Distributions and light absorption property of water soluble organic carbon in a typical temperate glacier, southeastern Tibetan Plateau

Abstract

Water-soluble organic carbon (WSOC) widely stored in glaciers from local and distant sources, and then released it to downstream environments under a warming climate. Climatic driven changes to glacial run-off are larger and represent an important flux of organic carbon. However, very few WSOC data are currently available to fully characterize WSOC variation in the temperate glacierized regions of the Tibetan Plateau (TP). This study first systematically evaluated the concentration characteristics and light absorbing property of WSOC, and insoluble particulate carbon (IPC) in snow and ice of a typical temperate glacier on Mt. Yulong. Average concentrations of WSOC were 0.61 ± 0.21 mg L−1 in Baishui glacier on Mt. Yulong. WSOC concentrations in surface aged snow were dramatically decreased with the time extension during the entire monsoon season due to extensive glacial melting and scavenging effects by meltwater. The MAC values of WSOC calculated at 365 nm was 6.31 ± 0.34 m2 g−1 on Mt. Yulong, and there exists distinct spectral dependence of MACwsoc within the wavelength range (260–700 nm). The low AAE330–400 values suggest the light absorption of WSOC is more spectrally neutral. The flux of WSOC in Baishui glacier was 0.99 gC m−2yr−1, while the IPC flux was 4.77 gC m−2yr−1. Total WSOC storage in the Baishui glacier was estimated to be 1.5 tone C and total IPC storage was 7.25 tone C (1 tone = 106 g). Moreover, glacial melting was reinforced by the soluble and insoluble light absorbing impurities (ILAIs) in glaciers, Baishui glacier can be considered as a fraction of carbon source under the scenario of a warming climate, more importantly, WSOC in snow and ice needs to be taken into account in calculating the radiative forcing of ILAIs and accelerating glacial melting.