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Title: Indexing Permafrost Soil Organic Matter Degradation Using High-Resolution Mass Spectrometry

Microbial degradation of soil organic matter (SOM) is a key process for terrestrial carbon cycling, although the molecular details of these transformations remain unclear. This study reports the application of ultrahigh resolution mass spectrometry to profile the molecular composition of SOM and its degradation during a simulated warming experiment. A soil sample, collected near Barrow, Alaska, USA, was subjected to a 40-day incubation under anoxic conditions and analyzed before and after the incubation to determine changes of SOM composition. A CHO index based on molecular C, H, and O data was utilized to codify SOM components according to their observed degradation potentials. Compounds with a CHO index score between –1 and 0 in a water-soluble fraction (WSF) demonstrated high degradation potential, with a highest shift of CHO index occurred in the N-containing group of compounds, while similar stoichiometries in a base-soluble fraction (BSF) did not. Additionally, compared with the classical H:C vs O:C van Krevelen diagram, CHO index allowed for direct visualization of the distribution of heteroatoms such as N in the identified SOM compounds. We demonstrate that CHO index is useful not only in characterizing arctic SOM at the molecular level but also enabling quantitative description of SOM degradation,more » thereby facilitating incorporation of the high resolution MS datasets to future mechanistic models of SOM degradation and prediction of greenhouse gas emissions.« less
 [1] ;  [1] ;  [2] ;  [3] ;  [3] ;  [1] ;  [1] ;  [3] ;  [3] ;  [1] ;  [1] ;  [1] ;  [1] ;  [4]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Kent State Univ. (Ohio)
  3. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  4. Tennessee State Univ., Nashville, TN (United States)
Publication Date:
Grant/Contract Number:
AC05-76RL01830; AC05-00OR22725
Accepted Manuscript
Journal Name:
Additional Journal Information:
Journal Volume: 10; Journal Issue: 6; Journal ID: ISSN 1932-6203
Public Library of Science
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
54 ENVIRONMENTAL SCIENCES; 58 GEOSCIENCES; soil organic matter; Arctic soil; microbial degradation; climate change; warming; ion cyclotron resonance mass spectrometry
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1212345