Chemical Characterization and Source Apportionment of PM2.5 near Semi-Urban Residential-Industrial Areas

This study aims to determine the concentrations of the trace metals (TM) and water soluble inorganic ions (WSII) of the PM2.5 pollutant collected in the suburban industrial-residential airshed during the southwest (SW), inter-monsoon (IM) and northeast (NE) monsoons in Skudai, Johor Bahru. The PM2.5 samples were collected using the MiniVol™ portable air sampler equipped with filter paper. The TM and WSII of PM2.5 were determined by using the inductively coupled plasma-mass spectrometry (ICP-MS) and ion chromatography (IC), respectively. The sources of the PM2.5 composition were determined using the Positive Matrix factorisation (PMF) and the origin of the measured air-masses were determined by the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT). The results show that the major TM identified were Fe > Ba > Zn > Mg > Al. Meanwhile for the WSII, the major contributor was the secondary inorganic aerosols (SIA); NO3−, SO42− and NH4+. The six predominant sources identified were (1) mineral dust pollution (4.2%), (2) source of mixed road dust and biomass burning (18.1%), (3) mixed secondary inorganic aerosol and road dust emission (18.1%), (4) emission of the non-combustion traffic source (25.4%), (5) industrial emission (18.1%) and (6) undefined (16.1%).