A review of eco-hydrology of stable isotope of water bodies in global alpine mountains

The alpine mountains serve as significant water conservation and ecological barrier areas. Building upon prior research findings, this study aims to synthesize the knowledge of isotope ecohydrology in alpine mountains worldwide. The study establishes that the local meteoric water line in global alpine mountains is δD = 7.91×δ¹⁸O + 8.49 (R² = 0.95), exhibiting a lower slope and intercept than the global meteoric water line. Stable isotopes in precipitation, groundwater, and glacier snow meltwater in these mountains show a diminishing trend with increasing latitude. Moreover, river water follows a decreasing trend from south to north and from west to east. Furthermore, the temperature effect of stable isotopes in precipitation becomes more pronounced at higher latitudes. In most regions of middle and low latitudes, the influence of precipitation on stable isotopes is evident. Moisture sources in the study region are complex, primarily dominated by the southwest monsoon, westerly winds, and Atlantic water vapor. Due to the differences in water supply and environmental effects, the slope of the local evaporation line of stable isotopes in different water bodies is glacier snow meltwater > groundwater > river water. Vegetation in alpine mountains primarily relies on soil water, and the water utilization rate by plants closely correlates with vegetation types and the regional environment. Water vapor recirculation is an important part of the source of precipitation moisture sources. Based on an analysis of existing data and research on eco-hydrology in alpine mountains, this study highlights the paucity of studies exploring the coupling of complex multi-parameter hydrological models and stable isotope tracing. Consequently, there is an imminent need to develop a novel eco-hydrology model based on stable isotope tracing, to comprehensively elucidate the isotope eco-hydrology processes in cold regions.