Impact of the Fukushima accident on tritium, radiocarbon and radiocesium levels in seawater of the western North Pacific Ocean: A comparison with pre-Fukushima situation. (January 2017)

• Record Type: Journal Article
• Authors: Povinec, P.P.; Liong Wee Kwong, L.; Kaizer, J.; Molnár, M.; Nies, H.; Palcsu, L.; Papp, L.; Pham, M.K.; Jean-Baptiste, P.
• Is Part Of: Journal of environmental radioactivity. Volume 166:Part 1(2017:Jan.)
• Page Start: 56
• Page End: 66
• Publication Date: 2017-01
• Subjects: Fukushima accident -- Radionuclides in seawater -- KoK cruise -- GEOSECS -- WOCE -- WOMARS; Radioactivity -- Periodicals; Radiation, Background -- Periodicals; Radioecology -- Periodicals; Radioactive pollution -- Periodicals; Environmental Pollutants -- Periodicals; Radioactive Pollutants -- Periodicals; Radioactivity -- Periodicals; Radioécologie -- Périodiques; Pollution radioactive -- Périodiques; Fond de rayonnement -- Périodiques; 539.752
• DOI: 10.1016/j.jenvrad.2016.02.027
• Languages: English
• ISSNs: 0265-931X

Abstract

Abstract: Tritium, radiocarbon and radiocesium concentrations in water column samples in coastal waters offshore Fukushima and in the western North Pacific Ocean collected in 2011–2012 during the Ka'imikai-o-Kanaloa (KoK) cruise are compared with other published results. The highest levels in surface seawater were observed for 134 Cs and 137 Cs in seawater samples collected offshore Fukushima (up to 1.1 Bq L −1 ), which represent an increase by about three orders of magnitude when compared with the pre-Fukushima concentration. Tritium levels were much lower (up to 0.15 Bq L −1 ), representing an increase by about a factor of 6. The impact on the radiocarbon distribution was measurable, but the observed levels were only by about 9% above the global fallout background. The 137 Cs (and similarly 134 Cs) inventory in the water column of the investigated western North Pacific region was (2.7 ± 0.4) PBq, while for 3 H it was only (0.3 ± 0.2) PBq. Direct releases of highly contaminated water from the damaged Fukushima NPP, as well as dry and wet depositions of these radionuclides over the western North Pacific considerably changed their distribution patterns in seawater. Presently we can distinguish Fukushima labeled waters from global fallout background thanks to short-lived 134 Cs. However, in the long-term perspective when 134 Cs will decay, new distribution patterns of 3 H, 14 C and 137 Cs in the Pacific Ocean should be established for future oceanographic and climate change studies in the Pacific Ocean. Highlights: Radiocesium, tritium and radiocarbon showed elevated levels in seawater of the western North Pacific. The water column inventories of 137 Cs and 3 H were 2.7 ± 0.4 and 0.3 ± 0.2 PBq, respectively. The radiocarbon levels were by about 9% above the global fallout background. Released radionuclides will be useful in future oceanographic and climate studies.