Influence of vehicular emissions and meteorological factors towards anionic surfactants in the urban atmospheric aerosol of Kuala Lumpur, Malaysia

Abstract

This study aimed to determine the influence of vehicular emissions and meteorological factors on the level of surfactants in urban atmospheric aerosol from Kuala Lumpur city center, Malaysia. Aerosol samples were collected using a high-volume sampler equipped with the cascade impactor to separate fine mode (< 1.5 µm) and coarse mode (> 1.5 µm) particles. Besides, the exhaust particulate matter from various diesel and petrol vehicles was collected using a soft brush during dry weather. Colorimetric analysis was performed to determine the concentration of anionic surfactants as methylene blue active substances (MBAS), and the absorption was determined by using a UV spectrophotometer at a wavelength of 650 nm. Correlation analysis was conducted to determine the influence of vehicular emissions (NOx, SO2, CO and O3), and exhaust particulate matter on the level of surfactants. Results showed that surfactants as MBAS in fine particles showed the dominant values. Correlation analysis showed that the MBAS was positively correlated with NOx (p <0.05) and SO2 (p <0.01), and negatively correlated with O3 (p <0.01), which indicated that the traffic-related air pollutant may influence the anionic surfactants level. It is supported by the high level of MBAS in diesel exhaust particulate matter, particularly from the construction machinery, followed by lorries and buses.