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 40 K, 232 Th, and 226 Ra as well as radiological hazard indices for environmental risk assessment.The radioactivity concentrations of 40 K, 232 Th, and 226 Ra 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, 40 K and 232 Th were above the global average while 226 Ra was below, Iγr and AGDE were above UNSCEAR's recommended levels. Group 2 radioactivity concentrations of 40 K, 226 Ra, and 232 Th 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 40 K, 232 Th, and 226 Ra 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.