| 摘要: | 桃園市位處於台灣北部都會區，區內設有五大工業區，加上一座運輸便利的國際機場，整體組合成一個結構完備之綜合型工商城市。不過，也由於工業興盛與交通繁榮，其周界空氣中人為所產生的有害懸浮微粒的含量相對地可能因此而提高。而與細懸浮微粒相關的污染物當中，多環芳香烴化合物(Polycyclic Aromatic Hydrocarbons﹐PAHs)為一群具有高分子量、高沸點、高熔點、水溶解度極低、穩定且不易揮發等特性，同時也被歸類為持久性有機污染物(即POPs)的有害物質，但此類污染物在細懸浮微粒的分佈與組成為何，尤其是具代表性的PAHs本土濃度分佈資料，現階段可得的資訊仍舊極為有限。有鑑於加強PAHs本土濃度流佈資料庫的建立可提高敏感受體族群與區域環境的暴露程度及風險上的掌握，本研究於民國102-104年之間，分別於夏季與冬季在桃園機場鄰近的國民小學以PS-1大流量採樣器進行大氣中懸浮微粒及PAHs樣品的採樣，並以氣象層析質譜儀(GC/MS)分析19種PAHs化合物，期能在航空城開發之初，建立機場附近大氣環境中PAHs的含量及組成分等背景(即基線)資訊，同時針對桃園機場鄰近敏感受體國民小學大氣中的PAHs進行完整詳盡之特徵分析。研究結果顯示：第一次採樣(102年7月)所得之PAHs濃度值範圍為44~147 ng/m3、平均濃度值為76.0 ng/m3，第二次採樣(103年1月)監測的濃度值範圍為89~264 ng/m3、平均濃度值為136.9 ng/m3，在第三次採樣(103年8月)分析所得之範圍為218~370 ng/m3、平均濃度值為289.9 ng/m3，第四次採樣(104年1月)所測得的濃度範圍則為45~128 ng/m3、平均濃度值為73.4 ng/m3。四次所得之數據雖以第三次採樣(夏季)的PAHs平均濃度值最高，但這與一般學理所述之冬季時混合層高度小而擴散條件不佳、日照少故光化學反應較慢，因此理論上PAHs濃度值冬季應較夏季高的觀點不吻合，推測可能由於有其他不確定且未知的影響因子存在所致；即使如此，本研究在第一年度的採樣監測值確實顯現出冬季濃度較夏季高的趨勢，與一般學理觀點相符合。而四次的監測值亦顯示三所小學環境中暴露的PAHs組成分，主要分布在2環的Naphthalene(Nap)與2-Methylnaphthalene(2-MNap)，此二種化合物對人體的健康毒性與Benzo(a)pyrene(Bap)相形之下雖然較不強烈，但其所引起的生物累積性效應依舊不容忽視。本研究所得的監測結果對於未來若要建立PAHs管制標準濃度值或有幫助，且對於未來航空城計畫如有啟動，亦可做為航空城開前後環境PAHs監測的比對參考資料;Taoyuan is a metropolitan city located in the Northern Taiwan that contains five industrial parks and an international airport, making it a leading industrial and commercial center. However, such industrialization and developments in transportation have resulted in elevated levels of hazardous suspended particles observed in the ambient air of this city. Among these airborne pollutants, polycyclic aromatic hydrocarbons (PAHs), a group of compounds that are chararacterized with high molecular weights, high boiling as well as melting points, and extrely low solubility in water, are of particular concern because several of the PAHs have been considered as persistant organic pollatants and endocrine disruptors. Nonetheless, littlle is known about the distribution and composition of the airborne PAHs that can be representative of the local conditions in Taiwan. Given that having this information would improve the management on the exposure risk of the sensitive receptors (such as children and elderly persons) to PAHs, ambient air, including both gasous- and particulate-pahses, of the elementary schools situated in the neighboring area of the Taoyuan Airport were sampled during the summers and winters of the years 2013 to 2015 using a large flow volume sampling apparatus, and analyzed for the specific nineteen PAH congeners using the gas chromatography-mass spectrometry (GC/MS) method. Results showed that the total levels of PAHs ranged from 44 to 147 ng/m3 (with 76 ng/m3 as the averaged concentration), 89 to 264 ng/m3 (with averaged 137 ng/m3), 218 to 370 ng/m3 (with ageraged 290 ng/m3), and 45 to 128 ng/m3 (with the mean concentration of 73 ng/m3) for the samples obtained from the first (in July 2013), second (in January 2014), third (in July 2014), and fourth (in January 2015) sampling campaigns, respectively. When examining the data closely, it is noted that while the concentrations of PAHs in the winter samples of the first year appeared higher than those in the summer of the same year, an opposite trend was observed in the third year (i.e., the summer had higher PAH levels than the winter), which seemed to contradict the theoretical notion that pollutions are generally considered weaker in winter than in summer due to the occurrence of a relatively low altitude of the mixling layer, poor diffusioin conditions, and slower photo-chemical reations in winter. We speculated that this might have been resulted from some uncertainty or unknown factors. Regardless, our data indicated that the major compoenents of the PAHs in the ambient air of the three studied elementary schools were Naphthalene (Nap) and 2-Metrylnaphthalene (2-MNap). While the toxicity of these two compounds is not considered as strong as that of Benzo(a)pyrene (Bap), potential problems of biological accumulation resulted from these two compounds can not be ignored. Together, these results not only can be used for the establishment of the requlatory PAH concentrations in the future, but can also be regarded specifically as the reference (or baseline) ambient air quality data for Taoyuan Aerotropolis. |
