Stable isotope discrimination during soil denitrification: Production and consumption of nitrous oxide

Menyailo, Oleg V. and Hungate, Bruce A. (2006) Stable isotope discrimination during soil denitrification: Production and consumption of nitrous oxide. Global Biogeochemical Cycles, 20 (3). GB3025. ISSN 1944-9224

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Abstract

Measuring the stable isotope composition of nitrous oxide ( N(2)O) evolved from soil could improve our understanding of the relative contributions of the main microbial processes ( nitrification and denitrification) responsible for N(2)O formation in soil. However, interpretation of the isotopic data in N(2)O is complicated by the lack of knowledge of fractionation parameters by different microbial processes responsible for N(2)O production and consumption. Here we report isotopic enrichment for both nitrogen and oxygen isotopes in two stages of denitrification, N(2)O production and N(2)O reduction. We found that during both N(2)O production and reduction, enrichments were higher for oxygen than nitrogen. For both elements, enrichments were larger for N(2)O production stage than for N(2)O reduction. During gross N(2)O production, the ratio of delta(18)O- to-delta(15)N differed between soils, ranging from 1.6 to 2.7. By contrast, during N(2)O reduction, we observed a constant ratio of delta(18)O- to-delta(15)N with a value near 2.5. If general, this ratio could be used to estimate the proportion of N(2)O being reduced in the soil before escaping into the atmosphere. Because N(2)O- reductase enriches N(2)O in both isotopes, the global reduction of N(2)O consumption by soil may contribute to the globally observed isotopic depletion of atmospheric N(2)O.

Item Type:	Article
Publisher’s Statement:	Copyright 2006 by the American Geophysical Union.
ID number or DOI:	10.1029/2005GB002527
Keywords:	abundance; artificial afforestation experiment; Budget; fractionation; fresh-water; n2o isotopomers; nitrate; Nitrification; origin; ratios
Subjects:	Q Science > QH Natural history
NAU Depositing Author Academic Status:	Faculty/Staff
Department/Unit:	College of Engineering, Forestry, and Natural Science > Biological Sciences Research Centers > Merriam-Powell Center for Environmental Research
Date Deposited:	08 Oct 2015 20:08
URI:	http://openknowledge.nau.edu/id/eprint/716

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