Environmental Gamma-Ray Observation in Deep Sea

Kumagai, Hitoshi; Iwase, Ryoichi; Kinoshita, Masataka; Machiyama, Hideaki; Hattori, Mutsuo; Okano, M.

doi:10.5772/36392

Cited by 7 publications

(11 citation statements)

References 8 publications

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“…The off Hatsushima Island observatory was wholly replaced in 2000, since then the gamma-ray observation has been carried out [4]. The gamma-ray sensor is composed of 3 inch spherical NaI(Tl) scintillation detector and multi-channel (256 ch) pulse height analyzer, and is enclosed in a titanium chassis.…”

Section: Long-term Gamma-ray Observationmentioning

confidence: 99%

“…Fig. 7 shows the energy spectra on every January 1 st in each year from 2003 to 2011 [4]. The peaks are shifting to lower channels as time passes and calibration is necessary.…”

Section: Long-term Gamma-ray Observationmentioning

confidence: 99%

“…Sudden increase occurred just after the earthquake in March 2011. It might reflect some geological events, however, there also might be the effects of natural sedimentation [4] or of the atomic power plant accident. More detailed analysis is undergoing.…”

Section: Long-term Gamma-ray Observationmentioning

confidence: 99%

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Detection of deep-sea current associated with tsunami and possible biogenic acoustic signals — Several topics of multidisciplinary observation with JAMSTEC cabled observatory

Iwase

Takahashi²

2013

2013 IEEE International Underwater Technology Symposium (UT)

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On the occasion of "Off the Pacific Coast of Tohoku Earthquake" in 2011, water current changes in deep sea associated with tsunami were detected through the analysis at cabled observatories off Kushiro-Tokachi in Hokkaido and off Hatsushima Island in Sagami Bay, while it is usually difficult to detected them because they are usually much smaller than other oceanic events, such as tidal current, and some fluctuations after the earthquake in long-term gamma-ray observation data on deep seafloor in Sagami Bay were reported. In the "excavation" of possible biogenic and other episodic acoustic signals in a huge amount of legacy data accumulated for almost 20 years for the purpose of obtaining basic data for the development of species identification technologies for marine organisms. peculiar low frequency signals were found which might possibly be biogenic, though more detailed research is necessary.

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Section: Long-term Gamma-ray Observationmentioning

confidence: 99%

“…Fig. 7 shows the energy spectra on every January 1 st in each year from 2003 to 2011 [4]. The peaks are shifting to lower channels as time passes and calibration is necessary.…”

Section: Long-term Gamma-ray Observationmentioning

confidence: 99%

See 1 more Smart Citation

Detection of deep-sea current associated with tsunami and possible biogenic acoustic signals — Several topics of multidisciplinary observation with JAMSTEC cabled observatory

Iwase

Takahashi²

2013

2013 IEEE International Underwater Technology Symposium (UT)

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“…This system was applied to surveys around the Sella eld nuclear fuel reprocessing plant to measure the distribution of radionuclides discharged from the plant into the nearshore sea oor sediment. Before the FDNPP accident, the Japan Atomic Energy Research Institute developed a submersible gamma-ray system that comprises a germanium detector mounted on a remotely operated vehicle 12 .…”

Section: Introductionmentioning

confidence: 99%

Visualization of Radiocesium Distribution in Surface Layer of Seafloor Around Fukushima Daiichi Nuclear Power Plant

Sanada

Urabe²,

Misonou

et al. 2021

Preprint

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Large quantities of volatile radionuclides were released into the atmosphere and the hydrosphere following the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident on March 11, 2011. Monitoring of radiocesium in sediment is important for evaluating the behavior of radiocesium in the environment and its effect on aquatic organisms. In this study, the radiocesium distribution in the surface sediment around the FDNPP was visualized as a radiocesium map using periodical survey data from a towed gamma-ray detection system. The uncertainty of the radiocesium map was evaluated via comparison with a large amount of sediment core sample data. The characteristics of the radiocesium distribution were examined considering the seafloor topography and a geological map, which were obtained via acoustic wave survey. The characteristics of the formation of 137Cs anomaly at the estuaries were analyzed using a contour map of 137Cs concentration combined with water depth. Validation of the created map showed that it was comparable with actual sediment core samples. The map generated using the towed radiation survey depicted the 137Cs concentration distribution as the position resolution of a 1 km mesh. Finally, the 137Cs concentration decreased with time in consideration of such uncertainty.

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“…Radioactivity in sea water would also be an indicator of hydrothermal activities as the source in sea water of hydrothermal area is dissolved radioactive radium and radon emanated from hydrothermal vents (Kumagai et al 2012).…”

Section: Introductionmentioning

confidence: 99%

Gamma Ray Doses in Water Around Sea Floor Hydrothermal Area in the Southern Mariana Trough

Toyoda

Banerjee

Kumagai

et al. 2014

Subseafloor Biosphere Linked to Hydrothermal Systems

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The dose rates in sea water in the Southern Mariana Trough sea floor hydrothermal area were investigated. The dose rate in sea water was less than detection limit (about 0.1 mGy/year) near the sea surface while it was around 2 mGy/year at the sea floor of hydrothermal area, where those levels of dose rates will be negligible for ESR (electron spin resonance) dating of barite of sulfide deposits. During the dive by a submarine vehicle, there were three locations at which the level of dose rate increases more than ten times as much as the usual level. One was very close to a hydrothermal vent, but no hydrothermal activities were found near the other locations.

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Environmental Gamma-Ray Observation in Deep Sea

Cited by 7 publications

References 8 publications

Detection of deep-sea current associated with tsunami and possible biogenic acoustic signals — Several topics of multidisciplinary observation with JAMSTEC cabled observatory

Detection of deep-sea current associated with tsunami and possible biogenic acoustic signals — Several topics of multidisciplinary observation with JAMSTEC cabled observatory

Visualization of Radiocesium Distribution in Surface Layer of Seafloor Around Fukushima Daiichi Nuclear Power Plant

Gamma Ray Doses in Water Around Sea Floor Hydrothermal Area in the Southern Mariana Trough

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