[Characteristics of Black Carbon Aerosol and Influencing Factors in Northern Suburbs of Nanjing].

ABSTRACT

Based on the hourly averaged data of black carbon(BC) aerosol, PM2.5, gaseous pollutants, and meteorological data in the northern suburb of Nanjing from January to October 2015, characteristics and influencing factors of BC concentration variation were analyzed. The mean concentration of BC was found to be (2524±1754) ng·m-3 during the observation period. BC concentrations in Nanjing showed strong seasonality, the highest mean concentration of BC occurred during winter reaching (3468±2455) ng·m-3, and the lowest mean BC concentration was found during spring being (2142±1240) ng·m-3; a distinct diurnal variation of BC with two high peaks occurred, one in the morning during 0700 to 0800 and the other in late evening during 2100 to 2200 local time. The strong correlation between BC and NOx indicated a greater impact of vehicle emissions on BC concentration, while a lower rate of ΔBC/ΔCO was found in the northern suburb of Nanjing, suggesting that biomass burning emission might be another important source of BC in here. BC concentration increased with decreasing wind speed. BC concentration lower than 2000 ng·m-3 mainly occurred in westerly wind and adjacent wind in all seasons, whereas BC concentration higher than 6000 ng·m-3 more frequently appeared in easterly winds in autumn and winter. BC concentration was higher in hazy and heavy hazy weather, which were 2 and 2.3 times as large as that in non-hazy weather, respectively.