近400年来新疆策勒红柳沙包稳定氧同位素与气候变化

The characteristics of stable oxygen isotope in Tamarix cone and climatic change in recent 400 years in Qira region,Xinjiang

建立红柳沙包沉积纹层年代序列和提取气候环境信息是高分辨率古气候环境变化研究的重要手段。利用策勒达玛沟红柳沙包高度约450 cm沉积纹层红柳落叶的稳定氧同位素数据,结合策勒气象站1960~2011年观测数据,运用移动平均法对稳定氧同位素和气象数据进行平滑处理后,运用相关分析及逐步回归法,定量重建了策勒地区近400年来的4月平均气温和3月降水量序列。研究结果表明:红柳落叶δ^18O平均值为33.96‰,波动范围为27.18‰~44.07‰,波动幅度为16.89‰,δ^18O变化受多个气候要素的综合影响。δ^18O与4月平均气温呈显著负相关,与2月和12月平均气温呈显著正相关;δ^18O与10月、4月、5月、9月、7月以及全年的空气相对湿度呈显著正相关;δ^18O与3月、9月和8月的降水量呈显著正相关,与2月降水量呈显著负相关;δ^18O与2月日照时数呈显著正相关,与9月和10月的日照时数呈显著负相关。策勒地区近400年来气候变化可划分4个阶段:1635~1725年为暖干期,1726~1792年为冷湿期,1793~1897年为暖干期,1898~2009年为冷湿期。

There are Tamarix cones distributed in the Qira region(35°17'~39°30'N,80°03'~82°10'E).Tamarix cone is not only a high-resolution dating method,but also contains a wealth of information on climate and environmental evolution.At the site of 37.09°N,81.08°E,we take 141 samples in a top part of the Tamarix cone from the top layer to the 250.0 cm deep layer according to every layers with thickness of 0.5~2.8 cm,and 10 samples according to a average thickness of 20.0 cm from 250.0 cm depth to the bottom.Based on the sedimentary vein counting and other dating methods such as AMS 14C,137 Cs and 210 Pb of Tamarix cone sedimentary veins,the time sequence of Tamarix cone sedimentary veins in Qira Oasis,southern margin of Taklimakan Desert has been established,which is from 1590 to 2010.Based on theδ^18O of the Tamarix cone sedimentary veins,combined with the observation data at Qira Meteorological Station from 1965 to 2009,and using the correlation analysis and the Stepwise Regression method,the temperature sequence in April and precipitation sequence in March for recent nearly 400 years in Qira region have been reconstructed quantitatively.The research results show that:the average ofδ^18O values is 33.96‰,the fluctuation range is 27.18‰~44.07‰,and the fluctuation value is 16.89‰.The change ofδ^18O sequence is influenced by multiple climatic factors including temperature,precipitation,relative humidity,and sunshine hours,and so on.Theδ^18O changes have the obvious correlations with the monthly mean temperatures in April,February and October respectively;with monthly relative humidity in October,April,May,September,July and annual relative humidity respectively;with the monthly precipitation in March,September,February and August respectively;with sunshine duration in February,September and October.The reconstructed April's temperature in recent about 400 years could be divided into 4 periods:the warm period from 1635 to 1725;the cold period from 1726 to 1792;another warmer period from 1793 to 1899,during the period from 1835 to 1852 and from 1870 to 1880 the temperature is lower;another cold period from 1900 to 2009,but there are several periods of small cooler and warmer periods.The reconstructed March's precipitation sequence consists of four stages:the partial dry period from 1635 to 1725;the obvious wet period from 1726 to 1792;the partial dry period from 1793 to 1897,in which the precipitation increased during the two periods from 1837 to 1852 and from 1867 to 1883;from 1898 to 2009,it was a wet period,during which there were several periods of partial or partial wetness.In Qira region the climate could be divided into four climate stages in the past 400 years:the warm and dry period from 1635 to 1725,the cool and wet period from 1726 to 1792,the warm and dry period from 1793 to 1897,and the cool and wet period from 1898 to 2009.