Fluorescence characteristics, absorption properties, and radiative effects of water-soluble organic carbon in seasonal snow across northeastern China

Abstract. Water-soluble organic carbon (WSOC) in the cryosphere can significantly influence global cycle and radiation budget. However, WSOC snowpack has received little scientific attention to date. This study reports fluorescence characteristics, absorption properties, radiative effects of based on 34 snow samples collected from sites northeastern China. A significant degree regional variability is found, with concentrations ranging 0.5±0.2 5.7±3.7 µg g?1 (average concentration: 3.6±3.2 g?1). The three principal fluorescent components are identified as (1) high-oxygenated humic-like substances (HULIS-1) terrestrial origin, (2) low-oxygenated (HULIS-2) mixed (3) protein-like (PRLIS) derived autochthonous microbial activity. In southeastern Inner Mongolia (SEIM), a region dominated by desert exposed soils, exhibits highest humification index (HIX) but lowest (FI) biological (BIX) indices; signal mainly attributed HULIS-1 thus implicates soil primary source. By contrast, HIX (FI BIX) value (highest), percentage PRLIS remote area (NEIM), suggesting primarily For south north China (SNC NNC), both which characterized intensive agriculture industrial activity, HULIS-2, HIX, FI, BIX values all moderate, indicating origins for (anthropogenic soil). We also observe that, throughout China, light HULIS-1, followed HULIS-2 PRLIS. contribution albedo reduction 3.6 g?1) ultraviolet–visible (UV–Vis) band approximately half that black (BC average 0.6 Radiative forcing 3.8 (0.8) W m?2 old (fresh) snow, equating 19 % (17 %) BC. These results indicate profound impact solar balance.