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

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 129I and 127I to understand water mass exchange. Results showed that the 129I/127I atomic ratios
variedwith thewater mass,with higher values of (10–20) × 10−11 in the coastal regions and lower values of
b8 × 10−11 offshore. Inventories of 129I were estimated to be (0.23–1.7) × 1012 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 129I 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 129I from Changjiang (Yangtze River) terrestrial watershed (b7.5%) and atmospheric fallout
(b2.7%) were small. Those from the Fukushima accident were negligible during this investigation. The 129I/127I
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°N).
Besides, our results suggest that the 129I/127I profile is useful to indicate the seawater mixing process in ocean
marginal systems.
Publication Name: 
Science of The Total Environment
Page Number: 
Wang, Jinlong; Fan, Yukun; Liu, Dantong; Lu, Tong; Hou, Xiaolin; Du, Jinzhou