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implies interconnections between long-term biological processes determining carbon content in soils and their thermal properties. Soil incubation experiments represent a common tool to evaluate biological processes. In such experiments, biological

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Agrokémia és Talajtan
Authors: Erika Michéli, Márta Fuchs, József Attila Tóth, Ádám Csorba, and Tamás Szegi

Chambers , F.M. , Beilman , D.W. , Yu , Z. 2011 . Methods for determining peat humification and for quantifying peat bulk density, organic matter and carbon content for palaeostudies of climate and peatland carbondynamics

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attributed to a certain DTG peak might be completed in the non-consecutive thermal treatment at a lower temperature. Table 1 Carbon content (in % w/w) in non-heated and in thermally treated samples of TEA

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and airborne spectroscopy for monitoring organic carbon content in agricultural soils. Geoderma. 144. 395–404. Stoner, E. R. & Baumgardner, M. F., 1981. Characteristic variations in reflectance on surface soils. Soil Sci

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Journal of Radioanalytical and Nuclear Chemistry
Authors: J. Leonhardt, H. Bothe, E. Langrock, E. Maul, P. Morgenstern, D. Müller, and H. Thümmel

Abstract  

The elemental concentration of C, Ca, Fe, Sr, Si, S were determined for 5 borehole brown coal samples by means of NAA, PAA and X-ray techniques. The correlation function between carbon content and the heat values and also between Si, Fe, Ca and Sr contents and ash content are discussed.

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Abstract  

Theoretical and experimental results have shown that109Cd X-rays are suitable for radioanalytical determinations of ash content in moistened coal. Errors due to variation of moisture are practically equal to zero, while those connected with the variations in iron and carbon content are acceptable.

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Physical supporting or defense structures of plants, which decrease palatability, remain in plant tissue after a plant’s death and so decrease detritus decomposition rates. Consequently, palatability and detritus decomposition rate are expected to be positively correlated. Carbon is the main component of these restricting structures, whereas nitrogen is expected to increase plant attractiveness for herbivores. In this study, we tried to confirm the expected positive relationship between palatability and detritus decomposition rate and to find the species functional traits that are responsible for this concordant response. Some traits are shared by species as a consequence of their common phylogenetic history; consequently, we also studied the effect of phylogenetic correction on the expected relationships.We assessed the palatability of meadow plant species to a generalist slug Arion lusitanicus in an aquarium grazing experiment and detritus decomposition rate in a field litter-bag test. The two characteristics are positively correlated and the relationship is strengthened by phylogenetic correction. The relationship was strongest for the decomposition rates during the first three months of exposition, but weakened when the exposition period was from six months to a year. Palatability was negatively affected by plant carbon content, but no relationship was found between plant palatability and nitrogen content. Similarly, only the relationship of litter decomposition with litter carbon content was significant. The regression tree method was used to detect the influence of species traits on species palatability and detritus decomposition rate. In general, leaf dry matter content, litter carbon content and seed weight were chosen as the best predictors of plant palatability response. Results for the detritus decomposition rate response mainly reflect supporting or defensive structure contents. Litter carbon content, seed weight and plant height are the most apparent common predictors of these variable responses.In general, our study confirmed the positive relationship between plant palatability and detritus decomposition. Both plant tissue grazing and detritus decomposition are slowed down by plant tissue supportive structures, manifested as high dry matter content or high tissue carbon content.

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Studies in heavy ion activation analysis

V. Determination of carbon in steel by6Li activation

Journal of Radioanalytical and Nuclear Chemistry
Authors: J. Ojo, B. Lass, and E. Schweikert

Abstract  

Nondestructive heavy ion activation analysis has been used to determine the carbon content in various NBS SRM steel samples with a 7.0MeV6Li+ beam. The reaction12C(6Li, αn)13N allows for carbon analysis with the only possible interference being beryllium,9Be(6Li, 2n)13N. Under interference-free conditions, and employing a post-irradiation etch, the detection limit for carbon analysis in steel was 5 ppm.

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Abstract  

The thermal decomposition behavior of hard coal fly ash (HCA2), obtained from the combustion of an Australian hard coal in thermoelectric power plants, in different atmospheres (air, N2 and N2-H2 mixture), was studied using thermogravimetry (TG), infrared-evolved gas analysis (IR-EGA), differential scanning calorimetry (DSC) and thermodilatometry (DIL) techniques. It was found that changing of the applied atmosphere affects the carbon content of the ash which results in different thermal decomposition behaviors. In air, the carbon content was oxidized to carbon dioxide before the decomposition of carbonate. In N2 or in N2-H2 atmospheres, the carbon content acts as a spacer causing a fewer points of contact between calcium carbonate particles, thus increasing the interface area which results in a decrease of the carbonate decomposition temperature. Following the carbonate decomposition, the iron oxide content of the ash undergoes a reductive decomposition reaction with the unburned carbon. This oxidation-reduction reaction was found to be fast and go to completion in presence of the N2-H2 mixture than in the pure nitrogen atmosphere due to the reducing effect of the hydrogen. The kinetics of the carbonate decomposition step, in air and N2-H2 mixture was performed under non-isothermal conditions using different integral methods of analysis. The dynamic TG curves obeyed the Avrami-Erofeev equation (A2) in air, and phase boundary controlled reaction equation (R2) in N2-H2 mixture. The change in the reaction mechanism and the difference in the calculated values of activation parameters with the change of the atmosphere were discussed in view of effect of the atmosphere on the carbon content of the ash.

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The objective of this work was to determine the change for straw production, carbon and ash content in vegetative tissues through ten cycles of recurrent selection in bread wheat, evaluated under tilled (CT) and non-tilled (NT) soils. Twenty-four wheat genotypes, four for each one of the 0, 2, 4, 6, 8 and 10 cycles of recurrent selection (RS), were used in this study. Experiments were established during two successive seasons. Ash content was expressed on dry mass basis. To estimate the carbon content, we based our calculation on the assumption that organic matter is 50% carbon. Straw dry weight was measured. For each trait, a linear mixed model (regression) was fitted to the experimental data. In response to the number of selection cycles, the ash content percentage increased under CT and decreased under NT. Carbon content decreases under CT, but increases under NT. The sequestered straw carbon and the straw production significantly decrease under CT meanwhile there was no change under NT. The observed increase for straw ash content would be related to the highest rate of transpiration in the more advanced recurrent selection cycles. Consistent with these results, the percentage of straw carbon content decreased because of the mobilization of reserves from the stems and leaves to the grains.

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