Stable Isotopes In Different Water Samples And Their Relation With Moisture Sources At The Monh Hayrhan Glacier, Altai Mountains

Altai Mountains are the northern periphery of the central Asian mountain system and the southern periphery of the Asian Arctic basin, which makes those mountains as ideal areas for the analysis of climatic records relating to both westerly jet and polar air masses.Based on field survey and experiment, the characteristics of hydrogen and oxygen isotopic composition of fresh snow, refreezing ice, meltwater, glacial-fed river water and snow pit samples collected at the Monh Hayrhan glacier, Altai Mountains were analyzed.We observe a reverse altitude effect of stable oxygen isotopic composition (δ18O) in fresh snow, refreezing ice and glacial river samples, with altitudinal gradients 1.2‰ /100m for fresh snow,0.6‰/100m for refreezing ice and 0.4‰/100m for glacial river. Based on the HYSTLIP air trajectory model, we attribute the reverse altitude effect of stable isotopes to different moistures at different altitudes. At high altitudes, water vapor evaporated from the Caspian might make the largest contribution to the snow, while at low altitudes most of the water vapor might come from Arctic or west Siberia.The high d-excess values in snow pit samples indicate that at least in the early summer in 2010 the reevaporated vapor made a great contribution to the precipitation of study area. Based on the HYSTLIP air trajectory model, we plotted the mean backward trajectories during May to June of 2010. The trajectories show that water moisture for precipitation of the study area mainly origin from the evaporation of wetland in West Siberia. The reevaporated vapor from the Caspian and west Siberia both lead to high d-excess in precipitation at different altitudes.By aid of the data from GNIP (Global Network of isotopes in Precipitation) and previous study, we made a further discussion on the isotopic composition in precipitation of Altai Mountains and the surrounding areas. We found remarkable differences in spatial and temporal distributions of δ18O and d-excess in precipitation between the southern and northern Altai. We attribute those differences to the different influence of polar air mass.Daily variations of δ18O and d-excess are quite slight in both meltwater and glacial-fed river water. The former might indicate the slight melting at high altitude while the later might be caused by the supplying of ground water and soil water.