碩士 / 國立臺灣大學 / 海洋研究所 / 105 / As one of the largest marginal seas in the Western Pacific Ocean, the South China Sea(SCS) annually receives large amount of sediments from surrounding continental rivers. In addition, SCS is also frequently influenced by natural hazards like typhoon, earthquake and volcanic eruption. It makes SCS has potential to preserve the natural hazard records in the deep-sea sediments. In this study, we attempt to clarify the characteristics of the SCS modern deep-sea event-layer through the sediment composition and the provenances of particulate organic carbon(POC), moreover, to find out the features of POC distribution in different regions.
In Spratly Islands, the natural hazards related event-layers were found in the core top of gravity cores. According to the total organic carbon(TOC)(0.07 to 0.71%), d13C-values(-18.4 to -22.4‰) and TOC/TN ratio(5 to 10) in the gravity cores, we suggest the organic carbon is mainly from marine algae, however, the lighter d13C-values in event-layers may influenced by marine algae of different species or regions. The terrestrial signal only can be seen in the event-layer which located at the southern channel of the Zhenghe Qunjiao(OR1-1068-4). The relatively lower TOC can also be found in event-layer which caused by dilution of carbonate. Three cores which were taken from the Central Basin are almost entirely affected by event-related activities, and its TOC is between 0.17 to 1.39%, d13C-values range from -18.9 to -22.8‰ and TOC/TN ratio ranges from 3 to 9. The composition of organic carbon indicates it may be formed by mixing of terrestrial and marine materials. The highest TOC is found in the third event-layer in the center of Central Basin(OR1-1133-A1), the result suggests it may be composed by nearshore sea grasses and marine algae.
We further utilized n-alkanes analysis of the event-layer in core OR1-1068-8 which located at north of Reed Bank. It shows higher TOC/TN with increasing n-C26~35 of entire n-alkanes, which reveals TOC/TN and d13C can be used to identify the provenances of organic carbon in this region. Furthermore, the Carbon Preference Index(CPI) of the organic carbon in event-layer is similar to soil on land. It implies that large amount of terrestrial organic carbon might be delivered from land and formed thick event-layer in deep-sea and has great impact on carbon burial.
| Identifer | oai:union.ndltd.org:TW/105NTU05279015 |
| Date | January 2017 |
| Creators | Hsing-Chien Juan, 阮行健 |
| Contributors | 蘇志杰 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 91 |
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