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Altitudinal Variations and Local Emission Contributions to Black Carbon and Ion Deposition on Tibetan Plateau Glaciers

Yixi Liu , Chao Zhang, Fangping Yan, Pengling Wang, Chaoliu Li

Abstract

Rationale. Glaciers in the Tibetan Plateau (TP), especially in the Himalayas, are retreating rapidly due to rising air temperature and increasing anthropogenic emissions from nearby regions. Traditionally, pollutants deposited on the glaciers have been assumed to originate from long-range transport from its outside. Methodology. This study investigated the concentrations of black carbon (BC) and major ions in snowpit samples collected from two glaciers in the southeastern TP (Demula and Palongzangbu) and one glacier in the west Himalayas (Jiemayangzong). The radiative forcing of BC was calculated based on BC concentration and glacier characteristics. Results. The results revealed that BC/Ca2+ ratio in snowpit samples from Palongzangbu, located near residential villages, is around 2.05 times higher than that of Demula, which is mainly influenced by long-range transported pollutants. Furthermore, on Jiemayangzong glacier, snowpit samples collected with 100 m vertical resolution, exhibited that BC-induced radiative forcings at low altitude are approximately 2.37 ± 0.16 times greater than that of high altitude. Discussion. These findings demonstrated that, in addition to long-range transport, emissions from local residents also make substantial contributions to BC and certain major ions (e.g., SO2- 4). To accurately assess the sources and radiative forcing of BC and other light-absorbing impurities on glaciers of the TP, it is necessary to consider the impact of local populations and altitude-dependent variations.

EN24093  Accepted 19 February 2025

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