红柳沙包环境代用指标在塔克拉玛干沙漠南缘地区环境变化研究中的优选应用
The Preferred Application of Environmental Proxies of Tamarix Cone in Environmental Change Research in the Southern Source of the Taklimakan Desert

塔克拉玛干沙漠位于新疆维吾尔自治区南部,西有帕米尔高原,东为罗布泊盆地,北依天山,南临阿尔金山、昆仑山,与青藏高原融为一体,地势西南高东北低。三面环山且身居亚欧大陆中心地带,远离海洋,造就其成为亚洲最为干旱的地区,而塔克拉玛干沙漠南缘着众多的绿洲,是干旱区的核心地带。研究塔南地区的环境变化对于整个干旱区的环境变化研究有着重大意义。但是,由于传统环境变化信息载体的缺乏,限制了该区域环境变化研究的深入。由枯枝落叶层和风沙层交替沉积所形成的红柳沙包沉积纹层,就如同树木的年轮一样,是一种高分辨率的计年方法,同时也蕴含着丰富的古气候环境信息,成为了干旱区环境演变研究的有效手段。本文以塔克拉玛干沙漠南部的民丰县、策勒县为研究区域,以安迪尔古城、安迪尔牧场以及达玛沟乡三个区域的典型红柳沙包为研究对象,以野外调查采样和室内实验分析处理相结合的研究方法,对红柳沙包沉积纹层中所蕴含的沙物质粒度、有机质碳氮、落叶阳离子、稳定碳同位素、稳定氧同位素等进行综合优选和分析,建立气候环境指标与气象数据的相关关系,运用逐步回归方法,重建塔南地区近几百年来的气候环境变化序列,并且与单一指标重建结果、相关地区的研究结果、标准化序列研究结果等进行对比分析,得到塔南地区气候环境变化序列,主要结论有:(1)枯枝落叶层和沙物质粒度对气候变化响应积极。气候代用指标与年均温度相关性总结得出:标准偏差>峰度>分选系数>偏度>Mg2+>K+>平均粒径>△δ13C>中值粒径>Na+>C/N>TN>TOC>Ca2+18O;沙物质粒度参数、落叶阳离子及△δ13C响应敏感;年均温度与标准偏差、峰度、Mg2+、K+均通过置信度检验。气候代用指标与年均降水量相关性总结得出:偏度>平均粒径>中值粒径>分选系数>标准偏差>峰度>TOC>△δ13C>Na+>Mg2+>K+>Ca2+>C/N>TN>δ18O;沙物质粒度参数、TOC及△δ13C响应敏感;年均降水量与偏度均通过置信度检验。气候代用指标与年均风速相关性总结得出:标准偏差>分选系数>△δ13C>峰度>K+>Mg2+>C/N>偏度>TN>Na+>平均粒径>中值粒径>TOC>Ca2+18O;沙物质粒度参数、△δ13C及落叶阳离子响应敏感。(2)安迪尔古城采样点各个气候代用指标与年均温度、年均降水量、年均风速相关性绝对值的平均值可知:峰度>偏度>标准偏差>分选系数>△δ13C>Mg2+>K+>Na+>平均粒径>中值粒径>δ18O>TOC>C/N>Ca2+>TN;干旱区内自然因素影响较大的地区可参考安迪尔古城,优选指标为沙物质粒度参数、△δ13C及落叶阳离子。安迪尔牧场采样点:峰度>偏度>标准偏差>△δ13C>平均粒径>分选系数>中值粒径>C/N>Na+>TOC>K+>TN>Mg2+>Ca2+18O;干旱区内既受自然条件控制又有人为活动影响的地区可参考安迪尔牧场;优选指标为沙物质粒度参数、△δ13C。达玛沟采样点:分选系数>K+>Mg2+>标准偏差>中值粒径>平均粒径>TN>C/N>峰度>偏度>Na+>△δ13C>TOC>δ18O>Ca2+;干旱区内人为活动影响较大的地区可参考达玛沟,优选指标为沙物质粒度参数、落叶阳离子。(3)气温、降水和风速的重建中,只有红柳沙包中的粒度参数、落叶阳离子、TOC和△δ13C的因子进入逐步回归方程,对于以后的气候分析与重建起到参考作用,可以只分析沙物质粒度、落叶阳离子、TOC和△δ13C的数据,尤其是沙物质粒度及落叶阳离子表现良好,不仅降低了工作量,还能较好地代表塔南地区的气候。(4)安迪尔古城采样点可用峰度重建年均温度,偏度重建年均降水量,△δ13C、Na+重建年均风速;安迪尔牧场采样点可用标准偏差、中值粒径、K+重建年均温度,TOC重建年均降水量量,△δ13C重建年均风速;达玛沟采样点可用K+重建年均温度,中值粒径重建年均降水量量,分选系数重建年均风速。(5)多种指标共同作用重建的气候变化序列与单一指标重建的气候序列相比更具有优越性。根据标准化序列可知塔南地区环境变化是由冷干趋向于暖湿:15901630年为暖湿期,16311790为冷湿期,17911819年为暖干期,18201834年为暖湿期,18351887年为冷湿期,18881933年为冷干期,19341988年为暖干期,19892010年为暖湿期,风速在20世纪90年代后都呈现减弱的趋势。

The Taklimakan Desert is located in the southern part of Xinjiang Uygur Autonomous Region.It has the Pamir Plateau in the west,the Lop Nur in the east,the Tianshan Mountain in the north,the Altun Mountains,the Kunlun Mountains and the Qinghai-Tibet Plateau in the south.The terrain is high in the southwest and low in the northeast.It is surrounded by mountains on three sides.The center of the Eurasian continent is far from the ocean,making it the most arid region in Asia.The southern source of the Taklimakan Desert has many oases and is the core of the arid region.Studying the environmental changes in the southern source of the Taklimakan Desert is important for studying the environmental changes in the arid region,but the lack of traditional information carriers due to environmental changes limits the study of environmental changes in the region.Tamarix sediment veins formed by alternating deposition of litter layers and sand layers,just like the annual rings of trees,it is a high-resolution dating method,and it also contains rich information on paleoclimate environment,which has become an effective means of studying environmental evolution in arid regions.This paper takes Minfeng County and Cele County in the southern source of the Taklimakan Desert as the research area,and takes the typical Tamarix sediment veins in the three areas of Andir,the Andir Ranch and Damagou Town as the research object,and analyzes and processes the field survey and laboratory experimentsasthe research method,Comprehensive optimization and analysis of sand grain-size,the organic matter carbon and nitrogen,positive ion content in Tamarix fallen leaves,stable carbon isotope and stable oxygen isotope contained in the Tamarix sediment veins.Establish a correlation between climate environmental indicators and meteorological data,using the stepwise regression method,the sequence of climate change in the southern source of the Taklimakan Desert has been reconstructed for hundreds of years,and compared with single indicator reconstruction result,related area research result,and standardized sequence research result,the sequence of climate environment change in the southern source of the Taklimakan Desert is obtained.The main conclusions are:(1)The litter layers and sand layers responded positively to environmental changes.The correlation between climate proxy index and annual average temperature is summarized as follows:standard deviation>kurtosis>sorting coefficient>skewness>Mg2+>K+>mean grain size>△δ13C>median particle size>Na+>C/N>TN>TOC>Ca2+18O;sand grain-size、positive ion content in Tamarix fallen leaves and△δ13C are sensitive;The annual mean temperature and standard deviation,kurtosis,Mg2+and K+were all tested by confidence.The correlation between climate proxy index and annual average precipitation is summarized as:skewness>mean grain size>median particle size>sorting coefficient>standard deviation>kurtosis>TOC>△δ13C>Na+>Mg2+>K+>Ca2+>C/N>TN>δ18O;sand grain-size、positive ion content in Tamarix fallen leaves and△δ13C are sensitive;The average annual precipitation and skewness were tested by confidence.The correlation between climate proxy index and annual average wind speed is summarized as follows:standard deviation>sorting coefficient>△δ13C>kurtosis>K+>Mg2+>C/N>skewness>TN>Na+>mean grain size>median particle size>TOC>Ca2+18O;sand grain-size、△δ13C and positive ion content in Tamarix fallen leaves are sensitive.(2)The average value of the correlation between the climate climatic indicators and the annual average temperature,annual average precipitation,and annual average wind speed at the sampling point of the ancient city of Andir is known as:kurtosis>skewness>standard deviation>sorting coefficient>△δ13C>Mg2+>K+>Na+>mean grain size>median particle size>δ18O>TOC>C/N>Ca2+>TN;For areas with a large impact on natural factors in the arid zone,reference can be made to the ancient city of Andir.The preferred indicators are sand grain-size,△δ13C and positive ion content in Tamarix fallen leaves.Samples of Andir Ranch:kurtosis>skewness>standard deviation>△δ13C>mean grain size>sorting coefficient>median particle size>C/N>Na+>TOC>K+>TN>Mg2+>Ca2+18O;Areas in the arid zone that are both controlled by natural conditions and affected by activities can refer to Andir Ranch;The preferred indicators are sand grain-size and△δ13C.Damagou sampling point:sorting coefficient>K+>Mg2+>standard deviation>median particle size>mean grain size>TN>C/N>kurtness>skewness>Na+>△δ13C>TOC>δ18O>Ca2+;For areas with a greater impact on human activities in the arid zone,refer to Damagou;The preferred indicators are sand grain-size and positive ion content in Tamarix fallen leaves.(3)In the reconstruction of air temperature,precipitation and wind speed,only sand grain-size,positive ion content in Tamarix fallen leaves,TOC and△δ13C factors in the Tamarix sediment veins enter the stepwise regression equation,which can be used as a reference for future climate analysis and reconstruction.The data of sand grain-size,positive ion content in Tamarix fallen leaves,TOC and△δ13C,especially sand grain-size and positive ion content in Tamarix fallen leaves perform well,which not only reduces the workload,but also better represents the climate of the southern source of the Taklimakan Desert.(4)The sampling point of the ancient city of Andir can reconstruct the annual average temperature with kurtosis,the average annual precipitation can reconstruct by skewness.the annual average wind speed can be reconstructed by△δ13C and Na+.Samples of Andir Ranch can reconstruct the annual average temperature with standard deviation,median particle size,K+.the average annual precipitation can reconstruct by TOC.the annual average wind speed can be reconstructed by△δ13C.Damagou sampling point can reconstruct the annual average temperature with the K+.the average annual precipitation can reconstruct by median particle size.The annual average wind speed can be reconstructed by sorting coefficient.(5)The climate change sequence in which multiple indicators work together is more advantageous than the climate sequence reconstructed by a single indicator.According to the normalized sequence,it is known that the environmental change in the Southern region of the Taklimakan Desert region is from cold and dry to warm and wet:15901630 is the warm and wet period,16311790 is the cold and wet period,17911819 is the warm and dry period,18201834 is the warm and wet period,18351887 is the cold and wet period,18881933 is the cold and dry period,19341988 is the warm and dry period,1989-2010 is the warm and wet period,and the wind speed is weakening after the 1990s.

环境变化; 红柳沙包; 回归分析; 气候重建; 塔南地区;

environmental change; Tamarix cone; regression analysis; climate reconstruction; south region of Taklimakan Desert;

赵元杰;

X171

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