Spatial and vertical distribution of radiocesium in seawater of the East China Sea

The 137Cs activity in surface water of the East China Sea (ECS) was 0.66–1.36 Bqm−3 during May of 2011. The
low activities were observed in the Changjiang Estuary and Zhejiang-Fujian coast and high activities were observed
in the south offshore and Kuroshio Current pathway, suggesting that the influence from the current
system in the ECS. The 134Cs were undetectable (< 0.03 Bqm−3) and the contribution of the Fukushima accident
to ECS is estimated to be below 3%; hence it is negligible during the investigation period. Using the vertical
profiles of 137Cs in the ECS, the mass balance is obtained, which suggests that the oceanic input dominates the
137Cs source in the ECS. 137Cs is potentially useful to trace water mass movement in the ECS. Our study provides
comprehensive baseline of 137Cs in the ECS for evaluation of the possible influence of the nuclear power plants in
the future.
Marine Pollution Bulletin
Lijun Zhao, Dantong Liu, Jinlong Wang, Jinzhou Du, Xiaolin Hou, Yifei Jiang