Stabal Isotopeanalysis Of Atmospheric Precipitation In The Same Latitude On The Loess Tableland

The content of hydrogen and oxygen stable isotopes of precipitation is not high, it changes with latitude, altitude, seasonal changes, temperature, precipitation and other factors that have a relationship, the change process has certain features and its own pattern. This study is in the background of the Loess Plateau, we mainly select Qing Yang City, Huan County Qing Yang City, Gansu Province, An Sai County, Yan An City, Yan Chang County Yan An City, Hai Yuan County,Zhong Wei City, Datong city and Jie Xiu city seven pilot sites, the study period including the full year 2015, and in each test point we collect rainfall in months. In this study we used the precipitation collection devices that were made by Chinese Academy of Agricultural Water Saving in Arid Regions of Northwest A and F University for each test point rainfall collection After several months of equipment product and cleaning work, we installed rainwater collection device on a regular basis at each test point for their rainwater harvesting, and the hydrogen and oxygen stable isotopes of the samples were analyzed and measured to obtain the samples’ s oxygen stable isotope values ??of different points in the month, and then we can come to the Loess Plateau latitude precipitation with hydrogen and oxygen stable isotopes and their spatial and temporal distribution of temperature, precipitation and response relationship, the initial establishment of the study area local meteoric water line equation, to facilitate future studies, to analyze the source of terrestrial water cycle of water vapor, water vapor transfer, motion and subsequent relevant tests relating to the Loess Plateau groundwater recharge sources to provide basic data and theoretical basis. The results of this study show that:Compared with the global meteoric water line equation, Regional equation slope and intercept of atmospheric precipitation lines were lower. The slope and intercept is smaller,more intense precipitation in the presence of evaporation, cloud show raindrops by secondary evaporation occurs under strong dynamic isotope fractionation in the precipitation process, so that the slope and intercept precipitation line becomes small.The process of stable isotopes in precipitation of each tested point in the Loess Plateau with same latitude have different variations and influence, Hai Yuan County mainly affectedby temperature effects, seasonal changes and their stable isotope values are mainly high in summer and low in winter,Datong City caused by monsoon activity effects of precipitation and low temperature which make its value of stable isotopes in precipitation significantly lower than other test points, the stable isotopes in precipitation of Qing Yang City, and Huan County, Qing Yang City do not have obvious stable isotopes seasonal variation.the stable isotopes in precipitation of An Sai County,, Yan Chang County, and Jie Xu City are almost high in winter and low in summer.The study of atmospheric precipitation δ¹⁸O each test point is mainly affected by temperature and precipitation, each of the test points with different characteristics: Hai yuan County Main Effect by temperature, the precipitation have higher δ¹⁸O value, while the remaining points due to strong impact of the monsoon rainfall effect caused by the activities,resulting in precipitation δ¹⁸O value of its relatively low, especially in pilot sites in Datong,precipitation effects caused by monsoon activity and colder climates such that the value of its significant δ¹⁸O lower than other test points.