Transformation mechanism of ions on different waters in alpine region.

The study investigates transformation mechanism of ions on different waters in Alpine region through analyzed the hydrochemical characteristics of the major ions of precipitation, glacier and snow meltwater, supra-permafrost water and river water in permafrost regions in the Tibetan Plateau under climate warming. The results showed that, The relation between recharge and discharge was the major ways for ionic transformation of each water body. Precipitation and glacier and snow meltwater are the main input sources for ionic transformation, and river water is the final output source. Different water bodies had different ionic concentrations and different hydrochemical types. However, different water bodies in different months (from June to September) also had different hydrochemical types. The water - rock interaction, reactions for ions, dilution effect and other effect for ions played an important role in the process of ion transformation. The increasing of temperature would lead to the accelerated melting of glaciers, permafrost and snow in the alpine regions, so the amount of supra-permafrost water and glacier and snow meltwater will increase, which leads to the increase of runoff. Meanwhile, the increase of temperature makes evaporation stronger. The strong of evaporation will accelerate the transformation of liquid water to gaseous water. Moreover, ion translation and water conversion are synchronous. Accordingly, ions are also accelerating transformation in the process of accelerated transformation of water body. Climate change is not only the main driving force for multiphase water transformation, but also the main driving force for the ion transformation of various water bodies.

The sources of supra-permafrost water and its hydrological effect based on stable isotopes in the third pole region.

The sources of supra-permafrost water and its hydrological effects were studied, based on the presence of stable isotopes in 562 samples collected in different ablation periods from the source regions of the Yangtze River. The δ18O (δD and d-excess) values for the initial ablation, ablation, and end ablation periods were -10.18‰ (-71.39‰ and 10.08‰), -12.14‰ (-85.58‰ and 11.51‰) and -11.50‰ (-78.75‰ and 13.23‰), respectively. The order of the slopes for the supra-permafrost water evaporation lines from the different ablation periods was initial ablation (IA) > ablation (A) > end ablation (EA). An anti-altitude effect is documented here, for a specific altitude range, in what is believed to be the first record of such an occurrence. Outside of that range, clear altitude effects were apparent. We have been able to show that supra-permafrost water was mainly recharged by atmospheric precipitation, ground ice, and glacier and snow meltwater, in the initial ablation and end ablation periods, and contributions from glacier and snow meltwater were mainly concentrated in higher altitude regions. In contrast, in the ablation period, supra-permafrost water was mainly recharged by atmospheric precipitation and ground ice. The contributions of precipitation to supra-permafrost water were 78.79%, 85.47%, and 82.99% in the initial ablation, ablation, and end ablation periods, respectively. The contributions of ground ice to the supra-permafrost water were 14.05%, 14.53%, and 11.94%, respectively, while contributions of glacier and snow meltwater were 7.15% and 5.07% in the initial and end ablation period. For the initial ablation, ablation, and end ablation periods, contributions from atmospheric precipitation to the supra-permafrost water were 85.47%, 86.86%, and 86.84%, while contributions from ground ice were 14.53%, 13.14% and 13.16%, respectively.

[Characteristics of Stable Isotopes and Analysis of Water Vapor Sources of Precipitation at the Northern Slope of the Qilian Mountains].

This study is based on precipitation samples from eight sites at the northern slope of the Qilian Mountains, combined with meteorological factors over the same period. Precipitation isotope characteristics, influence factors and the vapor sources of precipitation were analyzed, and the results show that:① The stable isotopes of precipitation in the study area show obvious seasonal changes, which are characterized by enrichment in the summer half-year and depletion in the winter half-year. The spatial precipitation δ18O value shows a significant downward trend with increasing altitude, and the altitude effect of the annual precipitation δ18O is -0.19‰/100 m, respectively;② At all stations, the slope and intercept of local meteoric water lines show an increasing trend from low altitude to high altitude. The high-altitude mountains above 2000 m are affected by local water vapor recirculation;③ The temperature effect is more significant and the temperature effect of δ18O is 0.64‰, and there is only a weak precipitation effect in summer;④ The results indicate that sub-cloud evaporation has a great influence on the δ18O of precipitation; the average raindrop evaporation rate of δ18O is 23%, 11%, 12%, and 16%,and the δ18O composition has been enriched by 46%, 27%, 38%, and 32% in May, June, July, and August from cloud base to ground, respectively.⑤ Under the condition of continuous rainfall in summer, the vapor sources of precipitation mainly come from the west and are affected by local evaporation of water vapor. The study enhances knowledge of isotopic evolution of precipitation and provides a basis for further study of isotopic hydrology in arid regions.

[Space-Time Characteristics and Environmental Significance of the Stable Isotopes in Precipitation in the Gulang River Basin].

Based on the precipitation samples and meteorological data simultaneously collected during individual precipitation events at the Gulang (2085 m a.s.l.) and Anyuan stations (2700 m a.s.l.) in Gulang, this article analyzes the temporal variation and local meteroic water lines and discusses the relationship between precipitation stable isotopes and temperature and precipitation and relative humidity. The results show that:① Gulang and Anyuan have higher δ18O values in summer and autumn and lower δ18O values in spring and winter, respectively; ② The vaule of δ18O decreases with increasing altitude, while the value of the d-excess increases, reflecting the gradual depletion of stable isotopes of precipitation when the air mass is rising along the slope; ③ The slope and intercept of the local meteroic water lines deviate from that of the global meteroic water lines, showing that they may also be affected by local water vapor recirculation, except for the dry environment and strong evaporation effect; and ④ The temperature effect of Gulang in the low-altitude area is more significant than that of the Anyuan station and the Gulang River Basin does not show a precipitation effect. It has been proven that precipitation is not the fundamental factor determining the δ18O of the precipitation in arid areas. The results of this study are helpful to further understand the water circulation mechanism in the Gulang River Basin.

[Environmental Significance of the Stable Isotopes in Precipitation at Different Altitudes in the Tuolai River Basin].

Precipitation samples and meteorological data were collected simultaneously during individual precipitation events at Tuole station (3367 m a.s.l.) and Jiayuguan station (1658 m a.s.l.) in the Tuolai River Basin. A study of temporal variation, Local Meteoric Water Lines, and altitude change on precipitation stable isotopes was conducted. The relationships between precipitation stable isotopes and temperature, precipitation, average vapor pressure, and relative humidity were determined in order to explore the environmental significance of the stable isotopes at different altitudes in the middle reaches of the Qilian Mountains. The analysis indicated that the stable isotopes of the precipitation in Tuole and Jiayuguan station were characterized by pronounced seasonal variation, with Tuole having higher δ18O values in summer and autumn and lower δ18O values in spring and winter, while Jiayuguan displays higher δ18O values in spring and lower in other seasons. The d-excess was correlated negatively with δ18O, and the correlation coefficients between δ18O and d-excess decreased with increasing altitude due to weakening sub-cloud evaporation. The slope and intercept of the Local Meteoric Water Lines from Jiayuguan to Tuole rose significantly, showing an increasing trend from low altitude to high altitude. For the precipitation events above 10℃, δ18O of Tuole was positively correlated with the temperature, but the Jiayuguan results indicated the opposite. Sub-cloud evaporation weakened with high precipitation events in Jiayuguan. δ18O and d-excess were positively correlated with the average vapor pressure, which declined from Tuole to Jiayuguan. Since the water vapor pressure and saturated water vapor pressure increased, it was difficult to form precipitation with decreasing altitude. The local strong sub-cloud evaporation caused δ18O and δD was positive at low altitude, while the effect of moisture recycling is obvious, such that δ18O and δD are negative in high altitude areas. There is no significant positive correlation between the δ18O and the relative humidity of the precipitation in Jiayuguan, while Tuole displays an opposite pattern. The results of the study will provide a scientific basis for further study of precipitation isotopes in the Tuolai River basin.