5:15 PM - 7:15 PM
[HCG22-P06] Analysis of total carbon and total organic carbon in soil
Keywords:Soil, Carbon concentration, Organic carbon, Soil profile survey
[Introduction]
In order to clarify the distribution area of radioactive fallout from the atomic bombings, analysis of fine charcoal particles derived from the combustion of buildings by the bombs and radioactive cesium, a fission product, is being conducted. For the analysis of fine-grained charcoal, we are attempting to develop a rapid measurement method for fine-grained charcoal analysis using a TOC meter, and for this purpose, it is necessary to first determine the carbon content in the soil, including organic carbon. In addition, it is known that organic matter in soil influences the behavior of radiocesium and other elements in soil, and analysis of carbon content in soil is necessary from this perspective. The amount of organic matter in the soil plays an important role in determining soil properties by influencing soil pH and permeability, as well as increasing the cation exchange capacity. Soil organic matter is supplied by litter, such as fallen leaves, branches, and roots, and decomposed in the soil; approximately half of soil organic matter is composed of organic carbon [1]. In addition to organic carbon, soils sometimes contain inorganic carbon such as carbonate, but in the case of Japanese soils, inorganic carbon is known to be present in very small amounts, if at all, except in soils made of limestone matrix [2]. In this study, we measured total carbon (TC) and total organic carbon (TOC) concentrations in soil in the vertical direction. In addition, a soil profile survey was conducted to examine the relationship between carbon concentrations and other survey parameters such as stratigraphy, color tone, and soil properties.
[Methods]
A multi N/C 3100 +HT 1300 (analytik jena) was used to measure TC and TOC concentrations in the soil. In order to determine the organic carbon concentration, a pretreatment was first performed to remove inorganic carbon from the soil. The pretreatment was performed using hydrochloric acid [3], and the soil samples were dried after the addition of hydrochloric acid.
[Results]
Vertical TC and TOC concentrations in the soil showed high values in the surface layer, decreasing with depth and gradually becoming constant in many locations. In many locations, the TOC concentrations were highest in the surface layer, decreased significantly from the surface to a depth of about 5 cm, decreased slightly in the deeper layers, and remained approximately constant in the deeper layers. The TOC concentrations in the surface layer were smaller than those in the other sites, but as in the other sites, the TOC concentrations in the lower layers were also smaller in soils that were not high in organic matter. and it was confirmed that the measured soil contained almost no inorganic carbon.
The results of the soil profile survey showed that carbon concentrations were high or relatively high in the sedimentary organic matter layer (layers L, F, and H) and the mineral soil layer (layer A), and low in the mineral soil layer (layer B). In general, the higher the carbon concentration, the lower the lightness and saturation [4], and the comparison of lightness + saturation values and carbon concentration at each sampling site showed that the carbon concentration was higher in layers with smaller lightness + saturation values, and similar results were obtained in this study. The same results were obtained in this study.
Acknowledgments: This study was commissioned by the Ministry of Health, Labour and Welfare of Japan, to which the authors thanks are due.
References: [1] Morio Matsuzaki: The relationship of soil organic matter (SOM) and crop production: a review, Journal of the NARO Research and Development, Volume.2021, Issue.6, Pages.1-9, 2021.
[2] Masamichi Takahashi: Organic matter in forest soil and estimation of carbon storage, Japanese Journal of Forest Environment, Volume.42, Issue.2, Pages.61-69, 2000.
[3] Analytik jena, TOC 0019, Application Note, TOC Solid Analyzer, 2019.
[4] Atsushi Torii et al.: How can we estimate soil carbon stock by soil profile description?, The Japanese Forest Society Congress 119, 2008.
In order to clarify the distribution area of radioactive fallout from the atomic bombings, analysis of fine charcoal particles derived from the combustion of buildings by the bombs and radioactive cesium, a fission product, is being conducted. For the analysis of fine-grained charcoal, we are attempting to develop a rapid measurement method for fine-grained charcoal analysis using a TOC meter, and for this purpose, it is necessary to first determine the carbon content in the soil, including organic carbon. In addition, it is known that organic matter in soil influences the behavior of radiocesium and other elements in soil, and analysis of carbon content in soil is necessary from this perspective. The amount of organic matter in the soil plays an important role in determining soil properties by influencing soil pH and permeability, as well as increasing the cation exchange capacity. Soil organic matter is supplied by litter, such as fallen leaves, branches, and roots, and decomposed in the soil; approximately half of soil organic matter is composed of organic carbon [1]. In addition to organic carbon, soils sometimes contain inorganic carbon such as carbonate, but in the case of Japanese soils, inorganic carbon is known to be present in very small amounts, if at all, except in soils made of limestone matrix [2]. In this study, we measured total carbon (TC) and total organic carbon (TOC) concentrations in soil in the vertical direction. In addition, a soil profile survey was conducted to examine the relationship between carbon concentrations and other survey parameters such as stratigraphy, color tone, and soil properties.
[Methods]
A multi N/C 3100 +HT 1300 (analytik jena) was used to measure TC and TOC concentrations in the soil. In order to determine the organic carbon concentration, a pretreatment was first performed to remove inorganic carbon from the soil. The pretreatment was performed using hydrochloric acid [3], and the soil samples were dried after the addition of hydrochloric acid.
[Results]
Vertical TC and TOC concentrations in the soil showed high values in the surface layer, decreasing with depth and gradually becoming constant in many locations. In many locations, the TOC concentrations were highest in the surface layer, decreased significantly from the surface to a depth of about 5 cm, decreased slightly in the deeper layers, and remained approximately constant in the deeper layers. The TOC concentrations in the surface layer were smaller than those in the other sites, but as in the other sites, the TOC concentrations in the lower layers were also smaller in soils that were not high in organic matter. and it was confirmed that the measured soil contained almost no inorganic carbon.
The results of the soil profile survey showed that carbon concentrations were high or relatively high in the sedimentary organic matter layer (layers L, F, and H) and the mineral soil layer (layer A), and low in the mineral soil layer (layer B). In general, the higher the carbon concentration, the lower the lightness and saturation [4], and the comparison of lightness + saturation values and carbon concentration at each sampling site showed that the carbon concentration was higher in layers with smaller lightness + saturation values, and similar results were obtained in this study. The same results were obtained in this study.
Acknowledgments: This study was commissioned by the Ministry of Health, Labour and Welfare of Japan, to which the authors thanks are due.
References: [1] Morio Matsuzaki: The relationship of soil organic matter (SOM) and crop production: a review, Journal of the NARO Research and Development, Volume.2021, Issue.6, Pages.1-9, 2021.
[2] Masamichi Takahashi: Organic matter in forest soil and estimation of carbon storage, Japanese Journal of Forest Environment, Volume.42, Issue.2, Pages.61-69, 2000.
[3] Analytik jena, TOC 0019, Application Note, TOC Solid Analyzer, 2019.
[4] Atsushi Torii et al.: How can we estimate soil carbon stock by soil profile description?, The Japanese Forest Society Congress 119, 2008.