Thesis (M.Sc.)--Chulalongkorn University, 2009

The objective of this research is to investigate aerosol chemical concentrations and compositions in Thailand. Moreover, the relationship between aerosol chemical concentrations and temperature of the surface atmosphere were studied. The aerosol samples were analyzed for the ground-based aerosol compositions and concentrations during June 2007 to June 2008 at the Observatory for Atmospheric Research at Phimai, Changwat Nakhon Ratchasima. Multi-nozzle cascade impact samplers collected aerosol samples once per 15 days for 13 months. Each sample was the representative data of a half month. The samplers consisted of quartz fiber filters and polycarbonate filters. The samples were analyzed for carbonaceous aerosols by optical thermal OC/EC analyzer, for water-soluble aerosols by ion chromatography and for trace elements by particle induced x-ray emission. Meantime, the soil samples around the Observatory were determined using x-ray fluorescence. It was found that the combined measurable aerosol concentrations were high in November 2007 owing to sulfate but the concentrations were high in January 2008 due to OC. Both sulfate and OC were originated from human activities, for example, transportation etc. Consequently, the main sources of aerosols at the Observatory were the local activities. Cl⁻/Na⁺ ratios of the aerosols were different from the ratios of sea water and soil samples so salt particles at the Observatory originated from both soil dust and sea water. Moreover, the low surface temperature was the cause of the high aerosol concentrations because the aerosol could not be spread widely by wind.