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

The radioactive concentrations of 40 K, 232 Th and 226 Ra in 11 intertidal sediment cores in the Red River Delta were determined, and radiological hazard indices for environmental risk were assessed. The values of 40 K, 232 Th and 226 Ra activity were 656 Bq/kg, 49.8 Bq/kg and 37.0 Bq/kg, respectively. The values of radiological hazard indices such as radium equivalent activity (Ra eq ), absorbed dose rate (ADR), equivalent annual effective dose (AEDE), representative gamma index (I γr ), index active use, external hazard index (H ex ), annual gonadal equivalent dose (AGDE) were 158.7 Bq/kg, 74.5 nGy/h, 0.09 mSv/year, 1.18, 1.0, 0.40, and 496.4 µSv/year, respectively. The results obtained of this study showed that eleven sediment cores can be divided into two groups, of which the radioactive concentrations of 40 K, 232 Th and 226 Ra in group 2 were higher than in group 1, and the concentration of radionuclides in sediments was higher than the global average, except for 226 Ra in group 1. The ADR, AEDE, I γr and AGDE indices were above UNSCEAR's recommended levels for both groups. The results of this study show that sediments have the potential to impact organisms in the intertidal zone and are safe for use as construction materials. [ABSTRACT FROM AUTHOR]

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