title: Chemical Composition of Microbe-Derived Dissolved Organic Matter in Cryoconite in Tibetan Plateau Glaciers: Insights from Fourier Transform Ion Cyclotron Resonance Mass Spectrometry Analysis.
abstract: Cryoconite in mountain glaciers plays important roles in glacial ablation and biogeochemical cycles. In this study, the composition and sources of dissolved organic matter (DOM) in cryoconite from the ablation regions of two Tibetan Plateau glaciers were determined using electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) and fluorescence spectrometry. A marked absorbance between 300 and 350 nm in the DOM absorption spectra was observed which was consistent with microbe-derived mycosporine-like amino acids. Fluorescence excitation-emission matrices showed that DOM had intense signals at protein-like substance peaks and weak signals at humic-like substance peaks. The high-resolution mass spectra of FT-ICR-MS showed cryoconite DOM from both glaciers contained diverse lignins, lipids, proteins, and unsaturated hydrocarbons. The lipids and proteins were consistent with material from microbial sources, and the lignins and unsaturated hydrocarbons were probably from vascular plant material supplied in atmospheric aerosols and debris from around the glaciers. Almost one-third of the identified DOM molecules had low C/N ratios (≤20), indicating their high bioavailability. Using a conservative cryoconite distribution on Chinese mountain glacier surfaces (6%) and an average debris mass per square meter of cryoconite (292 ± 196 g m-2), we found that the amount of DOC produced in cryoconite on Chinese glaciers as much as 0.23 ± 0.1 Gg per cryoconite formation process. This dissolved organic carbon may absorb solar radiation, accelerate glacial melting, and be an important source of bioavailable DOM to proglacial and downstream aquatic ecosystems.
authors.affiliation: State Key Laboratory of Cryospheric Sciences, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences , Lanzhou 730000, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Feng
authors.affiliation: State Key Laboratory of Cryospheric Sciences, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences , Lanzhou 730000, China.
authors.forename: Jianzhong
authors.identifier: 0000-0002-9933-1744
authors.initials: J
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Cryospheric Sciences, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences , Lanzhou 730000, China.
authors.forename: Shichang
authors.initials: S
authors.lastname: Kang
authors.affiliation: State Key Laboratory of Cryospheric Sciences, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences , Lanzhou 730000, China.
authors.forename: Xiaofei
authors.initials: X
authors.lastname: Li
authors.affiliation: Institute of Tibetan Plateau Research, Chinese Academy of Sciences , Beijing 100101, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.affiliation: State Key Laboratory of Heavy Oil Processing, China University of Petroleum , Beijing 102249, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Jiang
authors.affiliation: State Key Laboratory of Heavy Oil Processing, China University of Petroleum , Beijing 102249, China.
authors.forename: Quan
authors.initials: Q
authors.lastname: Shi
mesh_terms: D017357:Cyclotrons; D005583:Fourier Analysis; D046448:Ice Cover / Q000737:chemistry*; D013058:Mass Spectrometry; D018609:Tibet