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引用本文:吉磊,王苏民,郑长苏,羊向东,沈吉.浅钻岩芯揭示的固城湖4000年来环境演化.湖泊科学,1993,5(4):316-323. DOI:10.18307/1993.0404
Ji Lei,Wang Sumin,Zheng Changsu,Yang Xiangdong,Shen Ji.Environmental evolution of gucheng lake for the past 4000 years revealed by a short core. J. Lake Sci.1993,5(4):316-323. DOI:10.18307/1993.0404
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浅钻岩芯揭示的固城湖4000年来环境演化
吉磊, 王苏民, 郑长苏, 羊向东, 沈吉
中国科学院南京地理与湖泊研究所湖泊沉积与环境开放研究实验室, 南京 210008
摘要:
对固城湖6.2m深的现代沉积物柱状岩芯进行了放射性同位素、粒度、有机质含量、有机质σ13C和孢粉分析。沉积记录巾各项环境指标的变化表明, 4ka以来固城湖经历了高湖面—低湖面—高湖面的显著变化。气候变化是影响湖泊环境演化的重要自然因素, 但2.5ka以来人类活动对湖泊演化的影响显得更为明显。特别是2.5ka和1.1ka两次人类对湖泊水系的改造是引起湖泊环境两次突变的主要因素。
关键词:  湖泊沉积  环境演化  气候变化  固城湖
DOI:10.18307/1993.0404
分类号:
基金项目:湖泊沉积与环境开放研究实验室资助项目(No.91003)
Environmental evolution of gucheng lake for the past 4000 years revealed by a short core
Ji Lei, Wang Sumin, Zheng Changsu, Yang Xiangdong, Shen Ji
Laboratory of Lake Sediment and Environment, Nanjing Institute of Geography and Limnology, Academia Sinica, Nanjing 210008
Abstract:
The sediment from a columnar core with a depth of 6. 2 min Gucheng Lake was analyzed with regard to radioisotope, grain size, organic matter content, δ13C of organic matter and pollen. 14C dating of 3630+230a was obtained from the organic mud sample 6. 1 m below the core top. The average sedimentary rate of recent sediments is 0. 71mm/a resulting from 210Pb dating technique. According co the lithology and various environmental m ar kers of the sediment five lithoiogical beds and five correspondins stages of environmental evolution may be divided from the core profile:(1)5.1-6.2m , green-greymud and siltymud.Clay content(CL), organic matter conent(LOI)and δ13C values are all higher(77.5 , 5.6 and - 25.36‰ PDB respectively ) in th interva1. High-lake level was reflected during the period .(2) 3 .5- 5· 1n1, grey silty m ud. CL, LOI and δ13C va]ues are reduced slightly (62.2% , 5.0% , and-25.98%0 respectively). Lake-level was also higher in the period .(3) 1.2- 3.5m , grey muddy fine grained sand and sir. CL .LOI an d 6 C are all at their low est values in the profile (13.3 .3.7 and 26.31‰ respectively).Thelake—level was verylow in thetime. (4) 0.3- 1.2m. grey sandY an d silty mud. CL , LOI, and 6 C values are risen again to some extent(41.2% , 7.8 and -25.`` respectively ).The lake was expan ded during the t[nle. (5) 0 0.3m , dark—grey silty mud. CL , LOI and δ13C values are all quite high (70.3-10.6 and - 22.1 4‰ respectively).The Inke-level was probably higher during the period-According to the pollen forms and contents in the core profile, eight palynological assemblage zones are divided as follows;(I)Quercus-Casta~ea zone, (Ⅱ)Pinus-Quercus- Polypodiaceae zone, (Ⅲ )Quercus-Graminca- Typha zone, (IV)Graminea-Arteinsria-Quercus zone, (V ) Quercus-Graminca- Typha zone, (VI) Gram inea Pigza-Quercu zone, (Ⅶ) Qercus-Pinus-Castanea zone an d (Ⅷ )P inus-Graminea-Ariternaisira-Qzone. Com par ison of climatic change sequence resulting from pollen an alysk to the lake—level evolution m ay lead to the discovery that the clim ate change was coincident w ith lake—level change before 2.5 ka B.P.(6.2— 3.5m in the core)and the climate waS the main controlling factor for the lake expansion. But the regularitlos of lake—level fluctuation ar e not conformable to the clim atic change s.nce 2.5 ka B.P.(0- 3.5m in the core). Obviously the lake environm ent change was not controlled dom inantly by clim ate factor during the time. On the contrar y, human activities were the leading factor that affected lake environment evolution. In the historical records, the Xux[River channaled at caused Gucheng Lake water our eastwards an d also caused the lake to shrink intensely.As a result, the lake was converted into Taihu Lake drainage bas in. U P to 893 A .D. as five bars were built along the Xuxi River.the lake water flowing eas twards was CUt off resultin g in an expansion of lake ar ea and the lake beca me the Changjan g River drainage bas in again. Therefore, it is inferred that the twice abrupt changes of lake environment at 3.5m and 1.2m of the core are resulted from hum an’g tras form atinn on the lake water system in historical time.
Key words:  Lake sediment  environmental evolution  climatic change  Gucheng Lake
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