Analysis on possible evolution of hydrogen and oxygen isotopes in lake water in Qaidam Basin, China

摘要

The δD-δ~(18)O line features of water bodies are very important properties of isotopic characteristics. The slope of the line is controlled by the environmental condition of the area. The hydrogen and oxygen stable isotopic transport of lake water in Qaidam Basin is mainly effect by temperature and relative humidity. Lake water samples show two groups due to heterogeneous distribution of lake water. Group 1 is depleted samples which indicate originated lake water that did not suffer the evaporation processes. Group 2 is highly enriched in isotopic compositions due to evaporation. The regression line of lake water in Qaidam Basin is δD = 3.13δ~(18)O - 21.61. The slope of theoretical evaporation line has positive relationship with relative humidity and has negative relationship with temperature. The effects analyses of temperature and h on the slop of evaporation line show the residual ratio ∮of Group 2 lake water samples are between 0.5-0.7. If Group 1 samples represent the initial isotopic composition of lake waters, the above results indicates that the most evaporated lake water (the Group 2) having lost 30%-50% of their initial volume.