碩士 / 國立彰化師範大學 / 生物學系 / 98 / Abstract
The study analyses the records of core HL, adopted in the lake from Haolaihure, Hexigten Banner, Chifeng City, Inner Mongol, to understand paleoenvironment climate changes. The total length is 7.14 m of this drill core and every alternate 4 cm is sampled as a unit of group, there are 123 groups of samples in all. A total of 39 genera and 126 species of diatom assemblages were found from this core, such as Aulacoseira, Amphora, Cyclotella, Cymbella, Fragilaria, and Navicula belong freshwater algae. The results showed that the absolute diatom abundance (ADA) of fossil diatom assemblages was ranged from 0- 2.10 ×109 valves/g DW, and having an average of 4.34 ×108 vales/g DW. The fluctuations among the amount of diatom genus and species were 0-36, 0-51. Aulacoseria spp. up to 80.5% was inferred that it rains a lot and the nutrients increase to become an eutrophication lake. According to the core HL of magnetic susceptibility, absolute abundance of diatom, relative abundance of diatom, the number of diatom species, magnetic material particle size, total carbon, total organic carbon, N, H, S, Si and opal inferred to the paleoenvironment climate changes. The environment evolution of this ancient lake since the Holocene has been divided in to 7 stages. I (714-668 cm, 13.1-12.3 cal ka BP), the climate was dry. II (668-620 cm, 12.3-11.4 cal ka BP), speculated that it was entering the warm period of Holocene, and rainfall increased, the lake became larger, the mud sedimented in the lake. III (620-475 cm, 11.4-8.6 cal ka BP), the climate was more arid and cold, and the water level declined. IV (475-386 cm, 8.6-6.9 cal ka BP), the climate remained relatively cool and relatively dry.V (386-325 cm, 6.9-5.8 cal ka BP), the climate was more humid, high water level, and the climate began warming.VI (325-184 cm, 5.8-3.1 cal ka BP), the climate was warm and wet, and it was the Holocene optimum. VII (184-95 cm, 3.1-1.4 cal ka BP), the climate was cold and dry, lake became smaller. The percentage curve of total carbon, total organic carbon and C/N ratio showed the consistence with the curve of fossil’s abundance of diatom. The period of high lake water level was from hundreds of years to tens of years. It shows that paleoenvironment climate was controlled by climate types, which drive the alternation of water level in the lake.
| Identifer | oai:union.ndltd.org:TW/098NCUE5112011 |
| Date | January 2010 |
| Creators | Chao-Jing Huang, 黃朝景 |
| Contributors | Wei-Lung Wang, 王瑋龍 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 66 |
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