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

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 seawater samples collected during the international expedition 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 μ Bq 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 represent an increase above the global fallout background by factors of about 1000, 30 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 in reasonable agreement with predictions obtained from the Ocean General Circulation Model, which indicates that the radionuclides have been transported from the Fukushima coast eastward. The ¹³⁷Cs inventory in the water column (the area from 34 to 37° N, and from 142 to 147° E) due to the Fukushima accident is estimated to be about 2.2 PBq. The amount of ¹²⁹I and ³H released and deposited on the NW Pacific Ocean after the Fukushima accident was estimated to be about 7 GBq and 0.1 PBq, respectively. 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 in the NW Pacific Ocean

Direct tritium emissions to the ocean from the Fukushima Dai-ichi nuclear accident

“…In general, 3 H in the ocean is supplied by rainwater and river water in addition to water vapor exchange. Therefore, higher 3 H concentrations are observed in the surface water layer, while lower concentrations result from its radioactive decay deeper in the water column, below a depth of 2000 m. Povinec et al (2013a) estimated the pre-Fukushima 3 H concentration (or the global fallout background) in surface northwestern Pacific waters as 0.6 ± 0.1 TU, equivalent to 0.07 ± 0.01 Bq/L, based on data stored in the GLOMARD/MARIS database. Such 3 H activity is also in line with the data summarized in the WOCE Hydrographic Atlas (accounting for the radioactive decay of 3 H since publication of the respective maps; Talley, 2007).…”

Mixtures of tritiated water, zinc and dissolved organic carbon: Assessing interactive bioaccumulation and genotoxic effects in marine mussels, Mytilus galloprovincialis

“…Tritium ( 3 H), a radioactive isotope of hydrogen is produced and discharged in large quantities by nuclear power plants and nuclear fuel reprocessing facilities (NFRF), mostly as tritiated water. The FDND is estimated to have released between 10 and 50 thousand TBq of tritium into the NW Pacific ocean [Povinec et al, 2013]. From 2005From -2008, the two NFRFs discharging into the English Channel/Irish Sea (i.e.…”

Certified reference materials of agricultural products and foods bearing radioactivity from the Fukushima nuclear accident

“…This situation is somewhat similar to that observed in the fate of fission products after nuclear testing in the Pacific region [24]. Experience in the era of global fallout showed the necessity of quality control for analysis of 90 Sr [5].…”