Does Solid-state 15N NMR Spectroscopy Detect all Soil Organic Nitrogen?

Smernik, Ronald J.; Baldock, J. A.

doi:10.1007/s10533-005-2857-8

Cited by 55 publications

(34 citation statements)

References 65 publications

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“…The theory and application of NEXAFS measurements to studies of these three elements lags considerably behind that of carbon and sulfur. There have been a few notable studies of N-NEXAFS in NOM (Vairavamurthy and Wang, 2002;Jokic et al, 2004a b;Leinweber et al, 2007), and this technique represents perhaps in principle the best method for examining pyridine, pyridone, pyrrazole, or pyrrole nitrogen in NOM, because NMR is relatively insensitive to heterocyclic nitrogen (Smernik and Baldock, 2005). However, energy ranges for amide nitrogen significantly overlap with those of most nitrogen heterocycles, making a full distinction between amino groups and nitrogen-substituted heterocycles difficult without additional information about the sample or complementary analyses by other techniques.…”

Section: Spectral Features and Peak Assignmentsmentioning

confidence: 99%

“…SyNCHROTRON-BASED NEAR-EDgE X-RAy SPECTROSCOPy spectroscopy is the opportunity to investigate the proportion of heterocyclic organic nitrogen, which is difficult to assess with other spectroscopic techniques such as NMR (Smernik and Baldock, 2005). Similarly, few studies of oxygen NEXAFS in natural samples have been conducted.…”

Section: Composition Of Natural Organicmentioning

confidence: 99%

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Synchrotron‐Based Near‐Edge X‐Ray Spectroscopy of Natural Organic Matter in Soils and Sediments

Lehmann

Solomon

Brandes

et al. 2009

Biophysico‐Chemical Processes Involving Natural Nonliving Organic Matter in Environmental Systems

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SyNCHROTRON-BASED NEAR-EDgE X-RAy SPECTROSCOPy discrete radii indexed by a principal quantum number n = 1,2,3 …, and discrete binding energies for single-electron atoms of E n = −E 0 Z 2 /n 2 , where Z is the atomic number and E 0 = 13.6 eV (see Figure 17.1). When the energy of incident photons is increased to match the binding energy of an electron, the photon absorption probability suddenly increases in what is called an X-ray absorption edge (step function in Figure 17.2, which is at about 290 eV for carbon), so that the electron is completely removed from the atom in an ionization event (absorption edges are also labeled figure 17.1. Atom in the Bohr model. The electrons surround the nucleus. An incoming photon can lift an electron to a not fully occupied, higher orbital or remove it entirely from the atom. Energy (eV)280 285 290 295 300 Normalized absorption Measured ModeledStep functionfigure 17.2. Carbon NEXAFS spectrum of NOM from the Suwannee River (IHSS standard humic acid mounted on indium foil; total electron yield using a dwell time of 200 msec and an exit slit of 50 µm, calibrated to CO at 287.38 eV, Canadian Light Source SgM beamline 11-ID.1) to show pre-edge features and the so-called "edge". The spectrum is deconvoluted using a series of gaussian curves (g) at energy positions of known transitions, along with a step function at the edge as described by .

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Section: Spectral Features and Peak Assignmentsmentioning

confidence: 99%

Section: Composition Of Natural Organicmentioning

confidence: 99%

Synchrotron‐Based Near‐Edge X‐Ray Spectroscopy of Natural Organic Matter in Soils and Sediments

Lehmann

Solomon

Brandes

et al. 2009

Biophysico‐Chemical Processes Involving Natural Nonliving Organic Matter in Environmental Systems

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“…Solid-state 15 N NMR spectroscopy indicated that the organic N in the silt and clay fractions was present mostly as amide N (Kögel-Knabner 1997; Schmidt et al 1997;Smernik and Baldock 2005). The C/N ratio of OM in the MAOM fraction removed by NaClO oxidation was 7.5-8.1 (Table 4).…”

Section: Infrared Spectroscopy Of the Density-size Fractionsmentioning

confidence: 99%

DRIFT spectroscopy combined with sodium hypochlorite oxidation reveals different organic matter characteristics in density-size fractions of organically managed soils

Aoyama

2016

Can. J. Soil. Sci.

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The objective of this study was to characterize the organic matter (OM) in density-size fractions of soil samples from a commercial organic farm using diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. The soil samples were separated by density fractionation with a sodium iodide (Nal) solution (1.6 g cm -3 ) into free particulate OM (fPOM), occluded particulate OM (oPOM), heavy particulate OM (hPOM), and mineral-associated OM (MAOM) fractions. The OM characterization by DRIFT spectroscopy was the difference in spectra obtained before and after sodium hypochlorite (NaClO) oxidation. However, the infrared absorption bands derived from the soil mineral matrix interfered with the detection of the absorption bands of polysaccharides. An increase in the amount of organic C under organic management was observed for all the density-size fractions, but the functional group composition of the NaClO-oxidizable OM differed among the fractions. The NaClO-oxidizable OM in the fPOM fraction was characterized by a high lignin content, whereas the oPOM fraction had high amounts of aliphatic compounds and lignin. The hPOM fraction contained less lignin and more proteinous materials, and the MAOM fraction was rich in proteinous materials. This study demonstrates that DRIFT spectroscopy combined with NaClO oxidation is a powerful tool for characterizing the relatively unstable OM in soils.Key words: density fractionation, DRIFT spectroscopy, manure application, particulate organic matter, sodium hypochlorite oxidation.Résumé : Le but de l'étude consistait à caractériser la matière organique (MO) en fonction de la densité et de la granulométrie des échantillons de sol prélevés dans une exploitation agricole biologique en recourant à la spectroscopie par réflectance diffuse dans l'infrarouge à transformée de Fourier (DRIFT). Les échantillons ont été séparés par fractionnement selon la densité dans une solution d'iodure (1,6 g cm -3 ) en particules libres de MO (fPOM), particules occluses de MO (oPOM), particules lourdes de MO (hPOM) et MO liée à des minéraux (MAOM). La caractérisation de la MO par la spectroscopie DRIFT repose sur la variation du spectre, observé avant et après oxydation dans de l'hypochlorite de sodium (NaClO). Les bandes d'absorption dans l'infrarouge venant de la matrice minérale du sol entravent la détection des bandes d'absorption des polysaccharides. Une hausse de la concentration de C organique a été relevée dans toutes les fractions du gradient de densité issues des échantillons du sol servant à l'agriculture biologique, mais la composition du groupe fonctionnel de la MO oxydable-NaClO différait d'une fraction à l'autre. Ainsi la MO oxydable-NaClO de la fraction fPOM contenait beaucoup de lignine alors que la fraction oPOM renfermait une grande quantité de composés aliphatiques et de lignine. La fraction hPOM contenait moins de lignine et plus de matières protéiques, tandis que la fraction MAOM se démarquait par une forte concentration de matériaux protéiques. Les résultats de l'ét...

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“…This has been used extensively in solid-state NMR analysis of soil C (Smernik and Oades 2000a, b), N (Smernik and Baldock 2005) and P (Dougherty et al 2005;McBeath et al 2006). Since most quantitation problems in NMR involve the under-detection of nuclei (e.g.…”

Section: Quantitationmentioning

confidence: 99%