“…Radionuclides of various origins are present in seawater, and some elements behave conservatively and remain in their soluble form in water, whereas others are insoluble, or adhere to particles, and sooner or later are transferred to marine sediments (IAEA 2005 ). In the marine environment, 238 U, 210 Pb, 210 Po, and 40 K are the most abundant natural radionuclides and are ultimately derived from the weathering of rocks or fallout from the atmosphere in the form of rain and are transported by river discharge (Cochran 1982 ; Chen et al 2016 ; Filizok and Uğur Görgün 2019 ; Mohan et al 2019 ; Peng et al 2019 ). Three main sources of isotopes of artificial radionuclides exist, namely, nuclear weapons testing, the nuclear accidents at Chernobyl as well as Fukushima, and waterborne discharges from nuclear reprocessing plants (Beresford et al 2020 ; Hirose et al 1999 ; Kaizer et al 2017 ; Kato et al 2018 ; Kawamura et al 2017 ; McKenzie and Dulai 2017 ; Nishikiori and Suzuki 2017 ; Ogata 2013 ; Ramzaev et al 2008 ; Savino et al 2017 ; Vlasova et al 2015 ).…”