Size-resolved airborne particles and their morphology in Central Jakarta

Abstract

Air pollution in Jakarta, the capital city of Indonesia, has become a serious concern with the potential to affect the health and well-being of its citizens. Since different sources emit particles in different size ranges, understanding the particle size distribution and their morphology is important in setting up effective control and management measures. Airborne particles in central Jakarta were sampled via a size-fractionating cascade impactor, and the mass loading of each fraction determined gravimetrically. The average total mass loading is 120 μg m −3 across the period, April 1994–October 1995. Using an inversion procedure based on a nonlinear iterative method, a bimodal lognormal size distribution was found. The two distribution maxima were centred at approximately 0.6 and 6.3 μm aerodynamic equivalent diameters, respectively. The elemental concentrations were analysed by Inductively Coupled Plasma-Atomic Emission Spectrometry. The crustal elements Al, Si and Ca showed a close association. The distribution pattern for these crustal-related elements suggests that crustal dust is contributing significantly not only to the coarse fraction but also to the fine fraction. The chemical components relating to anthropogenic sources such as Pb, Zn and K tended to accumulate in the fine particle range. Results revealed that Na had a sizeable loading in the coarse fraction, undoubtedly associated with a marine source. Scanning Electron Microscopy combined with an Energy Dispersive X-ray Detector was used for morphological characterisation of individual particles. Traffic-related particles such as carbon-based material from diesel vehicle exhaust and Pb-rich fine particles from combustion of leaded petrol were identified as being particular concerns.