Omeje Maxwell

Measurement of 238U, 232Th and 40K in boreholes at Gosa and Lugbe, Abuja, north central Nigeria

The purpose of this project is to evaluate the suitability of different sites as locations for obtaining underground water for consumption. The analysis of ²³⁸U, ²³²Th and ⁴⁰K from rock samples from each layer of borehole at a depth of ∼50 m at Site A borehole, S3L1-S3L6 in Gosa and 40 m at Site B borehole, S4L1-S4L5 in Lugbe, Abuja, north central Nigeria is presented. The gamma-ray spectrometry was carried out using a high-purity germanium detector coupled to a computer-based high-resolution multichannel analyzer. The activity concentrations at Site A borehole for ²³⁸U have a mean value of 26 ± 3, ranging from 23 ± 2 to 30 ± 3 Bq kg⁻¹, ²³²Th a mean value of 63 ± 5, ranging from 48 ± 4 to 76 ± 6 Bq kg⁻¹ and ⁴⁰K a mean value of 573 ± 72, ranging from 437 ± 56 to 821 ± 60 Bq kg⁻¹. The activity concentrations at Site B borehole for ²³⁸U have a mean value of 20 ± 2, ranging from 16 ± 2 to 23 ± 2 Bq kg⁻¹, ²³²Th a mean value of 46 ± 4, ranging from 43 ± 4 to 49 ± 4 Bq kg⁻¹, ⁴⁰K a mean value of 915 ± 116 and ranging from 817 ± 103 Bq kg⁻¹ to 1011 ± 128 Bq kg⁻¹. It is noted that the higher activity concentrations of ²³²Th and ²³⁸U are found in Site A at Gosa. Site B has lower radioactivity, and it is recommended that both sites are suitable for underground water consumption.

Assessment of natural radioactivity in various commercial tiles used for building purposes in Nigeria

Graphical abstract

ASSESSMENT OF DOSE INTAKE OF TOXIC ELEMENTS IN GROUNDWATER SAMPLES FROM ABUJA, NORTH CENTRAL NIGERIA

This study measured the concentrations of toxic carcinogenic and non-carcinogenic elements present in groundwater using Inductively Coupled-Plasma Mass Spectrometry (ICP-MS). The concentration values obtained were used to calculate the life average daily dose (LADD) exposure of the people whom rely on groundwater for consumption in Abuja, Nigeria. The highest LADD for the carcinogenic toxic element chromium (Cr) was 2.7 x 10-5 μg kg‒1 day‒1, whereas it was 3.3 x 10-4 μg kg‒1 day‒1 for the non-carcinogenic toxic element lead (Pb), identified in water samples collected by the Water Board. These LADD magnitudes of 10-5 and 10-4 for both carcinogenic and noncarcinogenic toxic elements in groundwater are far below the International Reference Dose according to the United States Environmental Protection Agency (USEPA) in 2008, which has a value of 10-1. The low magnitudes found in water samples may not pose significant health risks to the local population. The relevant authorities should, therefore, continue to monitor the impact of human activities on metal pollution in this area and take effective measures to control contamination of the public water supply

Integrated Geoelectrical And Structural Studies For Groundwater Investigation In Parts of Abuja, North Central Nigeria

Abuja, the capital city of Nigeria, West Africa, is underlain by Precambrian basement rocks consisting mainly of porphyroblastic gneisses, granitic-gneisses, migmatitic gneisses, amphibolites, Pan-African granites and undifferentiated schists. The geology of Abuja, therefore, makes the groundwater conditions in the area very unpredictable. Geophysical surveys were carried out at 12 locations within and around the Gosa area and the results integrated with 88 lineament (fractures) extracted from hill-shaded Shuttle Radar Topography Mission (SRTM) data. The dominant fracture trend for the area is NNE–SSW and N–S, which corresponds to the Pan-African trends in the basement complex of Nigeria. It is observed that in the Gosa area, whereas fractures exist, they do not possess sufficient interconnectivity; this may have adversely affected the permeability of the fractured zone, resulting in the incidence of dry wells in the area. Moreover, evidence from interpreted two-dimensional (2D) geoelectric sections reveals that in some parts of Abuja, the weathered overburden is not thick enough to support sufficient yield for a viable borehole. Interconnected fractures therefore become the desirable structural feature capable of improving the aquifer potential. This study demonstrates the usefulness of integrating conventional vertical electrical sounding (VES) surveys with structural data derived from enhanced SRTM imagery in a hydrologically complicated terrain.

Comparative Analysis of Natural Radioactivity Content in Tiles made in Nigeria and Imported Tiles from China

In this investigation, natural radioactive contents in tiles manufactured in Nigeria and tiles imported from China were measured using gamma ray spectroscopy. High Purity Germanium detector was used to estimate the concentrations of some radioisotopes present in 17 samples of various tiles from Nigeria and China. The average activity concentrations of 226Ra, 232Th, and 40K for the tiles were found to be 68.2 ± 0.5; 173.9 ± 9.2 and 490 ± 15 Bq/kg and 58.2 ± 0.5, 161.5 ± 9.4 and 455.7 ± 15.1 Bq/kg for the tiles from Nigeria and China respectively. Radiological hazard indices such as absorbed dose rate, radium equivalent activity, external Hazard Index (Hex), internal Hazard Index (Hin), Annual Effective Dose (mSv/y), Gamma activity Index (Iγ) and Alpha Index (Iα) were determined for both kind of tiles from Nigeria and China. The mean values obtained were: 354.56 and 317.16 Bq/kg; 169.22 nGyh−1 and 153.92 nGyh−1; 0.95 and 0.87; 1.14 and 1.08; 1.59 mSv/y and 1.52 mSv/y; 1 and 1.15 and; 0.34 and 0.29 respectively. The mean value of radium equivalent obtained in this study is less than that of the international reference value of 370 Bq/kg for the both kind of tiles.

LIFE AVERAGE DAILY DOSE OF RADIUM-226 ON SOME WATER SAMPLES COLLECTED AT GIRI AND KUJE AREA OF ABUJA, NORTH-CENTRAL NIGERIA

226Ra concentrations were studied to represent the radiological risk of groundwater of the Giri and Kuje areas of Abuja, North-Central Nigeria. Two borehole water samples were collected from the Giri and Kuje areas of Abuja with a hand-dug well and Abuja Water Board as control. Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was used to measure the concentrations of radionuclide of 226Ra exposed to the dwellers. The activity concentrations of 226R in groundwater supplies for drinking and domestic purposes ranges from 443

A laboratory assessment of the effect of varying roughness on dissolved oxygen using error correction method

Abstract Dissolved Oxygen (DO) is an important parameter to be monitored as far as water quality of rivers and streams are concerned. On the other hand, in rivers and streams, varying roughness occurs naturally but their contributions to DO availability is yet unknown. This paper examines the effects of varying roughness of different sizes and arrangement patterns on DO and also reveals how Error Correction Methodology as a modelling technique can be applied in river studies rather than using the traditional ordinary least square method with velocity (V), Froude number (Fr), roughness coefficient (K) and dispersion coefficient (d) captured as explanatory variables. The findings of this study revealed that roughness coefficient (K) had no effect on DO i.e. negative relationship with coefficient value of −0.796, with corresponding t-statistics (t = 0.615) suggesting its non-significance. In addition, Froude number (Fr) and dispersion coefficient (d) also showed negative relationships respectively (−77.71 and −2.039) with DO but with sharp significance as revealed by the corresponding t-ratio (t-ratio = −2.75 and −4.08). Thus, the study suggests that dispersion coefficient or its dimensionless number as a variable is important and should be included in the modelling, otherwise, the spread of pollutants (BOD) in the transverse and vertical directions rather than their single centre point values are essential to improve the outcome of DO and reaeration coefficient (k 2) modelling.

EXPERIMENTAL INVESTIGATION OF COPPER REMOVAL FROM AQUEOUS SOLUTION USING MUSA PARADISIACA AS A NOVEL ADSORBENT

The adoption of agricultural waste materials in the removal of heavy metals from contaminated waters has gained more recognition in recent times. This study capitalizes on the production of adsorbents from one of the predominant agricultural waste materials (Plantain Peel) in Ado-Odo Ota, to access its metal-removal efficiency. This work investigated Cu2+ adsorption using activated carbon processed from chemically modified unripe plantain (Musa paradisiaca) peel. Adsorption studies were performed using batch experiments wherewith the influence of pH of the solution, initial concentration, temperature and contact time have been cross-examined. The results displayed a 99.8% removal efficiency of Cu2+ at pH 7.5, 30°C and 150 mg/L concentration. The equilibrium adsorption capacity of unripe Musa paradisiaca peel has been obtained using linear models of Langmuir and Freundlich isotherms. The result is poised to elucidate the metal retention mechanism as a process involving ion exchange as the divalent metal ion binds to the activated unripe plantain peel.

PREDICTING DEGRADATION WITH BIOCHEMICAL OXYGEN DEMAND IN DISINFECTANT-POLLUTED SEWAGE

Most households frequently make use of disinfectants to annihilate infectious bacteria present in toilets and bathrooms. Unfortunately, some of these bacteria may be required for the degradation of sewage in the septic tank system (STS). This paper investigates how the performance (degradation capacity) of sewage will be affected by the inharmonious addition of disinfectants with biochemical oxygen demand (BOD) as the predictor. With a clean 50-litre container, a sewage sample was collected from a waste stabilization pond situated in a Nigerian Tertiary University, transported to the sanitary laboratory in the Department of Civil Engineering, University of Nigeria, Nsukka, and poured into five 4-litre white containers. Different doses of disinfectants – 0.5 ml, 1 ml, 1.5 ml, 2 ml, and 2.5 ml, were simultaneously added only at the initial day of experimental setup under aerobic conditions, and the pH, dissolved oxygen (DO), disinfectant dose, chemical oxygen demand (COD), and BOD were measured every three days for three weeks. Multivariate analysis was performed on the explanatory variable – pH, DO, disinfectant dosage, and COD – using e-Views 8.0, which revealed that the continuous addition of disinfectants to sewage inhibits its degradation, thereby resulting in increased organic loading within the STS, and may further lead to septic tank failure due to shock loading and a major source of ground water been polluted with emerging contaminants.

A STUDY OF NATURAL RADIOACTIVITY IN SOME BUILDING MATERIALS IN NIGERIA

Building materials of different brands were assessed for the concentrations of 226Ra, 232Th and 40K using HPGe detector. The activity concentrations in the measured samples ranged from 27 ± 8 to 82 ± 8 Bq kg-1 for 226Ra, 41 ± 4 to 101 ± 8 Bq kg-1 for 232Th and 140 ± 8 to 940 ± 19 Bq kg-1 for 40K, respectively. The Radium equivalent (Raeq) activity from the samples was found to be <370 Bq kg-1 as the recommended value for construction materials. This study will set a baseline data for significant standards on radiation exposure of the measured radionuclides in the selected building materials used in Nigeria.