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The aim of this study is to measure tritium concentrations, δ2H, δ18O and ion concentration in monthly precipitation collected at Sapporo, the northern part of Japan and to understand the regional precipitation chemistry. Tritium concentrations of monthly precipitation in Sapporo from July 2015 to the end of 2019 ranged from 0.24 to 1.59 Bq/L with a mean value (±S.D.) of 0.68 ± 0.30 Bq/L. Tritium seasonal patterns were determined with higher tritium concentrations in spring and lower tritium concentrations in summer. It was higher than the reported values in the southern area of Japan. It seemed that tritium concentrations changed with the meteorological conditions depending on the air masses of continental or marine origin and the contribution of cosmogenic tritium from the upper atmosphere. The strong correlation was found between tritium concentrations and NO3− and NH4+ (p < 0.05). It is necessary to accumulate more data as to long-term monitoring for a reliable analysis of ambient tritium concentrations.
Naofumi Akata; Hideki Kakiuchi; Masahiro Tanaka; Yoshio Ishikawa; Naoyuki Kurita; Masahide Furukawa; Miklós Hegedűs; Tibor Kovács; Maksym Gusyev; Tetsuya Sanada. Isotope and chemical composition of monthly precipitation collected at Sapporo, northern part of Japan during 2015-2019. Fusion Engineering and Design 2021, 168, 112434 .
AMA StyleNaofumi Akata, Hideki Kakiuchi, Masahiro Tanaka, Yoshio Ishikawa, Naoyuki Kurita, Masahide Furukawa, Miklós Hegedűs, Tibor Kovács, Maksym Gusyev, Tetsuya Sanada. Isotope and chemical composition of monthly precipitation collected at Sapporo, northern part of Japan during 2015-2019. Fusion Engineering and Design. 2021; 168 ():112434.
Chicago/Turabian StyleNaofumi Akata; Hideki Kakiuchi; Masahiro Tanaka; Yoshio Ishikawa; Naoyuki Kurita; Masahide Furukawa; Miklós Hegedűs; Tibor Kovács; Maksym Gusyev; Tetsuya Sanada. 2021. "Isotope and chemical composition of monthly precipitation collected at Sapporo, northern part of Japan during 2015-2019." Fusion Engineering and Design 168, no. : 112434.
A long-term measurement technique of radon exhalation rate was previously developed using a passive type radon and thoron discriminative monitor and a ventilated type accumulation chamber. In the present study, this technique was applied to evaluate the thoron exhalation rate as well, and long-term measurements of radon and thoron exhalation rates were conducted for four years in Gifu Prefecture. The ventilated type accumulation chamber (0.8 × 0.8 × 1.0 m3) with an open bottom was embedded 15 cm into the ground. The vertical distributions of radon and thoron activity concentrations from the ground were obtained using passive type radon-thoron discriminative monitors (RADUETs). The RADUETs were placed at 1, 3, 10, 30, and 80 cm above the ground inside the accumulation chamber. The measurements were conducted from autumn 2014 to autumn 2018. These long-term results were found to be in good agreement with the values obtained by another methodology. The radon exhalation rates from the ground showed a clearly seasonal variation. Similar to findings of previous studies, radon exhalation rates from summer to autumn were relatively higher than those from winter to spring. In contrast, thoron exhalation rates were not found to show seasonal variation.
Oumar Modibo; Yuki Tamakuma; Takahito Suzuki; Ryohei Yamada; Weihai Zhuo; Chutima Kranrod; Kazuki Iwaoka; Naofumi Akata; Masahiro Hosoda; Shinji Tokonami. Long-Term Measurements of Radon and Thoron Exhalation Rates from the Ground Using the Vertical Distributions of Their Activity Concentrations. International Journal of Environmental Research and Public Health 2021, 18, 1489 .
AMA StyleOumar Modibo, Yuki Tamakuma, Takahito Suzuki, Ryohei Yamada, Weihai Zhuo, Chutima Kranrod, Kazuki Iwaoka, Naofumi Akata, Masahiro Hosoda, Shinji Tokonami. Long-Term Measurements of Radon and Thoron Exhalation Rates from the Ground Using the Vertical Distributions of Their Activity Concentrations. International Journal of Environmental Research and Public Health. 2021; 18 (4):1489.
Chicago/Turabian StyleOumar Modibo; Yuki Tamakuma; Takahito Suzuki; Ryohei Yamada; Weihai Zhuo; Chutima Kranrod; Kazuki Iwaoka; Naofumi Akata; Masahiro Hosoda; Shinji Tokonami. 2021. "Long-Term Measurements of Radon and Thoron Exhalation Rates from the Ground Using the Vertical Distributions of Their Activity Concentrations." International Journal of Environmental Research and Public Health 18, no. 4: 1489.
In this study, to get a better understanding in characterizing groundwater and ensure its effective management, the radon concentrations in water samples were measured through Ryukyu limestone in southern Okinawa Island, Japan. Water samples were collected from a limestone cave (Gyokusendo cave, dropping water) and two springs (Ukinju and Komesu, spring water), and the radon concentrations were measured by liquid scintillation counters. The radon concentrations in the samples from the Gyokusendo cave, and Ukinju and Komesu springs were 10 ± 1.3 Bq L−1, 3.2 ± 1.0 Bq L−1, and 3.1 ± 1.1 Bq L−1, respectively. The radon concentrations showed a gradually increasing trend from summer to autumn and decreased during winter. The variation of radon concentrations in the dripping water sample from the Gyokusendo cave showed a lagged response to precipitation changes by approximately 2–3 months. The estimated radon concentrations in the dripping water sample were calculated with the measured radon concentrations from the dripping water obtained during the study period. Based on our results, groundwater in the Gyokusendo cave system was estimated to percolate through the Ryukyu limestone in 7–10 days, and the residence time of groundwater in the soil above Gyokusendo cave was estimated to be approximately 50–80 days. This work makes a valuable contribution to the understanding of groundwater processes in limestone aquifers, which is essential for ensuring groundwater sustainability.
Shunya Nakasone; Akinobu Ishimine; Shuhei Shiroma; Natsumi Masuda; Kaori Nakamura; Yoshitaka Shiroma; Sohei Ooka; Masahiro Tanaka; Akemi Kato; Masahiro Hosoda; Naofumi Akata; Yumi Yasuoka; Masahide Furukawa. Temporal and Spatial Variation of Radon Concentrations in Environmental Water from Okinawa Island, Southwestern Part of Japan. International Journal of Environmental Research and Public Health 2021, 18, 998 .
AMA StyleShunya Nakasone, Akinobu Ishimine, Shuhei Shiroma, Natsumi Masuda, Kaori Nakamura, Yoshitaka Shiroma, Sohei Ooka, Masahiro Tanaka, Akemi Kato, Masahiro Hosoda, Naofumi Akata, Yumi Yasuoka, Masahide Furukawa. Temporal and Spatial Variation of Radon Concentrations in Environmental Water from Okinawa Island, Southwestern Part of Japan. International Journal of Environmental Research and Public Health. 2021; 18 (3):998.
Chicago/Turabian StyleShunya Nakasone; Akinobu Ishimine; Shuhei Shiroma; Natsumi Masuda; Kaori Nakamura; Yoshitaka Shiroma; Sohei Ooka; Masahiro Tanaka; Akemi Kato; Masahiro Hosoda; Naofumi Akata; Yumi Yasuoka; Masahide Furukawa. 2021. "Temporal and Spatial Variation of Radon Concentrations in Environmental Water from Okinawa Island, Southwestern Part of Japan." International Journal of Environmental Research and Public Health 18, no. 3: 998.
Ten years have elapsed since the accident at the Fukushima Daiichi Nuclear Power Plant in 2011, and the relative contribution of natural radiation is increasing in Fukushima Prefecture due to the reduced dose of artificial radiation. In order to accurately determine the effective dose of exposure to artificial radiation, it is necessary to evaluate the effective dose of natural as well as artificial components. In this study, we measured the gamma-ray pulse-height distribution over the accessible area of Namie Town, Fukushima Prefecture, and evaluated the annual effective dose of external exposure by distinguishing between natural and artificial radionuclides. The estimated median (range) of absorbed dose rates in air from artificial radionuclides as of 1 April 2020, is 133 (67–511) nGy h−1 in the evacuation order cancellation zone, and 1306 (892–2081) nGy h−1 in the difficult-to-return zone. The median annual effective doses of external exposures from natural and artificial radionuclides were found to be 0.19 and 0.40 mSv in the evacuation order cancellation zone, and 0.25 and 3.9 mSv in the difficult-to-return zone. The latest annual effective dose of external exposure discriminated into natural and artificial radionuclides is expected to be utilized for radiation risk communication.
Koya Ogura; Masahiro Hosoda; Yuki Tamakuma; Takahito Suzuki; Ryohei Yamada; Ryoju Negami; Takakiyo Tsujiguchi; Masaru Yamaguchi; Yoshitaka Shiroma; Kazuki Iwaoka; Naofumi Akata; Mayumi Shimizu; Ikuo Kashiwakura; Shinji Tokonami. Discriminative Measurement of Absorbed Dose Rates in Air from Natural and Artificial Radionuclides in Namie Town, Fukushima Prefecture. International Journal of Environmental Research and Public Health 2021, 18, 978 .
AMA StyleKoya Ogura, Masahiro Hosoda, Yuki Tamakuma, Takahito Suzuki, Ryohei Yamada, Ryoju Negami, Takakiyo Tsujiguchi, Masaru Yamaguchi, Yoshitaka Shiroma, Kazuki Iwaoka, Naofumi Akata, Mayumi Shimizu, Ikuo Kashiwakura, Shinji Tokonami. Discriminative Measurement of Absorbed Dose Rates in Air from Natural and Artificial Radionuclides in Namie Town, Fukushima Prefecture. International Journal of Environmental Research and Public Health. 2021; 18 (3):978.
Chicago/Turabian StyleKoya Ogura; Masahiro Hosoda; Yuki Tamakuma; Takahito Suzuki; Ryohei Yamada; Ryoju Negami; Takakiyo Tsujiguchi; Masaru Yamaguchi; Yoshitaka Shiroma; Kazuki Iwaoka; Naofumi Akata; Mayumi Shimizu; Ikuo Kashiwakura; Shinji Tokonami. 2021. "Discriminative Measurement of Absorbed Dose Rates in Air from Natural and Artificial Radionuclides in Namie Town, Fukushima Prefecture." International Journal of Environmental Research and Public Health 18, no. 3: 978.
TSP and atmospheric 210Pb concentrations were observed at Tsukuba, Japan during July 2001 to March 2005. TSP concentrations ranged from 14.5 to 152.4 µg m−3. 210Pb concentrations ranged from 0.04 to 0.86 mBq m−3 which was low in summer and high in winter to spring. Although TSP concentrations changed annually, 210Pb concentrations had almost the same concentration level and seasonal variation. The correlation coefficient between 210Pb concentration and NO3− concentration was slightly higher than for other ion species. This result indicated that both had been attached to the same particle size and transported to the sampling site.
Naofumi Akata; Chie Iwata; Miki Nakada; Masahiro Tanaka; Hideki Kakiuchi; Tibor Kovács; Fumitaka Yanagisawa; Yutaka Kanai. Characterization of atmospheric 210Pb concentration and its relation to major ion species at Tsukuba, Japan. Journal of Radioanalytical and Nuclear Chemistry 2021, 327, 755 -760.
AMA StyleNaofumi Akata, Chie Iwata, Miki Nakada, Masahiro Tanaka, Hideki Kakiuchi, Tibor Kovács, Fumitaka Yanagisawa, Yutaka Kanai. Characterization of atmospheric 210Pb concentration and its relation to major ion species at Tsukuba, Japan. Journal of Radioanalytical and Nuclear Chemistry. 2021; 327 (2):755-760.
Chicago/Turabian StyleNaofumi Akata; Chie Iwata; Miki Nakada; Masahiro Tanaka; Hideki Kakiuchi; Tibor Kovács; Fumitaka Yanagisawa; Yutaka Kanai. 2021. "Characterization of atmospheric 210Pb concentration and its relation to major ion species at Tsukuba, Japan." Journal of Radioanalytical and Nuclear Chemistry 327, no. 2: 755-760.
Mamuju is a region of Indonesia with relatively high exposure to natural radiation. Since 2012, Mamuju has been a uranium and thorium exploration area. Several mapping studies of the region have been carried out to depict NORM (naturally occurring radioactive material) areas and areas with uranium anomalies. This paper is the first study to use radioactivity measurements of laterite and volcanic rocks to determine the characteristics of radionuclides and other mineral measurements, which are essential for categorising Mamuju rocks and exploring the region as a potential mining area. The radioactivity of the samples was measured using a high-purity germanium (HPGe) detector. Furthermore, we used X-ray fluorescence (XRF) to determine the rock mineral composition. Mamuju is anomalous due to its high content of 238U and 232Th concentrations of 539–128,699 Bq·kg−1 (average: 22,882 Bq·kg−1) and 471–288,639 Bq·kg−1 (average: 33,549 Bq·kg−1), respectively. The major elements are dominant, including Fe2O3, SiO2, Al2O3, and Na2O, with several other major elements such as MnO, TiO2, and CaO.
Ilsa Rosianna; Eka Nugraha; Heri Syaeful; Sugili Putra; Masahiro Hosoda; Naofumi Akata; Shinji Tokonami. Natural Radioactivity of Laterite and Volcanic Rock Sample for Radioactive Mineral Exploration in Mamuju, Indonesia. Geosciences 2020, 10, 376 .
AMA StyleIlsa Rosianna, Eka Nugraha, Heri Syaeful, Sugili Putra, Masahiro Hosoda, Naofumi Akata, Shinji Tokonami. Natural Radioactivity of Laterite and Volcanic Rock Sample for Radioactive Mineral Exploration in Mamuju, Indonesia. Geosciences. 2020; 10 (9):376.
Chicago/Turabian StyleIlsa Rosianna; Eka Nugraha; Heri Syaeful; Sugili Putra; Masahiro Hosoda; Naofumi Akata; Shinji Tokonami. 2020. "Natural Radioactivity of Laterite and Volcanic Rock Sample for Radioactive Mineral Exploration in Mamuju, Indonesia." Geosciences 10, no. 9: 376.
Activity concentrations of 234U, 235U, 238U, 226Ra, 228Ra, 222Rn, 210Po, 210Pb, 40K, 3H, 14C, 134Cs and 137Cs were determined in 20 different Japanese bottled drinking water commercially available in Japan. The origins of the mineral water samples were geographically distributed across different regions of Japan. Activity concentrations above detection limits were measured for the radionuclides 234U, 235U, 238U, 226Ra, 228Ra and 210Po. An average total annual effective dose due to ingestion was estimated for adults, based on the average annual volume of bottled water consumed in Japan in 2019, reported to be 31.7 L/y per capita. The estimated dose was found to be below the recommended World Health Organisation (WHO) guidance level of 0.1 mSv/y for drinking water quality. The most significant contributor to the estimated dose was 228Ra.
Aoife Kinahan; Masahiro Hosoda; Kevin Kelleher; Takakiyo Tsujiguchi; Naofumi Akata; Shinji Tokonami; Lorraine Currivan; Luis Leon Vintro. Assessment of Radiation Dose from the Consumption of Bottled Drinking Water in Japan. International Journal of Environmental Research and Public Health 2020, 17, 4992 .
AMA StyleAoife Kinahan, Masahiro Hosoda, Kevin Kelleher, Takakiyo Tsujiguchi, Naofumi Akata, Shinji Tokonami, Lorraine Currivan, Luis Leon Vintro. Assessment of Radiation Dose from the Consumption of Bottled Drinking Water in Japan. International Journal of Environmental Research and Public Health. 2020; 17 (14):4992.
Chicago/Turabian StyleAoife Kinahan; Masahiro Hosoda; Kevin Kelleher; Takakiyo Tsujiguchi; Naofumi Akata; Shinji Tokonami; Lorraine Currivan; Luis Leon Vintro. 2020. "Assessment of Radiation Dose from the Consumption of Bottled Drinking Water in Japan." International Journal of Environmental Research and Public Health 17, no. 14: 4992.
The deuterium plasma experiment was started using the Large Helical Device (LHD) at the National Institute for Fusion Science (NIFS) in March 2017 to investigate high-temperature plasma physics and the hydrogen isotope effects towards the realization of fusion energy. In order to clarify any experimental impacts on precipitation, precipitation has been collected at the NIFS site since November 2013 as a means to assess the relationship between isotope composition and chemical species in precipitation containing tritium. The tritium concentration ranged from 0.10 to 0.61 Bq L-1 and was high in spring and low in summer. The stable isotope composition and the chemical species were unchanged before and after the deuterium plasma experiment. Additionally, the tritium concentration after starting the deuterium plasma experiment was within three sigma of the average tritium concentration before the deuterium plasma experiment. These results suggested that there was no impact by tritium on the environment surrounding the fusion test facility.
Naofumi Akata; Masahiro Tanaka; Chie Iwata; Akemi Kato; Miki Nakada; Tibor Kovács; Hideki Kakiuchi. Isotope Composition and Chemical Species of Monthly Precipitation Collected at the Site of a Fusion Test Facility in Japan. International Journal of Environmental Research and Public Health 2019, 16, 3883 .
AMA StyleNaofumi Akata, Masahiro Tanaka, Chie Iwata, Akemi Kato, Miki Nakada, Tibor Kovács, Hideki Kakiuchi. Isotope Composition and Chemical Species of Monthly Precipitation Collected at the Site of a Fusion Test Facility in Japan. International Journal of Environmental Research and Public Health. 2019; 16 (20):3883.
Chicago/Turabian StyleNaofumi Akata; Masahiro Tanaka; Chie Iwata; Akemi Kato; Miki Nakada; Tibor Kovács; Hideki Kakiuchi. 2019. "Isotope Composition and Chemical Species of Monthly Precipitation Collected at the Site of a Fusion Test Facility in Japan." International Journal of Environmental Research and Public Health 16, no. 20: 3883.