Research On Water Source Information Recorded By Tamarix Cones In Lop Nur Region

The stable isotopes in natural water bodies and plant leaves are rooted in atmospheric water.The stable isotopes in atmospheric water participate in different circulation modes and water cycles of the atmosphere in the form of water vapor transport on a global scale,thus exhibiting extensive temporal and spatial distribution heterogeneity.When various kinds of water with different stable hydrogen and oxygen isotope ratios are converted into soil water and enter the plant body,they will respond to the changes in the atmospheric water environment with different composition characteristics.Therefore,stable isotope is a new index for studying water vapor sources,atmospheric circulation patterns and inversion of climate and environmental changes.In Lop Nur region has an arid climate,lacks of water resources,and prominent contradictions in water use,resulting in an extremely fragile ecological environment.It is one of the sensitive areas in response to the global climate and environmental changes.This paper takes this area as the key research area,uses the stable isotope data of 25 small watersheds from Taiyuan,Shanxi Province to Yecheng,Xinjiang Uygur Autonomous Region,and uses the Meteo Info model to simulate and analyze the differences and differences in water vapor sources in different regions.The stable isotope characteristics of water bodies in small watersheds and nearby plant leaves under the background of water vapor sources,and the isotope data of Tamarix Cones in Lop Nur area were used to explore the sources of water vapor in Lop Nur area.The researched result indicates:(1)The values of?¹⁸O and?D in the water bodies of small watersheds in the wide-area study area show a spatial pattern of decreasing from east to west.Compared with the stable isotope range of atmospheric precipitation in the world,China and the arid area of northwest China,the range of stable isotope values of water bodies in the small basins of the wide-area study area is relatively small,except for the?¹⁸O value of Aksai Xiaosugan Lake.In the national stable isotope range of atmospheric precipitation,other hydrogen and oxygen isotopes fall within the stable isotope range of atmospheric precipitation in the world,China and the arid region of northwest China.(2)The small watershed waterlines of the wide-area study area and the three sub-regions(i.e.Xinjiang Tarim Basin,Hexi Corridor and Eastern Loess Plateau)are?D=3.75?¹⁸O-27.23,?D₁=4.17?¹⁸O-24.11,?D₂=3.23?¹⁸O-26.59,?D₃=4.24?¹⁸O-28.28.The R²values in the formula are all high,respectively 0.88,0.81,0.91 and 0.95,indicating that the distribution of stable isotopes in the small watershed of the study area is relatively concentrated,and the composition of the two stable variables has a high consistency,which also indicates that the composition and changes are affected.In proportion to the global and Chinese atmospheric vertical lines,the slope and intercept of the waterline of the small watershed in the study area are small,and the intercept is negative,indicating that the temperature in the study area is high,the humidity is low,and the water body is strongly affected by non-equilibrium evaporation.Most of the hydrogen and oxygen isotope values fall near the atmospheric refractive index line,indicating that the orientation has a certain replenishment effect on the small watershed in the study area.(3)The d value of the wide-area study area is lower than the d value of global atmospheric precipitation,showing a spatial pattern gradually increasing from east to west.The d value in the Tarim Basin in Xinjiang is the highest,indicating that its water vapor originates from arid areas,and it also characterizes weak monsoon activity and strong westerly wind transport.The average value of d in the Hexi Corridor and the eastern part of the Loess Plateau is much lower than the global average of d,indicating that the water vapor in these two subregions comes from areas with relatively humid climates.(4)The sources of water vapor in the wide-area study area mainly include five sources of water vapor in the west wind zone,East Asian monsoon water vapor,polar air mass water vapor,South Asian monsoon water vapor,and local recirculation water vapor.In terms of spatial scale,the water vapor in the west wind belt can affect various subregions and always dominates.The East Asian monsoon water vapor is difficult to reach the Tarim Basin in Xinjiang.The influence of water vapor in the west wind,locally recirculated water vapor,East Asian monsoon water vapor,and polar air mass water vapor has a tendency to"decrease from one to the other"from west to east.The South Asian monsoon water vapor has the least impact on the wide-area study area.In terms of time scale,the contribution ratio of water vapor sources shows obvious seasonal variation:the average water vapor ratio in the west wind is high in autumn and low in summer,the average water vapor ratio in the polar air mass and the East Asian monsoon water vapor is high in summer and low in autumn,and the average water vapor ratio of local recirculation is low in autumn.Winter is high and summer is low.The South Asian monsoon water vapor is only transported to the wide-area study area in summer,and there is no water vapor input in other seasons.(5)From the perspective of spatial scale,the water vapor in Milan area mainly comes from the combination of 80%?100%water vapor in the westerly zone and0%?20%polar air mass.The water vapor in the ancient city of Andir mainly comes from a single westerly water vapor or 60%to 80%from the west wind water vapor and 20%to 40%from a combination of local recirculated water vapor.The water vapor in Damagou mainly comes from a single westerly water vapor or a combination of 80%to 100%of the water vapor in the west wind and 0%to 20%of the local recirculated water vapor.(6)From the time scale,the water vapor source changes in the Lop Nur and southern region of Taklimkan Desert are divided as follows:Milan is divided into four stages,namely 1839?1910,1911?1923,1924?1976 and 1977?2006 The ancient city of Andir is divided into three stages,namely 1792?1829,1830?1905,1906?2010;Damagou is divided into five stages,namely 1630?1817,1818?1896,1897?1917,1918?1937,1938?2008.The sources of water vapor at different stages all reflect the situation where water vapor in the westerly zone is dominated,and water vapor in polar air masses and locally recycled water vapor are supplemented.