Environmental Change Study Based On The Positive Ions Contained In Sediment Veins Of Tamarix Cones In The Southern Region Of Taklimakan Desert

Taklimakan Desert, located in the south of Xinjiang Uygur Autonomous Region, is in thecentral area of the Tarim Basin with an area of560,000square kilometers. In the north of thedesert is the Tianshan Mountains; in the west is the Pamirs; in the south is the KunlunMountains; in the east is the Lop Nur region. The landform of the desert inclines southwest tonortheast, and in the east where is the area of Lop Nur, the elevation has fallen down to780m.As a result of the uplifted tectonic movement of the ambient mountains, happened in the endof the Tertiary and the early Quaternary, it made the original central higher topography of theTarim Basin have changed tremendously. At present, it has formed the geographical structurethat all surrounded by high mountains, and it is located in the center land of Eurasia, far awayfrom the ocean, so its unique geographical location determines the formation of its aridenvironment. the distinctive climate is characterized by the little precipitation, drought andheavy sandstorm, especially that the Taklimakan desert is the driest region in Asia, while thesouthern region of the Taklimakan desert is the arid core zone in China. By the research of theenvironmental change of the southern region of Taklimakan desert, it will help a lot for theenvironment changes in Xinjiang, and even the entire arid areas’ environment.Strong sandstorm makes it more difficult to find the appropriate information carrier inthe desert, while the appearance of Tamarix cone provides us the new research methods andtheoretical basis to solve how to obtain the information of the environmental changes in aridareas. As the "annual layers", the sedimentary veins of Tamarix cone can be used to count theyears and store the information of the environments, and it is similar to the tree rings. Thesand material layer and the litter layer in the sedimentary veins of the Tamarix cone with astorage of a large number of environmental information can be used to explore and restore theclimatic and environmental changes of the desert in the centennial scale. It has become aneffective tool to study the ecology and environmental evolution in the desert. And it is of greathelp to environment change research of the arid desert regions. The paper will chooseTamarix cone in the southern region of the Taklimakan Desert as the main object of study,analyze the positive ion of the sedimentary veins in the layers of the fallen leaves of Tamarix cone.（1） Analyzing the content of Ca²⁺, K⁺, Na⁺, Mg²⁺from the sedimentary veins of Tamarixcone in the layers of the fallen leaves, the result indicating that the content of Ca²⁺is thehighest, and it has a good relativity between the total amount of positive ion, which indicatesthat the total amount of positive ion or the content of Ca²⁺can be used to analyze theenvironmental change. The sampling points located nearby oasis edge area or rivers, thecontent of positive ion is inverse ratio to temperature, that means when the temperatureincreases, the positive ion content decreases.（2） The results of the annual average temperature reconstruction and the annual averagewind speed reconstruction of Andier meadow of Minfeng county （since1922） and Damagouof Qira county （since1884） in the southern region of the Taklimakan Desert are in accordancewith the measured results. The results showed that the annual average wind speed is inverselyproportional to the average annual temperature, that indicates when the wind speed is big, thetemperature will be lower, the climate becomes cold; On the contrary, when the wind speed issmall, the temperature will be higher, the climate becomes warm.（3） There is a good correspondence between the changes of positive ion content from thesedimentary veins of Tamarix cone in the layers of the fallen leaves and the regional floodevents.（4） The thickness of the sand is connected with the richness of the sand source; and thethickness of the sand layer is proportional to the annual average wind speed, the greater thewind speed is, the thicker the sand layers are, however, it is inversely proportional to theaverage relative humidity in the location of the sand layer, that is the smaller the humidity is,the thicker the sand layers are.（5） The positive ion content of fallen leaves of Tamarix cone can be a kind ofinformation carrier, which can indirectly reflect the climate element changes. And it providesa kind of research method for the environmental evolution in the southern region of theTaklimakan desert.