| Abstract: | 環境中有害空氣污染物(Hazardous Air Pollutants, HAPs)的來源眾多，以固定污染源而言，管道或逸散等污染源排放HAPs經大氣擴散後，可能對鄰近居民區造成急性與慢性健康危害，尤甚者甚至致癌。環境部於民國110年公告「固定污染源有害空氣污染物排放標準」，從固定源73項HAPs中優先納管22項排放管道及周界排放標準值，其中有14項為揮發性有機化合物(Volatile Organic Compounds, VOCs)，我國現行針對環境HAPs VOCs檢測方法為採用預抽真空之不鏽鋼筒採樣，搭配氣相層析質譜儀(GC-MS)分析，為離線檢測技術。國家環境研究院於民國110年成功開發線上質譜監測技術，在環境部監測資訊司支持下，於112年3月起於高雄市仁大工業區周界建立我國第一座環境HAPs自動連續監測示範站，可即時獲得87項有機HAPs逐時資料，有效掌握工業區周界環境大氣濃度變化。本篇研究為建立我國第一座HAPs硬體維護和數據品保與品管方法，並藉由監測結果篩選重要HAPs項目。
儀器設備使用商業化除水與熱脫附設備(Thermal Desorption, TD)串聯GC-MS，簡稱TD-GC-MS，應用注氫技術(Jetclean)大幅延長離子源使用壽命，可連續監測長達三週；藉由控管內標準品趨勢觀察儀器穩定度與感度變化，從而建立硬體維護保養與數據品保品管的規範。
一年的連續監測結果顯示部份HAPs VOCs出現偶發高值事件，可藉由其它VOC指紋趨勢判斷可能排放源，並結合氣象資料繪製風瑰圖進行溯源調查。監測期間，每季會執行一次連續四小時的離線採樣，並將樣品送認證實驗室分析，檢測結果顯示監測數據具有良好的比對結果，多數數據皆落於1:1線周圍；另與光化學監測站GC-FID平行比對，結果顯示數據呈現高度相關性(r>0.7)。本研究另外發現光化站GC-FID之甲基環戊烷與1,2-二氯乙烷共析，藉由GC-MS之離子碎片區分兩者，結果顯示濃度>1 ppb時，甲基環戊烷測值應為1,2-二氯乙烷。GC-FID為單純藉由滯留時間區分污染物，若遇共析之VOCs則會誤判，將造成健康風險結果大相逕庭。
本研究利用吸入性致癌風險篩選仁大工業區重要HAPs，主要項目為丁二烯(24.4%)、丙烯腈(23.7%)、苯(11.1%)與氯化物等，已佔總風險80%。未來執行線上量測HAPs排放時需同時考量毒理性質與濃度，才能達成源頭管制與管末排放減量，有效降低民眾的健康風險，將HAPs監測站發揮最大效用。;The sources of Hazardous Air Pollutants (HAPs) in the environment are numerous. For stationary sources, HAPs emitted from pipelines or fugitive sources can disperse through the atmosphere and potentially cause acute and chronic health hazards to nearby residential areas, with some even being carcinogenic. In 2021, the Environmental Protection Administration announced the "Emission Standards for Hazardous Air Pollutants from Stationary Sources," prioritizing the regulation of 22 out of the 73 HAPs from stationary sources, including standards for emissions from pipes and boundary concentrations. Among these, 14 are Volatile Organic Compounds (VOCs). Currently, the method for detecting HAPs VOCs in the environment in Taiwan involves sampling with pre-evacuated stainless steel canisters, followed by analysis with Gas Chromatography Mass Spectrometry (GC-MS), which is an offline detection technique. In 2021, the National Institute of Environmental Research successfully developed an online mass spectrometry monitoring technology. With support from the Ministry of Environment of Department of Monitoring and Information, the first environmental HAPs automatic continuous monitoring demonstration station in Taiwan was established at the perimeter of the Ren Da Industrial Area in Kaohsiung City in March 2023. This station can obtain hourly data for 87 organic HAPs in real-time, effectively tracking changes in ambient air concentrations around the industrial area. This study aims to establish maintenance standard operating procedure (SOP) for the HAPs monitoring hardware and quality assurance and quality control (QA/QC) methods, and to identify critical HAPs items through the monitoring results.
Utilizing commercialized dewater and thermal desorption(TD) equipment in conjunction with GC-MS, referred to as TD-GC-MS, the application of Jetclean technology significantly extends the lifespan of the ion source, allowing continuous monitoring for up to three weeks. By controlling the trends of internal standards, the stability and sensitivity of the instrument can be observed, thereby establishing SOP for hardware maintenance and data quality assurance and quality control.
The results of one year of continuous monitoring indicate occasional high-value events for certain HAPs VOCs. Potential emission sources can be identified by analyzing the trends of other VOC fingerprints, and by combining with meteorological data to draw wind rose diagrams for source tracing investigation. During the monitoring period, offline sampling is conducted once per quarter for a continuous four hours, with samples sent to certified laboratories for analysis. The results show that the monitoring data correlate well, with most data points falling around the 1:1 line. Additionally, a parallel comparison with the photochemical monitoring station′s GC-FID shows a high correlation (r>0.7). This study also discovered that methylcyclopentane and 1,2-dichloroethane co-elute in the GC-FID at the photochemical station. By using ion fragments in GC-MS to distinguish between them, the results indicate that when concentrations exceed 1 ppbv, the measured value of methylcyclopentane should be attributed to 1,2-dichloroethane. GC-FID relies solely on retention time to differentiate pollutants, which can lead to misidentification in the case of co-eluting VOCs, resulting in significant discrepancies in health risk assessments.
This study screened important HAPs in the Ren Da Industrial Area based on inhalation carcinogenic risk, with major contributors including butadiene (24.4%), acrylonitrile (23.7%), benzene (11.1%), and chlorides, accounting for 80% of the total risk. Future online measurements of HAPs emissions must consider both toxicological properties and concentrations to achieve source control and end-of-pipe emission reduction, effectively lowering public health risks. This approach will maximize the utility of the HAPs monitoring station. |
