Chemical composition of inorganic and organic species in snow/ice in the glaciers of western China

Abstract

Recent studies have revealed the abundance of dissolved organic matter (DOM) in snow/glaciers of the Tibetan Plateau (TP). Here, we present a comprehensive study on the chemical compositions of snowpit samples collected from widely distributed eight glaciers in the western China (six from the TP) to investigate the spatial variation of deposited atmospheric aerosols. An Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) was used to chemically characterize the DOM in snow samples which can offer chemical properties of DOM. Highest mass concentration of dissolved species mass was observed in Tienshan Baishui No 1 glacier (TS, 6.55 ± 0.85 mg/L) close to Takalamagan Desert, whereas lowest (0.89 ± 0.18 mg/L) was observed in Zadang Glacier (ZD) in the central TP. DOM (8–40%) and calcium as well as magnesium (9–67%) were generally the most abundant chemical species. Average DOM concentration in the TP glaciers among the investigated sites were comparable. DOM was found highly oxidized with an oxygen to carbon ratio (O/C ratio) ranging from 0.82 to 1.03. Highly oxidized DOM could have related with aerosol aqueous processes as illustrated by observed organic acids. This study provides insights into the spatial variations of the DOM and dissolved inorganic matter, as well as oxidized organic aerosol, were most likely due to local and regional contribution.