Characteristics of Ambient Particle-bound Polycyclic Aromatic Hydrocarbons in the Angkor Monument Area of Cambodia

Abstract

The characteristics of ambient particle-bound polycyclic aromatic hydrocarbons (PAHs) in the Angkor monument area of Cambodia were studied to evaluate the status of air pollution and the influence of possible emission sources. Ambient particulates were sampled at four sites during the same seasons: Angkor monument area, including Angkor Wat, in Siem Reap city, along a main road, and on a small hill beside Lake Tonle Sap. Monitoring of ambient particles in the city and Angkor Wat were conducted on a continuous basis. Meteorological data were continuously monitored at two sites to evaluate the role of wind in the transport of pollutants. The concentrations of total suspended particulates (TSP), PAHs and heavy metals were analyzed to examine the influence of anthropogenic emissions, as well as contributions from soil and miscellaneous particles. Profiles of 15 PAH compounds were compared to determine the influence of wind direction on the seasonal characteristics of PAHs. TSP concentration proved to be proportional to the sum of the concentrations of Al, Ca and Fe, which were the major metals present in particles, regardless of location and season. The mass fraction of PAHs with 4-6 rings in Angkor Wat was almost equal to, or larger than, that found in the city. During the rainy season’s southwest monsoon, the PAH profile in Angkor Wat was similar to that found in the city, while it was similar to that found in the rural areas during the dry season’s north, or northeast, monsoon. This indicates that in the rainy season air pollutant transport from the city to the monument is an important factor. PAH concentration in Angkor Wat was similar to that measured in Bangkok, indicating a serious air pollution situation.