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

Investigation of natural radionuclides and radiation shielding potential of some commonly used building materials in Northwestern Nigeria

This study assessed the gamma-ray shielding potential of clay, sand, gypsum and kaolin commonly used as a building material in Northwestern, Nigeria. The radiological status of the samples was first evaluated by determining the activity concentrations of 238U, 232Th and 40K using NaI (Tl) detector after which elemental composition and mass density were determined using Neutron Activation Analytical Technique. After which the mass attenuation coefficients (MAC), linear attenuation coefficients (LAC), half value layer (HVL), tenth value layer (TVL), and effective atomic number (Zeff) were determined experimentally and theoretically using standard point sources of 137Cs and 60Co photon peaks (0.662 and 1.332, 1.173) MeV and Py-MLBUF software. The activity concentrations were found to range from 51 to 59 Bq kg-1 with a mean value of 59 Bq kg-1 for 238U, 24 to 27 Bq kg-1 with a mean value of 29 Bq kg-1 for 232Th, and 219 to 247 Bq kg-1 with a mean value of 247 Bq kg-1 for 40K which were about within the world recommended values of 33, 45 and 420 Bq kg-1 respectively. The results of the elemental compositions show that Si, Al, K, Fe, and Ba in clay and sand samples have concentrations in the range of 36.83-78.48%, 1.92-26.05%, 6.33-21.96%, 2.39-19.09%, and 0.09-1.44%, respectively, while in kaolin and gypsum, results revealed that Si, Al, K, Fe, and Ca range between 0.34 and 65.52%, 1.14-35.82%, 0.00-12.12%, 0.00-5.77%, and 0.00-96.6%, respectively. However, the concentrations of other elements such as Mg, Ti, Mn, Zn, Na, and Ba varied significantly with the samples. The results showed that clay has an average density of 1.96 g/cm3, sand has 2.32 g/cm3, kaolin has 2.63 g/cm3, and gypsum has the highest density with a value of 2.66 g/cm3 compared to other samples. During the measurements, a thallium-activated sodium-iodide NaI (TI) detector was used. A narrow beam transmission geometry condition was adopted for the measurements to ensure minimal scattered radiation. Absorption and attenuation of gamma beams as a function of sample thickness against gamma energy generally exhibit an increasing gamma ray behaviour as the sample thickness increases from 1 to 3 cm. The results showed that the gypsum, kaolin, sand, and clay were capable of attenuating 63.5%, 61.5%, 58.4%, and 44.2 of gamma-ray photons of energy 0.662 MeV at 3 cm thickness %, respectively, and 40.6%, 32.9%, 30.6%, and 27.3% of gamma energy 1.332 MeV at 3 cm thickness, respectively. The results showed that MAC, LAC, and Zeff of all the samples decreased with an increase in photon energy, while those of HVL and TVL increased. The experimental results for all the gamma-ray shielding parameters were found to be in good agreement with the theoretical values obtained using Py-MLBUF. The results have shown that all the samples have similar photon attenuation behaviours; however, gypsum has the best shielding potential than kaolin and this is attributed due to its highest density value.

Utilizing mollusk soft tissue and shells as biomarkers for monitoring heavy metal pollution in mangrove forests

The primary objective of the study was to examine the distribution of various elements, namely Cadmium (Cd), Copper (Cu), Iron (Fe), Nickel (Ni), and Lead (Pb), in the soft tissues, shells, and associated surface sediments of Cerithidea obtusa (C. obtusa) mangrove snails collected from Sungai Besar Sepang. To conduct the analysis, the preferred and most convenient methods employed were Instrumental Neutron Activation Analysis (INAA) and Atomic absorption spectrometry (AAS). The results showed that the mean concentration of elements in the sediments and soft tissues followed the order Fe > Cu > Ni > Pb > Cd, while for the shell of C. obtusa, it was Fe > Ni > Cu > Pb > Cd.•Iron (Fe) showed the highest concentration among all elements monitored in sediments, soft tissues, and shells of C. obtusa.•The PF results indicated higher incorporation of Pb and Ni into shells.•BSAF results showed that C. obtusa shells accumulated more Cu and Cd from sediments, making them effective biomonitors.

Groundwater conceptual pollution model and related human health hazards, the main dilemma of a desert aquifer near ophiolite complex

Groundwater is a finite resource in Davarzan region which is located between the ophiolite complex mountain in the north and salty playa at the south. The water samples were analyzed to assess the origin of groundwater pollution and explain links between the disturbed heavy metals composition of the earth's surface and the human health risks. The main heavy metal pollutants in the groundwater are Cr, Fe, As and Pb ions. In general, the groundwater salinity and some elements such as Cr and As are increased along with surface topography and groundwater flow directions from the northern ophiolite highlands recharge area to the adjacent desert discharging zone in the south. Despite the ophiolite complexes being the most enriched in Cr element, the lowest Cr concentration in the groundwater was measured near the ophiolite area, which is in the range of its discharged springs. Based on the groundwater conceptual pollution model, bedrock geochemistry controls the composition of soil and hence that of groundwater. The Cr samples show a direct relation with the EC value indicating that intrusion of salinity from the salt pan is probably another reason for the increased Cr concentration. The results of health risk assessment indicated that the groundwater suffered from significant contamination and if used for long-term without pre-treatment may pose serious health risks to human population via drinking water and irrigation of agricultural fields. This is the first attempt to apply hydrogeological setting along with the source of pollution and its health risk in a desert-ophiolitic area.

Evaluation of radiological risk associated with local building materials commonly used in Northwestern Nigeria

In this study, potential radiological risk due to the activity concentrations of primordial radionuclides (²²⁶Ra, ²³²Th, and ⁴⁰K) in commonly used local building materials (sand, clay, kaolin and gypsum) in Northwestern Nigeria were assessed using NaI (Tl) detector. The measured activity concentrations ranged from 47 to 63 Bq kg^-1 for ²²⁶Ra, 24-32 Bq kg^-1 for ²³²Th, and 219-257 Bq kg^-1 for ⁴⁰K respectively. The mean values of ²³²Th, and ⁴⁰K for all samples were below the respective world averages of 45 and 420 Bq kg^-1 with that of ²²⁶Ra for all the samples higher than the world average value of 32 Bq kg^-1. The potential radiological risks were assessed by determining radium equivalent activity (Ra_eq), internal and external hazard indices (H_in and H_ex), absorbed gamma dose rates (D_R), internal annual effective dose rates (IAED), and annual gonadal dose equivalent (AGDE) and activity utilization index (AUI). The assessed parameters were found to range between 104 and 125 Bq kg^-1, 0.99 to 1.15, 0.28 to 0.34, 48 to 58 nGyh^-1, 0.76 to 0.86 mSvy^-1, and 0.78 to 0.96 respectively. The Ra_eq and D_R for all the analyzed samples were found to be within International recommended limits of 370 Bq kg^-1 and 59 nGy h^-1 as recommended by UNSCEAR.

The status of natural radioactivity in Nigerian environments

Proper documentation of baseline radiation data of different environments is an important step toward adequate environmental monitoring, and it provides quick means to quantitatively check and determine possible radionuclide contamination by anthropogenic sources. Besides, such documentation is useful for decision making processes, assessment of dose rates to the public, epidemiological studies, and environmental regulations. This review summarizes the results of studies conducted on radioactivity in Nigerian environments. For most soil samples, the levels of radioactivity are well within the world averages of 33, 45, and 420 Bq kg^-1 for ²²⁶Ra, ²³²Th and ⁴⁰K, respectively. Other soil samples from regions such as Abeokuta in the southwest, and Jos in the northcentral have been described as high background radiation areas with radioactivity values comparable with those obtained from known high background radiation areas such as the Odisha (formerly Orissa) coast in India (with values reported as 350, 2,825, and 180 Bq kg^-1 for ²³⁸U/²²⁶Ra, ²³²Th, and ⁴⁰K, respectively). In some parts of Nigeria, surface and underground water sources used for drinking and other purposes also present elevated levels of ²²⁶Ra above the world range of 0.01 to 0.1 Bq l^-1 and the tolerable levels recommended by the World Health Organization and U.S. Environmental Protection Agency. Corresponding radiation doses due to measured radioactivities from different environments were estimated and compared with those reported in similar studies around the world. More so, the human and environmental health hazards that might be associated with the reported radioactivity in different environmental settings are discussed. The present report is expected to support authorities in developing appropriate regulations to protect the public from radiation exposure arising from environmental radioactivity. The report also examines other areas of consideration for future studies to ensure adequate radiation monitoring in Nigeria.

Concentration, Source, and Health Risk of Trace Metals in Some Liquid Herbal Medicine Sold in Nigeria

The ingestion of toxic metals through liquid herbal medicine over a long period of time, and in excessive dose, may result in chronic accumulation that could cause disorder to several organs of the body. This study evaluated the concentration, source, and probable health risk of 8 trace metals in liquid herbal medicines sold in Nigeria. Triplicate samples of 10 different brands of liquid herbal formulations were analyzed using flame atomic absorption spectrophotometer. Elemental concentrations (mg L^-1) ranged as < 0.00120 (nickel), 0.329-1.23 (zinc), < 0.00150-0.0750 (chromium), 0.565-6.94 (manganese), 1.75-19.4 (iron), < 0.00150-0.266 (cobalt),  < 0.0018-3.01 (lead), and < 0.00900-0.0281 (copper). The estimated hazard quotient (HQ) and hazard index (HI) of trace metals (zinc, chromium, manganese, iron, cobalt, lead, and copper) were < 1.00, except for one of the herbal products which depicted a value of < 1.50, an indication that there is no major probable health effect due to exposure. Carcinogenic risks were lower than the threshold level of 10.0^-6-10.0^-4; this probably reflects non-existent carcinogenic risk in both age groups. The principal component analysis revealed the likelihood of geogenic and anthropogenic activities as indirect sources of trace metals in the herbs. Using hierarchical cluster analysis, AAB and AHM herbal mixtures showed strong similarities in cluster 1, while the remaining herbs reflected identical association within cluster 2. Based on the results of this study, there is need to periodically monitor levels of toxic metals in herbal medicine in order to ensure regulatory compliance and safeguard the health of its consumers.

STATISTICAL ESTIMATION OF RADIOLOGICAL HAZARDS FROM RADIONUCLIDE CONTENTS IN BUILDING MATERIALS

Thirteen (13) types of building tiles and Sharp sand commonly used for building purposes were collected for their radionuclide contents analysis using gamma ray spectrometry. The average value of the Radium equivalent activity is 208.81 Bq/kg for all samples considered was found to be lower than the recommended safe limit of 370 Bq/kg. Similarly, both external and internal hazard indices (Hex and Hin) were noted to have mean values of 0.57 and 0.73, respectively, which were lower than the recommended safe standard of 1. More so, the average absorbed gamma dose rate was observed to be 94.31 nGy/h, much higher than the recommended safe limit of 59 nGy/h.

Investigation of natural environmental radioactivity concentration in soil of coastaline area of Ado-Odo/Ota Nigeria and its radiological implications

Natural radioactivity in coastaline area soil of Ado-Odo/Ota has been carried out to ascertain the presence of radionuclides using gamma-ray spectroscopy (HPGe detector). The result showed that U-238, Th-232 and K-40 ranged from 24 ± 7-49 ± 10; 67 ± 6-120 ± 9 and 88 ± 17-139 ± 20 Bqkg^-1 respectively. The radium equivalent for the samples ranged from 132.51 to 230.91 Bqkg^-1 with mean value of 185.89 Bqkg^-1. The mean value for the gamma dose rate for the soil samples was estimated to be 81.32 nGyh^-1. The estimated values of annual effective dose equivalent ranged from 0.61 to 1.07 mSv y^-1. The estimation of alpha index representative (Iα) ranged from 0.12 to 0.24 with mean value of 0.21 while the gamma representative index ranged between 0.465 and 0.810. The activity utilization index of the soil samples ranged from 1.09 to 1.89 with mean value of 1.53. The radiological implication in the study area has shown that the soil samples with gamma dose rate value of 89.99 nGyh^-1, 94.39 nGyh^-1, 97.40 nGyh^-1 and 101.04 nGyh^-1 respectively are higher than the recommended value of 80 nGyh^-1 and may pose health implication for long term exposure.

The sources and ecological risk assessment of elemental pollution in sediment of Linggi estuary, Malaysia

In this study, concentrations of heavy metals, rare earth elements (REEs), Uranium (U) and Thorium (Th) of the actinide group were determined from Linggi estuary sediment samples by neutron activation analysis (NAA) and inductive coupled plasma - mass spectrometry techniques. The geo-accumulation (I_geo) and ecological risk index (Ri) values were calculated to identify the quality status of Linggi estuary sediments. Results indicated Linggi estuary was polluted by arsenic (As), lead (Pb) and antimony (Sb). REEs, U and Th showed significant increase of concentration in Linggi estuary sediments. Ri of Linggi estuary was categorised as low to considerable ecological risk, which indicates no significant to moderate effect on the majority of the sediment-dwelling organisms. Correlation matrix and principal component analysis assessed pollution sources to be both natural and anthropogenic.

Radionuclides proportion and radiological risk assessment of soil samples collected in Covenant University, Ota, Ogun State Nigeria

The activity levels of ²³⁸U, ²³²Th and ⁴⁰K in soil surrounding major office complexes in Covenant University were analyzed for radiological hazards to determine the safety of the residents in such environment. Sixteen (16) soil samples were collected, prepared and sent to Acme laboratory in Canada for analysis with the use of high purity germanium detector. The mean activity concentrations of ²³⁸U, ²³²Th and ⁴⁰K were found to be 45 ± 10, 135 ± 8 and 195 ± 20 respectively. The concentrations of ²³⁸U and ²³²Th were found to be higher than the world recommended standard of 35 and 30, while the result for ⁴⁰K was noted to be lower than the world safe limit. The average values of Raeq, D, AED, I_yr, H_ex and ELCR in this study were estimated to be 252.33 Bq/kg, 110.15 nGy/h, 0.13 mSv/y, 1.78, 0.68 and 0.47 × 10⁻³ respectively. It was noticed that none of the measured parameters was higher than the internationally recommended safe limits. ²³²Th was found to be the major contributor to the environmental radionuclides in the area of study. Therefore, the inhabitants of the office complexes whose environment was assessed are considered not be exposed to any radiological hazards.

Radioactivity and radiological hazards from a kaolin mining field in Ifonyintedo, Nigeria

The concentrations of the radionuclides in the subsurface formation (soils and rocks) solely depend on their geological origin, which enables its variation from point to point on the Crust. Construction materials can possess elevated concentrations of radioactivity if their byproducts are mined from contaminated radionuclide sources. In this article, results of in situ measurements of radioactivity concentrations of ⁴⁰K, ²³²Th, and ²³⁸U as well as gamma doses and radiological hazards from kaolin mining field were presented and evaluated. Eleven stations were randomly occupied in order to cover the upper axis of a kaolin mining field in Ifonyintedo. The radiometric survey was achieved using Super-Spec (RS-125), equipment capable of measuring activity concentrations and gamma doses. For each location, measurements were taken four times, while its mean and standard deviation values were estimated for better accuracy. The overall mean activity concentrations (for ⁴⁰K, ²³²Th and ²³⁸U) and gamma dose were estimated as 93.9 Bq kg^-1, 65.1 Bq kg^-1, 38.2 Bq kg^-1, and 59.6 nGyh^-1 respectively. The estimated radiological hazards from the measured parameters showed that the overall mean concentrations of Radium Equivalent, External and Internal Hazards, Annual Effective Dose, Gamma and Alpha Indices, and Representative Level index are 138.5 Bq kg^-1, 0.37 0.48, 0.29 mSvyr^-1, 0.48, 0.19, and 0.97 respectively. By comparing the mean values of the activity concentrations and their radiological risks with the several world standards from the literature, kaolin deposits in Ifonyintedo are highly rich in thorium.

Assessment of radiological parameters and metal contents in soil and stone samples from Harrat Al Madinah, Saudi Arabia

The current work deals with measurement and distribution of natural radionuclides for twelve (12) soil and fifteen (15) stone samples collected from Harrats Al Madinah in western region of Saudi Arabia. Two methods were used in this investigation gamma-ray spectrometer (GRS) and X-ray fluorescence (XRF).The activity concentrations of radionuclides (226Ra, 232Th and 40K) were measured using γ-ray spectrometer NaI(Tl) model (A320) made in the U.S.A. The average values of the concentrations of 226Ra, 232Th and 40K were 37.5 ± 0.1, 28.0 ± 0.5 and 300.6 ± 1.7 Bq/kg respectively. The obtained results show that the mean radium equivalent activity, annual effective dose, external and internal hazard indices and radiation level index were 100.67 BqKg-1, 55.63μSv, 0.27, 0.37 and 0.73 respectively. The results were compared with the recommended limits in the literature from other locations and with the global allowable limits recommended by International Commission on Radiological Protection and United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). The obtained results are concordant with the magnitude of safe criteria and exposure risks which were recommended in public papers. The current study is considered as the first baseline data for the natural radioactivity and metal contents measured by X-ray fluorescence method in the Harrat Al Madinah city.

Assessment of toxic elements in sediments of Linggi River using NAA and ICP-MS techniques

Fourteen sediment samples were collected along Linggi River, Malaysia. Neutron activation analysis (NAA) and inductively coupled plasma-mass spectrometry (ICP-MS) techniques were used in the determination of toxic element contents. The results showed that As, Cd and Sb concentrations were higher at all sampling stations, with enrichment factor values ranging from 17.7 to 75.0, 2.1 to 19.5 and 6.6 to 28.4, respectively. Elements of Pb and Zn) were also enriched at most of the sampling stations whilst Cu, Cr and Ni were shown as background levels. The sediment of Linggi River can be categorised as low (<8.0) to very high degree of contamination (>32.0). The mean concentrations of elements viz. Cd, Cr, Ni, Pb, Sb and Zn were lower than the threshold effect level (TEL) of FSQGs values except for As. The concentration of As (arsenic) was higher than PEL and PEC of FSQGs values.