Abstract: In this study,the ²¹⁰Pb dating method was used to establish the sedimentary chronology sequence of lacustrine sediments of the Bosten Lake in Xinjiang,China. The purposes of the study were to research the grain size distribution of core sediment (41 cm),analyze the sediment components sensitive to environment by applying the grain size-standard deviation method,and reconstruct the history of lake water level change over the past 150 years. The contents of clay (<4 μm),fine silt (4-16 μm),medium silt (16-32 μm),coarse silt (32-64 μm) and the sand (>64 μm) in the core sediment of the Bosten Lake were 18%,40.2%,23.3%,13.4% and 5.1% respectively,and the vertical variations of different fractions were obvious. The average grain size of component C₂ (with particle size of 7.59-22.91 μm) was consistent with the median particle size (r=0.7,P<0.01),and the component C₂ was very sensitive to the change of sedimentary environment in the Bosten Lake Basin,which could be used to reconstruct the water level of the lake over the past 150 years. Water level of the Bosten Lake was low from the 1910s to the 1930s,which revealed that a large-scale regional drought occurred during this period. Under the joint effect of climate change and human activities,water level of the Bosten Lake was significantly fallen in the mid- and late-1980s. The change of sensitive components C₂ was consistent with the change of lake water level,and the water level fluctuation history of the Bosten Lake could be reconstructed from the sensitive components in lake sediments.

Key words: lacustrine sediment, grain size, grain size-standard deviation, environmental reconstruction, Bosten Lake, Xinjiang