彭佳嶼海域大氣懸浮微粒中金屬元素及水溶性離子之化學特性研究

Chemical Characteristics of Trace Elements and Water-Soluble Ions in Marine Aerosols over Pengchiayu Island

曾幀琳(Cheng-Lin Tseng)

指導教授 ： 林斐然

國立臺灣大學/理學院/海洋研究所/碩士(2008年)

https://doi.org/10.6342/NTU.2008.03162

摘要

本研究共分析365個採自彭佳嶼海域的大氣懸浮微粒標本，標本收集的時間為2004年12月至2006年2月，這些標本均以離子層析儀分析其中所含的水溶性離子，此包括Na+、Mg2+、K+、Ca2+、NH4+、Cl-、NO3-及SO42-等離子，另以感應耦合電漿質譜儀分析2005年春季標本中的金屬元素，此包括Al、Fe、Na、Mg、K、Ca、Sr、Ba、Ti、Mn、Co、Ni、Cu、Zn、Cd、Pb及Cr等元素。
彭佳嶼海域大氣懸浮微粒中水溶性離子的濃度分布呈現明顯的季節變化，以冬季和春季濃度較高，夏季濃度最低。與其他地區之大氣懸浮微粒水溶性離子濃度比較，彭佳嶼海域大氣中的地殼源以及污染源物質之比例較高，此主要是由中國大陸輸出的陸源物質所貢獻。大氣中Cl-/ Na+濃度之比值比海水的比值低，顯示彭佳嶼海域大氣懸浮微粒中出現Cl虧損的現象。NH4+／nss- SO42-莫耳濃度之比值計算結果顯示彭佳嶼海域大氣懸浮微粒的硫酸鹽主要是以NH4HSO4形式呈現。風向族群分析的結果顯示彭佳嶼海域大氣懸浮微粒中水溶性離子以北風族群的濃度較大，大約是南風族群的1.1倍到1.6倍。比較1996年及2005年的濃度數據可發現2005年彭佳嶼大氣懸浮微粒中NO3-及nss-SO42-的濃度比1996年高出一倍多。
本研究在在2005年春季一共偵測到三次沙塵暴事件，其中最大的一次是發生在2005年4月10日到15日之間，在此期間彭佳嶼海域大氣懸浮微粒中幾乎所有的元素均出現明顯的高值，特別是地殼元素。氣流軌跡回推圖顯示此沙塵暴物質是源自中國北方之內外蒙古一帶，經由長程傳輸至彭佳嶼海域，沙塵暴入侵時，大氣中Fe/Al的比值會下降至0.5左右，在此同時大氣中地殼來源的Na(Nacrust)濃度也會明顯增加，相對的會稀釋大氣中海水來源的Na(Nasea) 所佔的比例。主成分分析結果顯示在沙塵暴季節，彭佳嶼海域大氣化學組成之變化受陸源物質的影響最大，特別是地殼物質，污染物質的影響次之，海水物質的影響相對的比較小。其中污染物質又可區分為高溫污染成分如Ni、Cu和Cr及低溫污染成份K+、NH4+、nss-SO42-、NO3-、Cd及Pb，其在大氣中散佈的情形不盡相同，其中又以低溫污染成分的影響較大。

關鍵字

彭佳嶼 ； 大氣懸浮微粒 ； 沙塵暴 ； 東海

並列摘要

Three hundred and sixty five aerosol samples were collected at Pengchiayu Island from December 2004 to February 2006. All of the samples were analyzed for water-soluble ions Na+, Mg+2, K+, Ca2+, NH4+, Cl-, NO3- and SO42- , using ion chromatography. Samples collected from March to May of 2005 were also analyzed for trace elements Al, Fe, Na, Mg, K, Ca, Sr, Ba, Ti, Mn, Co, Ni, Cu, Zn, Cd, Pb and Cr, using inductively coupled plasma mass spectrometry.
The concentrations of water-soluble ions in aerosols collected at Pengchiayu island displayed strong seasonal variations with higher concentrations in winter and spring, and lower concentrations in summer. The aerosols at Pengchiayu Island contain high proportions of crustal and anthropogenic materials as compared with other areas, which are mainly exported from mainland China. The Cl-/Na+ ratios in aerosols are lower than that of sea water suggesting that there are chloride depletions in Pengchiayu aerosols. The calculations of molar ratios of NH4+/nss-SO42- reveal that the compound of sulfate in aerosols is mainly in the form of NH4HSO4. Wind populations analysis shows that the concentrations of water-soluble ions in north wind population are 1.1 to 1.6 times higher than that of south wind population. It can be found that the atmospheric concentrations of NO3- and nss-SO42- at pengchiayu Island in 2005 are higher nearly double than that of in 1996.
Three dust storm episodes have been identified in this study during the springtime of 2005. Among them the most heavily dust storm occurred in April 10 to 15, and the very high concentrations for most of elements are observed in this dust storm samples, especially for crustal elements. Airmass backward trajectories analysis suggests that the source materials of dust storm are from Mongolia in north China, which is transported to Pengchiayu Island through long-range transport. During the dust storm periods the concentration ratios of Fe/Al in aerosols generally fall down to about 0.5, in the meantime, the concentrations of crustal derived Na will be increased significantly, and he proportions of seawater derived Na will be reduced relatively. Principal component analysis (PCA) shows that during the dust storm season the variability of chemical composition of aerosols at Pengchiayu Island is greatly influenced by the supply of land source materials including crustal and anthropogenic materials, and the impact of seawater derived materials is relatively small. Based on PCA study, the anthropogenic sources can be further classified into two groups: high temperature burning type components Ni, Cu and Cr, and low temperature burning type components K+, NH4+, nss-SO42-, NO3-, Cd and Pb.

並列關鍵字

Pengchiayu ； Aerosols ； Asian dust ； East China Sea

參考文獻

林斐然 ，1993。台灣西南海域海洋大氣懸浮物之微量元素，國科會專題研究計畫成果報告，54頁，1993。

林斐然 ，1996。台灣海域大氣懸浮微粒之成分及來源探討(Ⅱ)。國科會專題研究計畫成果報告。32頁。

Adams, PJ J., JH. H. Seinfeld, DM M. Koch, 1999. Global concentrations of tropospheric sulfate, nitrate, and ammonium aerosol simulated in a general circulation model. J. Geophys. Res. Atmos. vol. 104 (D11) pp. 13791-13823

Arimoto, R,. R. A. Duce, B. J. Ray, W. G. Ellis Jr, J. T. Merrill, 1995. Trace elements in the atmosphere over the North Atlantic. J. Geophys. Res. Atmos. vol. 100, pp. 1199–1213

Arimoto, R, Duce, R A, Savoie, D L, Prospero, J M. 1996. Relationships among aerosol constituents from Asia and the North Pacific during PEM-West A. J. Geophys. Res. Atmos. vol. 101 pp. 2011-2023.