以VOC測站網探討中台灣臭氧成因; Use as VOC measure stand to probe into ozone formation at center Taiwan

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/6029

Title:	以VOC測站網探討中台灣臭氧成因;Use as VOC measure stand to probe into ozone formation at center Taiwan
Authors:	歐雅雯;Ya-Wei Ou
Contributors:	化學研究所
Keywords:	臭氧;ozone
Date:	2004-12-30
Issue Date:	2009-09-22 10:12:07 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	地表臭氧污染問題在台灣已日益嚴重，由於臭氧為前驅物經由光化反應所產生之二次污染物，因此試圖嘗試利用中部三測站(崇倫測站、草屯測站與竹山測站)所構成之監測網數據量測之逐時前驅物數據，配合逆溫儀及物種對方法，進而釐清台灣中部臭氧成因。本論文首先將56種VOCs排放源分三類，分別為瓦斯燃料洩漏、植物排放與移動污染物質排放，討論一次污染物的日夜以及月平均濃度變化，發現除了植物排放其他排放濃度皆有早晚高中午低的現象，日夜變化主要受光化學及逆溫影響發，季節性變化主要受逆溫影響。而isoprene濃度在冬天與汽機車排放有一樣早晚高中午低的現象，但是靠近越夏天時，呈現中午濃度最高現象。本論文利用物種光化反應速率不一樣，建立了兩組VOC氣團老化指標分別為ethylbenzene/m,p-xylene以及pentane/t-2-pentene，與臭氧濃度有極高的相關性，兩對物種對在指示臭氧靈敏度上有很大的差異，顯示做為指標的可靠性；兩物種對皆為汽機車排放，因此汽機車排放物質對於發生在竹山高臭氧有很大之貢獻。本論文充分把崇倫、草屯與竹山三測站利用物種對方法，顯示其老化程度不一，將其三站之上、下風處特質表現出來；而在兩下風處竹山與草屯兩站相關性好，因此竹山可代表整個南投縣下風處研究臭氧適合場所之ㄧ。最後釐清竹山臭氧原因為風速風向將移動污染物帶到竹山而造成竹山高臭氧成因，而植物性排放為春秋為墊高臭氧基礎值濃度之角色。 Surface ozone has become a series pollution problem in Taiwan as well as in other major developing urban environments. While the average concentration of particular matter showed a decreasing trend, ozone on the other hand, showed an increasing trend over the past decade. To elucidate ozone formation mechanism in certain ozone plagued areas of Taiwan, in-situ VOC monitoring station network, equivalent to the US PAMS (photochemical assessment monitoring stations) program, was adopted with the first 3 station network established in central Taiwan in both urban and rural areas. Monitoring data of 2003 and 2004 was examined for their diurnal and monthly variation and three types of VOCs with different origins, namely LPG leakage, vehicular exhaust, and biogenic emissions, are discussed. While all of the VOCs have similar diurnal profile with maximum appeared in the morning and evening due largely to emissions, the change of mixing height, and photochemistry, isoprene however showed similar profile with tailpipe type of species in winter but gradually shifted its peak emission towards noon as the time progressed into later spring (May). Our investigation has led to the development of 2 VOC indicators of air masses’ age due to photochemistry with drastic difference in indication sensitivity. Excellent agreement between ozone concentrations and ratios of ethylbenzene/xylene and pentane/t-2-pentene suggests ozone is the photochemical product of VOCs and that the car exhaust compounds control the downwind ozone peak values. Difference in the age of air parcels received at the 3 stations was also clearly revealed, based on which the Chushan (竹山) station in general received more aged air masses than the other two upwind Chunlun (崇倫) and Choaton (草屯) stations. The similarity between Choaton and Chushan proves that Chushan station can be a suitable site for representing most area of Nantou county for studying ozone formation in downwind environment. Although biogenic emissions with isoprene being the dominant species did not appear to control the downwind ozone peak values, at least not to the same degree as the car exhaust compounds, it is shown to exert more reactivity towards ozone formation potential than other types of precursors. Production of isoprene at noon in the warm seasons synchronizes in time with the ozone peak further creates a greater possibility for ozone to exceed dangerous levels should car exhaust VOCs also been brought down to the site of observation.
Appears in Collections:	[Graduate Institute of Chemistry] Electronic Thesis & Dissertation

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