Uranium content, 234U/238U activity ratio and chemical component of seepage water have been examined in the Tsukuba Tunnel, Ibaraki, northeast Japan. Quality of fracture water through granodiorite was varied from calcium carbonate type to alkali carbonate type in accordance with the distance from the adit mouth. Uranium content in fracture water through gabbro was less than that through granodiorite.234U/238U activity ratio was higher than 1.0 because of the recoil effect of234Th. The maximum value was 3.9. Uranium content of such a sample was high, even though the water was in reducing condition. It is concluded that this sample has been recharged by stagnant deep water that had been confined into rock fractures for a long time and led to have large amount of HCO3-.
To evaluate the usefulness for the detection of ischemic heart disease, ATP myocardial SPECT was perfomed in 35 patients (mean; 59±9.4 y.o.) with angina pectoris or old myocardial infarction. Coronary angiography (CAG) was performed in all patients. The ultra-short half-life of ATP required a continuous infusion for its use. ATP was infused intravenously at a rate of 0.16 mg/kg/min for 5 min, with201T1 injection taking place at 3 min. Myocardial SPECT imaging was begun 5 min and 4 h later after the end of ATP infusion. ATP caused a significant decrease in arterial blood pressure (p<0.01) and reflex increase in heart rate (p<0.01) . Double product increased slightly (from 8394±2452 to 9581±1 856) . The side effects were generally mild, transient, and no need for administration of aminophylline. The most frequent side effects include chest pain (26%), flushing, warmth (14%), headache (11%), palpitation (3%), dyspnea (3%), and arm discomfort (3%) . The second degree AV block was observed in 6% and ST depression was observed in 9% of patients. Usefulness of ATP201T1 myocardial SPECT for the detection of coronary artery disease (CAD) was evaluated using CAG as a golden standard. The sensitivity and specificiy for CAD detection were 82% and 90%, respectively. ATP myocardial SPECT is a promising new test for the detection of ischemic heart disease.
In this study, concentrations and distributions of134Cs, 137Cs, 7Be and40K in mosses collected in Japan were investigated.137Cs, 7Be and40K were detected in all samples of the 55 mosses, and134Cs were detected in the 33 samples of them. The average134Cs/137Cs radioactivity ratio in mosses was 0.057±0.026. This radioactivity ratio was not accordant with the calculated value, 0.10 derived from the ratio (0.5) of the Chernobyl accident in 1986. The concentrations of134Cs and137Cs in the mosses increased with the heights of sampling points. The correlation coefficients between the concentration of radioactive caesiums and the altitude of sampling points were significant, and the correlation coefficient of134Cs was higher than that of137Cs. Various parts of Hylocomium splendens, a moss, showing a typical stepwise annual growth, were investigated for the purpose of monitoring radioactivity which was concentrated in plants every year. The concentration of137Cs in the older part of Hylocomium splendens were higher than that in younger one. The degree of decrease in the concentration of137Cs at 1986, 1987 and 1988 was smaller than that of other years.134Cs was detected only in the leaves grown in 1986, 1987 and 1988. These results suggest that Hylocomiun splendens are useful for monitoring of radioactive caesium for past a few years.
Radioprotective effects were investigated in mice which received subcutaneously a single dose of each inorganic metal: Co, Cu, Rb, Sr, Mo and W 24h post irradiation of60Co γ-rays with a sublethal dose. The effects were observed in mice injected with Co at an optimum dosage of 20 mg/kg· body weight. Then to elucidate mechanisms of the effects, mice were injected with Co containing the radioactive tracer (60Co) following the radiation exposure, measured elimination of the radioactivity for 7 days, then sacrificed and divided to some tissues and organs. The radioactivity in whole body during this period resulted in a markedly higher retention than that for mice injected with [60Co] alone, as well as liver in the organs. These higher retentions appeared to be related to the radioprotective effects.
A well-type Ge detector was studied to use for determining radioactivities of U and T h-series nuclides in small amount of environmental samples. Peak efficiencies of the well-type detector decreased against the height of sample (relative variation rate (a'/Eff (at24mm) ) was about -1%/ mm in this study) . The principal reason is thought to be in self-absorption. It is convenient to use the first-order regression formula to calculate the efficiencies if sample height is lower than the well depth. This technique was applied to lake core samples to determine sedimentation rate, and a good result was obtained.
Long-term acid deposition on a forest ecosystem can have serious impacts on many physicochemical processes in the soil. Since 1984 extensive studies have been carried out in the “Höglwald”, an old Norway spruce stand near Munich, Germany. In 1986 a variety of radionuclides were deposited in the canopy and on the forest floor of the Höglwald following the reactor accident at Chernobyl. The amount of137Cs from Chernobyl was about 10 times larger than that present in the soil before Chernobyl. Six experimental plots were established in order to study the potential disturbances caused by artificial acid irrigation and compensative liming. Using these fields, investigations on the interception and retention of radionuclides by a coniferous woodland have been done together with the deposition and vertical migration of the radionuclides in the forest. One of the most important results obtained was that134Cs deposition velocity in the spruce stand was as high as 5.5mm/s, and thus higher by a factor of 10 than the corresponding value for the grassland. By evaluating the depth profiles of the Chernobyl-derived137Cs in the soil with a compartment model. The fixation of radiocesium in the forest soil was found to be a rather slow process.