CH4 oxidation and N2O emissions at varied soil water-filled pore spaces and headspace CH4 concentrations

M. I. Khalil, Elizabeth Baggs

Research output: Contribution to journalArticle

110 Citations (Scopus)

Abstract

Emission of N2O and CH4 oxidation rates were measured from soils of contrasting (30-75%) water-filled pore space (WFPS). Oxidation rates of C-13-CH4 were determined after application of 10 mu l C-13-CH4 I-1(10 at. % excess C-13) to soil headspace and comparisons made with estimates from changes in net CH4 emission in these treatments and under ambient CH4 where no C-13-CH4 had been applied. We found a significant effect of soil WFPS on C-13-CH4 oxidation rates and evidence for oxidation of 2.2 mu g C-13-CH4 d(-1) occurring in the 75% WFPS soil, which may have been either aerobic oxidation occurring in aerobic microsites in this soil or anaerobic CH4 oxidation. The lowest 13C-CH4 oxidation rate was measured in the 30% WFPS soil and was attributed to inhibition of methanotroph activity in this dry soil. However, oxidation was lowest in the wetter soils when estimated from changes in concentration of C12+13-CH4. Thus, both methanogenesis and CH4 oxidation may have been occurring simultaneously in these wet soils, indicating the advantage of using a stable isotope approach to determine oxidation rates. Application of C-13-CH4 at 10 mu l C-13-CH4 l(-1) resulted in more rapid oxidation than under ambient CH4 conditions, suggesting CH4 oxidation in this soil was substrate limited, particularly in the wetter soils. Application of (NH4NO3)-N-14-N-15 and (NH4NO3)-N-15-N-15 (80 mg N kg soil(-1); 9.9 at.% excess N-15) to different replicates enabled determination of the respective contributions of nitrification and denitrification to N2O emissions. The highest N2O emission (119 mu g N14+15-N2O kg soil(-1) over 72 h) was measured from the 75% WFPS soil and was mostly produced during denitrification (18.1 mu g N-15-N2O kg soil(-1); 90% of N-15-N2O from this treatment). Strong negative correlations between N14+15-N2O emissions, denitrified N-15-N2O emissions and C-13-CH4 concentrations (r=-0.93 to -0.95, N2O; r= -0.87 to -0.95, denitrified N-15-N2O; P < 0.05) suggest a close relationship between CH4 oxidation and denitrification in our soil, the nature of which requires further investigation. (c) 2005 Elsevier Ltd. All rights reserved.

Original languageEnglish
Pages (from-to)1785-1794
Number of pages9
JournalSoil Biology and Biochemistry
Volume37
DOIs
Publication statusPublished - 2005

Keywords

  • denitrification
  • methane oxidation
  • nitrification
  • nitrous oxide
  • soil water-filled pore space
  • stable isotopes
  • ELEVATED ATMOSPHERIC CO2
  • NITROUS-OXIDE PRODUCTION
  • TEMPERATE FOREST SOILS
  • METHANE OXIDATION
  • NITRIFIER DENITRIFICATION
  • METHANOTROPHIC BACTERIA
  • SHORT-TERM
  • NITRIFICATION
  • CONSUMPTION
  • AMMONIA

Cite this

CH4 oxidation and N2O emissions at varied soil water-filled pore spaces and headspace CH4 concentrations. / Khalil, M. I.; Baggs, Elizabeth.

In: Soil Biology and Biochemistry, Vol. 37, 2005, p. 1785-1794.

Research output: Contribution to journalArticle

@article{25ec754d36d24017895e39d6624bd4d1,
title = "CH4 oxidation and N2O emissions at varied soil water-filled pore spaces and headspace CH4 concentrations",
abstract = "Emission of N2O and CH4 oxidation rates were measured from soils of contrasting (30-75{\%}) water-filled pore space (WFPS). Oxidation rates of C-13-CH4 were determined after application of 10 mu l C-13-CH4 I-1(10 at. {\%} excess C-13) to soil headspace and comparisons made with estimates from changes in net CH4 emission in these treatments and under ambient CH4 where no C-13-CH4 had been applied. We found a significant effect of soil WFPS on C-13-CH4 oxidation rates and evidence for oxidation of 2.2 mu g C-13-CH4 d(-1) occurring in the 75{\%} WFPS soil, which may have been either aerobic oxidation occurring in aerobic microsites in this soil or anaerobic CH4 oxidation. The lowest 13C-CH4 oxidation rate was measured in the 30{\%} WFPS soil and was attributed to inhibition of methanotroph activity in this dry soil. However, oxidation was lowest in the wetter soils when estimated from changes in concentration of C12+13-CH4. Thus, both methanogenesis and CH4 oxidation may have been occurring simultaneously in these wet soils, indicating the advantage of using a stable isotope approach to determine oxidation rates. Application of C-13-CH4 at 10 mu l C-13-CH4 l(-1) resulted in more rapid oxidation than under ambient CH4 conditions, suggesting CH4 oxidation in this soil was substrate limited, particularly in the wetter soils. Application of (NH4NO3)-N-14-N-15 and (NH4NO3)-N-15-N-15 (80 mg N kg soil(-1); 9.9 at.{\%} excess N-15) to different replicates enabled determination of the respective contributions of nitrification and denitrification to N2O emissions. The highest N2O emission (119 mu g N14+15-N2O kg soil(-1) over 72 h) was measured from the 75{\%} WFPS soil and was mostly produced during denitrification (18.1 mu g N-15-N2O kg soil(-1); 90{\%} of N-15-N2O from this treatment). Strong negative correlations between N14+15-N2O emissions, denitrified N-15-N2O emissions and C-13-CH4 concentrations (r=-0.93 to -0.95, N2O; r= -0.87 to -0.95, denitrified N-15-N2O; P < 0.05) suggest a close relationship between CH4 oxidation and denitrification in our soil, the nature of which requires further investigation. (c) 2005 Elsevier Ltd. All rights reserved.",
keywords = "denitrification, methane oxidation, nitrification, nitrous oxide, soil water-filled pore space, stable isotopes, ELEVATED ATMOSPHERIC CO2, NITROUS-OXIDE PRODUCTION, TEMPERATE FOREST SOILS, METHANE OXIDATION, NITRIFIER DENITRIFICATION, METHANOTROPHIC BACTERIA, SHORT-TERM, NITRIFICATION, CONSUMPTION, AMMONIA",
author = "Khalil, {M. I.} and Elizabeth Baggs",
year = "2005",
doi = "10.1016/j.soilbio.2005.02.012",
language = "English",
volume = "37",
pages = "1785--1794",
journal = "Soil Biology and Biochemistry",
issn = "0038-0717",
publisher = "Elsevier Limited",

}

TY - JOUR

T1 - CH4 oxidation and N2O emissions at varied soil water-filled pore spaces and headspace CH4 concentrations

AU - Khalil, M. I.

AU - Baggs, Elizabeth

PY - 2005

Y1 - 2005

N2 - Emission of N2O and CH4 oxidation rates were measured from soils of contrasting (30-75%) water-filled pore space (WFPS). Oxidation rates of C-13-CH4 were determined after application of 10 mu l C-13-CH4 I-1(10 at. % excess C-13) to soil headspace and comparisons made with estimates from changes in net CH4 emission in these treatments and under ambient CH4 where no C-13-CH4 had been applied. We found a significant effect of soil WFPS on C-13-CH4 oxidation rates and evidence for oxidation of 2.2 mu g C-13-CH4 d(-1) occurring in the 75% WFPS soil, which may have been either aerobic oxidation occurring in aerobic microsites in this soil or anaerobic CH4 oxidation. The lowest 13C-CH4 oxidation rate was measured in the 30% WFPS soil and was attributed to inhibition of methanotroph activity in this dry soil. However, oxidation was lowest in the wetter soils when estimated from changes in concentration of C12+13-CH4. Thus, both methanogenesis and CH4 oxidation may have been occurring simultaneously in these wet soils, indicating the advantage of using a stable isotope approach to determine oxidation rates. Application of C-13-CH4 at 10 mu l C-13-CH4 l(-1) resulted in more rapid oxidation than under ambient CH4 conditions, suggesting CH4 oxidation in this soil was substrate limited, particularly in the wetter soils. Application of (NH4NO3)-N-14-N-15 and (NH4NO3)-N-15-N-15 (80 mg N kg soil(-1); 9.9 at.% excess N-15) to different replicates enabled determination of the respective contributions of nitrification and denitrification to N2O emissions. The highest N2O emission (119 mu g N14+15-N2O kg soil(-1) over 72 h) was measured from the 75% WFPS soil and was mostly produced during denitrification (18.1 mu g N-15-N2O kg soil(-1); 90% of N-15-N2O from this treatment). Strong negative correlations between N14+15-N2O emissions, denitrified N-15-N2O emissions and C-13-CH4 concentrations (r=-0.93 to -0.95, N2O; r= -0.87 to -0.95, denitrified N-15-N2O; P < 0.05) suggest a close relationship between CH4 oxidation and denitrification in our soil, the nature of which requires further investigation. (c) 2005 Elsevier Ltd. All rights reserved.

AB - Emission of N2O and CH4 oxidation rates were measured from soils of contrasting (30-75%) water-filled pore space (WFPS). Oxidation rates of C-13-CH4 were determined after application of 10 mu l C-13-CH4 I-1(10 at. % excess C-13) to soil headspace and comparisons made with estimates from changes in net CH4 emission in these treatments and under ambient CH4 where no C-13-CH4 had been applied. We found a significant effect of soil WFPS on C-13-CH4 oxidation rates and evidence for oxidation of 2.2 mu g C-13-CH4 d(-1) occurring in the 75% WFPS soil, which may have been either aerobic oxidation occurring in aerobic microsites in this soil or anaerobic CH4 oxidation. The lowest 13C-CH4 oxidation rate was measured in the 30% WFPS soil and was attributed to inhibition of methanotroph activity in this dry soil. However, oxidation was lowest in the wetter soils when estimated from changes in concentration of C12+13-CH4. Thus, both methanogenesis and CH4 oxidation may have been occurring simultaneously in these wet soils, indicating the advantage of using a stable isotope approach to determine oxidation rates. Application of C-13-CH4 at 10 mu l C-13-CH4 l(-1) resulted in more rapid oxidation than under ambient CH4 conditions, suggesting CH4 oxidation in this soil was substrate limited, particularly in the wetter soils. Application of (NH4NO3)-N-14-N-15 and (NH4NO3)-N-15-N-15 (80 mg N kg soil(-1); 9.9 at.% excess N-15) to different replicates enabled determination of the respective contributions of nitrification and denitrification to N2O emissions. The highest N2O emission (119 mu g N14+15-N2O kg soil(-1) over 72 h) was measured from the 75% WFPS soil and was mostly produced during denitrification (18.1 mu g N-15-N2O kg soil(-1); 90% of N-15-N2O from this treatment). Strong negative correlations between N14+15-N2O emissions, denitrified N-15-N2O emissions and C-13-CH4 concentrations (r=-0.93 to -0.95, N2O; r= -0.87 to -0.95, denitrified N-15-N2O; P < 0.05) suggest a close relationship between CH4 oxidation and denitrification in our soil, the nature of which requires further investigation. (c) 2005 Elsevier Ltd. All rights reserved.

KW - denitrification

KW - methane oxidation

KW - nitrification

KW - nitrous oxide

KW - soil water-filled pore space

KW - stable isotopes

KW - ELEVATED ATMOSPHERIC CO2

KW - NITROUS-OXIDE PRODUCTION

KW - TEMPERATE FOREST SOILS

KW - METHANE OXIDATION

KW - NITRIFIER DENITRIFICATION

KW - METHANOTROPHIC BACTERIA

KW - SHORT-TERM

KW - NITRIFICATION

KW - CONSUMPTION

KW - AMMONIA

U2 - 10.1016/j.soilbio.2005.02.012

DO - 10.1016/j.soilbio.2005.02.012

M3 - Article

VL - 37

SP - 1785

EP - 1794

JO - Soil Biology and Biochemistry

JF - Soil Biology and Biochemistry

SN - 0038-0717

ER -