10th International Aerosol Conference
September 2 - September 7, 2018
America's Center Convention Complex
St. Louis, Missouri, USA

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Physicochemical Characteristics and Source Apportionment of PM2.5 in an Inland City of Baoji, China

ZHOU BIANHONG, Li Meijuan, Fang Ni, Zhang Zhangquan, Liu Suixin, Baoji University of Arts and Sciences

     Abstract Number: 38
     Working Group: Source Apportionment

Abstract
PM2.5 samples were collected from March 2013 to March 2014 in inland city of Baoji, China. The daily and seasonal variations of PM2.5 mass and major chemical components were analyzed. The source apportionments were obtained by using positive matrix factorization ( PMF).
The concentrations of PM2.5 was 153.6±90.9 μg•m-3 during the sampling period. The seasonal variation of PM2.5 concentrations followed by the order of winter > autumn > spring > summer. SO42-, NO3- and NH4+ were the major ions, which accounting for 78%-91% of total ions. The concentration of SO42-, NO3- and NH4+ were highest in winter, however, SO42- was also abundant in summer. The seasonal ratio range of NO3-/SO42- is 0.52-0.79, indicating that pollutants are mainly emitted from stationary sources, especially from coal combustion. The seasonal trend of WSOC followed as winter > autumn > spring > summer. OC presented a highest concentration in winter. EC concentrations varied insignificantly in different seasons. Ca, Fe and Zn were the main elements. Ca, Ti and Fe were mainly emitted from natural sources, in contrast to Zn, As, Br and Pb, which were mostly derived by anthropogenic activities. However, Cr and Mn were affected by both natural and anthropogenic emissions. Material balance showed that organic matter (OM) accounts for 20.1%-31.4% of annual PM2.5 concentration, and the contribution of SO42-, NO3- and fugitive dust (FD) were 14.6%- 24.1%, 10.3%-16.3% and 10.3%-24.1%, respectively. OM and FD were the most abundant compositions in spring, accounting for 19.9%-29.4% and 17.9%-26.9% of PM2.5. On the contrast, SO42- was the highest contributor (25.2%-37.4%) in summer. In autumn and winter, PM2.5 was mostly consisted by OM (25.6% to 35.9% and 21.9% -37.2%). PMF results indicated that the major contribution factors are secondary sulfate (24%), coal combustion (18%), secondary nitrate (16%), biomass burning (15%), fugitive dust (15%) and motor vehicles (12%).