Assessment of radioactivity and radiological risk indices in the sediments of the Tam Giang-Cau Hai, Thi Nai, and Nai lagoons in the Center of Vietnam.

Using gamma and alpha spectrometers, the radioactive isotopes ²²⁶Ra, ²¹⁰Pb, ²³²Th, and ⁴⁰K were determined in three sediment cores from the Tam Giang-Cau Hai (TG), Thi Nai (TN), and Nai (DN) lagoons, and radiation risk indices were computed. The radioactivity concentrations of ²¹⁰Pb, ⁴⁰K, ²³²Th, and ²²⁶Ra were 55.46 Bq/kg, 675.78 Bq/kg, 67.22 Bq/kg, and 34.15 Bq/kg, respectively. The Ra_eq, ADR, AEDE, I_γr, AUI, Hex, and AGDE indices were 182.31 Bq/kg, 84.46 nGy/h, 0.10 mSV/y, 1.35, 1, 18, 0.49, and 598.71 µSV/y, respectively; the values of ⁴⁰K, ²³²Th, AEDE, ADR, I_γr, and AGDE were greater than the global average and UNSCEAR values. The radioactivity and radiation risk indices decreased in the order DN > TN > TG. [ABSTRACT FROM AUTHOR]