指導教授：林曉武臺灣大學：海洋研究所曾景暘TZENG, Jing-YangJing-YangTZENG2014-11-272018-06-282014-11-272018-06-282014http://ntur.lib.ntu.edu.tw//handle/246246/262605貝加爾湖因屬於寒帶的陸域湖泊，對氣候的變化反應較迅速且明顯，並良好記錄在湖泊之無機及有機物質的來源及生地化反應的變化。氣候變化不僅反應於沉積物有機碳、氮等地化參數，亦會影響硫的分布，包含硫酸鹽、黃鐵硫濃度與硫同位素值。間冰期時由河川輸入較多的硫酸鹽與有機碳，硫酸鹽經還原後形成黃鐵硫保存於沉積物中，反之，冰期時流量減少，產生的黃鐵硫變少。儘管其研究結果顯示沉積物中硫埋藏是河川受到氣候變遷所影響，但貝加爾湖屬於斷層湖，存在許多泥火山和溫泉，應也視為物質輸入的另一來源，更且貝加爾湖內亦有大量天然氣水合物與冷泉噴發存在，而溫泉與冷泉皆可能排放不同型態溶解硫化物，然而此類來源與變化卻是過往研究所忽略之處。 本研究於貝加爾湖採集了湖泊、河川、溫泉水樣與重力岩心樣品，分析其硫酸鹽濃度、硫同位素、黃鐵硫、有機碳與生物矽含量，探討硫的來源與冰河時期對沉積物中硫富集之影響。研究結果顯示三種不同類型的水樣其硫酸鹽與硫同位素值有著相當大的差異，其中不會受到氣候變化影響的溫泉水應為除了河川外。另一個硫輸入來源，影響著沉積物中硫之地化參數。於貝加爾湖中的北、中與南部盆地所採取的重力岩心顯示於冰期時，無明顯陸緣有機碳與硫酸鹽經河川輸入，卻記錄著高濃度的硫，表示此時應有硫以非河川輸入的形式進入水體，而冰期時因湖水垂直循環不甚良好造成缺氧，所以有高濃度的硫富集於沉積物中，並不單純由受控於氣候變遷的河川所控制。Lake Baikal is one of the deepest fresh water and the oldest lake in the world. Situated at the polar region, this is subjecting the lake easily responding to smaller magnitude of climatic changes. According to Watanabe （2004）, records of millions of years of climate change were kept in this lake and that climatic change was the only factor controlling the amount of terrigenous materials entering this lake as recorded in carbon, nitrogen, sulfur contents and isotopic compositions. In addition, limited redox reaction could occurred in this fresh water land lock lake environment due to a limit source of sulfur could entering this fresh-water environment such that sulfate become to be a limiting factor in the sulfur cycle. Climatic change could play a major role in alternating supply of sulfate to this environment. During interglacial warm period, increase fluxes of river sulfate and organic carbon entering the lake and resulting in higher flux of pyrite formation by a higher degree of anoxic sulfate reduction. On the other hand, little pyrite could deposit during cold glaciation periods with a limited river supply sulfate. Lake Baikal, however, unlike most other freshwater lake, is subjecting to continental rifting. A number of hydrothermal vents and cold seeps have been found in the lake which could bring in different types and extra sulfur to the Lake. In order to investigate sources of sulfur and influence of climate change may have had in this freshwater lake, we employed a lake wide sampling strategy, including lake, river, spring water samples as well as lake sediment for pore water sulfate, sulfur isotope, sedimentary pyrite, organic carbon and biogenic silica contents, and organic carbon C14. Similar to Watanabe''s results, this study also found large degree of variations in pyrite concentration in sediment. However, large degree of variations over sulfate concentration were found. Higher concentrations of sulfate existed, in particular, in hydrothermal vents and spring water as well as those in some limited areas of river water. Contrary to Watanabe’s finding, the results of this study indicate that river may not be the only source of sulfur entering this fresh water lake. Furthermore, pyrite enrichments in the sediment occurred not during climatic warm periods but during cold periods. Sediments rich in pyrite were also found in some cold seeps sediments. The result of this study showed that river is not the only source of sulfur entering this freshwater lake. The occurrences of higher degree of pyrite formation during climatic cold periods demonstrated that vents and seeps could be the major source（s） of sulfur in this freshwater lake.中文摘要Ι 英文摘要Ⅱ 目錄Ⅳ 圖目錄Ⅵ 表目錄Ⅷ 第一章 緒論1 1.1前言1 1.2研究區域沉積環境2 1.3硫酸鹽還原作用與黃鐵硫之產生3 1.4研究目的4 第二章 樣品採集及與分析方法8 2.1樣品採集8 2.1.1採樣位置8 2.1.2採樣方法8 2.2樣品前處理12 2.3分析方法12 2.3.1水樣硫酸鹽濃度14 2.3.2沉積物中甲烷濃度14 2.3.3沉積物總硫、有機碳與碳酸鈣含量14 2.3.4沉積物有機碳有機氮分析15 2.3.5沉積物酸可萃取硫與黃鐵硫含量15 2.3.6硫同位素分析16 2.3.7沉積物粒徑大小16 2.3.8沉積物生物矽含量17 2.3.9沉積物中有機碳之碳十四定年18 第三章 研究結果19 3.1水樣硫酸鹽濃度與硫同位素19 3.2沉積物硫酸鹽、總硫濃度與黃鐵硫硫同位素19 3.3沉積物中甲烷濃度21 3.4有機碳與碳酸鈣含量21 3.5有機碳氮莫耳比值與有機碳總硫比值22 3.6沉積物生物矽含量23 3.7沉積物粒徑分布23 3.8沉積物有機碳之碳十四定年23 第四章 討論36 4.1古氣候與沉積環境36 4.2總硫的形成與埋藏39 4.3岩心的年代分布42 4.4氣候變遷對於硫循環之影響43 第五章 結論56 參考文獻 5712002225 bytesapplication/pdf論文使用權限：不同意授權淡水湖泊古氣候變化硫酸鹽還原作用甲烷厭氧氧化作用[SDGs]SDG13thesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/262605/1/ntu-103-R00241403-1.pdf