| Haze is the most prominent pollution problem of atmospheric environment in China in recent years,with fine particulate matter(PM2.5)being the core pollutant as major components of PM2.5,water-soluble ions and carbonaceous components play an important role in the environmental and health hazards caused by PM2.5.Studying their pollution characteristics could help to understand the formation mechanisms of haze in related areas and conduct source trace analysis to clarify the targeted control solution of smog.However,the relevant researches were mainly concentrated on the urban atmospheric environment,awhile few studies were conducted in the coking industry gathering area.To make up this gap,PM2.5 samples were collected in different seasons in Jiexiu,a typical coking pollution area in Shanxi,and a background area-Fangshan,an agricultural region as a control in this study.And then,the pollution characteristics of water-soluble components and carbonaceous components in PM2.5 were studied.Based on those analyses,the main sources of water-soluble ions and carbonaceous components in PM2.5 in the coking pollution area were identified by using the Positive Matrix Factorization?PMF?model,and the main potential source contribution areas were analyzed by using the Potential Source Contribution Function?PSCF?model combined with the backward trajectory model,the main conclusions are as follows:?1?The annual average concentration of the total water-soluble ions in PM2.5 in Jiexiu is 94.40?g/m3,which is four times higher than that of thebackground point-Fangshan?21.79?g/m3?.The annual average proportion of total water-soluble ions mass in PM2.5 is 46.85%,of which the sum of the mass concentration of the secondary water-soluble ions SO42-,NO3-,NH4+accounts for 70.66%,both of those secondary water-soluble ions are higher than those in Fangshan.The seasonal change of the total water-soluble ions concentration in Jiexiu and Fangshan both follow the trend of winter>autumn>summer>spring.The most possibly exsited forms of secondary water-soluble ions in the two regions are?NH4?2SO4 and NH4NO3,but the aerosols in Jiexiu is acidic while that in Fangshan is basic.?2?The annual average concentrations of OC,EC and TCA?Total Carbon Aerosol?in Jiexiu are 38.48?g/m3,8.42?g/m3 and 69.98?g/m3,respectively,which are greater than those measured in Fangshan by 3 times.Compared with other cities in China,the average concentration of OC in PM2.5 in Jiexiu is at a relatively high level,while the average concentration of EC is at a medium level,and the main component is EC1.Under the influence of coal combustion,the concentration of carbonaceous components in PM2.5 in Jiexiu and Fangshan in winter is significantly higher than other seasons;Except for summer,the proportion of secondary organic carbon?SOC?in total OC in Jiexiu is lower than that in Fangshan,and the ratio of SOC/OC in autumn is higher than other seasons.The analysis of OC/EC ratio indicates that coal combustion and biomass combustion in autumn and winter have a great contribution to the carbonaceous components,while the contribution of motor vehicle exhaust in spring and summer is greater than that in autumn and winter.?3?The source apportionment,by PMF model found that the sources of water-soluble ions and carbonaceous components in PM2.5 in Jiexiu are mainly coking source,coal-burning source,vehicle exhaust,dust source and biomass-burning source,accounting for 37.2%,23.97%,20.93%,10.09%and7.82%of the total,respectively.PSCF analysis showes that the atmopshere near the Jiexiu sampling site might be also affected by the surrounding pollution sources in the directions of northeast,northwest,and southwest in addition to local sources.This study has clarified the pollution characteristics and main pollution sources of water-soluble ions and carbonaceous components in PM2.5 in coking area.The results above-mentioned can provide basic data and scientific support for the haze pollution control of local environmental protection departments. |
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