Comprehensive Source Apportionment Of Atmospheric PM_2.5

As an important transportation hub city in China,the haze pollution problem has gradually become prominent with the continuous advancement of industrialization in recent years,and the pollution of fine particulate matter(PM2.5)has also attracted widespread attention.The environmental receptor samples were collected of the typical months in the four seasons of 2018 in this study.The sites of Zhengzhou environmental monitoring center and the Zhengzhou University points represented the urban and suburban areas respectively.9 water-soluble ions,OC,EC and 27 inorganic elements were tested in PM2.5.The mass concentration,seasonal variation,differences between urban and suburban areas and chemical components of PM2.5 were discussed.The CMB-Iteration model was used to determine the pollution sources at two points in the four seasons,and the characteristics of the sources were analyzed.The CALPUFF model was used to simulate the concentration distribution of sulfur dioxide and nitrogen oxide emitted by 22 point-sources in the high-tech zone in four seasons in Zhengzhou.Then,the contribution of these point-sources to the secondary sulfate and nitrate of Zhengzhou University was estimated by calculating the conversion coefficient.In addition,the backward trajectory and potential source were also used to analyze the transport path of the air mass and the potential source area of PM2.5.The main conclusions are as follows:The annual average PM2.5 concentrations at the sites of Zhengzhou environmental monitoring center and Zhengzhou University were(59.7±24.0)and(74.7 ± 13.5)μg·m-3,respectively.The seasonal changes at the two points showed the characteristics of winter>autumn>spring>summer.The results of component analysis showed that the concentrations of Ca2+and SO42-were higher in spring and summer respectively,and the concentration of NO3-was higher in autumn and winter.In addition,the concentrations of K+ and Cl-increased in winter.In spring,PM2.5 has a good correlation with Ca2+ and Mg2+,and in other seasons,PM2.5 has a good correlation with sulfate,nitrate and ammonium.The OC concentration presented winter>autumn>spring>summer,and the EC concentration presented spring>autumn>winter>summer.Both points were affected by vehicle exhaust emissions,coal burning emissions and biomass combustion emissions.V,Cr,Mn,Ni,Cu,As,Zn,Pb and Sb were greatly affected by anthropogenic sources,among which As and Pb elements had potential ecological risks.After reconstruction,the urban area was more affected by organic matter,sulfate,nitrate and ammonium salt,while the suburbs are more affected by elemental carbon and crustal materials.It was found that crustal matter,sulfate and nitrate accounted for a relatively high proportion in the three seasons of spring,summer and autumn,respectively.The proportion of organic matter,nitrate and chloride in winter was relatively high while that of sulfate was relatively low.The occurrence of the pollution process may be affected by the reduction of wind speed,the increase of relative humidity and the increase of dew point temperature.First of all,in order to further determine the main pollution sources,the CMBIteration model was used in this study from the perspective of receptors.The results showed that the spring and summer were greatly contributed by the dust source and sulfate.In autumn and winter,it was greatly contributed by coal sources and nitrates.The contribution of SOC was highest in winter.The urban area received more contributions from nitrates,sulfates,motor vehicle sources,SOC and less contribution from dust sources and industrial sources.From the perspective of pollution emission,this study also conducted a study using CALPUFF to simulate the concentration distribution of SO2 and NOx in four seasons and their contribution to the receiving point.The results showed that the 22 point-sources in spring,summer,autumn and winter contributed 0.64%,0.2%,0.5%and 0.7%of the SO42-concentration,and 8.3%,3.1%,5.4%and 2.8%of the NO3concentration at Zhengzhou University site.The results of the model showed that the effect of the emission reduction policy was obvious,but NOx pollution was not optimistic.Therefore,the follow-up pollution prevention and control work of the hightech zone could start with increasing the NOx emission reduction efforts,strengthening the construction process and mobile source management.In addition,this study also analyzed the effects of transport on pollutants.The backward trajectory results showed that all four seasons are affected by the air masses from Shandong Province.Except for summer,it was affected by the long-distance air mass transmission in the direction of Inner Mongolia.All were affected by the southern air mass except in winter.Potential pollution sources in spring are in the province,and potential pollution areas in other seasons are mainly located at the junction of provincial boundaries.