||In atmospheric environment, synchronized survey of criteria air pollutants and volatile organic compounds (VOCs) are important for ambient air quality measurement. UV-DOAS (Ultra-violet Differential Optical Absorption Spectroscopy) in this research is an optics open-optical monitor based on the ultraviolet and visible-light absorption of gaseous pollutants. This measurement could be employed to examine the spatial average concentration of optical path in the open space, and to monitor criteria air pollutants (including O3, SO2, NO and NO2) as well as VOCs (including benzene, toluene, p-xylene). |
Aircraft takeoff and landing has serious impacts on the neighboring envvironment of Kaohsiung International Airport. Aircrafts generate two major pollution problems: chemical pollution (leaking flue from engine and fume with particulate and gaseous pollutants from incomplete combustion) and physical pollution (aircraft noise). Most air pollutant emissions from aero engine are generated during aircraft takeoff and landing. The distribution of gaseous pollutants along the runway is a linear pollution source. Restricted by flight safety, it is difficult to monitor and investigate aero engine pollution with traditional stationary monitors. Therefore, open-path monitoring has become a novel tool for research.
First, this study investigated the spatial average concentration of air pollutants around the runway of Kaohsiung International Airport and compared with monitoring data from nearby air quality monitoring station to evaluate the performance of the open-path monitoring system. Comparing the stationary monitors with the open-path monitoring showed relatively better correlations on O3 and NO2 than on SO2 and NO, which might be caused by the differences of local emissions. Overall, these two monitoring systems are identical on monitoring regulated pollutants. Furthermore, the open-path monitoring can also examine volatile organic compounds (ex: benzene, p-xylene, and toluene). The open-path monitoring is a practical and reliable monitoring system. It could be considered as one of the ambient air quality standard monitors in the future.
Secondly, this study chose the airspace of approach lane, located at west side of the runway 09 of Kaohsiung International Airport, as survey area. The open-path monitoring (OP-SIS) utilized UV-DOAS for sampling and monitoring the air quality of the survey area. It examined, recorded, and analyzed the criteria air pollutants (O3, SO2, NO and NO2) as well as VOCs (including benzene, toluene, p-xylene) to ascertain the impact of aircraft emissions on atmospheric environment. The results suggested that aircraft emissions influenced ambient air quality with high correlation to NO concentration. Additionally, the wind directions of land-sea breeze and monsoon also have influences on the concentration of air pollutants in the study area. In daytime, when wind direction was N or NNE, the variance of NO concentration was consistent with takeoff and landing time points with correlation coefficient of 0.60. After 5-6 minutes of an aircraft passed through the study airspace, the variance of instantaneous concentration of NO climbed up to 30 ppb. The results were contributed to understand the characteristics and sources of aircraft emitted air pollutants. It could provide the authority to have better judgment on reducing air pollutants as well as to assist the maintence and management of ambient air quality surrounding the airports.