Characteristics of PAHs in Particulates in the Atmospheric Environment of Hat Yai City, Thailand, and Relationship with Rubber-wood Burning in Rubber Sheet Production

摘要

Natural rubber is a main commodity of Thailand, half of which is formed into ribbed smoked sheets (RSS). Fuel wood is burned during RSS production to heat and dry the rubber sheets. Smoke from the burning wood contains chemical species in particles and gases, notably polycyclic aromatic hydrocarbons (PAHs). In this study, the influence of smoke from fuel-wood burning by rubber-smoking cooperatives on atmospheric air in the neighboring town of Hat Yai, Songkhla Province in southern Thailand, was evaluated for the year 2005. The particle size distributions of ambient air in downtown Hat Yai and Prince of Songkla University (PSU) clearly showed bi-modal behavior, indicating multiple sources of particles. TSP was generally low, averaging 45.6 and 46.2 μg/m3 for downtown Hat Yai and PSU, respectively. The TSP depended on precipitation, particularly when precipitation was high. The correlation between TSP and rubber sheet production from all rubber cooperatives in Songkhla Province is clear. PAH size distributions of ambient air particles clearly showed single-modal behavior, suggesting that most of the PAHs are associated with small particles. The relationship between wood burning and PAHs in ambient air in Hat Yai and PSU is also clear. Low PAH concentrations during the dry season could result partly from wind direction (E to NE), which blows inland from the Gulf of Thailand. During the rainy season, PAH concentration at both locations was low; however, it was inversely proportional to the precipitation. Hence, rubber sheet production, wind direction and precipitation are important determinants of PAH concentration in Hat Yai area.