Friday, November 18, 2011

Sample of Soil Absorption of Radiocaesium and Iodine-131

Depth distribution of 137Cs, 134Cs, and 131I in soil profile after Fukushima Daiichi Nuclear Power Plant Accident  Original Research Article
Journal of Environmental Radioactivity, In Press, Corrected Proof, Available online 26 October 2011
Hiroaki Kato, Yuichi Onda, Mengistu Teramage

[excerpts from conclusion]
In this study, we investigated the depth distribution of deposited radionuclides after the FDNPP accident triggered by a magnitude 9.0 earthquake and the resulting tsunami on 11 March 2011. Sectioned soil samples were taken from a home garden located in the Kawamata Town, in the northern part of Fukushima Prefecture.

The depth distribution of deposited radionuclides in the soil profile indicated that approximately 80% of the deposited radiocaesium and 131I were absorbed by the surface soil within the upper 2.0 cm. The relaxation mass depth (h0) derived from the depth distribution of 137Cs, 134Cs, and 131I in the soil profile at the study site were 9.1 kg m_2, 9.1 kg m_2 and 10.4 kg m_2, respectively. 

The penetration depth of 131I was slightly greater than that of radiocaesium. The h0 of 137Cs in the studied soil profile was greater than those for the cultivated soil nearby the Chernobyl NPP. 

A positive relationship was found between clay content of topsoil and the h0 of 137Cs. It was suggested that high clay content increased aggregate stability of topsoil, consequently increasing water infiltration and 137Cs transportation into deeper horizon of the soil profile.

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