Ambient Air VOCs Pollution Levels, Trends, Release Characteristics And Source Apportionment At Typical Outdoor Area In Nanjing

Ambient air pollution problems was seriously harm to people’s health in recent years.Compounds VOCs in the air on human health hazards were increasing, was the need to properly address the outstanding environmental problems. In this study,with three types of Nanjing typical outdoor areas for the study. Explore the region of VOCs in ambient air pollution levels.According to time, place, and environment factors of variation of VOCs.Through analysis and calculation research of VOCs gas laws.Using SPSS principal component analysis to explore sources of VOCs in the region. Use the USEPA risk assessment model for high risk health risk assessment inhighpollutedambientair..① In the spring of 2014, the author collected atmospheric samples from the typical transportation district and the background area of Nanjing using Tedlar bag. With reference to the method of American EPA TO-15,30 kinds of volatile organic components were detected. Besides, pollution characteristics and daily variation trends of VOCs in typical regions were researched. According to the result, the concentration of VOCs in the transportation district ranges from 96.29 to 249.97μg/m3,with the average value being (149.31±36.70)μg/m3;while that in background aera is between 19.04 and 65.17μg/m3,with the average value reaching(43.29±10.53)ug/m3.With respect to types of pollutants, olefins, aromatics, halogenated hydrocarbons and esters are the most prevalent contaminants in the atmosphere. In the transportation area, BTEX is the major volatile contaminant with the concentration ranging from 15.96 to 43.38μg/m3,the average value being (25.39±7.63)μg/m3.As for daily variation trends of BTEX, the peak value of the concentration appears at 9:00,12:00 and 18:00, which is closely related to the traffic volume. By contrast, the concentration of BTEX is relatively lower without apparent variation trends. On the basis of the principal component analysis of BTEX in the transportation district, it is clear that benzene, ethylbenzene, p-m-xylene, ortho-xylene,4-ethyl,1,3,5-tri methyl benzene,1,2,4-trimethylbenzene are major contribution factors. Automobile exhaust is the principal source of BTEX contaminants in the transportation district.② In September 2014,landfill gas samples were collected from five different landfill in Jiaozishan organic waste treatment plant,9 class of total 47 kinds of VOCs compounds were be detected.Results show that the concentration of TVOCs were (734.83±475.54) μg/m3;the highest concentration of the VOCs compounds was halogenated hydrocarbons(262.86±270.91)∴g/m3,,which were the major VOCs pollutants in landfill gas.Halogenated hydrocarbon compounds’concentration were increasing by the depth of the landfill, the concentration of halogenated compounds had a positive correlation versus time. The release rate and release flux of halogenated was positively correlatedto landfill depth,byhighest release rate and flux respectively 135.12μg/(m3h·h)、33.78μg/(m2h).Adopt principal component analysis by SPSS, halogenated components showed good homology to a single source. The main source was the degradationandrelease of organic waste.③In the spring of 2015 using the tedlar bag collection on the site in a chemical plant in Nanjing area to the wind and the wind environment in air samples, check out a total of 53 kinds of components of VOCs. Down wind TVOCs concentration(463.24±167.69)μg/m3,the upper hand to the TVOCsconcentration(46.70±13.15)μg/m3,the difference in the concentrations was significantly.Halogenatedhydrocarbons(101.36±61.57)(.ig/m3and olefin(149.91±55.63)∴g/m3 and aromatic(96.93±46.87)μg/m3 higher levels, is the main pollutants of downwind incontaminated sites.Contaminated sites downwind of halogenated hydrocarbons and benzene in the air component for principal components analysis.Results show that the halogenated hydrocarbon source is more complex, and the original pesticide production, caused by ethylene processing residues are closely related. In the original production of toluene and styrene residue in soil is part of the potential sources of aromatic hydrocarbons, and other heretics in automobile exhaust emissions on the ground on the way of benzene concentrations also have certain effects.17 compounds non-carcinogenic risk exposure through the skin between the 0～2.99E-05, respiratory pathway between non-carcinogenic in 0～4.18E-02;7 compounds exposure through the skin cancer risk in 0-3.60E-09 between the respiratory pathway between cancer risk in 0-5.95E-05.Benzene (4.75E-06) respiratory pathway risk index over the body of acceptable cancer risk (1.00E-06).Trichloroethylene was the highest risk of cancer,respiratory pathway of cancer risk is more than recommended by the ICRP carcinogenic risk acceptable maximum level in individual years (5.00E-05).Respiratory pathway is the main way to pose a human health risk.