Radioactivity concentration and risk indices in intertidal sediments of the Red River Delta, Vietnam

Abstract The radioactivity concentration in eleven intertidal sediment cores in the Red River Delta was determined 40K, 232Th, and 226Ra as well as radiological hazard indices for environmental risk assessment. The radioactivity concentrations of 40K, 232Th, and 226Ra were 656 Bq/kg, 49.8 Bq/kg, and 37.0 Bq/kg, respectively. The radium equivalent activity (Raeq) was 158.7 Bq/kg; the absorbed dose rate (ADR) was 74.5 nGy/h; the annual effective dose equivalent (AEDE) was 0.09 mSv/y; the representative gamma index (Iγr) was 1.18; the activity utilization index (AUI) was 1.0; the external hazard index (Hex) was 0.40; the annual gonadal dose equivalent (AGDE) was 496.4 µSv/y. Two sediment groups were split. Group 1 with lower the radioactivity concentrations than Group 2, 40K and 232Th were above the global average while 226Ra was below, Iγr and AGDE were above UNSCEAR’s recommended levels. Group 2 radioactivity concentrations of 40K, 226Ra, and 232Th were higher than global average; radiological hazard indices were higher than Group 1; the AUI, Iγr, and AGDE indices were above UNSCEAR’s recommended level. The radioactivity concentrations of 40K, 232Th, and 226Ra were above global average. The AUI, Iγr and AGDE indices were above UNSCEAR’s recommended levels. It is recommended that coastal sediments should not be used for construction purposes as this can affect organisms in intertidal areas.