Godfrey, Usiaka Aimua (2021) ASSESSMENT OF RADIOACTIVITY LEVELS AND BIOGENIC EFFECTS OF COASTAL ENVIRONMENT OF UNUMHERIN COMMUNITY IN DELTA STATE, NIGERIA. Masters thesis, Covenant University Ota..
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Abstract
This study investigates the radioactivity distributions and bioaccumulation of microbial in the coastal polluted areas of Unumherin Community in Niger Delta, South-South, Nigeria. The measurement of outdoor gamma dose rates and the activity concentrations of 40K, 238U, 232Th in the air of the study area was measured using calibrated hand-held gamma detector, (RS-125 Gamma-Spec) and NaI (Tl) gamma spectroscopy. The in-situ measurements were combined with the laboratory analysis of sediments, water and fish species from the same area using NaI (Tl) gamma spectroscopy. For fungal and bacterial culture, 1 ml of 103 dilutions were plated on molten sabouraud dextrose agar (SDA) at 25 0C for 5 to 7 days and 0.1 ml of 103 dilutions of the homogenates were inoculated in triplicates by pour plate technique on petri plates containing 15 ml molten nutrient and MacConkey agars at 370C for 24 to 48 hours. The results of the gamma dose rate indicates the hotspot at location 4 with a value of 100 nGy ℎ−1, almost twice higher that the recommended limits. The results revealed varying activities of the primordial radionuclides (40K, 238U and 232Th) with average values higher than the recommended limits for the sediments and water. Geologically, this may be attributed to marine incursion of regional tectonic subsidence during transgression. Statistically, the correlation results confirmed that the enhanced outdoor dose rates at the polluted coastlines was caused mainly by 238U, followed by 232Th and then 40K in magnitude. The results from the NaI (Tl) gamma detector revealed similar distribution observed in the in-situ measurements i.e. the activities of the primordial radionuclides were skewed (the distribution is mostly symmetric) in the range of -2 and +2. The highest activity concentrations of 40K, 238U and 232Th from the polluted coastlines are 288.09, 96.49, 136.12 Bqkg-1 for sediments and 257.31, 66.93, 96.57 Bqkg-1 for water, respectively. The highest mean activity concentration 40K and 238U was observed in Catfish with values of 151.87 and 38.00 Bqkg-1, whereas the highest activity for 232Th was observed in Tilo Fish with a value of 89.02 Bqkg-1. In comparison, all these values are higher than the recommended limits of 420.00, 32.00 and 45.00 Bqkg-1 for 40K, 238U and 232Th according to the United Nations Scientific Committee on the Effect of Atomic Radiation (UNCEAR). The estimated mean hazard indices for the sediments in the study area were higher than the recommended permissible limits according to International Commission on Radiological Protection (ICRP). Microbially, the accumulation of radioactive elements by fishes could be through ingestion and adsorption to surfaces, which culminate in speciation and mobility of radionuclides, alongside the feeding habits of fishes and other aquatic animals. The variability in the mean concentrations of the 40K, 238U, 232Th among the fish species could be attributed to species-specificity, which is a strong factor that influences bioaccumulation and biohazard exposure to the aquatic life. This study recommends further works on Geochemical and Biogeochemistry analysis to determine the toxicity changes for sediments, water and seafood in the same coastal environment.
| Item Type: | Thesis (Masters) |
|---|---|
| Uncontrolled Keywords: | Radioactivity, Microbial interaction, Marine water, Pollution, Niger Delta |
| Subjects: | Q Science > QC Physics |
| Divisions: | Faculty of Engineering, Science and Mathematics > School of Physics |
| Depositing User: | Mrs Patricia Nwokealisi |
| Date Deposited: | 01 Oct 2021 12:09 |
| Last Modified: | 01 Oct 2021 12:09 |
| URI: | http://eprints.covenantuniversity.edu.ng/id/eprint/15374 |
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