108

3,230 千元

科技發展-環境科學及技術之研究

2019/01/01

2019/12/31

周崇光

監資處

張志偉

中央研究院 環境變遷研究中心

大氣空氣

同位素、細懸浮微粒、空氣污染辨識

Isotope, PM2.5, Air Pollution Forensics

李崇德；李家偉；榮建誠

黃譯樘

02-27875983#

yitang@rcec.sinica.edu.tw

本計畫目的為透過建立高屏地區大氣和主要污染源排放之PM2.5的碳與鉛同位素特徵，探討高屏地區的大氣PM2.5污染來源。本計畫分別於2019年春季 (3月) 和夏季 (7月) 期間，採集位於高屏地區的橋頭站、左營站、鳳山站、小港站、林園站、大寮站、屏東站和潮州站等8站的大氣PM2.5樣本；此外，2019年春季 (4月) 和夏季 (8月) 期間，也陸續採集高雄地區的燃煤火力發電廠、煉油廠、鋼鐵廠燒結爐煙道和高雄港內外作業區排放之PM2.5樣本，並完成水溶性陰陽離子、有機碳、元素碳、地殼元素、重金屬和碳 (δ13C和14C) 與鉛同位素 (206Pb、207Pb和208Pb) 的分析。 三種固定污染源排放的PM2.5都以可凝結性微粒 (Condensable particulate matter，CPM) 為主，而除了煉油廠排放的CPM以有機組成為主外，其他2種固定污染源煙道排放的CPM都以無機成分為主。在化學組成部分，可發現1.) 火力電廠排放的PM2.5有較高的金屬元素與硫酸鹽，而金屬元素以Na (和該電廠採用海水脫硫有關)、Mg、K、Ni、Zn、Mo、Cr和Se等為主，平均206Pb/207Pb比值為1.1959 (1.1781~1.2115)，平均208Pb/207Pb比值為2.4305 (2.4108~2.4403)；2.) 煉油廠排放的PM2.5有較高的硫酸鹽比例 (54%)，特徵元素包括Fe、Mn、Ni、Zn、Mo、Pb和Cr等，平均206Pb/207Pb比值為1.1930 (1.1758~1.2106)，平均208Pb/207Pb比值為2.4318 (2.4171~2.4437)；3.) 鋼鐵廠排放的PM2.5有較高的硫酸鹽和鉀等金屬元素，其中硫酸鹽占了35%，特徵元素包括Fe、Mg、K、Ca、Mn、Zn、Mo、Cd、Tl、Pb、Cr、Se、Rb和Cs等；平均現代碳比例為18% (14~22%)，平均206Pb/207Pb比值為1.1908 (1.1664~1.2143)，平均208Pb/207Pb比值為2.4010 (2.3774~2.4229)；4.) 港口作業區 (第一港口、第二港口、前鎮漁港、旗津漁港和貨櫃區) 的主要化學組成為硫酸鹽、硝酸鹽、銨鹽、有機碳和元素碳；各作業區主要的金屬元素為Na、Zn和V；δ13C範圍在-31.3‰至-22.5‰之間，平均現代碳比例為34% (12~68%)，平均206Pb/207Pb和208Pb/207Pb分別為1.1561 (1.1406~1.1884) 和2.4295 (2.4013~2.4546)。 8個測站的日平均PM2.5濃度為19.9 ± 10.2 μg/m3，其值低於國家日平均標準 (35 μg/m3)。在傳統化學組成部分，8個測站PM2.5中的主要化學組成均為硫酸鹽、硝酸鹽、銨鹽和有機碳，其濃度各占PM2.5質量濃度的21%、20%、13%和24%；此外，高雄的現代碳與化石碳濃度占PM2.5質量濃度的比例相當 (化石碳：15%；現代碳：14%)，但位於屏東的2個測站則以現代碳占優勢 (化石碳：12%；現代碳：18%)，反映高雄和屏東的主要碳污染源不同。當以PM2.5濃度標準值將樣本劃分為PM2.5事件日和非事件日時，可發現相較於非事件日，事件日期間的硫酸鹽、硝酸鹽和銨鹽濃度加總對PM2.5總濃度的增量貢獻比例最大，顯示光化學反應前驅物的管制應有助於降低高屏地區的PM2.5濃度，化石碳對PM2.5總濃度的增量貢獻比例明顯，說明管制化石燃料的燃燒有助於降低高屏地區的PM2.5濃度。 春季和夏季的大氣平均δ13C分別為-25.7‰ (-28.2至-23.6‰) 和-25.1‰ (-28.7至-20.7‰)，分析結果顯示各測站δ13C數值有顯著差異，說明高屏地區不同測站的碳污染源有區域上的變異。在鉛同位素比值部分，春季和夏季的平均206Pb/207Pb分別為1.1554 (1.1298~1.1712) 和1.1572 (1.0974~1.1966)，春季和夏季的平均208Pb/207Pb分別為2.4263 (2.3985~2.4519) 和2.4295 (2.3714~2.4572)，多數測站的鉛同位素比值變異較大，顯示就單一測站而言，不同採樣日的鉛污染源可能不同。無論δ13C或鉛同位素比值，其量測值多和過去在中南部 (台中-彰化-南投-雲林-嘉義) 的量測結果相近，但多低於北部的量測結果，反映碳與鉛污染源有區域上的差異。 本計畫綜合傳統化學組成和同位素量測結果發現，工業污染源和燃料油的燃燒是高屏地區PM2.5的重要碳污染源，但鉛污染源的掌握種類仍有限，有待未來調查更多位於高雄污染源排放之PM2.5同位素特徵，提高鉛污染源的鑑識能力；此外，屏東站與潮州站的現代碳比例明顯偏高，因此調查及管制屏東與潮州當地的現代碳貢獻源，相信有助於改善當地的空氣品質。

同位素、細懸浮微粒、空氣污染辨識

108年度細懸浮微粒碳與鉛同位素分析技術之發展與應用研究計畫.pdf

12MB

2020/2/1 上午 12:00:00

The objective of this study is to investigate the compositions of carbon and lead isotopes in fine particulate matters (PM2.5) and, accordingly, to attribute potential sources of PM2.5 in Kaohsiung and Pingtung with the isotopic fingerprints. During the period from the spring (March) of 2019 to the summer (July) of 2019, ambient PM2.5 samples were collected from 8 sampling stations (Ciaotou, Zuoying, Fengshan, Siaogang, Daliao, Linyuan, Pingtung, and Chaozhou), respectively. In addition, this study also collected PM2.5 samples from 4 specific sources: a coal-fired power plant, an oil refinery plant, a steel plant, and Kaohsiung port in April and August, respectively. All the PM2.5 samples were characterized with the measurements of water-soluble ions, organic carbon, elemental carbon, crustal elements, heavy metals, and isotopic compositions of carbon (δ13C and 14C) and lead (206Pb, 207Pb, and 208Pb). The results revealed that condensable particulate matter (CPM) was predominant in the PM2.5 emitted from three stationary pollution sources. Moreover, the level of organic CPM was higher than inorganic CPM in oil-refinery plant, whereas the levels of inorganic CPM were higher in both coal-fired power plant and steel plant. The chemical compositions from four pollution sources were: (1) coal-fired power plant: sulfate was important species (10%), predominant elementals included Na (due to the flue gas desulfurization with seawater), Mg, K, Ni, Zn, Mo, Cr, and Se, average 206Pb/207Pb and 208Pb/207Pb were 1.1959 (1.1781~1.2115) and 2.4305 (2.4108~2.4403); (2) oil-refinery plant: sulfate was important species (54%), predominant elementals included Fe, Mn, Ni, Zn, Mo, Pb, and Cr, average 206Pb/207Pb and 208Pb/207Pb were 1.1930 (1.1759~1.2106) and 2.4318 (2.4171~2.4437); (3) steel plant: sulfate was important species (35%), predominant elementals included Fe, Mg, K, Ca, Mn, Zn, Mo, Cd, Tl, Pb, Cr, Se, Rb, and Cs, average 206Pb/207Pb and 208Pb/207Pb were 1.1908 (1.1664~1.2143) and 2.4010 (2.3774~2.4229), the percentage of modern carbon was 18% (14~22%); (4) Kaohsiung port: the major compositions included sulfate, nitrate, ammonium, organic carbon, and elemental carbon, predominant elementals included Na, Zn, and V, δ13C ranged from -31.3 to -22.5‰, average 206Pb/207Pb and 208Pb/207Pb were 1.1561 (1.1406~1.1884) and 2.4295 (2.4013~2.4546), the average percentage of modern carbon was 34% (12~68%). The average level of ambient PM2.5 from all sampling sites was 19.9 ± 10.2 μg/m3, which was lower than national air quality standard (35 μg/m3). The major constituents of the ambient PM2.5 in the study area included nitrate, sulfate, ammonium and total carbon, which accounted for 21%, 20%, 13%, and 24% of the PM2.5 mass, respectively. The contributions of fossil (15%) and modern (14%) carbon were similar in the six sampling sites in Kaohsiung. However, modern carbon was predominant in Pingtung and Chaozhou, which means that investigating and controlling the sources of modern carbonaceous aerosols is helpful to improvement of air quality in that area. It was found from the chemical analysis that the concentrations of inorganic secondary aerosols (sulfate, nitrate, and ammonium) and fossil carbonaceous aerosols were elevated during high PM2.5 episodes. These results implied that photochemical reactions and fossil combustion were important factors influencing the PM2.5 in the study areas. The averages of δ13C for ambient PM2.5 wee -25.7‰ (-28.2 to -23.6‰) and -25.1‰ (-28.7 to -20.7‰) in the spring and summer, respectively. The average 206Pb/207Pb ratios were 1.1554 (1.1298~1.1712) and 1.1572 (1.0974~1.1966) in the spring and summer, respectively, and 208Pb/207Pb ratios were 2.4263 (2.3985~2.4519) and 2.4295 (2.3741~2.4572), respectively. The variations of δ13C and Pb isotopic compositions were larger, which means the pollution sources were unstable in Kaohsiung and Pingtung for carbon and Pb. In comparison, the values of isotopic compositions were similar to the data in central Taiwan, but, the values were different from that in northern Taiwan, which reflects that there was spatial variation of carbon and Pb pollution sources in Taiwan. In this study, we combined the traditional chemical and isotopic compositions to investigate the air pollution sources for Kaohsiung and Pingtung. Our results indicated that industrial emission and oil-combustion were important pollution sources. However, it’s necessary to collect more isotopic fingerprints from various pollution sources of PM2.5 for pollution source forensics in the near future, particularly in Pb; moreover, modern carbon was a major component in Pingtung, it’s necessary to deeply investigate the carbon pollution source.

Isotope, PM2.5, Air Pollution Forensics