Characterization and source apportionment of carbonaceous aerosols in fine particles at urban and suburban atmospheres of Ankara, Turkey

Koçak, Ebru ( Aksaray, Yazar )In order to find the spatial distribution characteristics of elemental (EC) and organic (OC) carbon in fine particles, daily PM2.5 aerosol samples were collected at two different stations, between July 2014 and September 2015 in Ankara, Turkey. Concentrations of OC ranged from 2.1 to 42 mu g m(-3) at urban station. These concentrations were higher than those obtained for suburban station whose values ranged from 1.3 to 15 mu g m(-3). Concentrations of EC ranged from 0.7 to 4.9 mu g m(-3) at the urban station. As in OC case, the corresponding levels were higher than those measured for suburban station. The associated EC levels ranged from 0.1 to 3.4 mu g m(-3) for the suburban station. Daily changes in the levels of EC were larger than the OC levels. OC/EC ratios were lower with lower monthly variability in summer and higher with lower monthly variability in winter at the urban site. Medium and weak correlations were obtained between EC and OC in the winter and summer seasons, respectively, at both stations. Secondary organic carbon (SOC) was an important component of OC in PM2.5 at the urban and suburban sites. The winter SOC level was higher than the summer SOC level at the urban site but slightly lower than the summer SOC level at the suburban site. Total carbon was apportioned using factor analysis for the eight carbon fraction data (OC1, OC2, OC3, OC4, EC1, EC2, EC3, and OP). The main sources of pollutants in the urban and suburban settings were from vehicular emissions, biomass and coal combustions, and road dust