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© Springer Nature Switzerland AG 2020
D. K. Gupta, C. Walther (eds.), Uranium in Plants and the Environment,
Radionuclides and Heavy Metals in the Environment,
https://doi.org/10.1007/978-3-030-14961-1_8
Soil-to-Crop Transfer Factor:
Consideration on Excess Uranium
from Phosphate Fertilizer
Keiko Tagami and Shigeo Uchida
Abstract In this chapter, we used the initial U/Th concentration ratio in nonagricultural soil samples to estimate the concentrations of excess U ( ess U) in agricultural
fields in Japan due to long-term application of phosphate fertilizers as a means to
understand the bioavailability of added U to soil. We carried out a data survey and
obtained initial U/Th ratios from 210 nonagricultural soil samples collected throughout Japan; the values are distributed log-normally, and they ranged from 0.006 to 0.9
with the geometric mean value of 0.259. Because concentrations of Th are lower in
phosphate fertilizers than those of U, we assumed that Th concentrations in agricultural fields kept their initial values. Thus, the geometric mean of initial U/Th and Th
concentration in each agricultural soil sample was used first to calculate the initial
U concentration in the soil sample, and then, by subtracting the value from total U
in the soil sample, the ess U concentration in the soil was estimated. Uranium in phosphate fertilizer was thought to be soluble so we hypothesized that ess U would be
easily taken up by crops; however, there were no correlations between brown rice
and ess U nor for potato and ess U. These results suggested that the added U was fixed
to the soil particles so that ess U would not be easily taken up by crops. We also found
that there was no significant difference between soil-to-crop transfer factors obtained
in low and high ess U soil conditions for brown rice and potato; this means that the
ess U and the initial U in soil-to-crop systems had the same fate. Thus, soil-to-crop
transfer factors obtained using U in agricultural fields should be valid in long-term
radiation dose assessment models.
Keywords Environmental dose assessment · Phosphate fertilizer · Soil-to-crop
transfer factor · U/Th concentration ratio · Rock · Soil
K. Tagami (*) · S. Uchida
Biospheric Assessment for Waste Disposal Team, National Institute of Radiological Sciences,
National Institutes for Quantum and Radiological Science and Technology,
Inage-ku, Chiba, Japan
e-mail: tagami.keiko@qst.go.jp
© Springer Nature Switzerland AG 2020
D. K. Gupta, C. Walther (eds.), Uranium in Plants and the Environment,
Radionuclides and Heavy Metals in the Environment,
https://doi.org/10.1007/978-3-030-14961-1_8
Soil-to-Crop Transfer Factor:
Consideration on Excess Uranium
from Phosphate Fertilizer
Keiko Tagami and Shigeo Uchida
Abstract In this chapter, we used the initial U/Th concentration ratio in nonagricultural soil samples to estimate the concentrations of excess U ( ess U) in agricultural
fields in Japan due to long-term application of phosphate fertilizers as a means to
understand the bioavailability of added U to soil. We carried out a data survey and
obtained initial U/Th ratios from 210 nonagricultural soil samples collected throughout Japan; the values are distributed log-normally, and they ranged from 0.006 to 0.9
with the geometric mean value of 0.259. Because concentrations of Th are lower in
phosphate fertilizers than those of U, we assumed that Th concentrations in agricultural fields kept their initial values. Thus, the geometric mean of initial U/Th and Th
concentration in each agricultural soil sample was used first to calculate the initial
U concentration in the soil sample, and then, by subtracting the value from total U
in the soil sample, the ess U concentration in the soil was estimated. Uranium in phosphate fertilizer was thought to be soluble so we hypothesized that ess U would be
easily taken up by crops; however, there were no correlations between brown rice
and ess U nor for potato and ess U. These results suggested that the added U was fixed
to the soil particles so that ess U would not be easily taken up by crops. We also found
that there was no significant difference between soil-to-crop transfer factors obtained
in low and high ess U soil conditions for brown rice and potato; this means that the
ess U and the initial U in soil-to-crop systems had the same fate. Thus, soil-to-crop
transfer factors obtained using U in agricultural fields should be valid in long-term
radiation dose assessment models.
Keywords Environmental dose assessment · Phosphate fertilizer · Soil-to-crop
transfer factor · U/Th concentration ratio · Rock · Soil
K. Tagami (*) · S. Uchida
Biospheric Assessment for Waste Disposal Team, National Institute of Radiological Sciences,
National Institutes for Quantum and Radiological Science and Technology,
Inage-ku, Chiba, Japan
e-mail: tagami.keiko@qst.go.jp