关键词: 东居延海, 易溶盐, 中世纪暖期, 小冰期, 20世纪暖期

Abstract: By analyzing the distribution of the eight kinds of ions (K⁺, Na⁺, Ca²⁺, Mg²⁺, SO₄^2-, CO₃^2-, HCO₃^-, Cl^-) in soluble salt sediments of the East Juyan Lake and other related indicators, the variation features of them in strata are depicted. Based on the analyzing results and combined with the ¹⁴C dating ages, the vicissitude of the East Juyan Lake could be divided into several phases, such as the Sui-Tang Dynasty larger lake area period, the Song-Liao Dynasty lake area shrank period, the Medieval-Warm-Age lake area extended period, the Little-Ice-Age lake area shrank period and the 20^th Century lake dried up period, etc. In general, arid climate dominantly controlled the study region in the past (1 500) years, as result the East Juyan Lake shrank gradually. On the background of arid climate there existed fluctuations between arid and humid, and the fluctuations kept pace with the global climate changes. Apart from climate change factor human activity is also an important influencing factor on lake vicissitude, and they played the dominant role alternatively during different periods; the natural factor predominated in the former times, but the anthropogenic factor became decisive since the Ming Dynasty especially the Qing Dynasty.

Key words: the East Juyan Lake, soluble salt, Medieval Warm Period, Little Ice Age, 20^th Century Warm Period