Uranium in acidic mine drainage at the former Ogoya Mine in Ishikawa Prefecture of Japan

[研究報告

Residual neutron-induced radionuclides in a soil sample collected in the vicinity of the criticality accident site in Tokai-mura, Japan: A progress report

金沢大学理学部Residual neutron-induced radionuclides were measured in a soil sample collected in the vicinity of the location where a criticality accident occurred (in Tokai-mura, from 30 September to 1 October, 1999). Concentrations of 24Na,140La,122Sb,59Fe,124Sb,46Sc,65Zn,134Cs and 60Co in the soil sample were determined by γ-ray spectrometry, and neutron activation analysis was carried out for selected target elements in the sample. Tentative estimates of the apparent thermal and epithermal neutron fluences which reached the sample were obtained through combined analyses of 59Fe/58Fe,124Sb/123Sb,46Sc/45Sc,65Zn/64Zn,134Cs/133Cs and 60Co/59Co. (C) 2000 Elsevier Science Ltd

湖沼環境での物質循環に関する研究: 琵琶湖における天然放射性核種210Pbと210Poの挙動

金沢大学環日本海域環境研究センターThe behavior of 210Pb and 210Po in Lake Biwa, a large mesotorophic lake situated in the Kinki district of Japan, was investigated by analyzing lake water at various depths and precipitation at approximately monthly intervals for a period of 1.5 years, and sediments, streams flowing into and out of the lake. Flux balance calculation indicated that atmospheric deposition was the major source (97% of total) of 210Pb to the lake, and for 210Po growth in-situ from the decay of 210Pb contributed about 75% of the total 210Po supply to the lake. Most (about 90%) of all the 210Pb inputs to this lake was found to be incorporated into sediment. Residence times via sedimentation in the epilimnion and hypoliminion were estimated to be 27 (6-40) and 22 (5-45) days, respectively, for 210Pb and 95 (47-146) and 32 (7-109) days for 210Po. These residence times suggest that there is a difference between 210Pb and 210Po in the extent of their cycling in the water column, with a more rapid removal of 210Pb than 210Po. Overall, 210Pb and 210Po were, furthermore, found to be removed more efficiently during the transit periods of high biological productivity, such as plankton blooms