Artificial Radionuclides Database in the Pacific Ocean: HAM Database

Aoyama, Michio; Hirose, Katsumi

doi:10.1100/tsw.2004.15

Cited by 105 publications

(59 citation statements)

References 44 publications

(48 reference statements)

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“…2b, Tables 1 and 2). The outer box stations had a significantly lower 134 Cs activity range (< 2-333 Bq m −3 ), while stations within the core and to the south of the Kuroshio generally had 134 Cs activities at or below the detection limit of the method and 137 Cs levels (not shown) equivalent to the known background values for this region (1-2 Bq m −3 ) from past weapons testing fallout (Aoyama and Hirose, 2004). The highest 134 Cs and 137 Cs activities (3570-4580 Bq m −3 ) were associated with an eddy at station 29 ( Fig.…”

Section: Resultsmentioning

confidence: 99%

Radium-based estimates of cesium isotope transport and total direct ocean discharges from the Fukushima Nuclear Power Plant accident

et al. 2013

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Radium has four naturally occurring isotopes that have proven useful in constraining water mass source, age, and mixing rates in the coastal and open ocean. In this study, we used radium isotopes to determine the fate and flux of runoff-derived cesium from the Fukushima Dai-ichi Nuclear Power Plant (FNPP). During a June 2011 cruise, the highest cesium (Cs) concentrations were found along the eastern shelf of northern Japan, from Fukushima south, to the edge of the Kuroshio Current, and in an eddy ~ 130 km from the FNPP site. Locations with the highest cesium also had some of the highest radium activities, suggesting much of the direct ocean discharges of Cs remained in the coastal zone 2–3 months after the accident. We used a short-lived Ra isotope (²²³Ra, t_1/2 = 11.4 d) to derive an average water mass age (T_r) in the coastal zone of 32 days. To ground-truth the Ra age model, we conducted a direct, station-by-station comparison of water mass ages with a numerical oceanographic model and found them to be in excellent agreement (model avg. T_r = 27 days). From these independent T_r values and the inventory of Cs within the water column at the time of our cruise, we were able to calculate an offshore ¹³⁴Cs flux of 3.9–4.6 × 10¹³ Bq d⁻¹. Radium-228 (t_1/2 = 5.75 yr) was used to derive a vertical eddy diffusivity (K_z) of 0.7 m² d⁻¹ (0.1 cm² s⁻¹); from this K_z and ¹³⁴Cs inventory, we estimated a ¹³⁴Cs flux across the pycnocline of 1.8 × 10⁴ Bq d⁻¹ for the same time period. On average, our results show that horizontal mixing loss of Cs from the coastal zone was ~ 10⁹ greater than vertical exchange below the surface mixed layer. Finally, a mixing/dilution model that utilized our Ra-based and oceanographic model water mass ages produced a direct ocean discharge of ¹³⁴Cs from the FNPP of 11–16 PBq at the time of the peak release in early April 2011. Our results can be used to calculate discharge of other water-soluble radionuclides that were released to the ocean directly from the Fukushima NPP

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Section: Resultsmentioning

confidence: 99%

Radium-based estimates of cesium isotope transport and total direct ocean discharges from the Fukushima Nuclear Power Plant accident

et al. 2013

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“…Two marine radioactivity databases were developed: one at the International Atomic Energy Agency's Environment Laboratories in Monaco (the GLOMARD/MARIS database; Povinec et al, 2004Povinec et al, , 2012b and the second one at the Meteorological Research Institute 5484 P. P. Povinec et al: Cesium, iodine and tritium in NW Pacific waters in Tsukuba (the HAM database; Aoyama and Hirose, 2004 Fig. 1.…”

Section: Cesium-137mentioning

confidence: 99%

Cesium, iodine and tritium in NW Pacific waters – a comparison of the Fukushima impact with global fallout

et al. 2013

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Abstract. Radionuclide impact of the Fukushima Dai-ichi nuclear power plant accident on the distribution of radionuclides in seawater of the NW Pacific Ocean is compared with global fallout from atmospheric tests of nuclear weapons. Surface and water column samples collected during the Ka'imikai-o-Kanaloa (KOK) international expedition carried out in June 2011 were analyzed for 134Cs, 137Cs, 129I and 3H. The 137Cs, 129I and 3H levels in surface seawater offshore Fukushima varied between 0.002–3.5 Bq L−1, 0.01–0.8 μBq L−1, and 0.05–0.15 Bq L−1, respectively. At the sampling site about 40 km from the coast, where all three radionuclides were analyzed, the Fukushima impact on the levels of these three radionuclides represents an increase above the global fallout background by factors of about 1000, 50 and 3, respectively. The water column data indicate that the transport of Fukushima-derived radionuclides downward to the depth of 300 m has already occurred. The observed 137Cs levels in surface waters and in the water column are compared with predictions obtained from the ocean general circulation model, which indicates that the Kuroshio Current acts as a southern boundary for the transport of the radionuclides, which have been transported from the Fukushima coast eastward in the NW Pacific Ocean. The 137Cs inventory in the water column is estimated to be about 2.2 PBq, what can be regarded as a lower limit of the direct liquid discharges into the sea as the seawater sampling was carried out only in the area from 34 to 37° N, and from 142 to 147° E. About 4.6 GBq of 129I was deposited in the NW Pacific Ocean, and 2.4–7 GBq of 129I was directly discharged as liquid wastes into the sea offshore Fukushima. The total amount of 3H released and deposited over the NW Pacific Ocean was estimated to be 0.1–0.5 PBq. These estimations depend, however, on the evaluation of the total 137Cs activities released as liquid wastes directly into the sea, which should improve when more data are available. Due to a suitable residence time in the ocean, Fukushima-derived radionuclides will provide useful tracers for isotope oceanography studies on the transport of water masses during the next decades in the NW Pacific Ocean.

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“…A pH in seawater samples was adjusted to 1.6 by adding 14 M HNO 3 . In order to prepare insoluble AMP/Cs complex, CsCl of 0.26 g was added in each acidified seawater and well-mixed using a stirrer.…”

Section: Methodsmentioning

confidence: 99%

“…The data of 137 Cs in seawater has been accumulated as databases such as HAM and GLOMARD. 3,4 However, oceanic 137 Cs has not been comprehensively used as an oceanic tracer comparing with CFCs 5 (chloro-fluoro carbons) because there are only a few cases depicted cross section of oceanic 137 Cs distribution such as Geochemical Ocean Sections Study (GEOSECS). 6 Recently 137 Cs has been applied to validation of a global ocean circulation model.…”

Section: Introductionmentioning

confidence: 99%

Improvement of 137Cs analysis in small volume seawater samples using the Ogoya underground facility

Hirose

Aoyama

Igarashi

et al. 2008

J Radioanal Nucl Chem

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Artificial Radionuclides Database in the Pacific Ocean: HAM Database

Cited by 105 publications

References 44 publications

Radium-based estimates of cesium isotope transport and total direct ocean discharges from the Fukushima Nuclear Power Plant accident

Radium-based estimates of cesium isotope transport and total direct ocean discharges from the Fukushima Nuclear Power Plant accident

Cesium, iodine and tritium in NW Pacific waters – a comparison of the Fukushima impact with global fallout

Improvement of 137Cs analysis in small volume seawater samples using the Ogoya underground facility

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