• Ambient Concentrations of Black Carbon Aerosol and Its Emission Sources in Bangkok Ambient Air

    Panwadee Suwattiga

    Department of Agro-industry, Food and Environmental Technology, Faculty of Applied Science, King Mongkut’s University of Technology North Bangkok, Bangkok, Thailand.

    Abstract: Black carbon aerosol (BC) or elemental carbon (EC) in the atmosphere is known that formed by the incomplete combustion of fossil fuels, biofuels, and biomass. BC plays an important role as the solar absorber. It is a short-lived climate forcer (SLCF) which has atmospheric lifetime days to weeks while CO2 is more than 100 years. In addition, black carbon aerosol considers as air pollutant that affects human health and WHO support within its Health and Climate Change campaign “Road to COP21”. Identification the situation and sources of black carbon aerosol in the atmosphere is important for air quality management. The objective of this study is to determine black carbon ambient concentrations in suburban area north of Bangkok and find out its emission sources. This study measured BC concentration continuously 24 hours every 6 days for 4 years from January 2014 to December 2017. A Nano-sampler was used to determine the size distribution and carbon composition of the samples, and meteorological data especially wind direction and rainfall, were conducted on-site. Sampling location was suburban area north of Bangkok at King Mongkut’s University of Technology North Bangkok. BC concentration was measured by aethalometer. The results showed hourly BC concentrations had average value 1.84±0.21 ug/m3 to 3.72±0.65 ug/m3 with peaks in the morning and evening related to traffic. Seasonal BC concentrations were 1.88±0.68 to 4.78±1.13 ug/m3 during dry season (November to April) which higher than the concentration in the wet season (May to October) at valued of 1.46±0.14 to 2.85±0.95 ug/m3. The highest concentration occurred in January each year, except in 2017 was February, with value of 5.82, 5.27, 4.83 and 3.20 mg/m3, respectively. The results of 72-hour backward trajectories (NOAA Hysplit Model) in the months which had the highest and lowest value of BC concentrations, showed closely correlation of BC concentrations and wind directions. They showed that ambient air in Bangkok was affected not only from traffic in the city but also others activities such as biomass burning from neighboring province; east and northeast of Bangkok. Particle size distribution showed bimodal of particle sizes 0.5-1 mm and 2.5-10 mm. Mean ratio of OC: EC were range of 3.2-4.1 show signature of vehicle exhaust, biomass burning and may be the formation of secondary organic aerosol. In 2017, BC concentration had trend to decrease may be the effective measures of burning prohibiting.

    Keywords: Black carbon aerosol; Bangkok ambient air; Elemental carbon; Char-EC; Soot-EC.

    Pages: 197 – 210 | Full PDF Paper