Experimental study on the fractionation mechanism of hydrogen and oxygen stable isotopes in evaporation from water surface of evaporation pans

There is a close relationship between meteorological factors and evaporation.In this paper, the relationship between evaporation fractionation factor of stable isotopes and meteorological factors is analyzed through the water evaporation experiments under different meteorological conditions.The results indicate that the residual water is gradually enriched in heavy isotopes along with the evaporation In the outdoor evaporation experiment, isotopic stratification phenomenon takes place in different water layers of the evaporation pans where the isotopic ratios of surface water are more concentrated than that of deeper water due to the discrepancy of the sunlight radiation, heat convection and wind speed.It is also shown that the fractionation factor of stable isotopes is inversely proportional to the evaporation temperature.Moreover, the evaporation line of outdoor experiment obviously deviates from the local meteoric water line, which demonstrates that the evaporation action of the surface water is strong in course of the experiment Therefore, the research provides credible experimental data for revealing the evaporation fractionation mechanism further.