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Title: Carbon isotope fractionation by methane-oxidizing bacteria intropical rain forest soils

Abstract

Humid tropical forests have the potential to be significantsources or sinks of atmospheric methane (CH4), a radiatively importanttrace gas. Methane oxidation can consume a large fraction of the CH4produced in tropical soils, although controls on this process are poorlyunderstood. Using soil incubation experiments, we investigated theeffects of CH4 and oxygen (O2) concentrations on C isotope fractionationand CH4 oxidation in tropical rain forest soils. We also explored theeffects of these environmental variables on the isotope fractionationfactor for CH4 oxidation (alpha), which is widely used to evaluate therelative contributions of CH4 production and oxidation to the atmosphericCH4 pool. Methane oxidation was sensitive to CH4 at lower CH4concentrations (<850 ppmv) and insensitive to O2 concentrationsbetween 3 and 21 percent. Maximum rates of CH4 oxidation were between 8.2+- 1.2 and 11.3 +- 1.5 nmol CH4 hour-1 g dry soil-1. Measured values foralpha were sensitive to both CH4 oxidation rate and CH4 concentration.Alpha was inversely proportional to CH4 oxidation rate (r2 = 0.86, P<0.001) and positively correlated with CH4 concentration (r2 = 0.52, P<0.01). A multiple regression model that included CH4 oxidation rate,CH4 concentration, and the interaction of the two terms explained a highproportion of the variability in alpha (r2 = 0.94, P<0.0001). Thesedata suggestmore » that it is possible to accurately determine alpha, allowingfor more precise estimates of CH4 oxidation by isotope massbalance.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Director. Office of Science. Office of Basic EnergySciences. Chemical Sciences Geosciences and Biosciences Division; National Aeronautics and Space Administration Fellowship NGT5-50331,National Science Foundation Grants DEB-0206547 and BSR-8811902; California Agricultural Experiment Station 7069-MS
OSTI Identifier:
901042
Report Number(s):
LBNL-60692
Journal ID: ISSN 0148-0227; JGREA2; R&D Project: 468202; BnR: KC0303020; TRN: US200711%%769
DOE Contract Number:  
DE-AC02-05CH11231
Resource Type:
Journal Article
Journal Name:
Journal of Geophysical Research
Additional Journal Information:
Journal Volume: 111; Related Information: Journal Publication Date: June 2006; Journal ID: ISSN 0148-0227
Country of Publication:
United States
Language:
English
Subject:
54; BACTERIA; CARBON ISOTOPES; DATA; FORESTS; FRACTIONATION; INCUBATION; MASS BALANCE; METHANE; OXIDATION; OXYGEN; PRODUCTION; RAIN; SOILS; physiological ecology of methanotrophic bacteria isotopefractionation factor Rayleigh fractionation isotope mass balancemodels.

Citation Formats

Teh, Yit Arn, Silver, Whendee L, Conrad, Mark E, Borglin, Sharon E, and Carlson, Charlotte M. Carbon isotope fractionation by methane-oxidizing bacteria intropical rain forest soils. United States: N. p., 2005. Web.
Teh, Yit Arn, Silver, Whendee L, Conrad, Mark E, Borglin, Sharon E, & Carlson, Charlotte M. Carbon isotope fractionation by methane-oxidizing bacteria intropical rain forest soils. United States.
Teh, Yit Arn, Silver, Whendee L, Conrad, Mark E, Borglin, Sharon E, and Carlson, Charlotte M. 2005. "Carbon isotope fractionation by methane-oxidizing bacteria intropical rain forest soils". United States.
@article{osti_901042,
title = {Carbon isotope fractionation by methane-oxidizing bacteria intropical rain forest soils},
author = {Teh, Yit Arn and Silver, Whendee L and Conrad, Mark E and Borglin, Sharon E and Carlson, Charlotte M},
abstractNote = {Humid tropical forests have the potential to be significantsources or sinks of atmospheric methane (CH4), a radiatively importanttrace gas. Methane oxidation can consume a large fraction of the CH4produced in tropical soils, although controls on this process are poorlyunderstood. Using soil incubation experiments, we investigated theeffects of CH4 and oxygen (O2) concentrations on C isotope fractionationand CH4 oxidation in tropical rain forest soils. We also explored theeffects of these environmental variables on the isotope fractionationfactor for CH4 oxidation (alpha), which is widely used to evaluate therelative contributions of CH4 production and oxidation to the atmosphericCH4 pool. Methane oxidation was sensitive to CH4 at lower CH4concentrations (<850 ppmv) and insensitive to O2 concentrationsbetween 3 and 21 percent. Maximum rates of CH4 oxidation were between 8.2+- 1.2 and 11.3 +- 1.5 nmol CH4 hour-1 g dry soil-1. Measured values foralpha were sensitive to both CH4 oxidation rate and CH4 concentration.Alpha was inversely proportional to CH4 oxidation rate (r2 = 0.86, P<0.001) and positively correlated with CH4 concentration (r2 = 0.52, P<0.01). A multiple regression model that included CH4 oxidation rate,CH4 concentration, and the interaction of the two terms explained a highproportion of the variability in alpha (r2 = 0.94, P<0.0001). Thesedata suggest that it is possible to accurately determine alpha, allowingfor more precise estimates of CH4 oxidation by isotope massbalance.},
doi = {},
url = {https://www.osti.gov/biblio/901042}, journal = {Journal of Geophysical Research},
issn = {0148-0227},
number = ,
volume = 111,
place = {United States},
year = {Thu May 12 00:00:00 EDT 2005},
month = {Thu May 12 00:00:00 EDT 2005}
}