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| Titel |
Quantifying gross N2O flux and production using 15N2O pool dilution technique and direct gas-flow core method |
| VerfasserIn |
Yuan Wen, Zhe Chen, Michael Dannenmann, Andrea Carminati, Georg Willibald, Ralf Kiese, Benjamin Wolf, Edzo Veldkamp, Klaus Butterbach-Bahl, Marife D. Corre |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250102492
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| Publikation (Nr.) |
 EGU/EGU2015-1817.pdf |
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| Zusammenfassung |
| Soils are not only a major source but also a potential sink for atmospheric nitrous oxide
(N2O), a potent greenhouse gas and the most important substance for stratospheric
ozone depletion. Net N2O flux at the soil-atmosphere interface is the balance of
simultaneously occurring gross N2O production and consumption. N2O is consumed via
reduction to N2, i. e. the terminal product of the denitrification process, which is
difficult to measure against the high atmosphere background. The enigmatic lack of
measurements on gross N2O flux or N2 production still impedes our understanding of the
controls on soil N2O emissions and the closure of the global nitrogen cycle. Here,
we combined the 15N2O pool dilution technique and direct gas-flow core method
to disentangle 1) gross N2O fluxes at the soil-atmosphere interface, and 2) gross
N2O production and consumption in the soil. The 15N2O pool dilution method
entails adding 15N2O to the chamber headspace, measuring 14N2O and 15N2O
concentrations and applying a model to simultaneously solve for gross N2O flux and
consumption rate at the soil-atmosphere interface. The direct gas-flow core method
substitutes the soil air and chamber headspace with helium to a nearly N2-free
atmosphere in order to directly measure both N2O and N2fluxes; N2 flux is the gross N2O
consumption and its sum with N2O flux is the gross N2O production in the soil.
Soil samples were taken from grassland, cropland, beech and pine forest soils,
representing a broad range of land uses and soil types. Additionally, we compared
measurements from intact soil cores (reflecting inherent soil bulk density and porosity) and
sieved soils (eliminating heterogeneity in porosity). Gross N2O production rate in
the soil was highest in the silty grassland soil (41.04±4.6 μg N kg-1 h-1) and
lowest in the sandy pine forest soil (1.84±1.82 μg N kg-1 h-1). The intact soil
cores and sieved soils showed similar trends. Gross N2O production rates in the soil
exceeded gross N2O fluxes at the soil-atmosphere interface by at least an order of
magnitude, suggesting that most of the N2O produced is possibly directly consumed and
diffused as N2. The gross N2O consumption rate at the soil-atmosphere interface only
accounted for 7% of N2 production in the soil, suggesting that N2O in the soil air
that is diffusing to the atmosphere is seldom consumed. Gross N2O fluxes at the
soil-atmosphere interface, gross N2O production in the soil and N2 production were
all significantly correlated with soil water content, NH4+, dissolved organic C,
microbial biomass C and N (p |
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