AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Atmospheric Aerosols in Southeast Asia: Sources and Impacts
RAGHU BETHA, Xian Huang, Rajasekhar Balasubramanian, National University of Singapore
Abstract Number: 557 Working Group: Urban Aerosols
Abstract Atmospheric Aerosols in Southeast Asia (SEA) contain a complex mixture of organic and inorganic substances, derived from a wide variety of emission sources. These sources include combustion of fossil fuels for power generation, transportation, industrial processes, biomass burning and vegetation. Apart from direct emissions, new particles are also formed in the atmosphere. While the impacts of local urban sources of particulate air pollution have been characterized within SEA, the influence of biomass burning in particular peat fires on regional air quality, visibility degradation, climate change and public health remains incompletely understood because of its sporadic nature. In addition, there is a critical need to identify and quantify the major sources of aerosols in the context of urban air quality improvement. Field studies were conducted in Singapore to gain insights into the transport, source contributions, and the impacts of aerosols from various sources on the environment and public health. It was observed that trans-boundary smoke aerosols derived from peat fires were usually transported from Indonesia to Singapore above the boundary layer and were intermixed with relatively clean air masses of oceanic origin at surface levels by convective winds, resulting in unique physical, chemical and optical characteristics of urban aerosols at downwind sites. During episodic peat fires, the carbon content of atmospheric aerosols increased to 55% (~35% during clear days) of which nearly 70-75% was estimated to be contributed by peat fires. Relatively large fractions (60-75%) of aerosols are found to be in the sub-micron range and were elevated by a factor of 15 during peat fires. Changes in the radiative properties of aerosols were strongly influenced by “aged” carbonaceous aerosols. Secondary or new particle formation was suppressed during hazy days. Health risk estimates revealed that the carcinogenic risk to individuals exposed to biomass burning-impacted aerosols increased significantly by 40% compared to those who are not exposed.