Hydrogeochemistry And Environmental Isotope Study In Turpan Basin

Northwest region has always been our focus area of hydrogeological studies.Turpan Basin is located in eastern Xinjiang.There are iron ore,coal and other minerals located in Turpan Basin.The study of the formation and evolution of groundwater chemical composition is important for the utilization and protection of water resources.Predecessors have done a lot of work in this area and draw a number of important conclusions.This paper adopted the hydrological geochemical and environmental isotope method,combined with the topography and geomorphology,hydrology geology condition to research main chemical composition formation of groundwater of turpan basin and division of groundwater flow system.Research shows that in the low salinity stage,groundwater hydrochemistry change is mainly caused by mineral weathering dissolution;Increases as the salinity,the effect of evaporation salt dissolving became more and more obvious.Based on the topography and geomorphology,hydrology and meteorology and hydrology geological condition of the study area,the author believes that evaporation salt mainly comes from three sources:(1)the farmland irrigation water evaporation,the evaporate mineral is formed in the surface of soil layer,it is associated with irrigation water canals and field crops;(2)groundwater evaporates and mineral formed in soil and the vadose zone in shallow groundwater area;(3)floating sand and dust from the ground surface sediment in aydingkol lake and other dry salt lake landing to different locations.According to D—18O relation of groundwater samples of different deptn,Lurpan basin is divided into several flow systems:1)groundwater flow system is similar in the north of the Mountain of Flames:the typical groundwater flow forms as below:precipitation and snow melting water on the mountain flow through the watercourse and constantly recharge groundwater.Groundwater flow stopped by bedrock and became spings and oasins.Groundwater can enter the south of the Mountain of Flames through few gaps;2)There are several water systems in the south of the Mountain of Flames,which can be divided into two categories based on its forming conditions:? under natural conditions,groundwater discharge to aydingkol lake from east and west sides,at the same time,the south stream also discharge to aydingkol lake;? Due to people's life and activities concentrated in turpan city,the water consumption is big,so in order to satisfy local people's demand,coordinating a variety of water diversion is necessary.Therefore formed mixed water infiltration in turpan city and discharge to aydingkol lake.Since the middle holocene,the water level and area size of lake aydingkol,YiBiHu and the badain jaran desert declines and retreats in different degrees.Research shows that the climate of northwest part of our country has transimited from wet to dry and rainfall decrease and evaporation capacity increase in the past 6000 years.The author using radioactive isotope tritium and 14C to divide recharge time of groundwater.Except a stream from the KuMDaGe desert is recharged in late pleistocene glaciation,all of the groundwater was recharged in holocene wet period.lt is further proof and supplement the analysis resultsof stable isotope.