Comparative Assessment of Gross Alpha and Gross Beta Activity in Soil and Sediment from Oil-Spill Sites in Rivers State, Nigeria
S. I. Ovuomarie-kevin *
Nigerian Nuclear Regulatory Authority (NNRA), Nigeria.
A. I. Olanrewaju
Department of Physics, Federal University of Kashere, Gombe State, Nigeria.
C. P. Ononugbo
Department of Physics, University of Port Harcourt, Rivers State, Nigeria.
G. O. Avwiri
Department of Physics, University of Port Harcourt, Rivers State, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Aims: Oil exploration and frequent spill incidents have created environmental and radiological safety concerns about the mobilization of existing naturally radionuclides in Rivers State. This study is to assess and compare gross alpha and gross beta activity in soil and sediment samples taken from oil-spill sites in Rivers State.
Study Design: The study utilizes comparative design to assess and compare the concentrations of gross alpha and gross beta activity in selected environmental samples from oil spill sites.
Place and Duration of Study: Four crude oil spill sites were identified and sample of environmental matrices (soil and sediments samples) covers the oil spill areas in Te-oo-goo, Nupene, Bon-ngia and Bolte-kpan in Rivers State between May 2015 to June 2018, in Rivers State, Nigeria.
Methodology: Composite soil and sediment samples were obtained from multiple impacted and control sites, air-dried, homogenized, and analyzed under standard radiometric procedures using Protean Instrument Corporation (PIC) MPC 2000DP detector. Correlations were made among the variables (gross alpha and gross beta) to prove the interdependency or direct relationship in the investigated samples.
Results: The mean gross alpha and beta activity concentrations in sediment samples ranged from (14.80±2.22 - 52.10±2.59) Bq/kg and (25.60±4.11 - 129.00±4.08) Bq/kg while in soil samples ranged from (49.47±1.59 - 78.07±2.46) Bq/kg and (12.96±3.32 - 156.60±5.02) Bq/kg, respectively, across the sampled locations. The results indicate variations in activity levels among sampling sites, with soil generally exhibiting (78.07±2.46 / 52.10±2.59 Bq/kg for alpha activity) and (156.60±5.02 / 129.00±4.08 Bq/kg for beta activity) concentrations compared to sediments. The results of the gross alpha and gross beta activities in both soil and sediment samples were found to be greater than the gross alpha and beta activity for their control samples which indicates the possibility of mobilization or concentration of both alpha- and beta-emitting radionuclides and some degree of activity elevation in the sites. Correlations were made among the variables (gross alpha and gross beta) to prove the interdependency or direct relationship in the investigated samples and suggests probable radiological impact and migration patterns of radionuclides in oil-polluted sites.
Conclusion: The results indicate some degree of disturbance at the oil spill sites. Soil and sediment samples from the oil spill sites may not be harmful to local residents or the general public in and around the area, even though there is little to no radioactive contamination of the soil and sediment.
Keywords: Gross alpha, gross beta, soil and sediments samples, radiological risk and oil spill, Rivers state