大氣氣膠碳成分量測誤差與台北都會區有機氣膠特徵之研究; Investigation on measurement errors of the aerosol carbon in atmosphere and the characteristic of aerosol organic carbon in urban Taipei

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Title:	大氣氣膠碳成分量測誤差與台北都會區有機氣膠特徵之研究;Investigation on measurement errors of the aerosol carbon in atmosphere and the characteristic of aerosol organic carbon in urban Taipei
Authors:	黃薇如;Wei-Ru Huang
Contributors:	環境工程研究所
Keywords:	氣膠碳成分;氣膠碳成分分析比對;氣膠裂解碳校正;二次有機氣膠;都會區氣膠碳成分分佈;Aerosol carbon fractions;Aerosol carbon comparison;Pyrolyzed aerosol carbon correction;Secondary organic aerosol;Urban aerosol carbons
Date:	2006-06-28
Issue Date:	2009-09-21 12:16:00 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	大氣氣膠碳成分在偵測及解析方法上相當分歧，本文探討揮發性有機氣體(VOCs)對氣膠採樣的干擾，比較不同裂解碳(pyrolyzed carbon)矯正方法以及不同分析溫度協定造成的差異，瞭解現行氣膠碳成分自動監測儀器的基本性能，以期能分辨不同分析方法導致的氣膠碳成分差異，建立可靠的氣膠碳成分分析結果。此外，為瞭解台北都會區有機氣膠的特徵，本文在2006年3月底至5月中在台灣大學進行大氣氣膠碳成分的監測，使用的自動儀器包括以Sunset 5040碳分析儀監測有機碳(OC)和元素碳(EC)及以Magee AE-31吸光儀監測黑碳濃度(BC)，獲得台北地區的氣膠碳成分日夜分布情形；同時並以DRI 2001碳分析儀針對R&P 2000人工採樣器獲得的濾紙進行大氣氣膠碳成分分析，比較不同分析溫度協定的差異，探討有機氣膠受到溫度影響的揮發情形，並進行二次有機氣膠的推估。研究結果顯示Sunset 5040及DRI 2001碳分析儀器對OC、EC的偵測極限可達到0.13 μgC以下，再現性也不錯。TOT (Thermo-optical Transmittance)與TOR (Thermo-optical Reflectance)對OC、EC解析的結果顯示OCTOT比OCTOR高出7~15%，ECTOT則比ECTOR低了30~50%。大氣VOCs的存在對有機氣膠的量測呈現顯著的正干擾，日間VOCs主要影響較容易揮發的氣膠OC1及OC2成分的量測，夜間則以較不容易揮發的氣膠OC3成分干擾較為明顯。此外，不同分析儀器的比較，顯示Sunset 5040與DRI 2001得到的OC、EC濃度具有一致的變化趨勢，兩種儀器的EC絕對量也相近，但Sunset儀器量測到的OC較使用DRI 2001分析的結果低了約1.4 μg m-3。在EC與BC的比較上，Aethalometer測得的BC比Sunset及DRI的EC量測值高出50%左右。台北都會區氣膠的OC、EC佔PM10質量比例，分別約為15~17%及5~7％，氣膠碳成分日夜分布型態顯示EC及估計的一次有機碳(OCpri)與交通污染相關，估計的二次有機碳(OCsec)濃度高值則發生在中午11~13時光化反應最強的時段。OCpri與EC的特徵比值約為1.47顯著低於過去的研究結果，研究成果顯示台北市有機碳以OCpri為主，平均濃度約為4.49~4.84 μg m-3，佔總OC約73%，與過去研究結果相似。在氣膠碳成分分布上，台北都會區大部分的有機碳屬於揮發溫度較高的OC3，次高為OC2，EC成分則是以EC1為主要來源。強光化學反應時的OCsec與O3相關性良好，在中午前後兩者同時出現明顯峰值，在光化事件的案例分析中，10~16時兩者的R2高達0.92，TC中OCsec的平均比例高達40.5%，顯示強光化學反應發生時二次有機物有明顯生成現象。 The detection and analysis of atmospheric aerosol carbon are widely varied. This study investigates the interference of volatile organic carbons (VOCs) on the collection of aerosol carbons, compares the deviations from different corrections of pyrolyzed carbon and temperature protocols in carbon analysis, understands basic functions of commercialized automated aerosol-carbon monitors, and aims at resolving the differences from various analytical methods in aerosol carbons. In addition, this study collects atmospheric aerosol for carbon analysis at National Taiwan University to characterize organic aerosol in Taipei metropolis from the late March to middle May 2006. Meanwhile, diurnal cycle of atmospheric aerosol carbons are monitored using Sunset 5040 Carbon Analyzer for organic carbon (OC) and elemental carbon (EC) and Magee AE-31 Aethalometer for aerosol black carbon (BC). The filter-based aerosol carbons are analyzed in laboratory using DRI 2001 Carbon Analyzer for resolving deviations from different temperature protocols, assessing temperature effects on volatilization of organic aerosol, and estimating secondary organic aerosol. The results show that the OC and EC detection limits of Sunset 5040 and DRI 2001 can reach below 0.13 μgC with excellent repeatability. The comparison between TOT (Thermo-optical Transmittance) and TOR (Thermo-optical Reflectance) on the resolving of OC and EC shows that OCTOT is higher than OCTOR for 7~15% and ECTOT is lower than ECTOR for 30~50%. A positive interference from atmospheric VOCs is found for filter-based organic aerosol. The influenced species are low-temperature evolved aerosol OC1 and OC2 in daytime, while high-temperature evolved aerosol OC3 is much more interfered in nighttime. The instrument comparison shows that Sunset 5040 is consistent with DRI 2001 both in OC and EC variations and in EC quantification; however, the OC measured from Sunset is lower than DRI 2001 for about 1.4 μg m-3. For the comparison between EC and BC measurements, the BC from Aethalometer is around 50% higher than EC from Sunset and DRI instruments. The fractions of OC and EC in PM10 in Taipei metropolis determined from this syudy are 15-17% and 5-7%, respectively. Analysis of diurnal cycle of aerosol carbon indicates EC and the estimated primary OC (OCpri) are related to traffic activity. The peak value of estimated secondary OC (OCsec) appears at around 11:00-13:00 (local time) when photochemical reactivity is the most vigorous. In this study, the estimated OCpri and EC ratio is at 1.47, which is significantly lower than previous findings. Aerosol OC in Taipei metropolis is dominated by OCpri with concentration ranging from 4.49 to 4.84 μg m-3 and around 73% in OC, which is consistent with previous study. In Taipei aerosol-carbon fractions, the predominant OC species is OC3 followed by OC2, while EC1 is the major fraction of EC. The correlation between OCsec and O3 is high, significant peak values appear concurrently around noon time when photochemical activity is vigrous. In the study of photochemical events, the R2 between OCsec and O3 can be as high as 0.92 and OCsec in TC high around 40.5% which suggests the formation of secondary organic aerosol.
Appears in Collections:	[Graduate Institute of Environmental Engineering ] Electronic Thesis & Dissertation

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