In order to investigate the characteristics of lagoon waters in Niigata Prefecture in recent years, oxygen stable isotope ratios(i.e., δ18Ο), the concentrations of dissolved organic carbon(DOC), and major ions in water samples of Sakata and Toyanogata were measured. Samples were generally taken monthly from 2004 to 2006 at the fixed sampling points from these lagoons. In addition, to survey the influence of rainfall event on these lagoons, δ18Ο and major ions in some samples were determined before and after rain in June -July, 2005. Consequently, the following matters have been mainly clarified. (1)δ18Ο value of sample waters in Sakata lagoon was larger than the values of other environmental waters in Niigata Prefecture, and was especially large in summer. It can be closely related to the biological process such as the activity of Crustacea plankton and to the recharge from surrounding groundwater as well as the effect of evaporation. (2)No remarkable hourly variation of δ18Ο was found in sample waters of Sakata. (3)The effect of rainfall event on δ18Ο(and the concentrations of major ions) in lagoons was obviously different between Sakata and Toyanogata. (4)The relationship between δ18Ο and DOC was relatively good in water samples in Sakata(as compared with that in Toyanogata).
Recently, natural water such as ground water and/or spring water of various places is popular for the environmental preservation and safety of food. Measurement of the radon concentration in ground water is important for risk estimate of drinking water and whether the water can be authorized as the mineral spring(74Bq/L). In this work, radon concentration in ground water from eight places which were utilized for Saijo sake breweries was measured by means of γ-ray spectrometry. Radon concentration in each well was measured every month for two years. The variation in the radon concentration was investigated for seasonal variation, difference between the type of well, correlations with pH, water temperature and atmospheric temperature. The results are as follows:An average value of the radon concentration was 160Bq/L which meant most of ground water satisfies the mineral spring standard. The radon concentration of the drilling well was higher than that of the punched well. The variation in the radon concentration shows no seasonal variations, nor depends on the water temperature, the atmospheric temperature and the pH.
The gamma-ray spectrum analysis program(GAMA-08) by the Windows personal computer for the neutron activation analysis(NAA) has been developed. The gamma-ray peaks of the spectrum were searched automatically by inputting analytical conditions. The gamma-ray peak areas were analyzed by means of the fitting technique based on the non-linear least squares method. The positions, energies and intensities of the peaks were calculated. The intensities were corrected for decay of the corresponding nuclide. The contents and concentrations of elements of interest in the sample were calculated by comparison with the intensitities of standard samples. The overlapping multiple peaks have been analyzed precisely and easily by this analysis program.
A questionnaire survey on safety of nuclear medicine studies was conducted under the subcommittee for radionuclide imaging and nuclear medicine technology of Japan Radioisotope Association to promote patient safety. Questionnaires were sent to 1300 hospitals and 21 clinical laboratories in Japan with 1034 facilities responded(78.3%). Sixty percents of the workers in the facilities were nuclear medicine technologists. Medical doctors comprised 20% of the workers, but 32% in the university hospitals. The number of laboratory technologists decreased in all categories of the facilities. Composite PET/CT scanners increased sharply, whereas 2-detector and 3-detector imaging systems decreased. Regular maintenance was performed in approximately 80% of the SPECT imaging systems, while the single head imaging systems were maintained less frequently. Filmless systems were employed in 25.3% of all of the facilities responded, with the higher rate in the university hospitals. The number of accidents and incidents in the facilities decreased. Falls on floor and fall from an examination bed were reported. The nuclear medicine technologists were concerned about safety mechanism of imaging systems, and dimension and height of examination beds. They also wanted prompt supply of safety information and easy interconnectivity among different data of various vendors′systems. The results of this survey may be a valuable source of information on safety of nuclear medicine procedures.