#1Mass balance of radiocaesium derived from Fukushima accident and estimation of latest fluxes among atmosphere, land and ocean Michio Aoyama1, Daisuke Tsumune2, Yayoi Inomata3, Yutaka Tateda2 1 Faculty of Life and Environmental Sciences, Univ. of Tsukuba, 305-8577, Japan 2 Environmental Science Research Laboratory, Central Research Institute of Electric Power Industry, 1646 Abiko, 270-1194, Japan 3 Institute of Nature and Environmental Technology, Kanazawa University, Kanazawa, 920-1192, Japan EGU2020-12301 8 May 2020, EGU2020 online CC 0 BY#2Summary In this presentation, we summarizes mass balance of the Fukushima-derived 137Cs released to the atmosphere and ocean prior to 2018 as well as the 137Cs inventories on land and in the ocean, biota, and sediment. We propose that the consensus value of the total amount of 137Cs released to the atmosphere was 15-21 PBq; atmospheric deposition of 137Cs on land was 3-6 PBq; atmospheric deposition of 137Cs on the North Pacific was 12-15 PBq; and direct discharge of 137Cs to the ocean was 3-6 PBq. We also evaluated the movement of 137Cs from one domain to another for several years after the accident. We calculated that the amount of 137Cs transported by rivers might be 40 TBq. The annual deposition of 137Cs due to resuspension at Okuma during the period 2014-2018 was 4-10 TBq year-1. The 137Cs discharged to the ocean was 0.73-1.0 TBq year-1 in 2016-2018. The integrated amount of FNPP1-derived 137Cs that entered the Sea of Japan from the Pacific Ocean from 2011 until 2017 was 0.27 ± 0.02 PBq, 6.4 % of the estimated amount of FNPP1-derived 137Cs in Subtropical Mode Water in the North Pacific. The integrated amount of FNPP1-derived 137Cs that returned to the North Pacific. Ocean through the Tsugaru Strait from the Sea of Japan was 0.11 ± 0.01 PBq. Decontamination efforts removed 0.134 PBq of 137Cs from surface soil prior to February 2019, an amount that corresponded to 4 % of the 137Cs deposited on land in Japan.#3Presentation outline Why is mass balance important? • Mass balance in the environment of radioactivity originating from the Fukushima accident Amount and initial distribution of artificial radioactive materials released by the Fukushima accident Behavior in the environment: Estimation of the amount of movement after being released to land and ocean (land to land, land to sea, one sea area to another sea area, etc.)#4Why is mass balance important? • The conservation of mass is the basic law. Somewhere in the reports and discussions that are out of balance. If you don't see the whole picture, you won't know the truth. There is an example of not integrating the integrated region in order to obtain the quantity when reporting the quantity, or integrating it by covering only part of it with actual constraints. The same was true at the time of the Fukushima accident.#5Mass balance: Fukushima accident Σ Ri = Σ lj the law of conservation of mass Where Ri are released amount to each domain and lj are inventory in each domain. i: 1=atmosphere, 2=direct discharge J: 1=atmosphere (zero), 2= land, 3=ocean, 4=sediment, 5= biota R1+R2=11+12+13+14+15=<total in the core R1-12=13-R2#6Need to look at whole structure It is a story of a group of blind men (or men in the dark) who touch an elephant to learn what it is like. Each one feels a different part, but only one part, such as the side or the tusk. They then compare notes and learn that they are in complete disagreement This image is considered to have no known copyright restrictions by the institutions of the Brooklyn Museum.#7137Cs (134Cs)mass balance at the beginning 15-20 PBq to the atmosphere Aoyama et I., 2016 atmosp 3-6 PBq to the land Aoyama et al., 2016 140 PBq in stagnant water 700 PBq was in the three (Nishihara et al.,, 2011) 70N 60N- 50N- 40N- 30N- 20N- 10N- EQ 10DE 120E 140E 160E 180 160W 140W 12-15 PBq to the ocean Aoyama et al., 2016 Total in the Ocean:15-18 PBq Aoyama et al., 2016, Tsubono et al., 2016, Inomata et al., 2016 3.6±0.7 PBq to the ocean (Tsumune et al., 2013) core 230 PBq recovered TEPCO unpublished data#8Mass balance in the ocean Inomata et al., 2018 'MK2_Cs134_dep(Bq/m2/d)_1.5x1_2011'0315 110° 120° 130° 140° 150° 160° 170° 180° 60° 60° 80 120° 50° 40° 30° 20° 50° 60° 40° 30° 20° 10° 110° 120° 130° 140° 150 160 170 180 10° 40° OiCs134_20110311'c_'30'd_R'800'_ram'100 150 180° -150° -120° 80° 60 40° B Estimate of 134Cs deposition in STMW,LCMW,DCMW, TRMW in the western North Pacific Ocean. 150° 180° -150° Distribution of 134Cs in Oct.-Dec. 2012. Decay corrected to 11 Mar. 2011. Estimated inventory in surface seawater OICS 134; 7.9±1.4 PBq OICS137; 13±0.93 PBq 50 20 10 580 9 8 7 6 5 4 3 2 0#9Mass balance calculations in the ocean interior Σ R₁ = Σ I₁ R₁+R2=11+12+13+14+5 (1) (2) (11.7-14.8 PBq; Aoyama et al., 2016b) R₁: Atmospheric deposition. R2: Direct discharge (3.5±0.7 PBq; Tsumune et al., 2013) R₁+R2: 15.2 to 18.3 PBq 15.3 ± 2.6 PBq (Inomata et al., 2016) by Ol 13 = (R₁+R₂) −11 −12 (3) 11 Surface water inventory 7.9±1.4 PBq 12 STMW 13 CMW 14 Biota 4.2±1.1 PBq (Kaeriyama et al., 2016) 2.5 ± 0.9 PBq (Inomata et al., 2018) negligible 200 GBq (Aoyama et al., 2019) 15 Sediment negligible 130 +- 60 TBq (Kusakabe et al., 2014)#10137Cs (134Cs )mass balance at the beginning 15-20 PBq to the atmosphere Aoyama et I., 2016 atmosph 3-6 PBq to the land Aoyama et al., 2016 ↓ 12 15 PBq to the ocean Aoyama et al., 2016 Total in the Ocean: 15-18 PBq Aoyama et al., 2016, Tsubono et al., 2016, Inomata et al., 2016 3.6 0.7 PBq to the ocean (Tsumune et al., 2013) 140 PBq in stagnant water 700 PBq was in the three core (Nishihara et al.,, 2011) 230 PBq recovered TEPCO unpublished data Issues we should know during 7 years after the accident 1) Relatively higher deposition, due to flux from forest? 2) Continuous release from the site and other sources, eg. river water and resuspension. 3) Transport from STMW in the North pacific to Sea of Japan 4) Transport in the surface layer and into ocean interior 5) Results of de-contamination work#11ELSEVIER Journal of Environmental Radioactivity 217 (2020) 106206 Contents lists available at ScienceDirect Journal of Environmental Radioactivity journal homepage: http://www.elsevier.com/locate/jenvrad Mass balance and latest fluxes of radiocesium derived from the fukushima accident in the western North Pacific Ocean and coastal regions of Japan Michio Aoyama, Daisuke Tsumuneb, Yayoi Inomata, Yutaka Tateda *Center for Research in Isotopes and Environmental Dynamics, Univ. of Tsukuba, Tsukuba, Japan Environmental Science Research Laboratory, Central Research Institute of Electric Power Industry, Chiba, Japan Institute of Nature and Environmental Technology, Kanazawa University, Ishikawa, Japan. b ARTICLE INFO Keywords: Fukushima accident. Mass balance Radiocesiun 137Cs Inventory Flux ENVIRONMENTAL Check for updstoc ABSTRACT This article summarizes and discusses mass balance calculations of the activities of Fukushima-derived 137Cs released to the atmosphere and occan prior to 2018 as well as the 137Cs inventorics on land and in the occan, biota, and sediment. We propose that the consensus value of the total amount of 137Cs released to the atmosphere was 15-21 PBq; atmospheric deposition of 137Cs on land was 3-6 PBq; atmospheric deposition of 137Cs on the North Pacific was 12-15 PBq; and direct discharge of 137Cs to the ocean was 3-6 PBq. We also evaluated the movement of 137Cs from one domain to another for several years after the accident. We calculated that the amount of 137Cs transported by rivers might be 40 TBq. The annual deposition of 137Cs due to resuspension at Okuma during the period 2014-2018 was 4-10 TBq year 1. The 137Cs discharged to the ocean was 0.73-1.0 TBq year in 2016 2018. The integrated amount of FNPP1-derived 137Cs that entered the Sea of Japan from the Pacific Ocean from 2011 until 2017 was 270 ± 20 TBq, 6.4% of the estimated amount of FNPP1-derived 137Cs in Subtropical Mode Water in the North Pacific. The integrated amount of FNPP1-derived 137Cs that returned to the North Pacific Ocean through the Tsugaru Strait from the Sea of Japan was 110 ± 10 TBq. Decontamination efforts removed 134 TBq of 13/Cs from surface soil prior to February 2019, an amount that corresponded to 4% of the137Cs deposited on land in Japan. 1. Introduction The total amount of radionuclides released to the environment from the Fukushima Dai-ichi Nuclear Power Plant, hereafter FNPP1, as a result of the accident in March 2011 as well as the impact of those ra- dionuclides on biota, and especially humans, have been among the major concerns related to the FNPP1 accident. The radionuclide of principal concern with respect to human health has been radiocesium, and it is thus particularly important to know how much radiocesium was released to the environment. Many articles and several review articles have already been published concerning this issue (Buesseler et al., 2017; IAEA, 2015; Mathieu et al., 2018; Smith, 2014), but there has been no discussion based on mass balances between the atmosphere, land, and ocean. It is important to consider mass balances in discussions of the total amount of radionuclides released to the environment because the law of conservation of mass is a basic principle, and mass balance is one of the strongest constraints on estimates of the total amount of radionuclides released to the environment and to inventories in the air, on the land, and in the North Pacific Ocean. In this paper, we have summarized the results of studies of the amounts of Fukushima-derived 137 Cs that were released to the atmo- sphere and ocean as well as estimates of the 137Cs inventories on land, in the ocean, in biota, and in sediments. We propose consensus values of these inventories based on mass balance considerations. Finally, we discuss the fluxes of 137Cs between domains for several years after the FNPP1 accident. We consider in particular fluxes from the land to the ocean via rivers, releases from the accident site to the ocean, and delayed effects of the accident associated with resuspension from the land to the atmosphere, deposition from the atmosphere onto the land and ocean, and transport of FNPP1-derived 137Cs from the North Pacific Ocean to the Sea of Japan. Finally, we consider the total amount of 137 Cs in surface soil removed by human activity as a part of decontamination work. *Corresponding author. E-mail address: [email protected] (M. Aoyama). https://doi.org/10.1016/j.jenvrad 2020.106206 Received 10 October 2019; Received in revised form 6 February 2020; Accepted 12 February 2020. Available online 21 February 2020 0265-931X/2020 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Aoyama et a., 2020, JER, 10.1016/j.jenvrad.2020.106206#12Movement during 7 years after the accident 4 TBq year‍¹ to 10 TBq year‍¹ flux as resuspension and fallout 2014-2018 (20TBq to 50 TBq) decontamination works 134 TBq of 137Cs was removed from surface soil until Feb. 2019 To Sea of Japan 270 TBq Until 2017- 100000 by the revers 40 TBq June 2011-2016 0.73 - 1.0 TBq year‍1 discharge in 2016-2018 Raw Aerial monitoring of radioca. http://explore.data.gov/Geography-a Response-to-2011-Fukushima-Incident-Ra/prrn-6s35 Details are in Aoyama et a., 2020, JER, 10.1016/j.jenvrad.2020.106206#13resuspension from forest Observed monthly deposition of 137Cs at Tokyo/Tsukuba, Fukushima-Shi and Futaba-Gun 107 1370s Bq m-2 Fukushima_shi + 1870s Bq m-2 Futaba eun 1370s Bq m-2 Tsukuba/Tokyo 137 - 'Cs monthly deposition ( Bq m month¯1) 105 Nuclear tests by China 1964-1980 103 Resuspension Obdroby accident from forest 10¹ former USSR. USA 10-1 and others 1945-1962] 103 !! 1950 1960 1970 1980 1990 2000 2010 2020 date Aoyama, 2019, Kagaku July 2019, Iwanami, in Japanese#14Mass balance of FNPP1 derived radiocaesium Atmospheric input 15.2-20.4 PBq 700 PBq in the three core 140 PBq in stagnant water (Nishihara et al.,, 2011) Ocean/Direct release 3.5 ± 0.7 PBq (Tsumune et al., 2012) Atmospheric deposition - Total 11.7 14.8 PBq (Aoyama et al., JO, 2016) Land/3.4-6.2 PBq (Aoyama et al., JO, 2016) North Pacific Ocean 134 CS 15.2-18.3 PBq (Aoyama et al., JO, 2016): Total 15.3 ± 2.6(Inomata et al., 2016) 16.1 ± 1.4 (Tsubono et al., 2016) (STMW 2.2-4.9 PBq, CMW 7.5-9.3 PBq by the models) SOJ 0.27±0.02 PBq 6.4% STMW Surface CMW 4.2 ± 1.1 7.9 ± 1.4 2.5 ± 0.9 (42%) PBq PBq Re-NPO PBq (Kaeriyama et Inomata et al., JRNC, 2018b, ENVIRA2019 0.11 ±0.01PBq 2.7% al. 2016)#15Schematic diagram of transport/inventory of 50°N- radiocaesium 7.9 ± 1.4 PBq Surface Water 0.11 ±0.01PBq 40°N 0.27±0.02 PBq 30°N 20°N Subtropical Mode Water Central Mode Water 2.5 ± 0.9 PBq 4.2 ± 1.1 PBq 10°N 120°E 150°E 180° 150°W 120°W Longitude#16Conclusions 1 We propose that the consensus amount of total atmospheric release of 137Cs was 15- 21 PBq. The fallout of 137Cs from the atmosphere was 3-6 PBq onto the land and 12-15 PBq onto the North Pacific. The direct discharge of 137Cs to the ocean was 3-6 PBq. The total inventory of 137Cs in the North Pacific was 15-18 PBq. We also estimated the inventory of 137Cs in the surface layer and CMW to be 7.9 ± 1.4 and 2.5 ± 0.9 PBq, respectively.#17Conclusions 2 The amount of 137Cs transported by rivers from land to the ocean for several years after the FNPP1 accident might be 0.04 PBq, which corresponds to 1.3% of the 137Cs deposited in the Fukushima region of Japan. The annual deposition of 137Cs at Okuma during the period 2014-2018 means that 4–10 TBq year-1 was resuspended from the land to the atmosphere, an amount that corresponds to about 0.1-0.3% of the total amount of 137Cs deposited on land in Japan.#18Conclusions 3 The 137Cs activity at the 56N canal in 2016-2018 corresponded to 0.73-1.0 TBq year-1 of 137Cs discharged to open water from the FNPP1 site. The integrated amount of FNPP1-derived 137Cs that entered the SOJ from the North Pacific Ocean until 2017 was estimated to be 0.270 ± 0.002 PBq, whereas 0.11 ± 0.01 PBq returned to the North Pacific Ocean through the Tsugaru Strait. Decontamination efforts were estimated to have removed 0.134 PBq of 137Cs from surface soil, an amount that corresponds to 4.5 % of 137Cs deposited on land in Japan prior to February 2019.#19Thank you for your attention!!