Nitrous oxide nitrification and denitrification 15N enrichment factors from Amazon forest soils
Trumbore, Susan E.
de Camargo, Plinio
Piccolo, Marisa C.
Cerri, Carlos C.
MetadataShow full item record
KeywordAmazon forest soils; Denitrification; Isotopic enrichment factors; Isotopomers; Nitrification; Nitrous oxide; Site preference
The isotopic signatures of 15N and 18O in N2O emitted from tropical soils vary both spatially and temporally, leading to large uncertainty in the overall tropical source signature and thereby limiting the utility of isotopes in constraining the global N2O budget. Determining the reasons for spatial and temporal variations in isotope signatures requires that we know the isotope enrichment factors for nitrification and denitrification, the two processes that produce N2O in soils. We have devised a method for measuring these enrichment factors using soil incubation experiments and report results from this method for three rain forest soils collected in the Brazilian Amazon: soil with differing sand and clay content from the Tapajos National Forest (TNF) near Santarém, Pará, and Nova Vida Farm, Rondônia. The 15N enrichment factors for nitrification and denitrification differ with soil texture and site: −111‰ ± 12‰ and −31‰ ± 11‰ for a clay-rich Oxisol (TNF), −102‰ ± 5‰ and −45‰ ± 5‰ for a sandier Ultisol (TNF), and −10.4‰ ± 3.5‰ (enrichment factor for denitrification) for another Ultisol (Nova Vida) soil, respectively. We also show that the isotopomer site preference (δ15Nα − δ15Nβ, where α indicates the central nitrogen atom and β the terminal nitrogen atom in N2O) may allow differentiation between processes of production and consumption of N2O and can potentially be used to determine the contributions of nitrification and denitrification. The site preferences for nitrification and denitrification from the TNF-Ultisol incubated soils are: 4.2‰ ± 8.4‰ and 31.6‰ ± 8.1‰, respectively. Thus, nitrifying and denitrifying bacteria populations under the conditions of our study exhibit significantly different 15N site preference fingerprints. Our data set strongly suggests that N2O isotopomers can be used in concert with traditional N2O stable isotope measurements as constraints to differentiate microbial N2O processes in soil and will contribute to interpretations of the isotopic site preference N2O values found in the free troposphere.
Author Posting. © Ecological Society of America, 2006. This article is posted here by permission of Ecological Society of America for personal use, not for redistribution. The definitive version was published in Ecological Applications 16 (2006): 2153–2167, doi:10.1890/1051-0761(2006)016[2153:NONADN]2.0.CO;2.
Showing items related by title, author, creator and subject.
Groffman, Peter M.; Altabet, Mark A.; Bohlke, John K.; Butterbach-Bahl, Klaus; David, Mark B.; Firestone, Mary K.; Giblin, Anne E.; Kana, Todd M.; Nielsen, Lars Peter; Voytek, Mary A. (2005-07-15)Denitrification, the reduction of the nitrogen (N) oxides, nitrate (NO3-) and nitrite (NO2-), to the gases nitric oxide (NO), nitrous oxide (N2O) and dinitrogen (N2), is important to primary production, water quality and ...
Coupled nitrification–denitrification measured in situ in a Spartina alterniflora marsh with a 15NH4+ tracer Hamersley, Michael R.; Howes, Brian L. (Inter-Research, 2005-09-01)Measurements of N losses by denitrification from saltmarsh sediments have proved difficult because of the importance of plant metabolism and tidal cycles to sediment N cycling. In vitro approaches often do not measure the ...
Amazon deforestation alters small stream structure, nitrogen biogeochemistry and connectivity to larger rivers Deegan, Linda A.; Neill, Christopher; Haupert, Christie L.; Ballester, M. Victoria R.; Krusche, Alex V.; Victoria, Reynaldo L.; Thomas, Suzanne M.; de Moor, Emily (2010-08-29)Human activities that modify land cover can alter the structure and biogeochemistry of small streams but these effects are poorly known over large regions of the humid tropics where rates of forest clearing are high. We ...