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.

An improved CeO2 method for high-precision measurements of 17O/16O ratios for atmospheric carbon dioxide.

RATIONALE: The oxygen isotopic composition of carbon dioxide originating at the Earth's surface is modified in the stratosphere by interaction with ozone which has anomalous oxygen isotope ratio (Δ(17)O = 1000 * ln(1 + δ(17)O/1000) - 0.522 * 1000 * ln (1 + δ(18)O/1000) >0). The inherited anomaly provides a powerful tracer for studying biogeochemical cycles involving CO(2). However, the existing methods are either too imprecise or have difficulty in determining the small Δ(17)O variations found in the tropospheric CO(2). In this study an earlier published CeO(2) and CO(2) exchange method has been modified and improved for measuring the Δ(17)O values of atmospheric carbon dioxide with high precision. METHODS: The CO(2) fraction from air samples was separated by cryogenic means and purified using gas chromatography. This CO(2) was first analyzed in an isotope ratio mass spectrometer, then artificially equilibrated with hot CeO(2) to alter its oxygen isotopes mass-dependently and re-analyzed. From these data the (17)O/(16)O and (18)O/(16)O ratios were calculated and the Δ(17)O value was determined. RESULTS: The validity of the method was established in several tests by using artificially prepared CO(2) with zero and non-zero Δ(17)O values. The published value of the CO(2)-H(2) O equilibrium slope was also reproduced. CONCLUSIONS: The CO(2)-CeO(2) equilibration method has been improved to measure the oxygen isotope anomaly (Δ(17)O value) of atmospheric CO(2) with an analytical precision of ±0.12‰ (2σ).

SPECIATION OF CESIUM ISOTOPES IN RIVER WATER: A CASE STUDY IN THE UKEDO RIVER.

137Cs in river systems can be taken up by aquatic animals. In this paper, total 137Cs concentration in the Ukedo River system and 137Cs presence in dissolved, acid-soluble and -insoluble fractions in river water samples were determined. Total 137Cs concentration had the maximum value of 2.08 Bq kg-1 below the Ogaki Dam in May 2012. In the base flow condition, > 87% of 137Cs existed in the dissolved state, and the acid-soluble state and the insoluble state were <13% and the undetectable level, respectively. After the heavy rain event, the particulate fraction (acid-soluble state + insoluble state) was elevated to 65%, which corresponds to twice as much as that in the base flow condition. Particulate 137Cs, especially the acid-soluble Cs, can play a role when taken into the food chain in aquatic ecosystems.

Some physical and radiobiological properties of immunologically reactive mouse spleen cells.

Three classes of immunologically reactive cells, differing only slightly in size from each other, are required for the production of hemolysin-forming cells in culture. The three classes of cells can be detected in the normal mouse spleen by the combined use of rosette formation, velocity sedimentation, and irradiation. One class of cells (peak sedimentation velocity, 3.2 mm per hr) forms rosettes. The capacity of these cells to participate in immune responses to foreign erythrocytes is inhibited by relatively low doses of irradiation. These cells may be the immediate precursors of hemolysin-forming cells. A second class of cells (peak sedimentation velocity, 3.6 mm per hr) facilitates the production of hemolysin-forming cells by small numbers of normal spleen cells. Their facilitative activity is resistant to a relatively large dose of radiation. They do not form rosettes. The requirement of a third class of cells was deduced from the results of mixing experiments. Neither rosette-forming cells nor spleen cells largely depleted of rosette-forming cells could give rise to hemolysin-forming cells when cultured either alone or in the presence of large numbers of heavily irradiated cells. However, when rosette-forming cells, cells depleted of rosette-forming cells, and heavily irradiated cells were mixed together, hemolysin-forming cells were produced. The peak responses were found in fractions sedimenting at 4 mm per hr. Thus, it is suggested that these fractions contain a third class of cells. This class of cells does not form rosettes, but its function is inhibited by relatively low doses of radiation.

Lymphocyte transformation induced by autologous cells. II. Stimulation by mitogen-induced lymphoblasts.

Lymphocytes incubated with phytohemagglutinin or concanavalin A develop the capacity to stimulate autologous lymphocyte transformation. This is not attributable to residual mitogen contaminating the lymphoblastic cell preparation as: (a) the dissociation of mitogen from the lymphoblastic cell preparation increases the degree of stimulation observed and (b) the kinetics of lymphocyte transformation stimulated by phytohemagglutinin-induced lymphoblasts is different from that stimulated by phytohemagglutinin. The appearance of the stimulatory determinants on lymphocytes exposed to phytohemagglutinin precedes morphological transformation.

Uptake of 133Cs and 134Cs by Ceratophyllum demersum L. under field and greenhouse conditions.

The phytoremediation abilities of Hornwort (Ceratophyllum demersum L.) were tested under greenhouse and field conditions. Plants were exposed for 8, 16, and 24 days (greenhouse with stable isotope 133Cs), 8 days (field with 133Cs), and 8 days (climabox with radioactive isotope 134Cs). The plants were exposed to different concentration of stable Cs provided as CsCl (0.008, 0.033, 0.133, 0.267, 0.533, 0.800, 1.067, and 1.333 mM) and different activities of 134Cs (4.46, 4.46, 4.74, 4.64, 2.23 and 2.26 kBq). The results of the experiment revealed a significant effect (p < 0.001) of exposure time on Cs uptake. The results showed highest average 133Cs removal rates of 11%, 17% and 19% for 8, 16, and 24 days, respectively, in the greenhouse, 10% for the 134Cs experiment, and 27% for the field experiment with 133Cs. The results indicated that increasing the length of exposure lowered the uptake ability, hence indicating that the plant has limited capacity for Cs removal. The accumulated amount of Cs by plants is significantly dependent (p < 0.001) on the concentration of treatment and complies to a sigmoid curve. Comparison of experiments revealed the greenhouse experiment with 133Cs and the experiment with 134Cs did not differ significantly in their removal rate. However, the field experiment was significantly different from the previous two (p < 0.001), providing a higher removal rate. C. demersum was also able to resist phytotoxic effects of Cs in the greenhouse experiment for 16 days without significant effects (p > 0.05) on health. Even after 24 days of exposure, the plant resisted up to 0.267 mM treatment concentration with no significant tissue lesion (p > 0.05). These results indicate that C. demersum has potential for remediating aquatic habitats, especially in the case of acute events, where a short duration of phytoremediation may take place.

Mechanism of the cation effect in subfractionation of microsomes.

It was previously found that cations introduced into a discontinuous sucrose gradient exert a very pronounced effect on microsomal vesicles, and this principle proved to be effective in microsomal subfractionation. The mechanism of the cation effect was investigated. By using the radioactive isotopes (137)Cs and (85)Sr, it could be calculated that the amount of ions bound to the various subfractions increases their density by 0.14%, thereby enhancing the sedimentation velocity by only approximately 7%. In the presence of Cs(+) the total volume of the microsomal pellet was decreased by approximately 15%. Assuming this change in volume to be due to a contraction of the individual vesicles, a roughly 2(1/2)-fold increase in sedimentation velocity would be expected. It is further demonstrated, on the basis of light scattering and millipore filtration experiments, that monovalent cations cause an extensive aggregation of rough microsomes and a less pronounced aggregation of smooth microsomes. The mean radius of the sedimenting particles of rough microsomes was found to be at least doubled or trebled in the presence of Cs(+), which would give a 4- to 9-fold increase in the sedimentation velocity. Aggregation, therefore, appears to be the main factor in the accelerated sedimentation of rough microsomes in the presence of CsCl. Divalent cations exert a similar effect on a subfraction of the smooth microsomes. Isolated smooth microsomes are very unstable and often exhibit spontaneous aggregation. The presence of attached ribosomes, however, appears to impart greater stability to the rough microsomes as well as increasing their ability to bind monovalent cations. The primary cause of the aggregation of microsomal vesicles is probably due to a change in net charge.

Cesium-137 body burdens in Alaskan Eskimos during the summer of 1965.

Cesium-137 body burdens of Anaktuvuk Pass, Alaska, residents during the summer of 1965 were about 30 percent less than during 1964. Lower amounts of cesium-137 in the people reflected a similar decrease of this isotope in caribou flesh, which serves as the principal food of the natives.

Polonium-210 content of human tissues in relation to dietary habit.

Concentrations of polonium-210, a natural fallout nuclide, in human placentas collected in northern Canada ranged up to 27.8 picocuries per 100 grains, or 80 times the average United Kingdom value. High levels are related to the inclusion of reindeer or caribou meat in the diet, and a correlation exists between the eoncentrations of polonium-210 and cesium-137 in the placentas.

Radiation effects in free-ranging pocket mice, Perognathus parvus, during the breeding season.

Captive and free-ranging Great Basin pocket mice, Perognathus parvus, were exposed to ionizing radiation during the breeding season, April-June, in 1971. The values for the median lethal dose (LD(50)) at 30 days plus or minus the standard deviation were 880 +/- 14 rads and 780 +/- 27 rads, respectively, and the slopes of the survivorship curves were significantly different. These differences suggested that there was a synergism between radiation-induced and environmental sources of mortality, since the field data were corrected for natural mortality (5 percent) in the controls.

Strophanthidin-sensitive transport of cesium and sodium in muscle cells.

Uptake of cesium-134 ions into muscle cells is reduced to very low values by the presence of 10(-5)M strophanthidin in the Ringer solution. Cesium ions can induce extrusion of sodium from muscle cells in which the intracellular sodium content is elevated. The cesium-induced extra efflux of sodium-22 is inhibited by the external presence of 10(-5)M strophanthidin. The coupling between inward movement of cesium and outward movement of sodium appears to be chemical in nature. The evidence suggests that cesium ions are transported into muscle cells by a system of sites or carriers that requires a source of metabolic energy for ion turnover to occur.

Explosions and radioactive material: a primer for responders.

A comprehensive primer on the threat posed by radiological dispersion devices, or "dirty bombs," and the management challenges for first responders is presented. The discussion is scenario-driven, presenting guidance for medical responders as to triage and treatment priorities in the face of radiation risk. Key questions are posed that present the need for operational and tactical planning, equipping, and training around this scenario. Decontamination priorities and potential medical management are discussed for both victims and responders.

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.

Hippocampal neuron number is unchanged 1 year after fractionated whole-brain irradiation at middle age.

PURPOSE: To determine whether hippocampal neurons are lost 12 months after middle-aged rats received a fractionated course of whole-brain irradiation (WBI) that is expected to be biologically equivalent to the regimens used clinically in the treatment of brain tumors. METHODS AND MATERIALS: Twelve-month-old Fischer 344 X Brown Norway male rats were divided into WBI and control (CON) groups (n = 6 per group). Anesthetized WBI rats received 45 Gy of (137)Cs gamma rays delivered as 9 5-Gy fractions twice per week for 4.5 weeks. Control rats were anesthetized but not irradiated. Twelve months after WBI completion, all rats were anesthetized and perfused with paraformaldehyde, and hippocampal sections were immunostained with the neuron-specific antibody NeuN. Using unbiased stereology, total neuron number and the volume of the neuronal and neuropil layers were determined in the dentate gyrus, CA3, and CA1 subregions of hippocampus. RESULTS: No differences in tissue integrity or neuron distribution were observed between the WBI and CON groups. Moreover, quantitative analysis demonstrated that neither total neuron number nor the volume of neuronal or neuropil layers differed between the two groups for any subregion. CONCLUSIONS: Impairment on a hippocampal-dependent learning and memory test occurs 1 year after fractionated WBI at middle age. The same WBI regimen, however, does not lead to a loss of neurons or a reduction in the volume of hippocampus.

(137)Cs baseline levels in the Mediterranean and Black Sea: a cross-basin survey of the CIESM Mediterranean Mussel Watch programme.

The common mussel Mytilus galloprovincialis was selected as unique biomonitor species to implement a regional monitoring programme, the CIESM Mediterranean Mussel Watch (MMW), in the Mediterranean and Black Seas. As of today, and upon standardization of the methodological approach, the MMW Network has been able to quantify (137)Cs levels in mussels from 60 coastal stations and to produce the first distribution map of this artificial radionuclide at the scale of the entire Mediterranean and Black Seas. While measured (137)Cs levels were found to be very low (usually < 1 Bq kg(-1) wet wt) (137)Cs activity concentrations in the Black Sea and North Aegean Sea were up to two orders of magnitude higher than those in the western Mediterranean Basin. Such effects, far from representing a threat to human populations or the environment, reflect a persistent signature of the Chernobyl fallout in this area.

Calibration of Safecast dose rate measurements.

A methodology is presented to calibrate contributed Safecast dose rate measurements acquired between 2011 and 2016 in the Fukushima prefecture of Japan. The Safecast data are calibrated using observations acquired by the U.S. Department of Energy at the time of the 2011 Fukushima Daiichi power plant nuclear accident. The methodology performs a series of interpolations between the U.S. government and contributed datasets at specific temporal windows and at corresponding spatial locations. The coefficients found for all the different temporal windows are aggregated and interpolated using quadratic regressions to generate a time dependent calibration function. Normal background radiation, decay rates, and missing values are taken into account during the analysis. Results show that the standard Safecast static transformation function overestimates the official measurements because it fails to capture the presence of two different Cesium isotopes and their changing magnitudes with time. A model is created to predict the ratio of the isotopes from the time of the accident through 2020. The proposed time dependent calibration takes into account this Cesium isotopes ratio, and it is shown to reduce the error between U.S. government and contributed data. The proposed calibration is needed through 2020, after which date the errors introduced by ignoring the presence of different isotopes will become negligible.

Radioactive and stable cesium isotope distributions and dynamics in Japanese cedar forests.

Dynamics of the Fukushima-derived radiocesium and distribution of the natural stable isotope 133Cs in Japanese cedar (Cryptomeria japonica D. Don) forest ecosystems were studied during 2014-2016. For the experimental site in Yamakiya, Fukushima Prefecture, we present the redistribution of radiocesium among ecosystem compartments during the entire observation period, while the results obtained at another two experimental site were used to demonstrate similarity of the main trends in the Japanese forest ecosystems. Our observations at the Yamakiya site revealed significant redistribution of radiocesium between the ecosystem compartments during 2014-2016. During this same period radionuclide inventories in the aboveground tree biomass were relatively stable, however, radiocesium in forest litter decreased from 20 ± 11% of the total deposition in 2014 to 4.6 ± 2.7% in 2016. Radiocesium in the soil profile accumulated in the 5-cm topsoil layers. In 2016, more than 80% of the total radionuclide deposition in the ecosystem resided in the 5-cm topsoil layer. The radiocesium distribution between the aboveground biomass compartments at Yamakiya during 2014-2016 was gradually approaching a quasi-equilibrium distribution with stable cesium. Strong correlations of radioactive and stable cesium isotope concentrations in all compartments of the ecosystem have not been reached yet. However, in some compartments the correlation is already strong. An increase of radiocesium concentrations in young foliage in 2016, compared to 2015, and an increase in 2015-2016 of the 137Cs/133Cs concentration ratio in the biomass compartments with strong correlations indicate an increase in root uptake of radiocesium from the soil profile. Mass balance of the radionuclide inventories, and accounting for radiocesium fluxes in litterfall, throughfall and stemflow, enabled a rough estimate of the annual radiocesium root uptake flux as 2 ± 1% of the total inventory in the ecosystem.

The Uptake and Translocation of 99Tc, 133Cs, 237Np, and 238U Into Andropogon Virginicus With Consideration of Plant Life Stage.

Hydroponic uptake studies were conducted to evaluate the uptake and translocation of Tc, Cs (stable analog for Cs), Np, and U into established and seedling Andropogon virginicus specimens under controlled laboratory conditions. Plant specimens were grown in analyte-spiked Hoagland nutrient solution for 24 h, 3 d, and 5 d. Translocation to shoots was greatest for Tc and Cs, likely due to their analogous nature to plant nutrients, while U (and Np to a lesser extent) predominantly partitioned to root tissue with less extensive translocation to the shoots. Plant age contributed significantly to differences in concentration ratios for all nuclides in shoot tissues (p ≤ 0.024), with higher concentration ratios for seedling specimens. Additionally, duration of exposure was associated with significant differences in concentration ratios of Cs and Tc for seedlings (p = 0.007 and p = 0.030, respectively) while plant part (root or shoot) was associated with significant differences in concentration ratios of established plants (p < 0.001 for both nuclides). Statistically significant increases in radionuclide uptake in seedling specimens relative to established plants under controlled conditions suggests that, in addition to geochemical factors, plant life stage of wild grasses may also be an important factor influencing radionuclide transport in the natural environment.

Superficial and juxtamedullary nephron function during saline loading in the dog.

A modification of the microdissection technique of Hanssen was utilized in dogs to measure superficial (SNGFR) and juxtamedullary nephron filtration rate (JMGFR) in control and saline-expanded dogs. During control studies SNGFR was 60+/-4 and JMGFR was 72+/-5 nl/min. During saline loading SNGFR was 74+/-8 and JMGFR was 65+/-6 nl/min. The ratio SNGFR: JMGFR significantly increased from 0.84+/-0.03 to 1.15+/-0.08. Glomerular perfusion rate (GPR) was measured with the microsphere method during control and saline loading. Superficial GPR did not change significantly but juxtamedullary GPR increased from 225+/-42 to 323+/-39 nl/min. Calculated superficial nephron filtration fraction was unchanged after saline expansion but juxtamedullary filtration fraction decreased from 0.34+/-0.07 to 0.24+/-0.07. The data demonstrate a tendency for filtration to shift toward the superficial part and plasma flow toward the deep part of the kidney cortex. GFR in juxtamedullary nephrons appears to be less plasma flow-dependent than in superficial nephrons. The fall in filtration fraction in the deep cortex may affect sodium excretion by juxtamedullary nephrons.