Difference in cesium accumulation among rice cultivars grown in the paddy field in Fukushima Prefecture in 2011 and 2012.

After the accident of the Fukushima 1 Nuclear Power Plant in March 2011, radioactive cesium was released and paddy fields in a wide area including Fukushima Prefecture were contaminated. To estimate the levels of radioactive Cs accumulation in rice produced in Fukushima, it is crucial to obtain the actual data of Cs accumulation levels in rice plants grown in the actual paddy field in Fukushima City. We herein conducted a two-year survey in 2011 and 2012 of radioactive and non-radioactive Cs accumulation in rice using a number of rice cultivars grown in the paddy field in Fukushima City. Our study demonstrated a substantial variation in Cs accumulation levels among the cultivars of rice.

The effect of fertilization on cesium concentration of rice grown in a paddy field in Fukushima Prefecture in 2011 and 2012.

After the accident of the Fukushima 1 nuclear power plant in March 2011, radioactive cesium was released and paddy field in a wide area of Fukushima Prefecture was contaminated. To reduce radioactive Cs uptake by rice, it is important to understand factors that affect Cs uptake in rice. Here we describe our study in 2011 and 2012 to investigate Cs concentration in two rice cultivars, Koshihikari and Hitomebore, the top two cultivars in Fukushima prefecture, grown under different fertilizer conditions in the contaminated paddy field. Our study demonstrated that high nitrogen and low potassium conditions increase Cs concentrations both in straw and brown rice.

Ecological half-life of 137Cs in mosses and lichens in the Ordu province, Turkey by Cevik and Celik.

Twenty-one years after the Chernobyl accident, lichen and moss samples were collected from the Ordu province, which was already chosen for a related study some years ago. It was observed that 137Cs activity concentration ranged from 31 to 469 Bq kg(-1) in the moss and from 132 to 1508 Bq kg(-1) in the lichen samples. The decrease of the activity concentrations in the present measurements (2007) relative to those in 1997 (over a period of 10 y) indicated ecological half-lives between 1.8 and 10.4 y for the moss and between 2.1 and 13.7 y for the lichen samples. It was observed that 137Cs was still eminent in the area studied. Moreover, 40K activity concentrations and K element concentrations were measured and their relationships were discussed.

Mechanisms underlying the radioprotective effect of histamine on small intestine.

PURPOSE: To examine the protective effects of histamine on intestinal damage produced by gamma-radiation. MATERIALS AND METHODS: 56 mice were divided into 4 groups. Histamine and Histamine-10 Gy groups received a daily subcutaneous histamine injection (0.1 mg/kg) starting 20 hours before irradiation and continued until the end of the experimental period; the untreated group received saline. Histamine-10 Gy and untreated-10 Gy groups were irradiated with a single dose on whole-body using Cesium-137 source (7 Gy/min) and were sacrificed 3 days after irradiation. Small intestine was removed, fixed and stained with hematoxylin and eosin. The number of intestinal crypts per circumference, and other histological characteristics of intestinal cells were evaluated. We further determined by immunohistochemistry the expression of proliferating cell nuclear antigen (PCNA), Bax, Bcl-2 (pro- and anti-apoptotic protein, respectively), antioxidant enzymes (Superoxide dismutase (SOD), Catalase and Glutathione peroxidase), histamine content and apoptosis by terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate biotin nick end labeling (TUNEL) assay. Cells in the S phase of the cell cycle were identified by immunohistochemical detection of 5-bromo-2'-deoxyuridine (BrdU) incorporation. RESULTS: Histamine treatment reduced mucosal atrophy, edema and preserved villi, crypts and nuclear and cytoplasmic characteristics of small intestine after radiation exposure. Additionally, histamine treatment increased PCNA expression and the BrdU-positive cell number, histamine content, decreased the number of apoptotic cells and significantly increased Catalase and copper-zinc-containing SOD of irradiated mice. CONCLUSIONS: Histamine prevents radiation-induced toxicity by increasing proliferation of damaged intestinal mucosa and suppressing apoptosis that was associated with an increase in SOD and Catalase levels. This effect might be of clinical value in patients undergoing radiotherapy.

Translocation of 133Cs administered to Cryptomeria japonica wood.

To reveal the in planta behaviour of caesium (Cs), the stable isotope 133Cs was administered into 3-year-old Cryptomeria japonica seedlings by the application of 133CsCl aqueous solution to the bark surface. The administered 133Cs was quantified by ICP-MS measurements, which showed transportation of 133Cs in an ascending direction in the stem. Distribution of 133Cs was visualized using freeze-fixed C. japonica woody stem samples and cryo-time-of-flight secondary ion mass spectrometry/scanning electron microscopy (cryo-TOF-SIMS/SEM) analysis. Cryo-TOF-SIMS/SEM visualization suggested that 133Cs was rapidly transported radially by ray parenchyma cells followed by axial transportation by pith and axial parenchyma cells. Adsorption experiments using powdered C. japonica wood samples and X-ray absorption fine structure (XAFS) analysis suggested that 133Cs was in the hydrated state following its deposition into tracheid cell walls.

Influence of water management and fertilizer application on (137)Cs and (133)Cs uptake in paddy rice fields.

Cesium-137 derived from the Tokyo Electric Power Company's Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident contaminated large areas of agricultural land in Eastern Japan. Previous studies before the accident have indicated that flooding enhances radiocesium uptake in rice fields. We investigated the influence of water management in combination with fertilizers on (137)Cs concentrations in rice plants at two fields in southern Ibaraki Prefecture. Stable Cs ((133)Cs) in the plants was also determined as an analogue for predicting (137)Cs behavior after long-term aging of soil (137)Cs. The experimental periods comprised 3 y starting from 2012 in one field, and 2 y from 2013 in another field. These fields were divided into three water management sections: a long-flooding section without midsummer drainage, and medial-flooding, and short-flooding sections with one- or two-week midsummer drainage and earlier end of flooding than the long-flooding section. Six or four types of fertilizer subsections (most differing only in potassium application) were nested in each water management section. Generally, the long-flooding treatment led to higher (137)Cs and (133)Cs concentrations in both straw and brown rice than medial- and short-flooding treatments, although there were some notable exceptions in the first experimental year at each site. Effects of differing potassium fertilizer treatments were cumulative; the effects on (137)Cs and (133)Cs concentrations in rice plants were not obvious in 2012 and 2013, but in 2014, these concentrations were highest where potassium fertilizer had been absent and lowest where basal dressings of K had been tripled. The relationship between (137)Cs and (133)Cs in rice plants was not correlative in the first experimental year at each site, but correlation became evident in the subsequent year(s). This study demonstrates a novel finding that omitting midsummer drainage and/or delaying drainage during the grain-filling period enhances uptake of both (137)Cs and (133)Cs.

Structure-activity relationships of several cardiotonic steroids with respect to inhibition of ion transport in frog muscle.

Cesium uptake by sodium-loaded frog sartorius muscles was inhibited 100% by 10(-6)M ouabain and 10(-6)M cymarin. The doses for 50% inhibition of cesium uptake by five cardiotonic aglycones were 1.5 x 10(-6)M for strophanthidin, 2 x 10(-7)M for telocinobufagin, 1.6 x 10(-6) for digitoxigenin, 2.4 x 10(-6)M for periplogenin, and 6.3 x 10(-6)M for uzarigenin. Because of the limited solubility of sarmentogenin the maximum concentration studied was 2 x 10(-6)M which inhibited cesium uptake about 36%. Inhibition of cesium uptake by cymarin was not reversed during a 3.5 hr incubation in fresh solution while the muscles treated with ouabain and strophanthidin recovered partly during this time. Cymarin was a more potent inhibitor of sodium efflux than strophanthidin and periplogenin was less potent. Increased cesium ion concentration in the external solution decreased the strophanthidin inhibition of cesium uptake but 25 mM cesium did not overcome the inhibition by 10(-8)-10(-6)M strophanthidin. Increased potassium ion concentration in the external solution decreased but did not completely overcome inhibition of sodium efflux by strophanthidin. It is concluded that potassium or cesium ions do not compete with these drugs for a particular site on the ion transport complex. The same structural features of the drugs are necessary for inhibition of ion transport in frog muscle as are required for inhibition of ion transport in other tissues, inhibition of sodium-potassium-stimulated ATPases, and toxicity to animals.

The influence of a whole-lake addition of stable cesium on the remobilization of aged 137Cs in a contaminated reservoir.

To document the short-term dynamics of Cs, 4 kg of (133)Cs were introduced into an 11.4-ha, 157 000 m(3) reservoir previously contaminated with (137)Cs from past reactor operations at the US Department of Energy's Savannah River Site near Aiken, South Carolina, USA. The (133)Cs addition resulted in an increase of 6.1 MBq of (137)Cs (1.9 mug (137)Cs) in the water column over the following 260 days. Possible sources for the increased (137)Cs included (1) release from the sediments, (2) release from the approximately 26 000 kg of aquatic macrophytes that occupied 80% of the reservoir, and (3) wash-in from the pond's watershed. Data are presented to indicate that release from the sediments was the principal source of the (137)Cs increase. The fraction of (137)Cs released from the sediments (0.7%) is consistent with laboratory measurements of (137)Cs desorption from neighboring ponds on the Savannah River Site.

Rice uptake and distributions of radioactive 137Cs, stable 133Cs and K from soil.

The distributions of radionuclides in plant components as to radionuclide transfer to animals are important for understanding the dynamics of radionuclides in an agricultural field. Most of the non-edible parts in these components are returned to the soil as organic fertilizer where they may again be utilized in the soil-plant pathway and/or are mixed with feed for livestock. Rice plants were grown in an experimental field and separated at harvest into different components, including polished rice, rice bran, hull, leaves, stem and root, and then the distributions of radioactive 137Cs, stable 133Cs and K in these components were determined. The distribution of 137Cs in polished rice and rice bran was similar to that of 133Cs, while that of K was different. The concentration ratios of 133Cs/K in leaf blade positions increased with aging, which means that the translocation rate of 133Cs in rice plants was slower than that of K. At harvest the distribution of dry weight in polished rice to entire rice plants was 34%, and the distributions of 133Cs in the polished rice and the non-edible parts were 7 and 93%, respectively, whereas those of K in the polished rice and the non-edible parts were 2 and 98%, respectively. Findings suggest that the transfer and distribution of 133Cs, not of K, provide better information on the long-term fate of 137Cs in an agricultural environment.

The transfer of stable ¹³³Cs from rice to Japanese sake.

Possible contamination by radioactive cesium (Cs), released by the Fukushima Daiichi Nuclear Plant Accident in Japan on March 2011, has been a matter of concern with respect to Japanese sake made from rice grains cultivated in affected fields. In this study, the behavior of stable (133)Cs, which is a useful analogue for predicting the behavior of radioactive Cs, was investigated in the production of sake using rice grains harvested in Japan in 2010. The concentration of stable (133)Cs in the polished rice grains decreased gradually with decreasing milling ratios until a ratio of 70% was reached, and below that point, it did not change significantly. The (133)Cs concentration in the 70% polished rice was approximately 20% of that found in brown rice. The sake was brewed on a small scale using 70% polished rice, and the transfer of (133)Cs from rice to sake was examined. Approximately 30-40% of (133)Cs in the 70% polished rice was removed during the washing and the steeping of the rice grains, and approximately 40% of the (133)Cs in the 70% polished rice was transferred to the sake. If the radioactive Cs species behaves similarly, these results suggest that brown rice containing 100 Bq/kg radioactivity of Cs would generate 70% polished rice grains containing 20 Bq/kg and that the sake brewed from these grains would contain 3-5 Bq/kg.