Vertical Concentration Profiles of Radioactive Caesium and Convective Velocity in Soil in a Paddy Field in Fukushima

Shiozawa, Sho; Tanoi, Keitaro; Nemoto, Keisuke; Yoshida, Shuichiro; Nishida, Kazuhiro; Hashimoto, Ken; Sakurai, Kenta; Nakanishi, Teruyuki; Nihei, Naoto; Ono, Yuji

doi:10.3769/radioisotopes.60.323

Cited by 35 publications

(19 citation statements)

References 2 publications

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“…This investigation also showed that the Cs velocity in organic soil was several times that in mineral soil. Cs) determined in an undisturbed paddy field in Fukushima Prefecture before plowing on May 24th, 2011, approximately 2 months after the radiocesium fallout (Shiozawa et al 2011). The top 0-15 cm of the soil was sampled, which was separated into six layers of 1-5 cm thickness.…”

Section: Retardation Of Cesium Migration As a Results Of Fixation To Smentioning

confidence: 99%

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Vertical Migration of Radiocesium Fallout in Soil in Fukushima

Shiozawa

2013

Agricultural Implications of the Fukushima Nuclear Accident

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The vertical migration of radiocesium fallout in the soil was monitored for 1 year at several locations in Fukushima after the nuclear power plant explosion. We determined the vertical gamma ray intensity profiles in boreholes in the soil using a scintillation survey meter with a lead collimator to restrict the incoming radiation, only allowing horizontal detection. The average migration distances of radiocesium at two time points were accurately determined based on the difference in the depth of the centroids of two gamma ray intensity profiles. The results showed that although the convective velocity of radiocesium was unexpectedly as high as 1/10th of the velocity of the infiltrating rainfall water 2-3 months after the nuclear plant accident, the velocity decreased to 1/100th-1/200th of that of the water after 6-12 months. This indicated that strong fixation of radiocesium to clay particles occurred during the initial 2-3 months. Radiocesium uptake by plant roots may have decreased remarkably along with the mobility of radiocesium in the soil.

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Section: Retardation Of Cesium Migration As a Results Of Fixation To Smentioning

confidence: 99%

“…A cylindrical scintillation probe (Health Physics Instruments, Model 5000) measuring 35 mm in diameter was covered with a handmade lead collimator that (Shiozawa et al 2011) had a slit window around the scintillation detector ( Fig. 6.3).…”

Section: Collimator and Monitoring Pipementioning

confidence: 99%

Vertical Migration of Radiocesium Fallout in Soil in Fukushima

Shiozawa

2013

Agricultural Implications of the Fukushima Nuclear Accident

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“…Thus, it is possible that there is a difference in the translocation of 137 Cs and 40 K to the aboveground parts from the current orchard soil. In particular, it is said that the radiocesium was high in the surface soil layer (5 cm) (Shiozawa et al 2011), but the roots of peaches are often at 5 cm or deeper, so it is assumed that 137 Cs, compared to 40 K, was not absorbed as much from the soil.…”

Section: Epidermismentioning

confidence: 99%

Translocation of Radiocesium in Fruit Trees

Takata

2016

Agricultural Implications of the Fukushima Nuclear Accident

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We report our findings on the translocation and distribution of radiocesium inside fruit trees after radiocesium (Cs) was released by the accident at the Fukushima Daiichi Nuclear Power Plant.We examined the differences in the rooting depth of grapes and figs and the translocation of radiocesium from the soil to the plants. Much of the radiocesium fallout from the nuclear accident remained on the surface soil layer; however, in environments such as orchards, radiocesium translocates more easily to aboveground parts of trees with shallower roots than of those with deeper roots. It was observed that if the old branches were the source of radiocesium, translocation occurred to both the new aboveground organs, such as leaves and fruits, and the underground parts, including pioneer roots. It was clarified that translocation from old organs contributed a much higher proportion of accumulated radiocesium to fruits than that from the soil. We reported that immediately after the accident, radiocesium that accumulated on the bark quickly infiltrated inside the trees. However, several months after the accident, it is possible that a decreased proportion translocated from the outer bark to the internal parts of trees, such as the wood. The translocation of radiocesium and potassium (K) into fruits and leaves may show some differences. Explaining the behavior of radiocesium translocation in perennial crops using K as an index is even more difficult than that in annual crops. To predict the radiocesium concentrations in the harvested fruits, the concentrations in the thinned fruits and the harvested fruits were compared. The results showed that there is a strong correlation between the two. However, since some trees were outliers, predictions must be made carefully.

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“…1.3 ). Many pipes were prepared on the ground and the radioactivity profi le along with the depth was measured (Shiozawa et al 2011 ). The left fi gure in Fig.…”

Section: Fallout On Soilmentioning

confidence: 99%

The Overview of Our Research

Nakanishi

2013

Agricultural Implications of the Fukushima Nuclear Accident

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The overview of our research projects for Fukushima is presented including how they were derived. Then, where the fallout was found, right after the accident, is briefl y summarized for soil, plants, trees, etc. The time of the accident was late winter, there were hardly any plants growing except for the wheat in the farming fi eld. Most of the fallout was found at the surface of soil, tree barks, etc., which were exposed to the air at the time of the accident. The fallout found was fi rmly adsorbed to anything and did not move for months from the site when they fi rst touched. Therefore, the newly emerged tissue after the accident showed very low radioactivity. The fallout contamination was not uniform, therefore, when radiograph of contaminated soil or leaves were taken, fallout was shown as spots. Generally, plants could not absorb radiocesium adsorbed to soil. Further fi ndings are described more in detail in the following sections. Keywords Research ProjectAfter the accident of Fukushima Daiichi nuclear power plant, thousands of measuring data have been piling up, especially in the web sites of government agencies. However, most of them are two kinds of the data. One is the radio activities of the places, including soil, air dust or sea water and the other is the measurement of the foods. These are just the monitoring data and it is diffi cult to fi nd out the research

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Vertical Concentration Profiles of Radioactive Caesium and Convective Velocity in Soil in a Paddy Field in Fukushima

Cited by 35 publications

References 2 publications

Vertical Migration of Radiocesium Fallout in Soil in Fukushima

Vertical Migration of Radiocesium Fallout in Soil in Fukushima

Translocation of Radiocesium in Fruit Trees

The Overview of Our Research

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