Figure 2

Temporal variations during 2018–2022: ¹³⁷Cs concentrations at the sea areas (a) adjacent to and (b) in the off-Doto region decay-corrected to the sampling date, with the decay curves calculated based on the effective half-life (13.7 years)¹⁹ and considering 0.9 mBq/L for the EKC and 1.4 mBq/L for the SWC in March 2011, respectively¹⁰; ¹³⁴Cs concentrations in the sea areas (c) adjacent to and (d) in the off-Doto region decay-corrected to the sampling date; and ¹³⁴Cs concentrations (e) adjacent to and (f) in the off-Doto region decay-corrected to the date of the FDNPP accident. Data of the ICW, EKC, and off-Doto waters in 2018 and 2019 are from previous reports^8,10,21.