Turnover of carbon in the free light fraction with and without charcoal as determined using the 13C natural abundance method

Geoderma ◽  
2007 ◽  
Vol 138 (1-2) ◽  
pp. 133-143 ◽  
Author(s):  
Evah W. Murage ◽  
Paul Voroney ◽  
Ronald P. Beyaert
Keyword(s):  
Light Fraction ◽  
Natural Abundance ◽  
13C Natural Abundance

13C natural abundance in the British diet: implications for13C breath tests

2000 ◽  
Vol 14 (15) ◽  
pp. 1321-1324 ◽  
Author(s):  
Douglas J. Morrison ◽  
Brian Dodson ◽  
Christine Slater ◽  
Tom Preston
Keyword(s):  
Natural Abundance ◽  
Breath Tests ◽  
13C Natural Abundance

NMR study of 13C-kinetic isotope effects at 13C natural abundance to characterize oxidations and an enzyme-catalyzed reduction

2006 ◽  
Vol 47 (24) ◽  
pp. 4045-4049 ◽  
Author(s):  
Lothar Brecker ◽  
Marion F. Kögl ◽  
Catrin E. Tyl ◽  
Regina Kratzer ◽  
Bernd Nidetzky
Keyword(s):  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Natural Abundance ◽  
13C Natural Abundance ◽  
Kinetic Isotope ◽  
Nmr Study

Structural and dynamic properties of soil organic-matter as reflected by 13C natural-abundance, pyrolysis mass-spectrometry and solid-state 13C NMR-spectroscopy in density fractions of an oxisol under forest and pasture

Soil Research ◽  
1995 ◽  
Vol 33 (1) ◽  
pp. 59 ◽  
Author(s):  
A Golchin ◽  
JM Oades ◽  
JO Skjemstad ◽  
P Clarke
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Isotopic Composition ◽  
Particulate Organic Matter ◽  
Organic Materials ◽  
Natural Abundance ◽  
13C Natural Abundance ◽  
Clay Particles ◽  
Density Fractions ◽  
Soil Organic Matter Turnover

Changes in the content and isotopic composition of organic carbon as a consequence of deforestation and pasture establishment were studied in three neighbouring areas on an Oxisol from Australia and used to measure the turnover of forest-derived carbon (C3) under pasture (C4) over 35 and 83 year time scales. The results indicated that the quantity of forest-derived carbon declined rapidly during the first 35 years under pasture but the content remained nearly stable thereafter, suggesting the presence of two pools of carbon with different turnover times. The calculated values for turnover time of labile and resistant fractions of forest-derived carbon were 35 and 144 years respectively. The soil samples were separated into five fractions with densities <1.6 (free and occluded), 1.6-1.8, 1.8-2.0 and >2.0 Mg m-3. Based on the spatial distribution of organic materials within the mineral matrix of soil, the soil organic matter contained in different density fractions was classified as free particulate organic matter (1.6 free), occluded particulate organic matter (<1.6 occluded, 1.6-1.8 and 1.8-2.0) and clay associated organic matter (>2.0 Mg m-3). The 13C natural abundance showed that the free particulate organic matter formed a significant pool for soil organic matter turnover when the forest was replaced by pasture. Compared with free particulate organic matter, the organic materials occluded within aggregates had slower turnover times. The occluded organic materials were in different stages of decomposition and had different chemical stabilities. Comparison of the chemistry and isotopic composition of occluded organic materials indicated that the O-alkyl C content of the occluded organic materials was inversely related to their stabilities whereas their aromatic C content was directly related to their stabilities. In soils under pasture, a considerable amount of forest-derived carbon was associated with clay particles in the fractions .2.0 Mg m-3. The rate of accumulation of pasture-derived carbon was also rapid in this fraction, indicating the presence of two different pools of carbon (C3 and C4) associated with clay particles. The forest-derived carbon had the highest stability in the fractions >2.0 Mg m-3, probably due to strong interaction with active aluminium or iron and aluminium oxides associated with clay surfaces.

Estimate of organic matter turnover rate in a savanna soil by 13C natural abundance measurements

1990 ◽  
Vol 22 (4) ◽  
pp. 517-523 ◽  
Author(s):  
A. Martin ◽  
A. Mariotti ◽  
J. balesdent ◽  
P. Lavelle ◽  
R. Vuattoux
Keyword(s):  
Organic Matter ◽  
Turnover Rate ◽  
Natural Abundance ◽  
13C Natural Abundance ◽  
Organic Matter Turnover ◽  
Savanna Soil

Conformational studies of polymorphic N-octyl-D-gluconamide with 15N (labeled) 13C (natural abundance) REDOR spectroscopy

2000 ◽  
Vol 2 (8) ◽  
pp. 1781-1788 ◽  
Author(s):  
I. Sack ◽  
S. Macholl ◽  
J. H. Fuhrhop ◽  
G. Buntkowsky
Keyword(s):  
Natural Abundance ◽  
13C Natural Abundance ◽  
Conformational Studies
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