Size spectra and source apportionment of fine particulates in tropical urban environment during southwest monsoon season

• Published in: Environmental pollution (1987) Vol. 244; pp. 477 - 485
• Main Authors: Zong, Yichen, Botero, Maria L., Yu, Liya E., Kraft, Markus
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.01.2019
• Subjects: Air Pollutants - analysis; Air Pollution - analysis; Atmosphere - analysis; Dust - analysis; Environmental Monitoring - methods; Humans; Particle Size; Particulate Matter - analysis; PM emission; PMF; Seasons; Singapore; Source apportionment; Southeast Asia; Tropical Climate; Vehicle Emissions - analysis; Singapore; PMF; Southeast Asia; PM emission; Source apportionment
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2018.09.124

In this study, we carried out high time-resolution measurements of particle number concentration and size distribution (5–1000 nm) in Singapore, which represents a tropical urban environment. The measurements were taken during the southwest monsoon season in 2017 using a fast-response differential mobility spectrometer at a sampling rate of 1 Hz. In the measurement, short-lived nucleation events were found prominent at early afternoon because of the abundant incoming radiation that enhances the photochemical reactions in atmosphere. For the first time in the region, a five-factor positive matrix factorization approach was applied to the size spectra data. Based on particle number concentration, two sources within nucleation mode (<30 nm) were resolved and account for 43% of total number concentration, which is higher than the available monitoring data in other big cities. Among the sources, O3-related atmospheric photochemical reactions with peak size at 10–12 nm is a unique factor and prominent in early afternoon nucleation events. The findings of this work can serve as a baseline for assessing influence of local and cross-border airborne emissions during various seasons in the future. [Display omitted] •Size spectra of airborne fine particulates were measurement at 1 Hz frequency.•Significant nucleation events were observed during southwest monsoon season.•Source apportionment on particle size spectra data was performed in Singapore.•A unique nucleation source was found that correlates with O3-related reactions. Short-lived nucleation is found prominent in tropical urban environment. A unique source is discovered correlated with O3.