王珮玲Wang, Pei-Ling臺灣大學:海洋研究所陳鑑禕Chen, Jian-IJian-IChen2010-05-062018-06-282010-05-062018-06-282008U0001-2608200815304300http://ntur.lib.ntu.edu.tw//handle/246246/181208自工業革命之後，環境酸化的問題日益嚴重。工業排放造成酸沈降中，含硫化合物正是酸沈降的主要組成之一。在森林生態系統中，硫也是重要的營養源之一，主要來源為大氣沈降，因此過多的酸沈降對森林生態有很大的影響。鴛鴦湖森林生態保留區是一酸化的雲霧森林生態系統，是研究酸沈降對森林生態影響的好題材。本研究採集2005年4月至2006年12月間鴛鴦湖保留區中各種森林沈降水與湖水，分析水樣之陰陽離子濃度及硫酸根離子的硫同位素組成，以期瞭解陰陽離子和硫在酸化森林中隨時間之變動情況，再配合硫同位素組成的分析結果，討論酸化森林環境中硫的變動情形及可能來源。酸根離子濃度在溼沈降、穿落水、幹流水中，隨時間呈現冬、春兩季較高而夏季較低的變動情況，應受到冬天季風的影響。在霧水中則是夏季濃度較高。與颱風出現的時間相符合，推論霧水中的離子濃度受到颱風的影響。森林沈降水中的硫酸根離子不僅有海鹽性來源，也有其他污染性來源，而霧水中的非海鹽源硫酸鹽所佔的比例較海鹽源硫酸鹽高出許多。湖水中硫酸根離子濃度亦呈現冬季高而夏季低的變動情況，且非海鹽源硫酸鹽所佔之比例皆較海鹽源硫酸鹽來得高，這些額外的非海鹽源硫酸鹽很可能是人為活動的污染物，隨著季風帶入保留區內。鉀離子不管在森林沈降或是湖水中，皆以污染源為主，鈣離子少部份來自海洋，其餘皆來自乾沈降或岩石風化，在幹流水、霧水、土壤水中，鈣離子與鉀離子濃度有高度相關性，推論鈣離子來源與鉀離子來源相近。鎂離子在森林沈降中多濃度很低，僅部份鎂離子源自海洋，而少數穿落水中有鎂離子富集現象，推論應受到由乾沈降額外的鎂離子。湖水中鎂離子與鈣離子有很高的相關性，推論兩者來源相似。水中硫酸根離子之硫同位素值介於1.9~3.0‰，隨深度增加而遞增，伴隨著硫酸根離子濃度隨深度增加而遞減，代表可能湖底沉積物中有硫酸還原菌進行著硫酸還原作用。霧水中硫酸根離子之硫同位素值介於3.4~7.4‰，較湖水之硫同位素值高，代表兩者來源不同或經歷不同作用。霧水可能與葉片表面進行交互作用，因而富集含有較重硫同位素組成的硫酸鹽。霧水中硫酸根離子之硫同位素值隨時間增高，但是由於缺乏同時期附近區域大氣傳輸來源組成的背景資料，故難以進一步判別是污染源比例降低或是其硫同位素值增加所致。Since the beginning of industrialization, the environmental acidification becomes a serious issue to influence the ecosystem stability. Of potential compounds related to acidification, the oxidized sulfur compounds are one of the important contributors of acid deposition. While sulfur is one of the important nutrients in forest ecosystems and mainly derives from atmospheric deposition, acid deposition may have great influence on the forest ecosystem. Previous studies indicated that the Yuanyang Lake Nature Preserve is an acidic cloud forest ecosystem and, therefore, may serve as an ideal studying site. In this study, different types of water were collected from the Yuanyang Lake and adjacent forest ecosystem from April 2005 to December 2006, and analyzed with the major anion, cation and sulfur isotopic composition. The goal of this study is to understand the variation and dynamics of chemical and sulfur isotopic compositions of forest precipitations and lake water and to evaluate the source and process with respect to sulfur in the Yuanyang Lake forest ecosystem.ulfate concentrations of bulk precipitation, throughfall and stemflow were higher in spring and winter, which may result from the winter monsoon. However, sulfate concentrations of fog water were higher in summer, which may relate to the typhoon events. Both the sulfate sources of the forest precipitation and the lake water were dominated by non-sea salt sulfate, an estimate based on the sodium contribution. The sulfate concentrations of lake water were higher in winter and lower in summer, suggesting that an important polluted source of sulfate transported by the winter monsoon was required. Under this circumstance, pollution would be also the main source of potassium in the forest precipitations and lake water. The source of calcium in the forest precipitations and lake water include ocean, dry deposition and rock weathering. Good correlations between calcium and potassium concentrations in stemflow, fog and soil water were evident, suggesting that they may have the same source. Magnesium concentrations were generally low in all types of water and higher concentrations were only measured in several throughfall samples. Magnesium may derive from the ocean and extra magnesium in stemflow was provided by dry deposition. A good correlation between calcium and potassium concentrations in lake water may infer the same source for these two ions.ulfur isotopic compositions of dissolved sulfate in the Yuanyang Lake ranged from 1.9 to 3.0‰. The inverse correlation between δ34S values and sulfate concentrations of lake water with depth indicate the microbial sulfate reduction in the lake sediments. Sulfur isotopic compositions of dissolved sulfate in the fog deposition ranged from 3.4 to 7.4‰. The value is significantly higher than the value of lake water, inferring different sources or various processes involved in the change of sulfur isotopic composition. The interaction between fog water and leaves may enrich sulfate with heavier sulfur isotopic compositions. The δ34S values of fog water increase through time, which may result from the polluted sources with smaller proportion or heavier sulfur isotopic compositions; however, it cannot be clarified with limited background observation of polluted sources.致謝.................................................I文摘要....................................II文摘要................................IV錄........................................VI目錄..............................................IX目錄.................................................. XI表目錄...........................................................................XII一章 緒論......................................................1.1前言.....................................................................1.2研究動機............................................................1.3研究目的.........................................................................................5.4研究區域簡介.........................................................5.5前人研究................................................6.5.1鴛鴦湖自然保留區之相關研究..................................6.5.2森林生態系統之硫的生地化與硫同位素研究.............................7.5.3森林集水區與湖泊之硫的生地化與硫同位素研究......................................9二章 研究方法.....................................................11.1研究材料與採樣...................................................11.1.1森林沉降.............................................11.1.2湖水...........................................................11.2水化學分析........................................................12.2.1陰離子分析..............................................12.2.2陽離子分析.........................................................12.3硫同位素分析........................................................12.3.1樣本分析限制.........................12.3.2樣本前處理.....................................................................13.3.3硫化銀氟化..............................................14.3.4氣相同位素質譜儀分析.....................................15三章 分析結果............................................................................17.1陰離子分析結果.......................................................................................................17.1.1森林沈降........................................................................................................17.1.1.1各種森林沈降水之陰離子濃度隨時間變化.....................................17.1.1.2不同陰離子在各種森林沈降水中的濃度隨時間變化.....................22.1.2湖水................................................................................................................25.1.2.1湖水之陰離子濃度隨時間的變化.....................................................25.1.2.2湖水之陰離子濃度隨深度的變化.....................................................28.2陽離子分析結果.......................................................................................................30.2.1森林沈降........................................................................................................30.2.1.1各種森林沈降水之陽離子濃度隨時間變化.....................................30.2.1.2不同陽離子在各種森林陳降水中的濃度隨時間變化.....................35.2.2湖水..............................................................................41.2.2.1湖水之陽離子濃度隨時間的變化....................................41.2.2.2湖水之陽離子濃度隨深度的變化......................47.3硫同位素分析結果....................................................................49.3.1霧水...........................................................................49.3.2其他水樣..........................................................51四章 討論..............................................................52.1陰離子濃度變化之原因探討......................................................52.1.1森林沈降................................................................................52.1.2湖水.....................................................................56.2陽離子濃度變化之原因探討.................................58.2.1森林沈降...................................................................58.2.2湖水..............................63.3硫同位素特徵與變化之原因......................................66.3.1湖水之硫同位素成分特徵與可能來源...........66.3.2 森林沈降之硫同位素成分隨時間變化的原因探討.................67五章 結論......................................68考文獻............................................69application/pdf2555971 bytesapplication/pdfen-US鴛鴦湖生態系統森林沈降水湖水硫酸鹽硫同位素Yuanyang lake ecosystemforest precipitationlake watersulfatesulfur isotopethesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/181208/1/ntu-97-R93241310-1.pdf