Assessment of Activity Concentration of Radionuclides in Sediment from Oil Producing Communities of Delta State, Nigeria

Abstract

Activity concentrations of twenty-six (26) samples of sediment collected from rivers from eleven (11) oil-producing communities and two (2) non-oil producing communities in Delta state of Nigeria were studied. Hyper Purity Germanium (HPGe) Detector was used for counting and detection of radionuclide content of all samples. Results of the samples analysed showed that the radioactivity concentrations of K 40 , Th 232 and U 238 in the sediment samples from oil-producing areas range from 32.47 Bq·kg -1 to 525.1 Bq·kg -1 with an average of 302.15 Bq·kg -1 , 6.31 Bq·kg -1 to 19.33 Bq·kg -1 with an average of 11.66 Bq·kg -1 , and 4.45 Bq·kg -1 to 18.69 Bq·kg -1 with an average of 8.66 Bq·kg -1 respectively. Activity concentrations at the control site ranged from 3.15 Bq·kg -1 to 4.80 Bq·kg -1 , 2.27 Bq·kg -1 to 4.18 Bq·kg -1 and 1.15 Bq·kg -1 to 1.76 Bq·kg -1 for K 40 , Th 232 and U 238 . These values are within the world average; natural radioactivity mapping of the study area is carried out using the Surfer software. Statistical analysis of the results showed that there is a significant difference between the radionuclide concentrations of the sediment samples from rivers in the oil producing site compared to results from non-oil producing communities, except for one of the oil producing site samples (Idumuesah) which has values that are close to those from the control sites for K 40 . The values of the radiological assessment indices obtained were observed to be within the permissible maximum values; hence the radiation hazard at study areas are negligible. However, concentration values of studied radionuclide at the oil-producing study areas were observed to be higher than values from the non-oil producing sites in most cases. It could therefore be reported that the operations of the oil companies in Delta state of Nigeria may have contributed to the high radioactivity level of the river sediments. Although the concentration at the time of this study poses no risk, further industrial activities in the study area may raise the activity concentration and radiological burden in the future.