@misc{oai:repo.qst.go.jp:00069897,
 author = {Ishii, Nobuyoshi and Koiso, Hiroyuki and Uchida, Shigeo and 石井 伸昌 and 小礒 寛之 and 内田 滋夫},
 month = {Oct},
 note = {In Japan, transuranic (TRU) waste is grouped into four types.  Group 2 type includes hulls and end pieces, which contain significant amounts of C-14.  As C-14 is long-lived, soluble and has little sorption properties, it is the key nuclide in safety assessment for a geological repository of TRU waste.
\nRecently, the possibility of leaching of organic carbon compounds from hull waste has been reported.  However, there is little information for reliable migration data sets of such organic C-14.  Thus, it is hard to deny any possible migration of organic C-14 from a TRU repository site to the sphere of human habitation.
\nTo assess human expose to C-14 through crops intake, it is necessary to understand the behavior of organic C-14 in agricultural fields.  In this study, we determined solid-, liquid-, and gas-partitioning ratios of organic C-14 in paddy and upland soils by using batch cultures.  Investigation of factors affecting the partitioning ratios between paddy soils and upland soils was also carried out.
\nPaddy soils (n = 63) and upland soils (n = 79) were collected from throughout Japan.  Each of these agricultural soils was flooded with deionized water at a solid-liquid ratio of 1:10 in a bottle.  The flooded samples supplemented with [1, 2-14C] sodium acetate were shake-incubated for 7 days.  At the end of incubation, radioactivites of C-14 in the soil suspension and the supernatant were counted by using liquid scintillation counting.  Values of the sample pH were measured at the end of incubation.
\nSolid-, liquid-, and gas-partitioning ratios of C-14 were 35.1 +- 8.5%, 5.4 +- 5.1%, and 59.5 +- 9.6%, respectively.  Values of pH correlated positively with liquid-partitioning ratios and negatively with gas-partitioning ratios.  The effect of pH on the partitioning ratios may be related to C-14 gas solubility.
\nThose partitioning ratios were significantly different between paddy soils and upland soils.  For the paddy soils, low solid- and liquid-partitioning ratios and high gas-partitioning ratios were observed.  The mean value of pH in the paddy samples significantly low compared to that for the upland samples.  The differences in liquid- and gas-partitioning ratios between paddy soils and upland soils would be explain by pH because pH correlated with those ratios.  In the present study, the contribution of pH to liquid- and gas-partitioning ratios was suggested.
\nThis work has been partially supported by the Agency for Natural Resources and Energy, the Ministry of Economy, Trade and Industry (METI) Japan., The 12th International Conference on Environmental Remediation and Radioactive Waste Management},
 title = {Partitioning Ratios among Solid-, Liquid-, and Gas-phases for C-14 Labeled Sodium Acetate in Paddy and Upland Soils},
 year = {2009}
}