利用熱脫附氣相層析質譜法分析空氣微粒中多環芳香烴並探討與特定污染源之相關性

Abstract

懸浮微粒 (particulate matter, PM) 是人類行為所產生的空氣污染物之一，其中細懸浮微粒 (fine particulate matter, PM2.5) 內有許多有機成分，包含多環芳香烴物質 (polycyclic aromatic hydrocarbons, PAHs)。數種多環芳香烴物已被證實有突變性與致癌性，對人體造成健康上的傷害。多環芳香烴主要產生於不完全燃燒，而都市中交通道路被認為是產生多環芳香烴的主要來源。 本研究使用石英濾紙採集大氣環境中細懸浮微粒，搭配熱脫附氣相層析質譜儀 (thermal desorption gas chromatography/mass spectrometry, TD-GC/MS) 分析附著於懸浮微粒上的多環芳香烴之濃度，熱脫附方法相較於傳統液體萃取法可減少實驗所需時間以及降低不必要的污染，本研究嘗試優化實驗參數以便分離、偵測多環芳香烴，於環境中所測得最高濃度物質為 Benzo[ghi]perylene，其春季平均濃度為 0.28 ng/m3、夏季為 0.26 ng/m3，合併文獻與本研究的環境濃度值，可看到北部地區不同區域之採樣結果，皆以較高環數物質濃度為主，利用特徵比值也顯示交通為重要污染來源。 另一方面本研究基於少量環境樣本推估人體暴露多環芳香烴之風險值為 1.87×10-5，高於可接受風險值10-6，顯示環境中的多環芳香烴可能具有致癌風險。同時運用風險來源鑑定分析 (risk apportionment)，推估研究區域中污染源之健康風險。在污染源當中，PM2.5 質量主要貢獻來源為衍生性氣膠，然而多環芳香烴物質量主要貢獻者來自油燃燒，此汙染源也為多環芳香烴風險值之最大貢獻來源，顯示出質量貢獻與健康風險之來源並不一定相同，在健康評估上應考慮各污染源之組成成分。又本研究僅探討多環芳香烴物可能對人體造成的毒性，應同時將多種有致癌風險的物質納入毒性考量，才能更有效保護人體健康。

Fine particulate matter (PM2.5), one of the most common anthropogenic air pol-lutants, comprises many organic species, including polycyclic aromatic hydrocarbons (PAHs). PAHs are known to be mutagenic and considered as potential human carcino-gens. Road traffic is well recognized as a major source of PAH emissions. To measure PAHs in PM2.5, ambient samples (n=29) were collected on quartz-fiber filters using Harvard Impactors and analyzed by thermal desorption gas chromatography/mass spectrometry (TD-GC/MS). Compared to solvent extraction (SE) approach, TD reduces sample pre-treatment and requires only a small portion of sample for analysis. This study attempted to optimize the TD operative parameters to improve the efficiency of PAH analysis. The optimized method was applied to the field samples collected during spring and summer in 2015. Results indicated that BghiP showed the highest average concentrations amon-gthe measured PAHs, which were 0.28 ng/m3 in spring and 0.26 ng/m3 in summer. The high molecular weight PAHs were dominant in PM2.5 compared to the low molecular weight PAHs. In addition, the BaP equivalent cancer risk calculated from the toxicology equivalency factor (TEF) was 1.87 X 10-5 during the study period, which is considered to be hazardous to human health. In this study, the largest contributor to PM2.5 mass concentration was secondary aerosol/ long-range transport factor while combustion factor was the major source of PAHs. This indicated a large contributor to mass concentration may not correspond to a higher risk. Therefore, the source composition should be considered when assessing health impact.