[en] Three cases of liver injury with inconsistent ultrasound and CT findings were reported . In two of the cases, abnormalities by CT were not reproduced by ultrasonic examination performed before and after the CT. In the other one, ultrasonic examination apparently distinguished subcapsular fluid retention from parenchymal changes, but this differentiation was difficult by CT findings. (Ueda, J.)

[en] Atmospheric deposition of Pu isotopes from the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident has been observed in the terrestrial environment around the FDNPP site; however, their deposition in the marine environment has not been studied. To fully understand this possible contamination of Pu isotopes from the FDNPP accident to the marine environment, we collected marine sediment core samples within the 30 km zone around the FDNPP site in the western North Pacific about two years after the accident. Pu (²³⁹Pu, ²⁴⁰Pu, ²⁴¹Pu) and radiocesium (¹³⁴Cs, ¹³⁷Cs) isotopes were determined. The high activities of radiocesium and the ¹³⁴Cs/¹³⁷Cs activity ratios with values around 1 (decay corrected to 15 March 2011) revealed that these samples were heavily contaminated by the Fukushima-released radionuclides. However, the activities of ^239+240Pu and ²⁴¹Pu were comparable with the background level before the FDNPP accident. The Pu atom ratios (²⁴⁰Pu/²³⁹Pu and ²⁴¹Pu/²³⁹Pu) suggested that global fallout and the Pacific Proving Ground (PPG) close-in fallout are the main sources for Pu contamination in the marine sediments. As Pu isotopes are particle-reactive and they can be easily incorporated with the marine sediments, we concluded that the release of Pu isotopes from the FDNPP accident to the marine environment was negligible. (author)

No abstract available

[en] Distributions of ¹³⁴Cs and ¹³⁷Cs activities in seawater and the surface layer of sediments (0-3 cm depth) were observed in the coastal area, a 5-30 km wide area from the Fukushima Dai-ichi Nuclear Power Station (FDNPS), in May 2013. ¹³⁴Cs and ¹³⁷Cs activities in seawater sampled south of the FDNPS were higher than the activities in seawater sampled east and north of the site and they decreased exponentially with increasing water depth. In the surface layer of sediments, ¹³⁴Cs and ¹³⁷Cs activities and inventories tended to be high at sampling locations that had a high percentage of grained silt and a high amount of organic matter. These results suggested that higher radiocaesium activities and inventories were caused by Cs activity in seawater as well as particulate size and composition in the surface layer of sediments. (author)

[en] The Fukushima Dai-ichi Nuclear Power Station (FDNPS) accident in March 2011 led to releases of large amounts of artificial radionuclides including ¹³⁴Cs and ¹³⁷Cs (radiocaesium) into the environment. As of January 2015, based on TEPCO's monitoring data, ¹³⁷ activities in seawater had exponentially decreased more than 10 times compared to these before the FDNPS accident. However, the activities in sediments have decreased more slowly than those in seawater and they have had large fluctuations. It is necessary to consider the differences of grain size composition in sediments in order to compare the lateral and vertical distributions of radiocaesium in coastal sediments. This study was aimed at elucidating spatial variation and the behavior of radiocaesium activities and inventories for different grain sizes in sediments collected in the Fukushima coastal area in May 2014. The collected sediments were divided into four classes based on grain sizes using Several mesh sizes: granules (grain size larger than 2 mm); very coarse to coarse sand particles (1-2 mm); coarse to very fine sand particles (0.063-1 mm); and silt to clay particles (smaller than 0.063 mm). The percent values (%) for granules and very coarse sand, coarse to very fine sand, silt, and clay particles were: 0.0-23 and 0.0-39, 38-98, and 0.0-51, respectively. The ¹³⁷Cs activities (Bq kg^-1-dry) for granules, very coarse sand, coarse to very fine sand, and silt to clay particles were in the ranges: 7.1-8.4, 7.3-12, 8.5-609, and 43-1487, respectively. In the uppermost layer of sediments (0-3 cm), the ¹³⁷Cs inventories (Bq m^-2) for granules, very coarse sand, coarse to very fine sand, and silt to clay particles were 390, 460, 988-25779, 3998-11555, respectively. The inventories in a water depth of 60 m tended to be higher with finer particles. In a water depth of 120 m, the inventories with coarse to very fine particles were higher than those with slit to clay particles. It is suggested that coarse and fine particles adsorbed ¹³⁷Cs due to bottom current resuspension and lateral transport and then resedimentation onto the flat surface bottom. (author)

[en] ²³⁷Np and Pu isotopes activities such as ²³⁹Pu, ²⁴⁰Pu and, ²⁴¹Pu in soil collected at five stations (sta. A-E) in the Namie town in Fukushima Prefecture in September 2017 were reported. At sta. A-E, ²³⁷Np activities ranged from (0.058±0.05) to (5.7±0.1) mBq/kg-dry and these values were ∼2 orders of magnitude lower compared to those in environmental samples collected in Japan until 2000's. ²³⁹Pu, ²⁴⁰Pu and,^239+240Pu activities were (5.8±1) ∼ (1717±63) mBq/kg-dry, (3.9±1) ∼ (1051±32) mBq/kg-dry, and, (9.7±1) ∼ (2768±70) mBq/kg-dry, respectively, and these values were also ∼2 orders of magnitude lower compared to those before the Fukushima Dai-ich Nuclear Stations (FDNPS) accident. At sta. A, B, C and, E, there is a positive correlation (p value<0.05, R²=0.60∼0.93) between ²³⁷Np and ^239+240Pu activities and ²³⁷Np/^239+240Pu activity ratio was (0.15±0.2) x 10^-3 ∼ (4.1±0.4) x 10^-3. For total 6 layers of litter and surface soil (core depth 0-2.5 cm) at sta. D, ²⁴¹Pu was detected and the contribution rate of Pu derived from the FDNPS accident was very small (<1%) based on the two end-member mixing model for source apportionment. Interestingly, ²⁴¹Pu/²³⁹Pu atomic rations approached the GF value from litter to deeper layers of soil surface. Because there was no significant correlation for ²³⁷Np activity and ²³⁷Np/²³⁹Pu atomic ratio between the layers the ²⁴¹Pu was those not detected, ²³⁷Np in soils in this study was generally originated from GF. (author)

[en] We reviewed the CT examinations and clinical records of 31 patients of purulent meningitis to evaluate the relation of CT findings to pathogenic bacteria and clinical course. The most frequently observed abnormal CT finding was an enlargement of the subarachnoid space and ventricles. There was no relationship between those abnormal CT findings and pathogenic bacteria. Enlargement of ventricles, low density area of the white matter and subdural effusion suggested the necessity of the surgical treatment or poor prognosis. The patients with convulsion or re-elevation of CRP had a tendency to show an exacerbation of such abnormalities. On the contrary, abnormal CT findings improved in the patients without convulsion or with decrease of CRP. We conclude that a follow-up CT examination is indicated in cases developing convulsion or re-elevation of CRP. (author)

[en] ²³⁷Np and Pu isotopes such as ²³⁹Pu and ²⁴⁰Pu in soil (three layers of core depth of 0-1 cm, 2-3 cm and 3-4 cm at C) and reservoir sediments (st. Y1∼Y3) collected around and in the Yamada-mae pond in Fukushima prefecture after the Fukushima Dai-ichi Nuclear Power Stations accident was reported. At C, Y1, Y2 and Y3, ²³⁷Np activities ranged from (0.060±0.01) to (0.50±0.04) mBq/kg-dry and these values were ∼2 orders of magnitudes low compared to those in environmental samples collected in Japan until 1980's, even considering radiation decay. ²³⁹Pu, ²⁴⁰Pu and ^239+240Pu activities ranged (14±2)∼(91±4) mBq/kg-dry, (17±2)∼(80±5) mBq/kg-dry, (24±3)∼(151±8) mBq/kg-dry, respectively and these values were also ∼2 orders of magnitude low compared to those before the FDNPS accident. ²³⁷Np/^239+240Pu activity ratio was (2.6±2)x10^-3∼(4.6±0.1)x10^-3 and ²⁴⁰Pu/²³⁹Pu atomic ratios were (0.18±0.01)∼(0.20±0.1). Both values were within range of global fallout (GF). ²³⁷Pu/²³⁹Pu atomic ratios were (0.37±0.02)∼(0.67±0.3) and the value at Y3 was higher compared to those at Y1 and Y2. From this study and last year reports, it is likely that ²³⁷Pu/²³⁹Pu atomic ratios between same deposition environments for catchment area were close values for few month scales. Moreover, it is suggested that very close values of ²³⁷Pu/²³⁹Pu at Y3 and C (0-1 cm layer) contributed input of terrestrial material due to heavy rain. In the future, it will need to verify these suggestions using more data and another approach. (author)

[en] After the accident at the Fukushima Dai-ichi Nuclear Power Station (FDNPS) happened in March 2011, large amounts of radionuclides were released from the FDNPS into the atmosphere and marine environments. The total amounts of ¹³⁴Cs and ¹³⁷Cs, which are volatile materials, released from the accident were estimated as 18 PBq and 15 PBq, respectively. In contrast, those of ²³⁸Pu, ²³⁹Pu and ²⁴⁰Pu, which are non-volatile materials, amounts were estimated as 1.9x10^-5 PBq, 3.2x10^-6 PBq and 3.2x10^-6 PBq and these amounts were not adequately compared to abundance of Pu isotopes existed in the environment before the accident (Report of Japan government to the IAEA Ministerial Conference on Nuclear safety, 2011). After the accident, ²⁴¹Pu, half-life of which is about 14 year, was detected in forest litter samples at some stations collected in April and May, 2011. From the results of ²⁴⁰Pu/²³⁹Pu and ²⁴¹Pu/²³⁹Pu atomic ratio, it is suggested that these samples were contaminated by Pu originated from the FDNPS accident. Many radionuclides including ²³⁹Np in terrestrial environment soil and pine leaf collected in front of FDNPS and Iitate Village were measured. It is possible to identify origin to Plutonium (Pu) and Neptunium (Np) isotopes using not only Pu isotope atomic ratio such as ²⁴⁰Pu/²³⁹Pu and ²⁴¹Pu/²³⁹Pu but also ²³⁷Np/²³⁹Pu atomic ratio since the global fallout sourced Pu and ²³⁷Np was characterized by a ²³⁷Np/²³⁹Pu atom ratio of (0.48±0.07) (: average of 30°N-71°N). Report for ²³⁷Np in Environment after the FDNPS accident was scarce. In this study, we discussed spatial distributions and origin for ²³⁷Np and Pu isotopes based on the results of the ²³⁷Np and Pu atom ratios (²³⁷Np/²³⁹Pu, ²⁴⁰Pu/²³⁹Pu, ²⁴¹Pu/²³⁹Pu) in four riverbed sediments (st. SR 1-4) collected of the Saruta river in June and July, 2018. At SR 1-4, the ²³⁷Np activities were about three order of magnitude lower than those of ^239+240Pu. ²⁴⁰Pu/²³⁹Pu atomic ratios were generally within global fallout ranges. ²³⁷Np activities and ²³⁷Np/²³⁹Pu atomic ratios were lower than those before the FDNPS accident. (author)

[en] About five years have passed since an accident of the TEPCO's Fukushima Daiichi Nuclear Power Station (FDNPS). Radiocaesium activities in seawater and plankton net samples collected off Fukushima were monitored from 2012 to 2015. The radiocaesium activities in seawater in the coastal area (less than the water depth of 100m) were gradually decreased from over 100 mBq/L to less than 10 mBq/L, although these in the offshore area were almost the same levels as before the accident. The radiocaesium activities in the plankton net samples collected in the coastal area in autumn 2012 and January 2013 were observed in the coastal stations (YK and U2). It is considered that these results were affected the higher radiocaesium activities were reported in seawater around off FDNPS in the monitoring survey. The apparent concentration ratios (CR)-Cs were calculated using the obtained activities of radiocaesium in seawater and the plankton net samples and they ranged from 35 to 4,100, and their range of geomean were 650-1100. Sediment-seawater distribution coefficients K_d (L/kg) were observed to be from 1,900 to 25,000 in the same area in 2013. The estimated CR-Cs in 2012-2015 was 100 times higher than in 2005-2006. For the estimated CR-Cs values, it is necessary to consider the influence by the sediment and suspended particles other than the plankton, as plankton net samples contain not only plankton but also organic matter, particulate matter and sediment in the coastal area. (author)