Environmental conditions for the formation of insoluble Tc in water ponds located above paddy fields

Ishii, Nobuyoshi; Koiso, Hiroyuki; Takeda, Hiroshi; Uchida, Shunsuke

doi:10.1016/j.jenvrad.2007.11.008

Technetium: Radionuclides

Hu

¹

2005

Encyclopedia of Inorganic Chemistry

1

0

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This article provides a review of Tc with regards to the basic chemistry, occurrence, speciation, separation, analysis, fate, and transport. Environmental 99 Tc originates from the nuclear fuel cycle, with most of the isotope (>90%) discharged from reprocessing plants in Europe. It has been recognized that 99 Tc is a very important dose contributor in risk assessment, because of its high abundance, long half‐lives, and presumably high mobility. Essentially all the technetium on the Earth has been created by human activities involving fissionable materials. Among 11 metastates of technetium, 97m Tc is the most stable, with a half‐life of 90.1 days. The common oxidation states of technetium include 0, +2, +4, +5, +6, and +7. Depending upon the redox conditions, Tc primarily exists in two (+7 and +4) stable oxidation states in the subsurface. Under oxidizing conditions, technetium (VII) will exist as the mobile pertechnetate ion (TcO 4 − ) in aqueous solution. Reduction of TcO 4 − to Tc(IV) species (TcO 2 · n H 2 O) will decrease Tc mobility, because Tc(IV) species are strongly retarded from mineral sorption and/or precipitation. ICP‐MS is the common analytical method used to quantify Tc levels.

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Technetium: Radionuclides

Hu

¹

2011

Encyclopedia of Inorganic and Bioinorganic Chemistry

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0

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This article provides a review of Tc with regards to the basic chemistry, occurrence, speciation, separation, analysis, fate, and transport. Environmental 99 Tc originates from the nuclear fuel cycle, with most of the isotope (>90%) discharged from reprocessing plants in Europe. It has been recognized that 99 Tc is a very important dose contributor in risk assessment, because of its high abundance, long half‐lives, and presumably high mobility. Essentially all the technetium on the Earth has been created by human activities involving fissionable materials. Among 11 metastates of technetium, 97m Tc is the most stable, with a half‐life of 90.1 days. The common oxidation states of technetium include 0, +2, +4, +5, +6, and +7. Depending upon the redox conditions, Tc primarily exists in two (+7 and +4) stable oxidation states in the subsurface. Under oxidizing conditions, technetium (VII) will exist as the mobile pertechnetate ion (TcO 4 − ) in aqueous solution. Reduction of TcO 4 − to Tc(IV) species (TcO 2 · n H 2 O) will decrease Tc mobility, because Tc(IV) species are strongly retarded from mineral sorption and/or precipitation. ICP‐MS is the common analytical method used to quantify Tc levels.

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Soil Applications of Slaked Lime and Organic Fertilizer for Reducing⁹⁹Tc Transfer from Soil to Rice Seeds

Choi¹,

Lim²,

Jun³

et al. 2013

Journal of the Korean Radioactive Waste Society

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To see if slaked lime and organic fertilizer applications to soil are useful as countermeasures for reducing 99 Tc concentrations in rice seeds after 99 Tc contamination of paddy fields, pot experiments were performed for two different paddy soils in a greenhouse. The upper soils for a depth of about 20 cm were treated with the agricultural materials and 99 Tc 15 d before transplanting. The effects were compared using the transfer factor (TF) defined as the ratio of the plant concentration to the soil concentration. In the case of control plants, TF values for brown rice in the two soils were 4.1×10 -4 and 4.3×10 -4 . Of various types of the application, only the application of slaked lime at a lower dose (about 0.6 kg m -2 ), which led to a 60% reduction in the TF value for one soil, seemed to be worth using as a countermeasure. Little effect of the same application was found in the other soil so it is important to determine the effect averaged for a number of soils. Organic fertilizer applications at both of two different doses increased the TF value. It is considered necessary to perform experiments for slake lime applications at doses lower than the above.

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Environmental conditions for the formation of insoluble Tc in water ponds located above paddy fields

Cited by 3 publications

References 14 publications

Technetium: Radionuclides

Technetium: Radionuclides

Technetium: Radionuclides

Soil Applications of Slaked Lime and Organic Fertilizer for Reducing⁹⁹Tc Transfer from Soil to Rice Seeds

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Environmental conditions for the formation of insoluble Tc in water ponds located above paddy fields

Cited by 3 publications

References 14 publications

Technetium: Radionuclides

Technetium: Radionuclides

Technetium: Radionuclides

Soil Applications of Slaked Lime and Organic Fertilizer for Reducing99Tc Transfer from Soil to Rice Seeds

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Product

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Soil Applications of Slaked Lime and Organic Fertilizer for Reducing⁹⁹Tc Transfer from Soil to Rice Seeds