To prepare adsorptive fiber capable of capturing strontium ions dissolved in seawater at high capacity, peroxotitanium complex (POTC) anions as precursor of sodium titanate were immobilized by repetitive immersion of dimethylaminoethyl methacrylate (DMAEMA)-grafted fiber in a POTC anion-containing solution. Through ten-times immobilization of POTC anions and their conversion into sodium titanate, impregnation percentage of the fiber amounted to 29％, which was approximately 1.6-fold higher than once immobilization and impregnation. A binding capacity of the resultant fiber in artificial seawater for strontium ions was raised up to 2.9 mg-Sr per gram of the fiber.
The Optical filter method is one of methods to vary the counting efficiency for TDCR (Triple to Double Coincidence) measurement. A method for the fabrication of optical filters for 147Pm standardization was developed using printed plastic film. Toner was printed on a piece of plastic film using the laser printer. The toner color was graduated in steps by a draw software. The counting efficiency was varied according to the amount of scintillation light absorption. The specific activity of 147PmCl3 solution was successfully measured using the printed optical filters.
Activity concentrations in pond water, soil and biota samples, collected at the ecology field in Saitama prefecture during the period of 2011 to 2013, were measured by γ-ray spectrometry. In all samples collected at the ecology field, Fukushima Dai-ichi Nuclear Power Plant derived 134Cs and 137Cs, and natural 40K were detected. The concentrations of 134Cs and 137Cs varied widely in each sample. Moreover, 110mAg was detected in crayfish, and the concentrations of 110mAg were in the range of 0.11～1.0 Bq/kg・wet. Concentration ratios of 137Cs in soil and biota (Bq/kg) to that in pond water (Bq/kg) were about 5～5400. It was so suggested that 137Cs tended to be accumulated in these samples at the ecology field.
Caesium (Cs) uptake in land plant is mainly carried out by potassium ion (K+) transport systems. Potassium ion uptake from the rhizosphere is regulated by two types of transport system, low affinity and high affinity transport systems, depending on the K+ concentration in soil solution. In both transport systems, there are several channels and transporters which mediate Cs+ transport also. In low affinity transport system, the inward-rectifying K+ and voltage-insensitive cation channels are involved in Cs+ uptake, while KUP/HAK/KT type transporters are the major Cs+ path in high affinity transport system. Within the plant body, Cs+ translocation is also mediated by outward-rectifying K+ channels. In addition to these Cs+ and K+ competitive transport systems, recent studies reported novel Cs+ transport systems without changing K+ behavior in plant. In this review, Cs+ transport systems dependent/independent to K+ transport mechanisms are introduced.