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A. J. Timothy Jull1.2, Ching-Chih Chang1,2*, George S Burr1,3, Joellen L. Russell2, Dana Biddulph1, Lara White1, Nancy G Prouty4, Yue-Gau Chen5, Chuan-Chou Shen5, Weijian Zhou6, Doan Dinh Lam7 1 NSF-Arizona AMS Laboratory, University of Arizona, Tucson, AZ, USA 2 Department of Geosciences, University of Arizona, Tucson, AZ, USA 3 Department of Oceanography, National Sun Yat-Sen University, Kaohsiung, Taiwan 4 US Geological Survey Pacific Coastal & Marine Science Center, Santa Cruz, CA, USA 5 Department of Geosciences, National Taiwan University, Taipei, Taiwan 6 Shaanxi Province Key Laboratory of Accelerator Mass Spectrometry Institute of Earth Environment, CAS, Xi’an 710043, China 7 Institute of Geology, Vietnamese Academy of Science and Technology, Hanoi, Vietnam 1. Iodine-129 is a long-lived radionuclide with a halflife of 15.7 million years. 2. It has been shown to be a useful tracer for environmental research due to in part to its high mobility in nature and significant anthropogenic production (Edwards, 1962; Muramatsu and Ohmomo, 1986; Santschi et al., 1996; Raisbeck et al., 1995; Schmidt et al., 1998; Hou et al., 2009; Povinec et al., 2010). There are two natural production pathways for 129I: 1) by spontaneous fission of 238U 2) 2) by the interaction of cosmic-rays with xenon in the atmosphere; 3) Pre-bomb 129I/127I values between 5 x 10-13 and 1.5 x 10-12 (Fabryka-Martin et al., 1984; Moran et al., 1998; Edmonds et al., 1998; Biddulph et al., 2006). Since the nuclear era began, anthropogenic 129I sources have overwhelmed natural production. These are dominated by nuclear fuels reprocessing activities, but also include aboveground nuclear testing and accidents. Sources, inventory and releases of 129I in natural samples (from Hou et al. 2009; Hu et al. 2010). Source Inventory/releas e (kg) 250 Natural sources 57 Nuclear weapons testing 5200 Marine discharge by European reprocessing up to 2007a 129I/127I in environment 10-12 10-11 to 10-9 10-8 to 10-6 (North Sea and Baltic Sea) Atmospheric discharge from European reprocessing up to 2007a 440 10-8 to 10-6 (in rain, lakes and rivers in western Europe) Atmospheric releaseb from Hanford reprocessing 275 10-6 to 10-3 (into air near Hanford) Columbia River release from Hanfordb ~167 10-6 to 10-3 (estimated from 131I) 129I 129I in the ocean environment time series from archived seaweed samples (modified from Yiou et al., 2002). Utsira (59oN, 5oE), Kiberg (70oN 31oE) and Ingoy (71oN 24oE) are sites along the coast of Norway. 1 IU = 1×10-10 129I/127I. Adapted from Hou et al. 2010) 129I in Modern Corals (Biddulph et al. 2006) Adapted from Bautista et al. 2016 Xisha Islands Con Dao Parola Island Chang et al. (2016) J. Env. Radioact. 165: 144-160 From Baustista et al. (2016), J. Env. Radioact. 164: 1-8. CTBTO map (UNSCEAR, 2000) A nuclear accident at the Fukushima Dai-ichi nuclear power plant (1FNPP), Japan occurred in March 2011 due to the failure of cooling system after the Tohoku earthquake and Tsunami on 11th March 2011. Significant quantities of radioactive materials were emitted into the atmosphere from 12th March through 24th March, with estimated atmospheric releases of 150-160 PBq of 131I and 10-15 PBq of 137Cs. Guilderson et al. (2014), Biogeosciences, 11, 4839–4852, 2014 (Povinec et al. 2013) Fukushima 129I plume in June 2011 (Hou et al., in press) 1. Since June 2011, we have been sampling seawater on a biweekly basis - from the inlet pipe of the Stephen Birch Aquarium for 129I levels, which is located at the end of the Scripps Institution pier. 2. We have also been collecting occasional samples at Kaoshiung, Taiwan. 3. Other point or monitored locations are at Long Beach and Santa Barbara (California) and point sampling has been done on the Oregon coast and Alaska. Many colleagues at the University of Arizona This work was supported in part by a grant from the National Science Foundation, EAR1313588.