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.