Characteristics Of Hydrogen And Oxygen Isotopes In Different Water Bodies In The Lower Tarim River And Tamarisk Water Use Strategies

Water is an important factor limiting plant growth in arid area.The lower reaches of Tarim River is in extreme arid area with little precipitation,so plant growth depends on river water and groundwater.The choice of plant water sources depends on the distribution of available water in the habitat and the plant's ability to use water.As a widely distributed shrub plant in arid and semi-arid areas,Tamarix has very important ecological and economic value.By using hydrogen and oxygen stable isotope technology to quantitatively analyze the water sources of Tamarix ramosissima,we can reveal the water use strategies of Tamarix ramosissima species in different growing periods and different habitats,enhance the cognition of water use strategies of desert plants,and provide scientific basis for desertification control and vegetation construction.This experiment will be carried out in 2019-2020.The river water,groundwater,soil water and plant samples are collected from different sections of Yingsu section,Khaldayi section,Yiganbu section and Ma section in the lower reaches of Tarim River.Using hydrogen and oxygen stable isotope technology and isotopic linear mixing model,direct view method and Iso Source software,An analysis of the hydrogen and oxygen isotope characteristics of tahe downstream in different water bodies,quantified the tamarisk in different periods of water depth,analyzes the lower reaches of tarim river tamarisk water use strategy,mainly to the following conclusion:according to the lower reaches of tarim river water,river water,groundwater,soil measured by 18 o established the lower reaches of tarim river delta and?D the water evaporation equation:?D=4.123?¹⁸O-32.012(R²=0.985),groundwater evaporation equation:?D=5.015?¹⁸O-25.775(R²=0.724).Compared with the global precipitation line?D=8?¹⁸O+10 and the global precipitation line?D=7.27?¹⁸O+6.47(R²=0.94),the intercept and slope of the soil water evaporation line?D=3.0779?¹⁸O-45.786(R²=0.897)are smaller,which shows the characteristics of arid area.The fluctuation of ?¹⁸O in the lower reaches of the Tarim River is smaller in autumn than in summer,and the fluctuation of?¹⁸O in summer is larger,which is due to the influx of new water sources brought by the ecological water transport project in autumn.18 in all times,the river delta o show kaerdayi cross-section profile>the Sue in accordance with dry cloth and linen section,reason may be that the British and the cross sections in accordance with dry cloth and linen section downstream water respectively from tahe starting point Da Xi Hai Zi reservoirs and tahe rump at close range the tema lake,there is a close water isotope exchange content,middle river water is relatively closed,illiquid evaporation;The?¹⁸O of the groundwater in the lower reaches of the Tarim River is more negative in summer than in autumn,and the general fluctuation range is very small.The?¹⁸O of the groundwater in all the sample sites are close to each other,which indicates that the groundwater in the lower reaches of the Tarim River is recharged by the same source,and the physical and chemical properties of the groundwater in the inner reaches of the Tarim River do not change in the seasonal range.The?¹⁸O of soil water in the lower reaches of Tarim River became negative gradually with the increase of soil depth,and showed a good linear relationship with soil depth.The R²of the sample point with the best correlation was0.98.In summer,soil water?¹⁸O was most enriched in July,and depleted in September and October.Soil water?¹⁸O in July was depleted in F3 and F11 in the UK and the Soviet Union compared with that in September and October.Therefore,it is speculated that the soil water supply pattern at these two sample points is different from that at other sample points.According to the principle of conservation of isotope mass,the recharge ratio of river water and groundwater to soil water in Yingsu section is calculated.With the increase of soil depth,the recharge ratio of groundwater keeps increasing.In the lower reaches of the Tahe River,the soil water content reached the maximum in September,and was close to that in July and October.After ecological water transport,the soil water was directly fed by the river,and there was no significant correlation between the soil water content and the?¹⁸O of the soil water.In July,Tamarix ramosissima mostly used soil water below 90cm or even 150cm.In autumn(September and October),the soil water absorption level of Tamarix ramosissima increased to 70?90cm.In the non-water transfer period,T.chinensis had a higher utilization rate of river water and ground water,but decreased in the water transfer period.The rule of absorption and utilization rate of Tamarix in Yingsu section is higher than that of ground water,while the rule of absorption and utilization rate of Tamarix in Kar Dayi section is higher than that of river water.In the non-water transfer period,the longer the distance from the river channel,the lower the utilization ratio of river water and groundwater,but there is no obvious rule in the water transfer period.