A 30-year record reveals re-equilibration rates of Cs in marine biota after the Fukushima Dai-ichi nuclear power plant accident: Concentration ratios in pre- and post-event conditions.

Concentration ratios (CRs), expressed by dividing Cs activity in seawater by that in marine biota (mainly fish), were obtained from the monitoring of Cs in coastal areas around Japan between 1984 and 2016. Before the TEPCO Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident (1984-2010), mean CRs of Cs, mainly from global fallout (i.e.