Modeling the Evaporation Line of Lake Water Isotopes in Golmud Drainage Basin, P.R. China

The δD-δ18O line features are very important properties of isotopic characteristics. The δD-δ18O line usually is estimated by regression analysis when samples are sufficient. In thisSuperscript text paper, the isotopic characteristic of rain water, shallow groundwater and lake water in Golmud drainage area of Qaidam Basin were analyzed, and the isotopic evaporation line of lake water was calculated with Rayleigh fractionation function because the regression analysis method is insufficient in the condition that measured samples of lake water are short. The result shows that the groundwater is the main source of lakes; and the isotopic fractionation of hydrogen and oxygen in lake water controlled by kinetic effect in the process of evaporation. The calculated evaporation line of lake water is δD=3.26δ18O-21.00, which is matched with measured samples. The sensitivity analysis of the slop to the temperature, dissolved salt composition in lake water and relative humidity of air shows that the slop is negative related to the temperature and dissolved composition and is positive related to relative humidity. In typical environmental condition, the slop is increased by 0.0303, 0.1016 and 0.0205, respectively, when temperature decreased 1°C, dissolved NaCl decreased 1mol/L and relative humidity increased by 1%.