Study On PAHs Pollution And Health Risk Assessment Of Atmospheric Particulate Matter PM 10 And PM 2.5 In The Southern Suburbs Of Xi'an

In this study,the samples of PM10 and PM2.5 were collected from a teaching building in Shaanxi Normal University on Chang'an District in Xi'an city from January in 2016 to January in 2017.The concentration of PM10 and PM2.5 in the whole sampling period was analyzed.The total concentration,monomer concentration and PAHs of 16 PAHs in PM10 and PM2.5 were quantitatively analyzed by high performance liquid chromatography(HPLC)and seasonal variation characteristics;and use the ratio method to analyze the main source of PAHs pollution.At the same time,the characteristics of PM10 and PM2.5 concentration and the characteristics,composition characteristics and source analysis of PAHs concentration were recorded in the holidays and typical pollution events.The health risk of air pollution during this period was assessed using the BaP equivalent toxicity method and the carcinogenic risk rate of PAHs contamination.The main conclusions of this paper are as follows:(1)During the sampling period,the average concentration of PM10 and PM2.5 are(260.28?g�m-3,158.96?g�m-3).Seasonal distribution is:winter>fall>spring>summer.The annual total mass concentration of PAHs in PM10 and PM2,5 are(71.OOlng � m-3,51.833ng � m-3),and PAHs in PM2.5 is contained about 70%of that in PM10.PM10 and PM2.5 concentrations of PAHs in one year shows that winter>autumn>spring>summer.(2)Components of PAHs:4-ring in the proportion of each season are the maximum;seasonal fluctuations of 4-ring content is that winter>spring>autumn>summer.Spring,autumn and winter is the seasons in which 4-ring and 5-ring concentration are larger,the largest proportion of summer is 6-ring.The amplitude of the 3-ring and 4-ring changes varies with the heating and non-heating periods.PAHs has the highest BkF content,followed by Chr and BbF.The mass concentration of the monomer is seasonal:winter>autumn>spring>summer.Winter winter Pyr,BaA,Chr and other coal-fired markers are significantly increased,(3)The main source of PAHs in atmospheric particles in Xi'an is mixed pollution of combustion source and traffic pollution source.The main source of the vehicle is the tail gas and diesel vehicle exhaust,and the diesel vehicle exhaust is mainly concentrated in spring and winter,the gasoline vehicle exhaust concentrated in the spring.Summer traffic sources are more obvious,spring and winter pollution sources in the heating period is based on the source of diesel fuel source contribution increased,autumn straw and other biomass combustion have a certain contribution.The higher the temperature,the lower the PAHs content,the greater the wind speed PAHs content is about low.(4)During Chinese New Year,May Day and National Day,PM10 and PM2.5 mass concentrations and concentrations of PAHs contained are:Holiday>Before and after the holiday,which shows that the human activities on holidays have some effect on atmospheric particulate pollution.During the Spring Festival,the pollution sources are coal source,traffic source and weather meteorological factors.The sudden increase of pollutant concentration comes from the discharge of fireworks.During May Day and National Day,the pollution change is mainly due to the traffic source of automobile exhaust.(5)The average concentrations of PM10 and PM2.5 in the typical polluted weather in Xi'an are:(541.67?g�m-3,363.27?g�m-3),and the average concentrations of PAHs were(160.99ng.m-3,115.30ng.m-3).The concentration of N02 and CO in the haze phase is 3 to 4 times that of other periods.The source of pollutants is mainly coal source and source of transportation,and coal source>traffic source.Typical pollution events in the weather PM10 and PM2.5 PAHs monomer concentration is as a whole high,the main pollution monomer Flua,Pyr,Chr,BbF,BaP.(6)The average concentrations of BaP in spring,summer,autumn and winter are 25.70ng�m-3,7.145ng�m-3,32.26ng'm-3,95.30ng�m-3.The average concentration of BaP in spring,winter and autumn exceed the national standard(1ng�m-3).Winter is over standard rate(WHO standard)which is close to 100 times.Four Seasons Average BEQ:Winter>Fall>Spring>Summer.BEQ toxicity contributes essentially from 4-ring,5-ring and 6-ring is 5-ring>4-ring>6-ring.4-ring equivalent toxicity is low,which is compared,5-ring and 6-ring toxicity relative are larger.(7)Carcinogenic risk:winter>autumn>spring>summer.Winter is 3 times for spring and autumn,10 times for summer.PM2.5 and PM10 risk ratio in winter and autumn are more obviously different,autumn and winter haze carcinogenic risk should be focused on,especially the typical pollution of the weather haze period in winter.