Spatial and vertical distribution of I-129 and I-127 in the East China Sea: Inventory, source and transportation

• Published in: Science of The Total Environment
• Main Authors: Wang, JL (Wang, Jinlong), Fan, YK (Fan, Yukun), Liu, DT (Liu, Dantong), Lu, T (Lu, Tong), Hou, XL (Hou, Xiaolin), Du, JZ (Du, Jinzhou)
• Format: Report
• Language: English
• Published: ELSEVIER SCIENCE BV 2019
• Subjects: I-129/I-127; Vertical profile; Water mass; Mixing process; Marginal sea; ANTHROPOGENIC I-129; NUCLEAR ACTIVITIES; WATER MASSES; PACIFIC WATERS; NORTH-ATLANTIC; FUKUSHIMA; SEAWATER; IODINE; SPECIATION; Environmental Sciences & Ecology; Environmental Sciences; Fukushima; Pacific; North Atlantic
• Online Access: http://ir.ieecas.cn/handle/361006/10951; https://doi.org/10.1016/j.scitotenv.2018.10.248

Iodirne-129 is useful for tracking water mass movement in the ocean. In this study, the concentration of iodine isotopes in seawater of the East China Sea (ECS) in October 2013 were analyzed to investigate the spatial and vertical distribution of I-129 and I-127 to understand water mass exchange. Results showed that the I-129/I-127 atomic ratios varied with the water mass, with higher values of (10-20) x 10(-11) in the coastal regions and lower values of <8 x 10(-11) offshore. Inventories of I-129 were estimated to be (0.23-1.7) x 10(12) atoms m(-2) (n = 18) in upper 100 m waters, which is comparable to those of other regions without being contaminated by the nuclear accidents or nuclear reprocessing facilities. The total amount of I-129 in the ECS water column was estimated to be 88 g in which over 90% is attributed to the oceanic input (e.g., West Pacific) via the Kuroshio Current (KC). The contributions of I-129 from Changjiang (Yangtze River) terrestrial watershed (<7.5%) and atmospheric fallout (<2.7%) were small. Those from the Fukushima accident were negligible during this investigation. The I-129/I-127 ratios versus salinity distribution showed the range and stratification of the Changjiang, Yellow Sea, and KC waters in the ECS. Our study shows that the Changjiang fresh water could be transported to the North Jiangsu coast in October; the Taiwan Warm Current water could intrude to Northern part of the Changjiang Estuary (32 degrees N). Besides, our results suggest that the I-129/I-127 profile is useful to indicate the seawater mixing process in ocean marginal systems.