| Summary: | 碩士 === 國立臺灣大學 === 環境工程學研究所 === 94 === This study observed the concentration of 56 VOCs of ozone precursors by using mobile laboratory in Sijhih, which has been one of the leeward areas of Taipei city, and then photochemical indicators are sifted by correlation regression analysis. It would also cooperate with meteorological factors, pollutant concentration analysis and MIR theory to discuss the variation tendency of ozone concentration and main contribution species during high ozone concentration period.
In the three observing experiments, the meteorological conditions of the first set were the most suitable for photochemical reactions in atmosphere. Moreover, the variation of wind direction was reflected on the change of pollutant’s concentration. By west wind, the sources of pollutants were mostly from Taipei city. A larger variation of NO, NO2 and VOCs concentrations, and higher ozone concentration were observed; By east wind, the pollutants were transported through Keelung river and the variation of the pollutants were less related. The photochemical indicators, including m,p-Xylene / Ethylbenzene, o-Xylene / Ethylbenzene and 1,2,4-Trimethylbenzene / n-Propylbenzene, were filtered by correlation regression analysis. They reflected the relationship between rush hour and the change of ratio after photochemical reactions. For example, the ratio of m,p-Xylene and Ethylbenzene was in the range of 0.8 to 2.4 for west wind direction and 0.8 to 1.4 for east wind direction. The results indicated that the photochemical indicators and the level of photochemical reactions are strongly correlated with the sources of pollutants, especially for ozone concentration.
During the high ozone concentration period, it would be compared with the ozone formation potential to estimate the largest ozone concentration by the consumed VOCs. The consumed VOCs, including 40.7% and 33.5% alkenes, aromatics account for 45.9% and 45.1%, would be produced about 192.5 ppb and 105.7 ppb in November 5 and 6. The results were nearer to the 132 ppb and 105.7 ppb observed than the 712.4 ppb before photochemical reactions were. In addition, the top ten main compounds were engaged about 78% of total ozone formation potentials, and the main three compounds were m,p-Xylene, Isoprene, and Toluene.
|
|---|
