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Title: Stimulation of anaerobic organic matter decomposition by subsurface organic N addition in tundra soils

Abstract

We present that increasing nitrogen (N) availability in Arctic soils could stimulate the growth of both plants and microorganisms by relieving the constraints of nutrient limitation. It was hypothesized that organic N addition to anoxic tundra soil would increase CH 4 production by stimulating the fermentation of labile substrates, which is considered the rate-limiting step in anaerobic C mineralization. We tested this hypothesis through both field and lab-based experiments. In the field experiment, we injected a solution of 13C- and 15N-labeled glutamate 35 cm belowground at a site near Nome on the Seward Peninsula, Alaska, and observed the resulting changes in porewater geochemistry and dissolved greenhouse gas concentrations. The concentration of free glutamate declined rapidly within hours of injection, and the 15N label was recovered almost exclusively as dissolved organic N within 62 h. These results indicate rapid microbial assimilation of the added N and transformation into novel organic compounds. We observed increasing concentrations of dissolved CH 4 and Fe(II), indicating rapid stimulation of methanogenesis and Fe(III) reduction. Low molecular weight organic acids such as acetate and propionate accumulated despite increasing consumption through anaerobic C mineralization. A laboratory soil column flow experiment using active layer soil collected from the samemore » site further supported these findings. Glutamate recovery was low compared to a conservative bromide tracer, but concentrations of NO 3 - and NH 4 + remained low, consistent with microbial uptake of the added N. Similar to the field experiment, we observed both increasing Fe(II) and organic acid concentrations. Lastly, together, these results support our hypothesis of increased fermentation in response to organic N addition and suggest that increasing N availability could accelerate CH 4 production in tundra soils.« less

Authors:
ORCiD logo [1]; ORCiD logo [1];  [2]; ORCiD logo [3]; ORCiD logo [3];  [4]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  4. Oakland Univ., Rochester, MI (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23); USDOE Office of Science (SC). Biological and Environmental Research (BER) (SC-23)
OSTI Identifier:
1490607
Alternate Identifier(s):
OSTI ID: 1499364
Report Number(s):
LA-UR-18-31765
Journal ID: ISSN 0038-0717
Grant/Contract Number:  
AC05-00OR22725; 89233218CNA000001
Resource Type:
Accepted Manuscript
Journal Name:
Soil Biology and Biochemistry
Additional Journal Information:
Journal Volume: 130; Journal Issue: C; Journal ID: ISSN 0038-0717
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; Anaerobic C mineralization; Microbial N limitation; Fermentation; Tundra; Methanogenesis; Stable isotope labeling; Earth Sciences

Citation Formats

Philben, Michael J., Zheng, Jianqiu, Bill, Markus, Heikoop, Jeffrey Martin, Perkins, George B., Yang, Ziming, Wullschleger, Stan D., Graham, David E., and Gu, Baohua. Stimulation of anaerobic organic matter decomposition by subsurface organic N addition in tundra soils. United States: N. p., 2018. Web. doi:10.1016/j.soilbio.2018.12.009.
Philben, Michael J., Zheng, Jianqiu, Bill, Markus, Heikoop, Jeffrey Martin, Perkins, George B., Yang, Ziming, Wullschleger, Stan D., Graham, David E., & Gu, Baohua. Stimulation of anaerobic organic matter decomposition by subsurface organic N addition in tundra soils. United States. doi:10.1016/j.soilbio.2018.12.009.
Philben, Michael J., Zheng, Jianqiu, Bill, Markus, Heikoop, Jeffrey Martin, Perkins, George B., Yang, Ziming, Wullschleger, Stan D., Graham, David E., and Gu, Baohua. Wed . "Stimulation of anaerobic organic matter decomposition by subsurface organic N addition in tundra soils". United States. doi:10.1016/j.soilbio.2018.12.009.
@article{osti_1490607,
title = {Stimulation of anaerobic organic matter decomposition by subsurface organic N addition in tundra soils},
author = {Philben, Michael J. and Zheng, Jianqiu and Bill, Markus and Heikoop, Jeffrey Martin and Perkins, George B. and Yang, Ziming and Wullschleger, Stan D. and Graham, David E. and Gu, Baohua},
abstractNote = {We present that increasing nitrogen (N) availability in Arctic soils could stimulate the growth of both plants and microorganisms by relieving the constraints of nutrient limitation. It was hypothesized that organic N addition to anoxic tundra soil would increase CH4 production by stimulating the fermentation of labile substrates, which is considered the rate-limiting step in anaerobic C mineralization. We tested this hypothesis through both field and lab-based experiments. In the field experiment, we injected a solution of 13C- and 15N-labeled glutamate 35 cm belowground at a site near Nome on the Seward Peninsula, Alaska, and observed the resulting changes in porewater geochemistry and dissolved greenhouse gas concentrations. The concentration of free glutamate declined rapidly within hours of injection, and the 15N label was recovered almost exclusively as dissolved organic N within 62 h. These results indicate rapid microbial assimilation of the added N and transformation into novel organic compounds. We observed increasing concentrations of dissolved CH4 and Fe(II), indicating rapid stimulation of methanogenesis and Fe(III) reduction. Low molecular weight organic acids such as acetate and propionate accumulated despite increasing consumption through anaerobic C mineralization. A laboratory soil column flow experiment using active layer soil collected from the same site further supported these findings. Glutamate recovery was low compared to a conservative bromide tracer, but concentrations of NO3- and NH4+ remained low, consistent with microbial uptake of the added N. Similar to the field experiment, we observed both increasing Fe(II) and organic acid concentrations. Lastly, together, these results support our hypothesis of increased fermentation in response to organic N addition and suggest that increasing N availability could accelerate CH4 production in tundra soils.},
doi = {10.1016/j.soilbio.2018.12.009},
journal = {Soil Biology and Biochemistry},
number = C,
volume = 130,
place = {United States},
year = {2018},
month = {12}
}

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