| 摘要: | 本研究探討了森林植物排放的揮發性有機化合物 (Volatile Organic
Compounds, VOCs) 特性，並提出以自動採樣與自動化熱脫附氣相層析質譜
(ATD-GC-MS)技術，解決現有需較大型設備獲得異戊二烯連續數據的侷限
性。根據文獻研究，生物源揮發性有機化合物 (Biogenic Volatile Organic
Compounds, BVOCs) 是大氣化學中的重要組成部分，其排放量遠超過人為
源 VOCs，，其中異戊二烯作為最主要的 BVOCs 之一，對大氣環境具有顯著
影響，例如:其為臭氧 (O₃) 及二次有機氣膠 (Secondary organic aerosol, SOA)
的前驅物。研究進一步指出異戊二烯濃度的變化對峰值臭氧濃度有直接影
響，且接近山地丘陵的區域有大量植被，這進一步強調了在山區佈等偏遠
地區進行連續監測的必要性。然而，現有的異戊二烯連續監測數據主要依
賴於光化測站 (Photochemical Assessment Monitoring Station, PAMS)，這些
測站設備複雜度高，且在山區佈署時面臨諸多挑戰，如電力供應不穩定和
設備維護困難等。
本研究使用了一種以電瓶為動力來源的輕便型採樣系統，利用主動式
吸附管獲取空氣中異物二烯逐時濃度變化，使用時將吸附管放入自動採樣
器，每小時採集一個樣品，在單次插入 32 根吸附管下，可連續獲得 32 小
時的濃度資料，。採樣件設設定為速 60 mL/min，，每樣樣品管的採樣時為為
1 小時，並透過自動熱脫附-氣相層析/質譜儀 (ATD-GC/MS) 進行異戊二烯
濃度分析，經過 TO-17 方法驗證，偵測下限 (Method Detection Limit, MDL)
為 0.195ppbv，。通過為期兩週的校園環境驗證實驗發現，，異戊二烯濃度與光
照強度及溫度成正相關，與光化測站數據同樣呈現典型的「午高晨低」日變
化特徵，但濃度差異顯著，充分反映植被覆蓋率與人為活動的影響差異。尤
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其在低溫降雨事設使異戊二烯排放銳減，證實其對氣象件設具有高度敏感
性。證明該系統在採樣效率和數據準確性方面均表現優異，不僅大幅降低
設備複雜度，更顯著提升系統在山區等偏遠地區的適用性，從而深入瞭解
森林植物排放的 VOCs 特性及其對大氣化學的影響，為未來森林生態系統
的 VOCs 排放研究提供了新的工具和方法。
;This study investigates the characteristics of volatile organic compounds (VOCs)
emitted by forest vegetation and proposes the use of an automated sampling
system combined with automated thermal desorption-gas chromatography-mass
spectrometry (ATD-GC-MS) technology to overcome the limitations of current
methods that require large-scale instruments for continuous isoprene monitoring.
According to literature, biogenic volatile organic compounds (BVOCs) are a
major component of atmospheric chemistry, with emissions far exceeding those
from anthropogenic sources. Among BVOCs, isoprene is one of the most
significant compounds, exerting a considerable impact on the atmosphere as a
precursor to ozone and secondary organic aerosols (SOA).Previous studies have
shown that variations in isoprene concentrations directly influence peak ozone
levels. Regions near mountainous or hilly areas, which are rich in vegetation,
further underscore the need for continuous monitoring in remote locations.
However, current continuous isoprene monitoring relies heavily on
Photochemical Assessment Monitoring Stations (PAMS), which are complex
systems and face several challenges when deployed in mountainous areas, such
as unstable power supply and difficult maintenance.
This study developed a portable, battery-powered sampling system that
collects hourly isoprene concentration data using active sorbent tubes. By placing
sorbent tubes into the automatic sampler, the system accommodates 32 tubes
sequentially, enabling 32 hours of continuous sampling. The sampling conditions
were set to a flow rate of 60 mL/min, with each sample collected over one hour.
The isoprene concentrations were analyzed using an automated thermal
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desorption-gas chromatography/mass spectrometry system (ATD-GC/MS), and
validated according to the TO-17 method, achieving a method detection limit
(MDL) of 0.195 ppbv. The two-week campus field validation experiment
revealed that isoprene concentrations exhibited a positive correlation with light
intensity and temperature. Similar to photochemical monitoring station data, a
characteristic diurnal variation pattern of "higher at noon and lower in the
morning" was observed. However, significant concentration differences were
detected, clearly reflecting the distinct impacts of vegetation coverage and
anthropogenic activities. Notably, low-temperature rainfall events sharply
reduced isoprene emissions, confirming its high sensitivity to meteorological
conditions. The system demonstrated excellent performance in sampling
efficiency and data accuracy. It not only reduces the complexity of traditional
equipment but also enhances applicability in remote areas such as mountainous
regions. This provides a new tool and methodology for in-depth understanding of
VOCs emissions from forest ecosystems and their impacts on atmospheric
chemistry, offering valuable support for future research on VOCs emissions in
forest environments. |
