A review of physicochemical properties of dissolved organic carbon and its impact over mountain glaciers

Investigating the characteristics and transformation of water-soluble carbonaceous matter in the cryosphere regions is important for understanding biogeochemical process in the earth system. Water-soluble carbonaceous matter is a heterogeneous mixture of organic compounds that is soluble in aquatic environments. Despite its importance, we still lack systematic understanding for dissolved organic carbon (DOC) in several aspects including exact chemical composition and physical interactions with microorganisms, glacier meltwater. This review presents the chemical composition and physical properties of glacier DOC deposited through anthropogenic emission, terrestrial, and biogenic sources. We present the molecular composition of DOC and its effect over snow albedo and associated radiative forcings. Results indicate that DOC in snow/ice is made up of aromatic protein-like species, fulvic acid-like materials, and humic acid-like materials. Light-absorbing impurities in surface snow and glacier ice cause considerable albedo reduction and the associated radiative forcing is definitely positive. Water-soluble carbonaceous matter dominated the carbon transport in the high-altitude glacial area. Owing to prevailing global warming and projected increase in carbon emission, the glacial DOC is expected to release, which will have strong underlying impacts on cryosphere ecosystem. The results of this work have profound implications for better understanding the carbon cycle in high altitude cryosphere regions. A new compilation of globally distributed work is required, including large-scale measurements of glacial DOC over high-altitude cryosphere regions, to overcome and address the scientific challenges to constrain climate impacts of light-absorbing impurities related processes in Earth system and climate models.