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Résumé :
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We show how the N-15 method for measuring denitrification can be combined with the C2H2 inhibition technique to check the effect of acetylene on N2O-reductase, respiration and nitrification. No method exists, however, for the analysis of N-15 in the N-2 and N2O of headspace samples which also contain 10% v/v C2H2. We describe a technique to remove C2H2 from headspace samples with alkaline KMnO4 prior to analysis by isotope-ratio mass spectrometry. The C2H2 removal procedure had no effect on the determination of N2O concentration, or on the determination of the N-15 content of N2O and N-2. Then using data for fluxes of N2O, N-2, (N2O + N-2), CO2 and the size and N-15 content of the soil NO2- pool for a soil incubation experiment, we show how the effects of C2H2 can be quantitatively assessed. The data also allowed the amount of denitrification, as estimated by the C2H2 inhibition technique, to be compared with that measured using the N-15 technique.
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