| Organic Pollutants are among the most important factors influencing the urban air quality and human health.In this study,PM10and PM2.5samples were collected in parallel in different function zones of Beijing city during four seasons of 2005.The extractable organic matter(EOM) were obtained by Soxhelt extraction,and their pollution level,distribution characteristics,seasonal variation were illustrated.Spatial-temporal variations and sources of Polycyclic Aromatic Hydrocarbons(PAHs)and Heterocyclic amines(HAs)in atmospheric PM10and PM2.5were analyzed detailedly.The average 24-h PM10and PM2.5concentration in summer were 155.37μg/m3 and 87.70μg/m3,respectively,being 1.04 and 1.35 times higher than ClassⅡcategory of the National Ambient Air Quality Standards in China and US EPA enacted in air quality standards(PM10, 150μg/m3;PM2.5,65μg/m3).The daily PM10and PM2.5concentration is mostly high in the daytime and low at night,and maximum values in different environments area corresponded different peak period of production activity.The annual mean concentration of organic compound in PM10and PM2.5was 41.39μg/m3 and 34.84μg/m3,being 1.44 times and 1.26 times higher than cleanliness district-Ming Tombs site. The organic pollution level in winter was most serious.Ratios of EOM in PM2.5to that in PM10in different seasons exceeded 60%,showing that preferential association of EOM with fine particles. The order of concentration of organic compositions indicated that organic pollution of Beijing city mainly results from coal-burning.The annual concentrations of PAHs in PM10and PM2.5were 36.40ng/m3 and 47.14ng/m3, respectively.Significantly Seasonal variation of the PAHs came mainly from contributions of 4 and 5 ring PAHs.The diagnostic ratios of PAHs indicated that PAHs in atmospheric PM in Beijing mainly originated from the source of coal combustion,the contribution of vehicle exhaust was less.A new validated liquid chromatographic method was developed for the determination of the 6 heterocyclic amines(HAs)in PM10and PM2.5.The method realized the complete base-line separation of 6 HAs and high sensitive determination after optimizing analytic conditions.The method is highly sensitive and accurate.The annual concentration of HAs in PM10and PM2.5were 8.12ng/m3 and 10.79ng/m3,respectively.The HAs monomer produced by different pollution sources displayed different enrichment characters in 2.5μm and 10μm particle fractions.There was good correlation between any one and another among 2-Amino-9H-pyrido[2,3-b] indole(AαC),2-Amino-3-methyl-9H-pyrido[2,3-b]indole(MeAαC),3-Amino-1-methyl-5H-pyrido[4,3-b]indole(Trp-P-2),which indicated that sources of those amino-carbolines were similar.The amino- carbolines being associated with fine particle in winter were related with low temperature.The effect of seasonal variation on the size distribution of 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine(PhIP)in PM was less.The results of distribution characteristics of HAs in different function zones suggest that cooking emission is the predominant sources for particulate HAs in Beijing;coal combustion, vehicle exhaust and biomass buring have some contributions to HAs.The distribution of HAs monomer in different area indicate that 2-Amino-3-methylimidazo[4,5-f]quinoline(IQ)probably due to cooking emission;PhIP and 2-Amino-3,4-dimethylimidazo[4,5-f]quinoline(MeIQ)are mainly formed by coal combustion,vehicle exhaust and cooking emission;meanwhile coal combustion and cooking emission are possible contributor to Trp-P-2,AαC and MeAαC.
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