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Abstract: Pot experiments were performed in a greenhouse to investigate the soil-to-soybean transfer of 99Tc in two different upland soils labeled with 99TcO4 − in two contrasting ways. One was to mix the soil with a 99 solution 26 d before sowing (pre-sowing deposition: PSD), and the other was to apply the solution onto the soil surface 44 d after sowing (growing-period deposition: GPD). The soil-to-plant transfer was quantified with the transfer factor (TF, ratio of the plant concentration to the average of at-planting and at-harvest soil concentrations) or the aggregated transfer factor (TFag, ratio of the plant concentration to the deposition density). For both the depositions, the transfer of 99Tc to aerial parts decreased in the order of leaf > stem > pod > seed. TF values (dimensionless) from the PSD were 0.22 and 0.27 (no statistically significant difference) for mature dry seeds in the respective soils, whereas a 600-fold higher value occurred for dry leaves. The post-harvest concentrations of the PSD 99Tc in the top 20 cm soils as a whole were about half the initial concentrations. Around 25% of the total applied activity remained in the GPD soils after the harvest. The post-harvest depth profiles of the GPD 99Tc in the two soils showed similar patterns of logarithmic activity decrease with increasing soil depths. Only 1.5–4.3% of the total applied activity was removed through the harvested biomass (seeds, pods and stems), and it was estimated that a great part of the total pant uptake returned to the soil through the fallen leaves. TFag values (m2 kg−1) were about 2–4 times higher for the GPD than for the PSD. This finding and generally high root uptake of Tc may indicate that the use of empirical deposition time-dependent TFag data is particularly important for predicting the plant concentrations of Tc after its growing-period deposition. [Copyright &y& Elsevier]

This paper describes the approach to non-human species radiation dose assessment in Korea. As the tentative reference organisms, one plant and seven animals were selected based on the new International Commission on Radiological Protection recommendation issued in 2007, and the size of the selected organisms was determined from the corresponding Korean endemic species. A set of 25 radionuclides was considered as a potential source term of causing radiological damage to organisms. External and internal dose conversion coefficients for the selected organisms and radionuclides were calculated by the uniform isotropic model or Monte Carlo simulation. Concentration ratios of some endemic species are being measured in laboratory experiments, in parallel with the review of existing data. [ABSTRACT FROM PUBLISHER]

Regarding the assessment of the terrestrial food chain dose to man, radioecology may be the field that is focused on the transfer of radionuclides from environmental media to food crops. In Korea, the environmental transfer of radionuclides to staple food crops have been investigated at Korea Atomic Energy Research Institute (KAERI) for the last 25 y mainly through radiotracer experiments in greenhouses. As a result, several hundreds of parameter values for the prediction of the radionuclide transfer have been produced. Many of them appear in two recent publications of International Atomic Energy Agency. This paper outlines the KAERI's past radioecological work and introduces the ongoing research and future plans. [ABSTRACT FROM PUBLISHER]

The transfer characteristics of 137Cs, 85Sr and 65Zn to earthworms (Eisenia andrei) in soils with different amounts of the radionuclides have been investigated. The time-dependent whole-body concentration ratios (CR) were derived for worms in artificially contaminated soils with three different activity concentrations. Two parameters of a first order kinetic model, the equilibrium concentration ratio (CReq) and the effective loss rate constant (k), were estimated by a comparison of experimental CR results with model predictions. The estimated CReq (Bq/kg fresh worm per Bq/kg dry soil) ranged from 3.9 × 10−4 to 4.1 × 10−3 for 137Cs, 1.39 × 10−3 to 2.94 × 10−2 for 85Sr, and 1.39 × 10−3 to 5.0 × 10−2 for 65Zn, and consistently decreased with increasing soil activity concentration but the trend was not statistically significant. The CReq for 137Cs was one to two orders of magnitude lower than previously reported CRwo-soil values (based on field data with much less contaminated soil), that for 85Sr was comparable with other reported values and for 65Zn was less two to three orders of magnitude lower than CRwo-soil values for stable zinc. The estimated k (d−1) values ranged from 9 × 10−2 to 1.4 × 10−1 for 137Cs, 7 × 10−2 to 2 × 10−1 for 85Sr, and 6 × 10−2 to 1.8 × 10−1 for 65Zn, and did not show a relationship with soil activity concentration. The effect of CReq on the total dose rate was insignificant for 137Cs or 65Zn because external dose rates to the soil dwelling earthworms due to these radionuclides were much greater than the internal dose rate. In contrast, the total dose from 90Sr was determined by the internal dose rate and therefore proportional to the CReq. [ABSTRACT FROM AUTHOR]