Organic and black carbon in PM_(2.5) at an urban traffic environment of Dhaka, Bangladesh

摘要

The measurements of organic (OC) and black carbon (BC) in PM2.5 were made during February 2010 to February 2011 at an urban, traffic influenced site (Farm Gate) in Dhaka using Air Metrics samplers. Other measured variables are PM_(2.5) mass, sulfur concentrations, and basic meteorological data. A good picture on several quantities associated with OC and BC could be obtained, including daily and seasonal variation of their concentrations, their distribution to the total PM_(2.5) mass and their relation to the meteorology. Daily average OC and BC concentrations were higher than the literature reports for urban environments. The OC/BC ratio correlated with wind speed, temperature and sulfur concentration. Based on these relationships, we concluded that the dominant sources of BC at this site are both local and regional. The local sources are traffic, coal and biomass burning. We also derived estimation for the OC/BC ratio representing the primary traffic-emitted aerosol.