Seasonal variations of 228Ra/226Ra and 228Th/228Ra ratios in surface water from the eastern East China SeaK. Yoshida, M. Inoue, Y. Kiyomoto, M. Minakawa, H. Kofuji, S. Nagao, Y. Hamajima and M. YamamotoEPJ Web of Conferences, 24 (2012) 04005DOI: https://doi.org/10.1051/epjconf/20122404005