The composition of hydrogen and oxygen stable isotopes in lake water is important to the researches in hydrology, meteorology and paleoclimatology. In this study, long-term and continuous measurement on the compositions of HDO and H218O in lake water (δDL and δ18OL) was conducted over Lake Taihu, the deuterium excess (dL) was calculated, and the temporal variability and controlling factors were analyzed. The results indicated that ① the variation of isotopic enrichment in lake water was significant, ranging from -59.8‰ to -24.2‰ for δDL, from -8.6‰ to -2.6‰ for δ18OL, and from -7.9‰ to 12.9‰ for dL, respectively. In comparison to cold season, δDL and δ18OL were higher and dL was lower during warm season. ② On monthly time-scale, lake evaporation and the ratio of total water inputs lost by evaporation controlled the isotopic enrichment in lake water. When lake evaporation or the ratio increased, δDL and δ18OL increased, but dL decreased. ③ Over Lake Taihu, the isotopic composition in precipitation and water temperature did not control the isotopic enrichment. The results provide scientific reference for isotope hydrology and the researches related to the isotopic enrichment in lake water in meteorology and paleoclimate.
Keywords: H218O; HDO; controlling factors; lake; temporal variability.