Discussions of Climatic and Environmental Changes of Central Taiwan by Using Carbon Indicators Derived from Zhoushui River Mouth Region

• Main Authors: Hsien-Cheng Liu, 劉憲承
• Other Authors: Yuan-Pin Chang
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/q3875z

碩士 === 國立中山大學 === 海洋科學系研究所 === 107 === The sedimentary core JRD-S, which has total length of 103 meters, which derived from the south estuary region of the Zhuoshui River, was used in this study for discussing long-term changes of regional environment and climate of fluvial plain at central Taiwan. The reconstructed age model based on radioactive carbon isotope dating shows that JRD-S can cover at least 90 ka and can trace back to last glacial cycle. Several proxies, such as TOC(%), C/N Ratio and organic-13C, were analyzed for tracing the possible organic matter sources and revealing the burial processes of sediment organic matters at Zhuoshui River mouth. Thus can help us to reveal the past environmental and climatic changes of Zhuoshui River catchment and the vegetation changes in the watershed area. Based on the results of TOC, C/N ratio and δ13C data reconstructing from the period of land-phase, we speculated that the main stream of Zhoushui River was migrated and the runoff reduced during dry-cold periods, and depositional environment of the coring site was the floodplain. During these periods, weathering sediments formed and deposited in the floodplain. C4 plants or herbaceous plants were dominated in central Taiwan. Otherwise, within the warm and humid periods, the coring site was again affected by the river channel. During the warm and humid period, the river brought more degraded rock materials from the upper and middle reaches. In addition, contrary to previous studies, it is considered to be transformed into fluvial channel facies between the period of 37 ka BP and 35ka BP. Furthermore, with the results of TOC, C/N ratio and δ13C data during the marine-phase period, we concluded that there was more terrestrial sediment deposited in the deep sea environment because of resuspended or lateral transported sediments. As the sea water depth became shallower, more marine sourced organic matters input into sediments and the influences caused by marine organisms became greater.