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Hagiwara, Kenta*; Ochi, Kotaro; Koike, Yuya*
Radioisotopes, 70(4), p.227 - 237, 2021/05
Behavior of radioactive caesium in river water and sediment in Tama river was investigated during 2012-2016. Concentrations of radioactive caesium in river water and sediment were decreased with time exponentially. Concentrations of suspended radioactive caesium, and radioactive caesium in sediment temporarily increased when sediments were resuspended due to rain. On the other hand, dissolved radioactive caesium was not easily impacted by this factor. Sequential extraction, elemental and crystal phase analysis were performed on the sediments and examined the chemical state of radioactive caesium as well as the adsorption mechanism. Radioactive caesium in sediment was present in a stable chemical form, and there is possibility that radioactive caesium was incorpolated in biotite.
Cs concentrations in east Japanese riversTsuji, Hideki*; Ishii, Yumiko*; Shin, M.*; Taniguchi, Keisuke*; Arai, Hirotsugu*; Kurihara, Momo*; Yasutaka, Tetsuo*; Kuramoto, Takayuki*; Nakanishi, Takahiro; Lee, S*; et al.
Science of the Total Environment, 697, p.134093_1 - 134093_11, 2019/12
Times Cited Count：17 Percentile：59.38(Environmental Sciences)To investigate the main factors that control the dissolved radiocesium concentration in river water in the area affected by the Fukushima Daiichi Nuclear Power Plant accident, the correlations between the dissolved Cs concentrations at 66 sites normalized to the average Cs inventories for the watersheds with the land use, soil components, topography, and water quality factors were assessed. We found that the topographic wetness index is significantly and positively correlated with the normalized dissolved Cs concentration. Similar positive correlations have been found for European rivers because wetland areas with boggy organic soils that weakly retain Cs are mainly found on plains. However, for small Japanese river watersheds, the building area ratio in the watershed strongly affected the dissolved Cs concentration.
Nakanishi, Takahiro
Isotope News, (765), p.22 - 25, 2019/10
Temporal change in concentration of radiocesium in Fukushima river water are outlined. Radiocesium concentration in river water keeps decreasing after several years, however, the declining trend for the dissolved radiocesium concentration is gradually decreasing with time.
Cs concentration in river water in the medium term and future following the Fukushima Nuclear accidentNakanishi, Takahiro; Sakuma, Kazuyuki
Chemosphere, 215, p.272 - 279, 2019/01
Times Cited Count：44 Percentile：87.7(Environmental Sciences)We conducted a three-year-long observation (April 2015 - March 2018) of the Cs concentration in two rivers affected by the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. The result revealed a declining trend for the dissolved and particulate Cs concentration in river water in the medium term after the FDNPP accident. The dissolved and particulate Cs concentrations showed declining trends with time, even though large seasonal variations related to water temperature were also observed in the dissolved Cs concentrations. The environmental half-life for the dissolved Cs concentration was longer than previous reported values in the early phase, suggesting that the declining trend for the dissolved Cs concentration is gradually decreasing with time. The temperature dependency of the dissolved Cs concentration became weaker year by year, and the dissolved Cs concentration will likely remain at the same level for several decades.
Tsuruta, Tadahiko; Niizato, Tadafumi; Nakanishi, Takahiro; Dohi, Terumi; Nakama, Shigeo; Funaki, Hironori; Misono, Toshiharu; Oyama, Takuya; Kurikami, Hiroshi; Hayashi, Seiji*; et al.
JAEA-Review 2017-018, 86 Pages, 2017/10
JAEA-Review-2017-018.pdf:17.58MB
Since the accidents at Fukushima Daiichi Nuclear Power Plant following the Tohoku Region Pacific Coast Earthquake on March 11th, 2011, Fukushima Environmental Safety Center has carried out research on natural mobilization of radionuclide (especially radiocesium) and future forecast from forest to water system and surrounding residential areas. The report summarizes the latest results that have been accumulated from each study field, of our agency together with the other related research organizations. The contents of the report is to be used as evidence-based information for the QA-styled pages in the website of JAEA Sector of Fukushima Research and Development at the time of next renewal.
Iijima, Kazuki
Chikyu Kagaku, 49(4), p.203 - 215, 2015/09
The Fukushima Dai-ichi Nuclear Power Plant accident led to the release of various and huge amount of radionuclides into the environment, and contamination of wide area of eastern Japan, mainly Fukushima prefecture. More than 70% of radioactive cesium, which dominates the exposure dose, was deposited in forest far from our living sphere and is considered to be remobilized with time by water flow and strong wind caused by natural events such as typhoons. Numerous researches on the behavior of radionuclides in the environment have been performed not only by observation in the contaminated regions but also by model analysis so far. This paper overviewed results of understanding and modeling of transport behavior of radiocesium from forests through river systems.
Yamamoto, Masahiro; Katayama, Hideki*; Sato, Tomonori; Tsukada, Takashi
Proceedings of 2014 Nuclear Plant Chemistry Conference (NPC 2014) (USB Flash Drive), 6 Pages, 2014/10
In the Fukushima Dai-ichi Nuclear Power Plant, seawater and natural river water were poured for emergency cooling. Corrosion of materials was worried because of high chloride ion concentration from seawater. The chloride ion concentration was decreased by de-chlorination operation. However, the water was not treated in the viewpoint of microbial breeding, so that many microbes could be alive and microbially induced corrosion (MIC) was worried. So, we attempted to examine the ability of MIC occurrence by using of corrosion potential analysis. Corrosion potentials of samples rose to about 300 mV nobler than the initial values in the NB added solution. The potentials of the welded samples more easily rose than the simple plate. These potential changes are attributed to the biofilms formed on the sample surface. After about 100 days' immersion, evidence of localized corrosion was not observed. More immersion time is needed to clarify the MIC ability.
Kugara, J.*; Trobradovic, H.*; Jo, Akinori*; Sugo, Takanobu; Tamada, Masao; Katakai, Akio
Nihon Ion Kokan Gakkai-Shi, 14(Suppl.), p.77 - 80, 2003/00
Chloromethylstyrene-grafted polyethylene-coated polypropylene fiber (0.9 denier) was functionalized by reaction with diethyl iminodiacetate and hydrolysis of the ester introduced. An acid capacity of the resulting chelating fiber (FIDA-f) was 4.3 meq/g. Although a maximum permissible flow rate of feeds was depressed with an increase in the conditioning pH of the FIDA-f column, breakthrough profiles of Pb(II) were independent of the flow rate of feeds up to 800/h in space velocity (SV). The usefulness of FIDA-f was demonstrated by quantitative removal of Pb(II) from 600 bed volumes of a Pb(II)-spiked river water (5 ppm) at a flow rate of SV 400/h.
*
JNC TJ7420 2000-001, 14 Pages, 2000/02
JNC-TJ7420-2000-001.pdf:0.27MB
no abstracts in English
Suzuki, Yasuhiro*; Nakaguchi, Yuzuru*; Hiraki, Keizo*; Nagao, Seiya; *; *
Chikyu Kagaku, 32, p.21 - 30, 1998/00
no abstracts in English
Suzuki, Yasuhiro*; Nagao, Seiya; Nakaguchi, Yuzuru*; Matsunaga, Takeshi; Muraoka, Susumu; Hiraki, Keizo*
Chikyu Kagaku, 31, p.171 - 180, 1997/00
no abstracts in English
Morishima, Hiroshige*; Koga, Taeko*
PNC TJ1630 96-001, 27 Pages, 1996/03
no abstracts in English
; ; ; Isozaki, Tokuju;
PNC TN8450 93-004, 144 Pages, 1993/06
Generally speaking, two kinds of water plumes which have different temperature, salinity and so on are not easily mixturred and have special boundary. So, it is possible to predict ocurrence of special boundary of sea water from observation of temperature, salinity of sea water. Not only marine environmental monitoring such as radioactivity analysis of sea water, sea-bed sediment, marine products but also observation of water current, water direction, surface and ventical observation of water temperature, salinity and so on in Tokai coastal area are carried out with some observation instruments by Environmental Protection Section, Tokai Works, PNC. The results of vertical observation from 1990 to 1991 are recorded in this report.
