Monthly Precipitation Collected at Hirosaki, Japan: Its Tritium Concentration and Chemical and Stable Isotope Compositions

Monthly precipitation samples were collected at Hirosaki, Aomori Prefecture from January 2018 to December 2020 to measure the ion species and stable hydrogen and oxygen isotope ratios in order to understand the regional properties. The tritium concentration ranged from 0.28 to 1.20 Bq/L, with mean values (±S.D.) of 0.52 ± 0.18, 0.67 ± 0.25 and 0.63 ± 0.21 Bq/L in 2018, 2019 and 2020, respectively. This concentration level was almost the same as for Rokkasho, Aomori Prefecture. The tritium concentration had clear seasonal variation: high in the spring and low in the summer. This trend was thought to arise from seasonal fluctuations in the atmospheric circulation. On the other hand, the pH tended to be low, and the electrical conductivity (EC) tended to be high from the winter to the spring. The ion components, which major ion species contained in sea salt, also tended to be high in the winter, and these components had a strong influence on EC. The d-excess values were high in the winter and low in the summer, and when this trend was considered from the viewpoint of the wind direction data in Hirosaki, these dust components were attributed to the northwest monsoon in the winter to the spring coming from the Asian continent

Caesium retention characteristics of knifc–pan resin from river water

The caesium retention characteristics of a potassium-nickel hexacyanoferrate resin in a polyacrylnitrile (KNiFC–PAN) matrix were tested in fresh water over the range of 2.5–400 mL min −1 . The experimental setup used 2 mL resin and 4-L aliquots of freshwater samples. The results showed nearly 100% retention at speeds below 10 mL min −1 , above 80% up to 100 mL min −1 , and approached 50% at 400 mL min −1 . Using 100 mL min −1 flow rate and KNiFC–PAN resin in a well-type HPGe detector, the minimum detectable concentration was reduced to 3 mBq kg −1 for 4-L aliquots of water samples from the previous 15 mBq kg −1 achieved by Powdex ion-exchange resin and a planar type HPGe detector