摘要
氣膠的物理化學特性在大氣中扮演相當重要的角色，尤其在其吸濕成雲的能力上更會對天氣與氣候產生影響。本研究於2015年3月31日至5月1日利用雲凝結核計數器(CCNc)、凝結核計數器(CPC)以及掃描式電移動度微粒分徑器(SMPS)於金門進行觀測。依據不同的氣象條件以及氣流逆軌跡分析，將觀測分為6個時期，這些時期的氣團來源分別為：4/1-4/6與4/17-4/20來自南方海面、4/6-4/9來自黃海一帶、4/9-4/14與4/20-4/23來自中國華南一帶、4/14-4/17主要為來自金門西北邊之沉降氣流。氣態汙染物在來自陸上的時期的濃度會高於來自海上的時期，尤其是SO2的部分。而測量粒子的活化率(NCCN/NCN)與粒徑分佈後，便可從理論推得乾粒徑(ddry)介於20-250 nm氣膠之吸濕參數(κ)，整個觀測期間平均的κ介於0.15-0.48間，與過去台灣都市地區的資料相比，金門粒子的吸濕性整體都較台北、台中都會區為佳，而較大粒子的吸濕性與高雄都會區的粒子相近。此外金門地區ddry小於70 nm的粒子其κ變異性較70 nm-250 nm之粒子為大，可能原因與當地數起新生粒子事件及黑碳成分有關。 另外一方面本研究也利用MOUDI採集不同濕粒徑(dwet)下之氣膠樣品，並利用離子層析(IC)法分析其組成，並利用化學組成來推算出dwet在17.7 μm至小於0.1 μm氣膠之吸濕參數，發現大於1.8 μm之粒子κ不同天數間有著顯著變化，介於0.46-0.09間，分析其化學組成可發現主要原因為不同來源時期其海鹽成分變化造成氣膠吸濕性質之改變。此外MOUDI採集之氣膠樣品也利用傅立葉轉換紅外線光譜儀(FTIR)進行組成之官能基分析，並與氣膠化學組成進行比較，結果發現量測之四種化學官能基的吸收度與掃描面積下之質量有著良好的相關性，各項官能基吸收度與質量間之趨勢線其R2皆大於0.6。 整個觀測時期於4/1-4/6與4/17-4/20發生兩起霧事件(霧事件I與霧事件II)，有著類似的可能成因與天氣現象，且都有觀測到在霧發生後隨時間推進黑碳在各粒徑間分佈的比例會逐漸往較大粒子移動之現象，可能為氣膠與霧發生交互作用有關。但兩次霧事件在霧滴粒徑分佈的數量模、液態水含量與霧滴數量濃度間都有差距，可能原因為海鹽GCCN之數量以及小粒子的吸濕能力差距導致。
並列摘要
The hygroscopicity of ambient aerosols was investigated using a cloud condensation nuclei counter (CCNc), a condensation particle counter (CPC) and a scanning mobility particle sizer system (SMPS) in the period of Mar 31st to May 1st, 2015 at Kinmen, Taiwan (24°24'26.70"N, 118°17'19.42"E). Base on the weather condition and NOAA back trajectory analysis, observation campaign was divided into 6 periods. Air parcels of 4/1-4/6 and 4/17-4/20 were came from South China Sea, 4/6-4/9 was came from Yellow Sea, 4/9-4/14 and 4/20-4/23 were came from South China, 4/14-4/17 was descending from North-West of Kinmen. Air pollution concertation, especially SO2, were higher during periods which were came from the continent than periods from sea. The single hygroscopicity parameter (κ) of different size aerosols were derive by the measured activation ratios (NCCN/NCN) and particle size distribution. For ddry (dry diameter) between 20-250 nm particles, κ was in the range of 0.19-0.8 thought out the campaign and showed a size dependent trend. κ at ddry < 70 nm showed strong temporal variation in contrast to that at 70 nm < ddry <250 nm possibly due to the new particle formation processes or soot composition. Compare with recent observation in several Taiwan urban area, aerosols’ hygroscopicity in Kinmen was better than Taipei city and Taichung city, but similar with Kaohsiung city. Aerosols at different sizes were collected using a micro-orifice uniform deposit impactor (MOUDI), and analyzed their chemical composition by Ion Chromatography, or their functional groups by an Attenuated Total Reflectance-infrared spectroscopy (ATR-IR). The method of using functional groups analysis to derive mass of the ion or BC that deposited on the MOUDI filter was evaluated as feasible, R2 of the trend line between absorbance of individual functional group species and mass were all larger than 0.6. Chemical composition information of MOUDI samples could also derive κ of μm scale particles, find out that κ at dwet > 1.8 μm was likely contributed by the significant sea salt composition, and therefore the variation of κ at dwet > 1.8 μm was high due to the changes of the aerosol source during the campaign. Two fog events during this campaign were observed during period 4/1-4/6 and 4/17-4/20(fog I and fog II). From fog droplet size distribution data, Fog I was thicker than Fog II and had an additional mode at 26 μm diameter, which possibly due to higher κ and the presence of sea salt GCCN during Fog I. The presence of fog can also affect the black carbon distribution and shift it to larger size due to the growth of the particles at higher RH and(or) the collision process of larger particles with small particles containing black carbon.