ca²⁺,F^–,Cl^–,NO₃^–,and SO₄^2–),25 elements?Be,B,Mg,Al,Si,K,Ca,Ti,V,Cr,Mn,Fe,Co,Cu,Zn,As,Se,Sr,Mo,Ag,Cd,Sn,Sb,Ba,and Pb?,and size-segregated chemical species were determined in the Jingguang Tunnel.Average mass concentrations of PM_2.5 in the present study were 198.5 ± 62.5 ?g m^-3,246.6 ± 44.9 ?g m^-3 for SP1,SP2,respectively.A total fleet of 190451 vehicles crossed the tunnel during the 10-h sampling periods,98% of them being light-duty vehicles?LDV?.In this study,carbonaceous constituents had the largest proportion,followed by SO₄^2-and then NO₃^-,the same to size-segregated particles PM<0.4,PM_0.4-0.7,PM_0.7-1.1,PM_1.1-2.1,PM_2.1-3.3,PM_3.3-4.7,PM_4.7-5.8,PM_5.8-9,PM_9-10.On average,particulate matter mass concentrated in the 1.1-2.1 ?m size range,as well as SO₄^2-,and OC,NH₄⁺,NO₃^-were concentrated in a smaller particle size range?0.7-1.1 ?m?.The average emission factors of PM_2.5,OC,and EC in the tunnel were 36.0,10.2,and 4.0 mg veh-1 km-1,respectively.The majority of PM₍x focused on the range of nucleation mode.Futhermore,the peak phenomenon appeared at about 6:00 A.M.and about 6:00 P.M.,which were the rush hours.K had the highest content of all the element,and Zn was likely associated with brake wear.Al,Ca,and Fe were more susceptible to suspended road dust,Pb decreased mainly because of the national policy promoting the use of lead-free gasoline.Compared with tunnel experimental results at home and abroad,domestic particulate matter chemical component concentration in the tunnel was obviously higher than foreign tunnel studies.The degree of particulate matter pollution in the mainland was more serious than that in Taiwan,it is imperative to improve vehicle particulate matter pollution status.