Influence of Rice Straw Burning Emission on Concentration of Semi-Volatile Organic Compounds in Pathumthani, Thailand

Abstract:
Thailand is an agricultural country where the paddy rice is the major crop. Currently, most of rice straw is disposed of by open burning which may contribute significantly to the ambient air pollution. In this study, an integrated monitoring approach consists of the field burning experiment and ambient air monitoring was conducted to assess the influence of rice straw burning emission in a rice growing area (Klong Luang, Pathumthani) where open rice straw burning emission would be significant. Khao Yai National Park was representative of less-intensive burning area (reference area). Ambient monitoring for PAHs, PCBs and pesticides was carried out for dry and wet season in both representative areas for comparison during 2005-2006 while source monitoring was conducted only in Klong Luang during dry season 2005. The smoke samples from open burning fields in Klong Luang were collected and analyzed for potential source signatures. It was found from source monitoring that PAHs (fluoranthene, pyrene, chrysene, BbF, BkF and BaP) were signatures of rice straw burning. In Ambient air, the rice straw burning signature PAHs were found more pronounced in Klong Luang ambient samples than the reference area samples. Concentrations of PCBs and pesticides in ambient air were higher in wet season comparing to concentrations in dry season due to contribution from industrial estate located nearby and agricultural uses in Klong Luang. Additionally, the characteristic of PAHs in Khao Yai and Klong Luang samples were different. PAHs were predominant in gaseous phase in Klong Luang samples similar to the smoke samples, whereas in Khao Yai more particulate PAHs were found. The results suggest the causative relationships between rice straw emission and ambient air pollution levels in the burning area. The procedure developed in this study can be applied in other studies to assess the influence of rice straw burning emission on ambient air quality.

Keywords: rice straw burning, semi-volatile organic compounds PAHs, PCBs, pesticides