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Real Time Monitoring of N 2 O Emissions from Agricultural Soils using FTIR Spectroscopy
Author(s) -
Dubowski Y.,
Harush D.,
Shaviv A.,
Stone L.,
Linker R.
Publication year - 2014
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2013.09.0390dgs
Subject(s) - cambisol , soil water , chemistry , environmental chemistry , denitrification , nitrification , nitrous oxide , nitrate , isotopic signature , greenhouse gas , nitrogen , analytical chemistry (journal) , stable isotope ratio , soil science , environmental science , geology , physics , quantum mechanics , oceanography , organic chemistry
Emissions of N 2 O from agricultural soils are an important source for this greenhouse gas. The present work examines the potential of Fourier transformed infrared (FTIR) spectroscopy coupled with a long path (LP) infrared (IR) gas cell for on‐line measurement of concentration and isotopic signature of N 2 O emitted from soils. Nitrous Oxide was spectrally monitored during incubations of soil samples in a closed system under different conditions. Its emission from a Grumosol (Vertisol) was measured in presence and absence of acetylene, with various additions of nitrate and glucose, under aerobic and anaerobic conditions, and for two soil thickness layers. For comparison N 2 O emissions from a Terra Rossa (Cambisol) and a Hamra (Luvisol) were measured in the presence and absence of acetylene. In an additional experimental set the isotopic signature of emitted N 2 O was quantified after enrichment with K 15 NO 3 . Acetylene addition led to an increase in N 2 O emissions in all three soils but at various extents. Under aerobic conditions, N 2 O emission from the Grumosol became detectable only when running the experiments with a thicker soil layer (10 mm), suggesting the existence of coupled nitrification–denitrification. Nitrate addition to soils enhanced N 2 O emissions especially when coupled with glucose addition. Addition of 15 NO 3 − to the Grumosol resulted in the emission of all four N 2 O isotopologues: 14 N 2 O, 15 N 2 O, 14 N 15 NO, and 15 N 14 NO. The observed slight delay in appearance of the species containing 15 N and the relatively lower 15 N enrichment of the N 2 O compared with the soil nitrate, indicate isotopic fractionation during denitrification. Yet, within the accuracy of our isotopic analysis, temporal emission patterns of 14 N 15 NO and 15 N 14 NO were similar indicating low possibility for “site preference” under the specific experimental conditions.