Formation of glacier runoff on the northern slope of Tavan Bogd mountain massif based on stable isotopes data

Abstract

This investigation is based on measurements of stable isotopes concentrations (δD and δ18О) in water, snow and ice samples. Glaciers are composed of ice, snow, and fi n of atmospheric origin. The isotopic composition of these components is different, so when melting they form the melted glacial water with different isotope characteristics. Summer precipitation contains the heaviest isotopes, but only a small part of them remains on the glacier. The average isotopic composition of glacier ice represents the average composition of precipitation that accumulates on it. However, snow and fi n of different seasons can occur on the glacier surface, the isotopic composition of which differs from the isotopic composition of glacier ice. At different times of the ablation season different parts of the glacier melt, therefore the isotopic composition of melt waters will be different. Differences in the isotopic composition of the major runoff-forming components on the Northern slopes of the massif Tabyn-Bogdo-Ola had been identified. A part of melting ice in the formation of the runoff on this massif is determined by estimation of the isotopic composition of snow, ice, and fi n on different glaciers of this region. The average δ18О of snow on the glacier surface is −11.9‰, and this snow can be attributed to the precipitation fallen in late spring or early summer. Measured average isotopic composition of precipitation (δ18О = −11.9‰) was compared with the online calculator of the isotope content in precipitation (OIPC). The isotopic composition of glacial melt waters on the Northern macro-slope in the middle of July 2015 (δ18О = −15.3‰) differs from the isotopic composition of the territory of the Mongolian part of the massif (δ18О = −17.4‰) obtained from results of the analysis of eight samples taken at different edges of the glaciers at the beginning of August 2013. Isotopic separation shows important role of summer snow in feeding the glacial rivers of the massif even in the middle of the ablation season, especially for glaciers in the central part of the massif. The role of seasonal snow in feeding the glacier streams depends on the morphological type of glacier. It is maximum for corrie glaciers and minimum for the valley ones.

Water Stable Isotopes in the Central Altai Mountainous Rivers as Indicator of Glacier Meltwater Fraction in Runoff

“…The isotopic composition of the ice from Bolshaya Taldura can be used in further isotopic separation research in the upper Chuya basin as the isotopic composition of meltwater. The obtained mean δ 18 O value is close to the isotopic composition of ice in the Eastern Altai [14]. In the Western Altai, glacier ice must be enriched with stable isotopes according to the greater fraction of summer snow in glacier feeding.…”

“…(Seasonal snow was The local meteoric water line (LMWL) was plotted from the event-based precipitation samples for each elevation separately. The slope of these lines is lower than that of the GMWL, which is common for Inner Asia summer precipitation [13,14,26,27]. The LMWL of the samples from the glacier surface (Figure 2, 3000 m) is close to the GMWL.…”

“…Earlier, we performed isotope studies at the Tavan-Bogdo-Ola, Tsambagarav and Mongun-Taiga mountain ranges [13,14]. In 2022, the first isotope samples were taken in the Taldura river basin [15].…”

The Components of the Glacial Runoff of the Tsambagarav Massif from Stable Water Isotope Data

“…Therefore, ancient glacial ice plays a significant role in the formation of the water balance of the territory. A similar investigation at the northern slope of Tavan-Bogd mountain massif (the border between Russia, China, and Mongolia) showed that the contribution of melted seasonal snow in glacier runoff at this massif was more significant than at the Tsambagarav [22].…”

Isotopic Composition of Glacier Ice and Meltwater in the Arid Parts of the Altai Mountains (Central Asia)

“…Most of the meltwater samples were taken in the Tavan-Bogd massif. Sampling was carried out in 2015 [19], 2018 and 2021 in the middle of ablation season. Meltwater samples were taken from the edges of most glaciers on the northern slope (Russian part of this massif).…”