Carbonaceous matter has an important impact on glacial retreat in the Tibetan Plateau, further affecting the water resource supply. However, the related studies on carbonaceous matter are still scarce in Geladaindong (GLDD) region, the source of the Yangtze River. Therefore, the concentration, source and variations of carbonaceous matter at Ganglongjiama (GLJM) glacier in GLDD region were investigated during the melting period in 2017, which could deepen our understanding on carbonaceous matter contribution to glacier melting. The results showed that dissolved organic carbon (DOC) concentration of snowpit samples (283 +/- 200 mu g/L) was much lower than that of precipitation samples (624 +/- 361 mu g/L), indicating that large parts of DOC could be rapidly leached from the snowpit during the melting process. In contrast, refractory black carbon (rBC) concentration measured by Single Particle Soot Photometer of snowpit samples (4.27 +/- 3.15 mu g/L) was much higher than that of precipitation samples (0.97 +/- 0.49 mu g/L). Similarly, DOC with high mass absorption cross- measured at 365 nm value was also likely to enrich in snowpit during the melting process. In addition, it was found that both rBC and DOC with high light-absorbing ability began to leach from the snowpit when melting process became stronger. Therefore, rBC and DOC with high light-absorbing ability exhibited similar behavior during the melting process. Based on relationship among DOC, rBC and K+ in precipitation, the main source of carbonaceous matter in GLJM glacier was biomass burning during the study period. (c) 2019 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.

Carbonaceous aerosols over the Tibetan Plateau originate primarily from biomass burning and vehicle emissions (BB and VEs, respectively). The light absorption characteristics of these carbonaceous aerosols are closely correlated with the burning conditions and represent key factors that influence climate forcing. In this study, the light absorption characteristics of elemental carbon (EC) and water-soluble organic carbon (WSOC) in PM2.5 (fine particulate matter smaller than 2.5 mu m) generated from BB and VEs were investigated over the Tibetan Plateau (TP). The results showed that the organic carbon (OC)/EC ratios from BB- and VE-sourced PM2.5 were 17.62 +/- 10.19 and 1.19 +/- 0.36, respectively. These values were higher than the ratios in other regions, which was primarily because of the diminished amount of oxygen over the TP. The mass absorption cross of EC (MAC(EC)) at 632 nm for the BB-sourced PM2.5 (6.10 +/- 1.21 m(2).g(-1)) was lower than that of the VE-sourced PM2.5 (8.10 +/- 0.98 m(2).g(-1)), indicating that the EC content of the BB-sourced PM2.5 was overestimated because of the high OC/EC ratio. The respective absorption per mass (alpha/rho) values at 365 nm for the VE- and BB-sourced PM2.5 were 0.71 +/- 0.17 m(2).g(-1) and 0.91 +/- 0.18 m(2).g(-1). The alpha/rho value of the VEs was loaded between that of gasoline and diesel emissions, indicating that the VE-sourced PM2.5 originated from both types of emissions. Because OC and WSOC accounts for most of the carbonaceous aerosols at remote area of the TP, the radiative forcing contributed by the WSOC should be high, and requires further investigation.