Characteristics And Source Appointment Of Carbonaceous Species In PM_2.5 In Urban Area Of Zhengzhou,Luoyang And Pingdingshan

PM_2.5 samples were collected from October 2014 to August 2015 representing the four seasons in three urban sites in Zhengzhou,Luoyang and Pingdingshan,which are located in Central Plains Economic Region?CPER?of China.Organic carbon?OC?,elemental carbon?EC?,and non-polar organic compounds including n-alkanes?C8–C40?and polycyclic aromatic hydrocarbons?PAHs?were quantified.The characteristics of their concentrations,seasonal variations,and sources of n-alkanes and PAHs were investigated.Diagnostic ratios and positive matrix factorization?PMF?were used to characterize carbonaceous species,identify their possible sources,and apportion the contributions from each possible source.The annual average of PM_2.5 in Zhengzhou,Luoyang and Pingdingshan during sampling period were(145 ± 66 ?g·m^-3),(97 ± 63 ?g·m^-3)and(100 ± 72 ?g·m^-3),respectively,which were 4.1-fold,2.8-fold and 3.9-fold of National Ambient Air Quality Standard of China(annual average: 35 ?g m^-3),respectively.Over 60% of daily average PM_2.5 concentrations during the sampling days exceeded the National Ambient Air Quality Standard of China(daily average: 75 ?g·m^-3).The annual OC concentration in Zhengzhou,Luoyang and Pingdingshan during sampling period were(27 ± 27 ?g·m^-3),(12 ± 9 ?g·m^-3)and(17 ± 16 ?g·m^-3),respectively;The annual EC concentration were(11 ± 1 ?g·m^-3),(5 ± 4 ?g·m^-3)and(7 ± 6 ?g·m^-3),respectively;The annual PAHs concentration were(58 ± 54 ng·m^-3),(72 ± 57 ng·m^-3)and(181 ± 104 ng·m^-3),respectively;The annual n-alkanes concentrations were(232 ± 24 ng·m^-3),(169 ± 100 ng·m^-3)and(231 ± 156 ng·m^-3),respectively.The concentrations of the components exhibited distinct seasonal variation,that is,the concentrations are high in winter and low in summer.This finding could be associated with increase in air pollutant emissions during heating season and stable weather condition.Total carbonaceous aerosol?TCA?were estimated by?1.6*OC+EC?,The estimated TCA accounted for 30%,25% and 34% of PM_2.5 in Zhengzhou,Luoyang and Pingdingshan,respectively.Hence,carbonaceous compounds were the major components of PM_2.5 in the study area.Additionally,the health risk assessment of PAHs indicated a relative high potential health risk in study area.The PMF results revealed that the contributions of coal source to PAHs in Zhengzhou,Luoyang and Pingdingshan were 39%,36% and 38%,respectively;The contributions of industrial sources were 20%,22% and 21%,respectively;The contributions of biomass burning were 9%,13% and 10%,respectively.The contributions of gasoline combustion sources were 22%,15% and 16%,respectively;The contributions of diesel combustion sources were 10%,14% and 15%,respectively.The main sources of PAHs were coal combustion and motor vehicles?gasoline and diesel vehicles exhaust emissions?.The contribution of industrial sources and biomass burning were relatively small.The contributions of coal source to n-alkanes in Zhengzhou,Luoyang and Pingdingshan were 31%,30% and 27%,respectively;The contributions of gasoline source were 10%,12% and 11%,respectively;The contributions of diesel were 20%?26% and 24%,respectively;The contributions of straw burning sources were 22%,15% and 16%,respectively;The contributions of biological source were 22%,21% and 16%,respectively.The PMF results indicated that the anthropogenic sources?including coal combustion,motor vehicle emissions and straw burning?are the main sources of nalkanes in the study area,and the contribution of higher plant sources was relative small.