https://scholars.lib.ntu.edu.tw/handle/123456789/37215
標題: | 由沉積物穩定氮同位素分析探討臺北盆地過去二十萬年之氣候變遷 | 其他標題: | Climate change of past 200 kys in Taipei Basin using stable nitrogen isotope analysis of core sediments | 作者: | 陳于高 | 關鍵字: | 臺北盆地;五股岩心;穩定同位素;碳氮比;Taipei Basin;Wu-ku core;stable isotope;C/N ratio | 公開日期: | 2002 | 出版社: | 臺北市:國立臺灣大學地質科學系暨研究所 | 摘要: | 本研究選擇臺北盆地五股岩心沈積 物,分析其中有機物質的碳氮比、以及碳 與氮同位素,佐以含硫量的測定,以期能 對臺北盆地地區的環境變化有更全面的瞭 解。在分析結果方面,由碳氮比與有機碳 同位素的良好對比看來,臺北盆地在深海 氧同位素地層stage2 與stage6 經歷了較乾 燥的氣候環境。此外,氮同位素分析的結 果,在深海氧同位素地層stage1 及板橋層 堆積時明顯變重,可能原因為臺北盆地沈 積環境中水體的營養鹽供應狀態在這些時 期改變為以再循環營養鹽為主;或由於有 較重同位素值的大型浮游植物生長在這樣 的環境而影響了沈積物的氮同位素,暗示 了臺北盆地可能在板橋層堆積時就已經受到海水的影響。 In this study, C/N ratios and d 15 N values of the Wu-ku core sediments were measured. Combining with d 13 C, the environmental change can be clearly understood. Based on the previous study, Taipei Basin was a lacustrine environment that could preserve a continuous sedimentary history of terrestrial environment. The sedimentation of Taipei Basin was triggered somewhat after 300ka. Except that the deposition of the rhythmic mud layer was affected by the local event, the environment around Taipei Basin was mainly controlled by the global change (Wei et al., 1997; Chen et al., 1999). Our results show a very good correlation between C/N and d 13 C. According to the d 13 C data, Taipei basin went through a period of time that the d 13 C shift to a heavy value, implying that C4 plant was an important source of organic matters. The flourishing of C4 plant indicates that the climate was relatively arid during oceanic isotope stage 2 and 6. From the heavy d 15 N values at the upper 50m and 330-390m, we think that one probable reason may be the recycled nitrate from denitrification was the important source of nitrogen for the primary producer, and resulted in heavy d 15 N (Altabet et al., 1999). The other one could be the influence of growth of high d 15 N macrophyte in the semi-salty water of estuarine environment. |
URI: | http://ntur.lib.ntu.edu.tw//handle/246246/11789 | 其他識別: | 902116M002010 | Rights: | 國立臺灣大學地質科學系暨研究所 |
顯示於: | 地質科學系 |
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902116M002010.pdf | 395.66 kB | Adobe PDF | 檢視/開啟 |
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