Observation of black carbon in fine particulate matter in the north suburb of Nanjing

In this paper,the seasonal and diurnal variation characteristics of black carbon (BC) in PM2.5 and the effects of heterogeneous reactions of traces gases within BC were studied by using the data collected in a north suburb of Nanjing from November 2008 to April 2010.The results showed that daily averaged concentrations of BC ranged from 1114 to 19408 ng·m-3.There was a double-peak pattern in the diurnal variation of BC level,which can be attributed to local anthropogenic emission and atmospheric boundary layer diurnal changes.Based on statistical methods and lognormal curve fitting analysis,the background level of BC in the north suburb of Nanjing was 2920 ng·m-3,which was higher than that of most cities in China.Observational results of SO2,NO2,HNO2 and O3 by DOAS were used to analyze the correlation between trace gases and BC.There were positive correlations between BC and SO2,NO2 and HNO2,with correlation coefficients of 0.290,0.615 and 0.676,respectively.In contrast,a negative correlation was found between BC and O3,with a correlation coefficient of-0.455.