Title: Molecular Insights into Arctic Soil Organic Matter Degradation under Warming

Abstract

Molecular composition of the Arctic soil organic carbon (SOC) and its susceptibility to microbial degradation are uncertain due to heterogeneity and unknown SOC compositions. Using ultrahigh-resolution mass spectrometry, we determined the susceptibility and compositional changes of extractable dissolved organic matter (EDOM) in an anoxic warming incubation experiment (up to 122 days) with a tundra soil from Alaska (United States). EDOM was extracted with 10 mM NH4HCO3 from both the organic- and mineral-layer soils during incubation at both -2 and 8 °C. Based on their O:C and H:C ratios, EDOM molecular formulas were qualitatively grouped into nine biochemical classes of compounds, among which lignin-like compounds dominated both the organic and the mineral soils and were the most stable, whereas amino sugars, peptides, and carbohydrate-like compounds were the most biologically labile. These results corresponded with shifts in EDOM elemental composition in which the ratios of O:C and N:C decreased, while the average C content in EDOM, molecular mass, and aromaticity increased after 122 days of incubation. This research demonstrates that certain EDOM components, such as amino sugars, peptides, and carbohydrate-like compounds, are disproportionately more susceptible to microbial degradation than others in the soil, and these results should be considered in SOC degradationmore » models to improve predictions of Arctic climate feedbacks.« less

Authors:

Chen, Hongmei  ^[1];

• Search DOE PAGES for author "Chen, Hongmei"
• Search DOE PAGES for ORCID "0000-0003-2460-838X"

Yang, Ziming  ^[2];

• Search DOE PAGES for author "Yang, Ziming"
• Search DOE PAGES for ORCID "0000-0003-0312-8408"

Chu, Rosalie K. ^[3]; Tolic, Nikola  ^[3];

• Search DOE PAGES for author "Tolic, Nikola"
• Search DOE PAGES for ORCID "0000-0003-3950-9130"

Liang, Liyuan ^[3]; Graham, David E.  ^[4];

• Search DOE PAGES for author "Graham, David E."
• Search DOE PAGES for ORCID "0000-0001-8968-7344"

Wullschleger, Stan D. ^[1]; Gu, Baohua  ^[1]

• Search DOE PAGES for author "Gu, Baohua"
• Search DOE PAGES for ORCID "0000-0002-7299-2956"

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+ Show Author Affiliations

1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Environmental Sciences Division
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Environmental Sciences Division; Oakland Univ., Rochester, MI (United States). Dept. of Chemistry
3. Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab
4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Biosciences Division

Publication Date:

Fri Mar 23 00:00:00 EDT 2018

Research Org.:

Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Biological and Environmental Research (BER)

OSTI Identifier:

1433414

Alternate Identifier(s):

OSTI ID: 1437889; OSTI ID: 1508778

Grant/Contract Number:  

AC05-00OR22725

Resource Type:

Published Article

Journal Name:

Environmental Science and Technology

Additional Journal Information:

Journal Name: Environmental Science and Technology Journal Volume: 52 Journal Issue: 8; Journal ID: ISSN 0013-936X

Publisher:

American Chemical Society (ACS)

Country of Publication:

United States

Language:

English

Subject:

59 BASIC BIOLOGICAL SCIENCES; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 54 ENVIRONMENTAL SCIENCES