| Given the serious PM2.5 pollution status in northern Henan province and the harm of PM2.5 to human body and environment,the study totally sampled 77 effective seasonal PM2.5 samples through gravimetric method during 2013.10 to 2014.11 in Jiaozuo,using Staplex? TFIA-2 high volume sampler.According to the light,medium and heavy pollution degree of PM2.5 samples,study selected a total of 20 samples of each season and each type.Using method of EDXRF,ICP-MS,IC,DMA,TOR and FSEM,study achieved full components analysis and morphological observation of each season samples,and then analyzed the concentration,correlation,enrichment and seasonal variation of each component.Utilizing chemical mass closure,PCA/MLR and PMF,all possible sources of PM2.5 and the source contribution in Jiaozuo were studied.The main conclusions are as follows.?1?The mean concentrations of PM2.5 are 165±63?g/m3 during sampling period,and 59% of samples belong to the severe pollution or more,only 6% qualified,chronically pollution.Seasonal variation shows winter > spring and autumn > summer,and concentrations of spring and autumn are both close to annual level.?2?Mass percentage of inorganic elements,water soluble ions,OC and EC in PM2.5 are 22.07±11.47%,39.65±12.43%,10.50±3.14%,4.84±1.66% respectively,and seasonal variations of concentration followed by winter > spring > autumn > summer;winter > summer > autumn > spring;winter > autumn > summer and spring;summer > autumn,winter and spring.S,Cl,Sb,Cd,Se,As and Pb are mainly from coal combustion,and Na is also associated with coal combustion in winter.Cu,V,Mn and Co are mainly from vehicle emissions,metallurgy or waste incineration,and emission intensity increases in autumn.By comparing NO3-/SO42-ratios of each season,we can see that the PM2.5 pollution of coal combustion is more serious than vehicle exhaust in Jiaozuo,especially in winter and summer.Carbon fractions are mainly from motor vehicle exhaust in spring and summer,but they are the joint product of vehicle exhaust,biomass buring and coal combustion in autumn and winter.FSEM analysis shows that secondary sulphate particles often coexist with Pb,and Hg is enriched in silicate particles.?3?Mass reconstruction shows that primary and secondary fractions play an equal important role in PM2.5,accounting for 40.27% and 38.67% respectively.Mineral dust and POA respectively account for 60.81% and 35.03% in primary fractions,and secondary inorganic aerosol?SIA?and SOA account for 74.70% and 25.30% respectively in secondary fractions.Their seasonal variations show that primary fractions are main components of PM2.5 in spring and autumn,while secondary fractions dominate PM2.5 in summer,and concentrations level of both are similar in winter.?4?Source apportionment results show that fugitive dust,mixed source of iron and fugitive dust,mixed source of vehicle exhaust and SIA,coal combustion,inductry and mixed source of incineration and SIA are the main sources of PM2.5 in Jiaozuo city.Their average contributions to PM2.5 are 24.9%,9.0%,19.4%,18.9%,12.6%,14.2%,respectively.Seasonal variations show that fugitive dust dominates PM2.5 in spring?39.7%?,and SIA dominates PM2.5 in summer?more than 50%?,and coal combustion dominates PM2.5 in winter?30.4%?.?5?Fine particulates from coal combustion in the air are mainly sulphate,nitrate and organic particles,their percentages in PM2.5 derived from coal combustion are 24.5%,22.5% and 20.8%,respectively.Cl-and crustal elements also have higher contribution,relative percentage of 6.7% and 6.2% respectively in PM2.5 derived from coal combustion.Contributions of coal combustion to Cl-account for 70.3% of total Clin PM2.5,and Ba,Br,Se and Hg account for 30.8%,30.8%,30.7% and 56.4% of its corresponding elements,respectively. |
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