Earth Science Frontiers ›› 2009, Vol. 16 ›› Issue (6): 162-167.

• Article • Previous Articles     Next Articles

 A preliminary study of the Holocene lake level changes and their causes derived from the sediment record of Zigetang Lake, Tibetan Plateau.

 LI Shi-Jie, Bernd Wünnemann, JIA Wei-Lan, XU Shou-Bing, CHEN De-Fu, JIANG Yong-Jian   

  1. 1State Kay Laboratory of Lake Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China
    2State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China
    3Interdisciplinary Centre of Ecosystem Dynamics Central Asia, Free University Berlin, D12249 Berlin, Germany
  • Received:2009-11-01 Revised:2009-11-10 Online:2009-12-16 Published:2009-12-10

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Abstract:

 The Zigetang Lake is an enclosed lake, located in the hinterland of the North Tibetan Plateau and within the marginal region of southwest monsoon. There is no distribution of glacier in the catchment, and the precipitation controlled by the southwest monsoon is the main water supply for the Zigetang Lake. Therefore, the expansion and contraction of lake water area reflects the changes of southwest monsoon directly. The carbonate concentration of enclosed lake sediments in semiarid region indicates the changes of the lake level sensitively. The carbonate concentration in the sediment core of Zigetang Lake has generally been in high value but there were several abrupt lowering stages during the Holocene period, which could reveal the evolution stages of the lake level better when associated with the changes of soluble salt (Cl- and SO2-4) concentration in the sediment core. The analysis results for a 740 cmlong core drilled in the central Zigetang Lake show that this core has completely covered the whole Holocene period and that the carbonate concentration decreased greatly during 9389 cal ka BP, 8378 cal ka BP, 5047 cal ka BP, 4038 cal ka BP, and 3127 cal ka BP, respectively, indicating the desalination of the lake and the rise of the lake level. The high value of carbonate and soluble salt (Cl- and SO2-4) content around 38 cal ka BP indicates the increase of salinity and the decline of the lake level. The content of carbonate and soluble salt decreased gradually since 1 cal ka BP, which indicates the gradual desalination of the lake and the slow rise of the lake level. However, the increase of soluble salt content in the past 100 years indicates the contraction of lake water area and the decline of the lake level, which is in accord with the warming and drying process of the climate. The fluctuations of southwest monsoon during the Holocene can be derived from the five extremely low value events of carbonate concentration in the sediment core from the Zigetang Lake.

Key words: Tibetan Plateau; Zigetang Lake; sediment record; Holocene lake level; southwest monsoon