Characterizations of Carbonaceous Aerosol in South and East Asia: A review from 2007 to 2014

The variations of carbonaceous aerosols in particulate matter (mostly in PM10 and PM2.5) were reviewed in South and East Asia during the period of 2007 to 2014. The selected countries in South and East Asia are Bangladesh, China, India and Nepal. The carbonaceous aerosols consist of organic carbon (OC) and elemental carbon (EC) and combination of two is known as total carbon (TC). Anthropogenic or biogenic sources and atmospheric oxidation of volatile organic compounds and subsequent gas-to-particle conversion processes are the major sources of carbonaceous aerosols. This paper is reviewed the numerous studies, which were carried out in various hotspot locations (namely residential, industrial, traffic intersections, rural, indoor environment etc) of selected countries in Asian con-tinent. OC/EC ratio in Bangladesh (Dhaka) varied from 0.78 to 1.3. OC/EC ratio in China (Chongqing, Xi’an, Xink-en, Pearl River Delta regions) varied from 1.13 to 6.92. OC/EC ratio in India (Delhi, Agra, and Mumbai) varied from 0.15 to 16.2. OC/EC ratio in Nepal (Kathmandu, Kathmandu valley) varied from 2.7 to 2.86. OC/EC ratio is gener-ally varies with seasons. Most of the country OC/EC ratio exceeded 2, indicating the formation of secondary organ-ic carbon (SOC). SOC is one of the major contributors of OC and its contribution varied from 18 to 61% in the se-lected locations. In Dhaka city, Bangladesh) EC concentrations were alarmingly high due to operation of diesel based power plants. The concentrations of OC in PM10 and PM2.5 varied from 15 to 33% and 26 to 46% respective-ly. Similarly the concentrations of EC in PM10 and PM2.5 varied from 3 to 10% and 9 to 10% respectively. The mor-phology study of particulate matter suggested that the origin of carbonaceous aerosols were mostly from combus-tion processes only. This work elucidates the characteristics, sources of carbonaceous aerosols in South and East Asia.