Continuous Real-Time Measurement of the Chemical Composition of Submicron Aerosol Particles in Kigali City Using Aerosol Chemical Speciation Monitor (ACSM)

Abstract

Three weeks of recording data from 29th April to 20th May, 2018 by Aerosol Chemical Speciation Monitor (ACSM) allowed for identifying, with a precise amount in 3 gm  , the chemical composition of non-refractory submicron aerosol particles (NR-PM1) emitted in Kigali city. Results revealed that average cumulative mass concentration of PM1 during the study period was 3 69.099.0   gm  , and the most abundant component of PM1 was organic aerosol with %57.85 , followed by ammonium (6.2%), nitrate (5.41%), sulfate (1.59%) and chloride (1.21%). The highest PM1 concentration was 3 01.4  gm  , whereas its lowest concentration was 301.0 gm  . Source apportionment of OA was carried out by applying positive matrix factorization (PMF) to the ACSM organic aerosol mass spectra. Three sources were identified: Hydrocarbon-like Organic Aerosol (HOA), Oxygenated Organic Aerosol (OOA) and Biomass-Burning Organic Aerosol (BBOA). OOA was the dominant source with an average 49.48% of the OA mass spectra, while HOA and BBOA represented 29.58% and 20.94% respectively. PMF results analysis indicates that the organic aerosols in kigali city are mainly emitted from the traffic, demostic cooking acitivities (i.e food cooking, meat charboiling and frying) and the oxidation of organic gaseous precursors. In addition, correlation between PM1 components mass concentrations and meteorological parameters was studied in this thesis. Three ( Org, NO3 and Chl) among five PM1 components were strongly correlated with the meteorological parameters. .