The Characteristics And Source Analysis Of PM_2.5 Based On The Recptor Model In Handan

A dataset of the online monitoringdata and the chemical compositions of the sampled PM_2.5 at four air-quality monitoring sites in Handan from January 1,2013 to December 31,2015,with the chemical compositions of the sampled PM_2.5 in Hebei University of Engineering from January 1,2013 to December 31,2015 were used to analyze the spatial,temporal,and chemical characteristics of PM_2.5 pollution,the pollution characteristics of PM_2.5 and its chemical compositions under different air quality grades,as well as the source analysis of PM_2.5 using PCA,HYSPLIT and PSCF.The major conclusions are as follows（1）PM_2.5 showed obvious temporal and spatial distribution characteristics at four sites in Handan.The spatial distribution characteristics was DWS>KY>CT>HBJ.The characteristics of temporal distribution showed that the PM_2.5 mass concentration and the over standard rates decreasing year by year from 2013 to 2015,especially in2015.In addition,it also showed a severe diurnal variation.The seasonal variation showed Winter > autumn > spring > summer.（2）Most of the water soluble ions and inorganic elements showed a trend of decreasing year by year,OC concentration decreased in 2014 and increased in 2015,while EC showed the opposite trend.The seasonal variation of water soluble ions showed winter > autumn > summer > spring.The seasonal variation of OC and EC showed that the concentration of OC,EC and OC/EC in autumn and winter were significantly higher than that in spring and summer.The seasonal variation of the total inorganic elements in PM_2.5 showed winter >spring >summer > autumn.（3）There was a strong photochemical reaction in four seasons in Handan,but SOR and NOR showed different seasonal variation,mainly due to the different sources and removal mechanisms of SO42-and NO3-.The secondary pollution of carbon components existed in four seasons in Handan,and the most serious pollution occurs in autumn,while the OC/EC ratio for most of the samples were about 6.0.The SOC/OC ratio were greater than 0.5,while the concentrations of OC were greater than 20 μg m-3for most of the samples in autumn,which illustrated that high concentration of SOC was the main factor leading to high concentration of OC,the secondary pollution was more likely to occur when the carboncomponents concentrations was high.（4）With the increase of air quality grade,the mass concentrations of most chemical components of PM_2.5 increased suddenly in severely polluted days,especially for EC and OM.The mass concentrations of EC and OM on severely polluted days were approximately 5.9 and 5.5 times those of fine days,respectively.The ratio of NO3-/SO42-increased with the degree of air pollution deterioration increased,and reached the maximum value（0.98）in the moderately polluted days,and heavily polluted decreased slightly,which may showed that the effect of fixed source on PM_2.5 in Handan city was larger than the mobile source.The ratio of OC/EC were greater than 2.3 under different air quality grades.From the fine days to heavily polluted days,OC/EC ratio increased linearly,which from 2.3 in fine days to 4.5 in heavily polluted days,while declined in severely polluted days,which showed that there were secondary pollution of carboncomponents in different levels of air quality.With the increase of air quality grades,the main source of PM_2.5 gradually change from the exhaust of diesel and gasoline vehicle emissions to automobile exhaust and coal mixed sources.The enrichment factors of anthropogenic elements in severely polluted days were 4.0-11.9times those of in fine days.Thus it demonstrated that the EF of all elements were rising obviously in severely days,and the EF of anthropogenic elements were elevated consistent with the increasing of AQI,while the elements from crustal sources were not observed the same growth.（5）The main source of PM_2.5 in Handan were coal combustion and biomass burning sources,industrial sources,soil dust,secondary aerosols,and gasoline vehicle exhaust.The air mass from northwest and south had the greatest proportion in spring,summer and winter,which had a greater impact on PM_2.5 of Handan.In autumn,the air mass from southwestern accounted for the relatively high proportion,and air mass from the other direction had the similar proportion and the path distribution were dispersed.In spring,the Yellow Sea waters near to Shandong and the northern region of Hebei were the main potential source areas in Handan,and long distance transportation also had a certain impact on PM_2.5 of Handan city.In summer,waters transfer effect on PM_2.5in Handan City was the most obvious.In autumn,the effect of long distance transportation occupied a dominant position of Handan city.PM_2.5 potential source areas were relatively complex in winter,which the influence both from the local and surrounding areas,as well as long distance transportation.