13C CP/MAS-NMR spectra of organic matter as influenced by vegetation, climate, and soil characteristics in soils from Murcia, Spain

2002 ◽  
Vol 82 (4) ◽  
pp. 403-411 ◽  
Author(s):  
A. Faz Cano ◽  
A R Mermut ◽  
R. Ortiz ◽  
M B Benke ◽  
B. Chatson
Keyword(s):  
Organic Matter ◽  
Functional Groups ◽  
Plant Community ◽  
Nmr Spectra ◽  
Climatic Conditions ◽  
Parent Material ◽  
Mas Nmr ◽  
Soil Parameters ◽  
Organic C ◽  
Cp Mas Nmr

Soils in southern Spain are low in organic matter (OM) and nutrients. Understanding the nature and dynamics of OM has potential to improve soil management technologies for sustainable crop production. The objective of this work was to establish the distribution of functional groups in organic-C from these soils using 13C CP/MAS-NMR spectroscopy and to investigate the influence of vegetation, climatic conditions, soil parameters, parent material, and soil order on these functional groups. No statistically significant variability in the distribution of organic-C groups was found as a result of the influence of either soil order or parent material. The content of O-alkyl-C in the soils under the Rhamno-Quercetum plant community was higher (95% probability) than in the soils under the Paronychio-Sideritidetum plant community. Soils located in the mesomediterranean climatic zone displayed a higher content of O-alkyl-C and a lower content of aromatic-C compared to the soils located in the thermomediterranean zone. These differences were statistically significant at 95% of probability. Vegetation and climatic conditions appear to play a major role in the OM decomposition processes in this region. Statistically significant and positive correlations were found between alkyl-C and both cation exchange capacity (CEC) and clay content indicating the recalcitrant nature of these organic compounds. Key words: Organic matter composition, Spanish soils, 13C CP/MAS-NMR spectra, Mediterranean soils, Alfisols, Mollisols, Aridisols

Hydration effects in the carbon-13 CP/MAS NMR spectra of solid (1 →3)-β-D-glucans

1984 ◽  
Vol 17 (3) ◽  
pp. 501-502 ◽  
Author(s):  
C. A. Fyfe ◽  
P. J. Stephenson ◽  
M. G. Taylor ◽  
T. L. Bluhm ◽  
Y. Deslandes ◽  
...  
Keyword(s):  
Nmr Spectra ◽  
Mas Nmr ◽  
Cp Mas Nmr

Labile soil organic matter pools under a mixed grass/lucerne pasture and adjacent native bush in Western Australia

Soil Research ◽  
2007 ◽  
Vol 45 (5) ◽  
pp. 333 ◽  
Author(s):  
A. J. Macdonald ◽  
D. V. Murphy ◽  
N. Mahieu ◽  
I. R. P. Fillery
Keyword(s):  
Organic Matter ◽  
Plant Material ◽  
Surface Soil ◽  
Organic C ◽  
Soil Solutions ◽  
Mixed Grass ◽  
N Enrichment ◽  
Organic Matter Fractions ◽  
Cp Mas Nmr ◽  
13C Cp Mas Nmr

Total C and N were measured in whole soils (0–0.15, 0.15–0.35, and 0.35–0.65 m), light organic matter fractions (<1 g/cm3 (LF 1.0) and 1.0–1.7 g/cm3 (LF 1.7)) in surface soils, and in leaf litter collected from a mixed grass/lucerne pasture and adjacent native bush at Moora, Western Australia. The C content of the plant material and light fractions was characterised by 13C cross-polarisation/magic angle spinning nuclear magnetic resonance (13C CP/MAS NMR) spectroscopy. Water-extractable organic C (WEOC) and N (WEON) were measured in soil, and dissolved organic C (DOC) and N (DON) were measured in soil solutions. In addition, both NO3-N and NH4-N (SMN) were measured in soil solutions and water extracts. Total soil C (0–0.65 m) did not differ significantly between land uses, but there was clear evidence of N enrichment under the pasture system, which contained significantly (P < 0.05) more total N in the surface soil (0–0.15 m) compared with that under native bush. The significantly (P < 0.05) smaller C/N ratios of the surface soil, plant litter, and light fractions (LF 1.0 and 1.7) under the pasture provided further evidence of N enrichment. The 13C CP/MAS NMR spectra for plant material and light fractions did not differ greatly between landuses, but in both cases the O-alkyl : alkyl carbon ratio declined with increasing density. The decomposition and subsequent mineralisation of the relatively N-rich organic matter fractions in the pasture system may have contributed to the significantly (P < 0.05) greater DOC, DON, and SMN concentration measured in soil solutions under pasture compared with those under native bush.

Molecular composition of black carbon in the cryoconite in Arctic by Two-Dimensional 1H-13C HETCOR and 13C CP/MAS

2020 ◽  
Author(s):  
Evgeny Abakumov ◽  
Viacheslav Polyakov
Keyword(s):  
Organic Matter ◽  
Nmr Spectroscopy ◽  
Black Carbon ◽  
Mas Nmr ◽  
Molecular Composition ◽  
Resonance Spectroscopy ◽  
Initial Surface ◽  
Current Time ◽  
Organic Matter Stabilization ◽  
Cp Mas Nmr

&lt;p&gt;Air pollution caused by human activities contributes to the deglaciations of Arctic ice and highland areas, accelerates the process of climate change on the planet and leads to land degradation. Black carbon is the second largest artificial contributor to global warming and accelerates the deglaciations rates after carbon dioxide. Black carbon is formed as a result of incomplete combustion of fossil fuels, biomass, etc. Another important aspect of organic matter role is the presence of specific formations of combined biogenic-mineral materials on the surface of the glaciers &amp;#8211; cryoconites. Cryoconites represent soil like bodies formed not on normal parent material, but on the surface of the ice. This type of accumulations appear in microdepressions, formed due to thawing of ice under accumulation of black carbon on the surface of ice. During the thawing, the cryoconite substances become located deeper in relation to initial surface and this result in additional accumulation of organic matter in microdepressions, they become wider and deeper. Spatial web of cryoconite became more developed and this result in degradation of the glacier surface. This cryoconite formation result in degradation of upper layers of ice and increases deglaciation rates. &amp;#160;The organic carbon of the cryoconite origin could be considered as specific form of natural organic matter stabilization and should be investigated on the molecular level. The advantage nuclear magnetic resonance spectroscopy method is the ability to quantify the content of groups of structural fragments and identify individual structural fragments in humic acid molecules. Studies on the organic compounds of HAs for the soils of the polar area by the &lt;sup&gt;1&lt;/sup&gt;H-&lt;sup&gt;13&lt;/sup&gt;C (HETCOR) NMR spectroscopy have not been carried out to current time. The advantage of this method is that, when analyzing the spectra of HAs, we can observe cross-peaks of H-C bonds, while for the &lt;sup&gt;13&lt;/sup&gt;C (CP/MAS) NMR spectroscopy we can only observe chemically bound carbon. The HETCOR method allows the study of single HAs fragments. Thus, the combination of the two methods &lt;sup&gt;1&lt;/sup&gt;H-&lt;sup&gt;13&lt;/sup&gt;C (HETCOR) and &lt;sup&gt;13&lt;/sup&gt;C (CP/MAS) NMR spectroscopy can reliably determine the molecular structure of HAs. In our research we investigate the cryoconitte on the Gr&amp;#248;nfjorden area in western Spitsbergen, Svalbard. Analysis of the molecular composition of HAs showed that the molecules of HAs formed on cryoconites are enriched with aromatic fragments and they contain in their composition a considerable number of aromatic fragments (41&amp;#8211;43%) with a relatively small fraction of carbohydrate periphery, as evidenced by higher values of AR/AL (0.75 and 0.69). Higher aromaticity of HAs causes their high stability and the degree of hydrophobicity of HAs in these soils is also higher, which indicates the stabilization of HAs.&lt;/p&gt;&lt;p&gt;Acknowledgements: This work was partially supported by Russian Foundation for Basic Research, projects No: 19-54-18003, 19-54-18003 and 19-05-50107&lt;/p&gt;

ChemInform Abstract: HIGH-RESOLUTION CARBON-13 CP/MAS NMR SPECTRA OF SOLID CELLULOSE OLIGOMERS AND THE STRUCTURE OF CELLULOSE II

1983 ◽  
Vol 14 (31) ◽  
Author(s):  
R. L. DUDLEY ◽  
C. A. FYFE ◽  
P. J. STEPHENSON ◽  
Y. DESLANDES ◽  
G. K. HAMER ◽  
...  
Keyword(s):  
High Resolution ◽  
Nmr Spectra ◽  
Mas Nmr ◽  
Cellulose Ii ◽  
Cp Mas Nmr
Sign in / Sign up

Export Citation Format

Share Document