Abstract
Sampling of ambient particulate matters were conducted along with the measurement of NO2 at three different sites in Phnom Penh including the central part of downtown, residential and river side areas. Day and night samplings of total suspended particulates (TSP) were conducted in the central downtown. Concentrations of TSP and NO2 as well as chemical composition of particulates, i.e. polycyclic aromatic hydrocarbons (PAHs) and heavy metals, were measured in order to discuss the contributions of emission sources.
TSP concentration in the central downtown area was 100-250μg/m3, which was higher in daytime than nighttime, being similar to the concentration change of elements from soil such as Al, Ca and Fe. This suggests that TSP is mostly road dust or soil re-suspended by wind. On the other hand, both concentrations of PAHs with four or more aromatic rings and their mass fractions in particles were found to be higher during the night. This may be attributed to the emissions from diesel and other small generators for supplemental electricity, from kerosene uses for lighting and from biomass fuel for cooking, etc. The Mekong and Tonle Sap rivers may influence the ambient air transport and pollutant dispersion in Phnom Penh. The concentration of PAHs in Phnom Penh was approximately forty times higher than Kanazawa, Japan, and six times higher than Bangkok, Thailand.
