The Indo-Gangetic Plain (IGP) is a major regional and global emitter of atmospheric pollutants, which adversely affect surrounding areas such as the Himalayas. We present a comprehensive dataset on carbonaceous aerosol (CA) composition, radiocarbon (D14C) -based source apportionment, and light absorption of total suspended particle (TSP) samples collected over a 3--year period from high-altitude Jomsom in the central Himalayas. The 3-year mean TSP, organic carbon (OC), and elemental carbon (EC) concentrations were 92.0 +/- 28.6, 9.74 +/- 6.31, and 2.02 +/- 1.35 lg m-3, respectively, with the highest concentrations observed during the pre-monsoon season, followed by the post-monsoon, winter, and monsoon seasons. The D14C analysis revealed that the contribution of fossil fuel combustion (ffossil) to EC was 47.9% +/- 11.5%, which is consistent with observations in urban and remote regions in South Asia and attests that EC likely arrives in Jomsom from upwind IGP sources via long-range transport. In addition, the lowest ffossil (38.7% +/- 13.3%) was observed in winter, indicating large contributions in this season from local biomass burning. The mass absorption cross- of EC (MACEC: 8.27 +/- 1.76 m2/g) and watersoluble organic carbon (MACWSOC: 0.98 +/- 0.45 m2/g) were slightly higher and lower than those reported in urban regions, respectively, indicating that CA undergo an aging process. Organic aerosol coating during transport and variation of biomass burning probably led to the seasonal variation in MAC of two components. Overall, WSOC contributed considerably to the light absorption (11.1% +/- 4.23%) of EC. The findings suggest that to protect glaciers of the Himalayas from pollution-related melting, it is essential to mitigate emissions from the IGP.(c) 2022 China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).

As an important component of carbonaceous aerosols (CA), organic carbon (OC) exerts a strong, yet insufficiently constrained perturbation of the climate. In this study, we reported sources of OC based on its natural abundance radiocarbon (14C) fingerprinting in aerosols and water-insoluble organic carbon (WIOC) in snowpits across the Tibetan Plateau (TP) - one of the remote regions in the world and a freshwater reservoir for billions of people. Overall, the proportions from C-14-based non-fossil fuel contribution (f(non-fossil)) for OC in aerosols was 74 +/- 10%, while for WIOC in snowpits was 81 +/- 10%, both of which were significantly higher than that of elemental carbon (EC). These indicated sources of OC (WIOC) and EC were different at remote TP. Spatially, high f(non-fossil) of WIOC of snowpit samples appeared at the inner part of the TP, indicating the important contribution of local non-fossil sources. Therefore, local non-fossil sources rather than long-range transportation OC dominants its total amount of the TP. In addition, the contribution of local non-fossil sourced WIOC increased during the monsoon period because heavy precipitation removed a high ratio of long-range transportation WIOC. The results of this study showed that not only OC and EC but also their different fuel sources should be treated separately in models to investigate their sources and atmospheric transportation.

Black carbon (BC) can be transported over long distances and is an important trigger of climate warming and glacier melting at remote high mountains and polar regions. It is normally assumed that the variation of BC flux in remote regions is dominated by its emissions. However, after a comprehensive investigation of potential influencing factors on temporal variations of BC from ice cores of the Himalayas, this short communication shows that in addition to BC emissions, contributions from dust storms and precipitation are also important (up to 56% together) in regulating the variation of BC deposition flux and concentrations derived from remote Himalayan ice core measurements. Therefore, besides BC emissions, the influence of precipitation and BC transported by dust storms should also be considered to better quantify the lifetime and behavior of BC during its long-range transport from source to sink regions as well as to quantify the climatic effects of BC over remote Himalayan glaciers.

At present, the glaciers in the Himalayas and the Tibetan Plateau (HTP) are retreating partly due to albedo reduction caused by deposited light-absorbing impurities such as mineral dust (MD) and black carbon (BC). Because BC also exists widely in MD from surface soil, it is necessary to further evaluate the contribution of BC from MD to the total BC at glacier region. This will help to improve the study of BC sources by considering the relative contributions from MD and direct combustion sources. Therefore, in this study, concentrations of total organic carbon (TOC) and fine particles of BC from 43 surface soil samples of the HTP were investigated. The contribution of BC from MD to total BC deposited at the glacier region was evaluated. The results showed strong correlations between TOC and BC of studied samples (R-2 = 0.70, p < 0.01), suggesting that they have similar sources and activity characteristics. The average BC concentration of studied samples was 2.02 +/- 1.55 mg g(-1), much lower than those of particles deposited at the glacier region and other regions with high soil TOC concentration. The contributions of BC from MD to total surface BC at two glaciers of the inner HTP (Zhadang and Xiaodongkemadi) were 17.66 +/- 10.84% and 20.70 +/- 16.35%, respectively. Therefore, the contribution of MD to glacier melting of the HTP is higher than that of previously assumed after BC coming along with MD is considered. Because MD concentration is higher at north and west part of the HTP, the contributions of MD at these glacier regions should be larger than previously assumed.

At present, the glaciers in the Himalayas and the Tibetan Plateau (HTP) are retreating partly due to albedo reduction caused by deposited light-absorbing impurities such as mineral dust (MD) and black carbon (BC). Because BC also exists widely in MD from surface soil, it is necessary to further evaluate the contribution of BC from MD to the total BC at glacier region. This will help to improve the study of BC sources by considering the relative contributions from MD and direct combustion sources. Therefore, in this study, concentrations of total organic carbon (TOC) and fine particles of BC from 43 surface soil samples of the HTP were investigated. The contribution of BC from MD to total BC deposited at the glacier region was evaluated. The results showed strong correlations between TOC and BC of studied samples (R-2 = 0.70, p < 0.01), suggesting that they have similar sources and activity characteristics. The average BC concentration of studied samples was 2.02 +/- 1.55 mg g(-1), much lower than those of particles deposited at the glacier region and other regions with high soil TOC concentration. The contributions of BC from MD to total surface BC at two glaciers of the inner HTP (Zhadang and Xiaodongkemadi) were 17.66 +/- 10.84% and 20.70 +/- 16.35%, respectively. Therefore, the contribution of MD to glacier melting of the HTP is higher than that of previously assumed after BC coming along with MD is considered. Because MD concentration is higher at north and west part of the HTP, the contributions of MD at these glacier regions should be larger than previously assumed.