Effects of biomass and agricultural waste burnings on diurnal variation and vertical distribution of OC/EC in Hat-Yai City, Thailand

Carbonaceous compositions, water-soluble ionic species and trace gaseous species were identified and quantified in Hat-Yai city, Thailand. All samples were collected every 3 h consecutively from 21 h December 17th to 21 h December 20th at Site 1 (30 m agl), Site 2 (60 m agl) and Site 3 (125 m agl). The averaged concentration of OC was significantly higher at the Site 1 than those detected at Site 2 and 3 suggesting that anthropogenic activities at ground level might play a major role in governing air quality at ground level. The morning peak of carbonaceous compositions observed during the sampling period of 6-9 emphasized the main contribution of traffic emissions on OC/EC contents in Hat-Yai city. In this study, it was found that aged maritime aerosols from long-range transportation and/or biomass burning particles overwhelmed carbonaceous aerosols at the top of building. Whilst hierarchical cluster analysis and Pearson correlation analysis show some considerable influences of night-time tourism activities on carbonaceous contents at ground level, principal component analysis highlights the impacts of maritime aerosols, biomass burning and possibly agricultural waster burning particles at higher atmospheric layer.