碩士 / 國立中山大學 / 海洋地質及化學研究所 / 87 / East China Sea as one of the most important continental marginal seas of the world with wide shelf and slope provides a region for particulate material cycling and its pathway to the deep sea. In order to determine the temporal or seasonal variation of the settling particulate flux as well as the uranium and thorium isotope compositions, four sediment traps (PPS-3) were deployed on the continental slope off northeastern Taiwan to collect settling particulates. The goals of this study are thus to understand the spatial and temporal variations of the particulate flux and the transport pathway of these particulates. The source functions of the particulates and associated transfer processes in the region between the continental slope of the southern East China Sea and the south Okinawa Trough were delineated based on the characteristics of the uranium and thorium isotopic compositions.
The study shows that, lateral transport and the distance away from Taiwan island are key factors controlling spatial variation of the mass flux, and that the temporal variation as well synchronized at each mooring station. Moreover, the mass flux in the second half year was higher than that of the first half year. At mooring T13, the mass flux measured at the middle trap was higher than at the bottom trap for the whole year, probably caused by tongue of high particulate concentration which was moving laterally from the slope or due to hydrothermal activities. Further investigation is needed. Uranium and thorium isotopes showed no significant seasonal variation, and so uncorrelated with particulate mass flux. Thorium isotopes were lower than those of marine sediment off northeastern Taiwan, presumably due to difference in particulate size and composition. The U-234/U-238, Th-230/Th-232, and Th-228/Th-232 activity ratios show that the settling particulates in the study area are mainly derived from the terrigenous clastic materials without thorium loss but with significant uranium loss due to leaching out during the transport of these particulates.
| Identifer | oai:union.ndltd.org:TW/087NSYSU271002 |
| Date | January 1999 |
| Creators | Wang, Li-wen, 王麗雯 |
| Contributors | Chung, Yu-chia, 鍾玉嘉 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 70 |
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