Environmental radiation measurement was carried out in several automobile mechanic workshops within Ugbowo area of Benin-City, Edo State, Nigeria. A Digilert 50 Nuclear Radiation monitor was used to ascertain the level of radiation to which these workers are daily exposed. The study revealed that the average annual effective dose rate from these sites is approximately 0.40 mSv/yr which is lower than the value of 1.0 mSv/yr averaged over five consecutive years according to the dose limit placed by the Basic Safety Standards (BSS) SCHEDULE II and the International Commission on Radiological Protection (ICRP) REPORT 60. However, the external background ionizing radiation exposure within the sites investigated varied between 0.1272 and 0.01411 mR/hr with an average of 0.01314 ± 0.000658 mR/hr in the locality which is relatively higher than the standard background radiation of 0.011 mR/hr recommended by the US Nuclear Radiation Commission. This level of background radiation seems to suggest that there is a possibility of the existence of radio nuclides within the area.
Global System for Mobile Communications (GSM) and other telecommunication technologies are now ubiquitous worldwide. There has been considerable increase in the radiofrequency (RF) radiation exposure of the public from GSM and telecommunication transmitting and receiving antennas. If the RF radiation emanating from these devices exceeds internationally recommended limits it may pose health risk to the public. There is, therefore, the need for database of RF distribution levels in Nigeria for safety assessment. In this study, the power density of mobile phone base station masts in Benin City, Edo State, Nigeria was measured and analyzed to check if it is within the public standard recommended by International Commission on Non-Ionizing Radiation Protection (ICNIRP). A total of forty (40) mobile phone base station masts were studied and their power density (mW/m2), magnetic field strength (A/m) and electric field strength (V/m) were determined by means of a digital Electrosmog meter, model MECO 9810 RF covering the frequency range 10 MHz 8 GHz. The measurements were made at the base of the masts and at distances 25, 50, 75 and 100 m respectively from the base of the masts. The results obtained show that the mean power density, magnetic field strength and electric field strength range from 0.589 ± 0.198 to 127.718 ± 11.301 mW/m2, 0.318 ± 0.056 to 4.166 ± 2.041 A/m and 0.934 ± 0.139 to 11.745 ± 3.427 V/m. The measured and calculated power density values were compared and found to indicate high positive correlation. Also the values of the power density obtained in this study at the different distances and locations were found to be far below the ICNIRP public exposure limits ranging from 2000 10000 mW/m2 in the frequency range of 10 MHz 300 GHz.
Crude oil samples from four oil wells in Nigeria were analyzed for the following seven trace elements: V, Cr, Mn, Fe, Co, Ni and Pb using Atomic Absorption Spectrometric (AAS) analytical technique. The mean concentrations of these elements on a weight to weight basis were found to range from 0.017 ± 0.005 to 1.977 ± 0.397ppm. The results also show that V was the most abundant metal with Ovia 1 Long String (OLS) Oil well containing the highest concentration of V. The V/Ni ratio from the method used shows that Ovia 1 Long String (OLS) and Ovia 1 Short String (OSS) were the most and the least matured oil wells respectively. All the samples had comparably the same V/Ni ratio (1.16—1.77) implying identical source for all the oils. Furthermore, the calculated values of American Petroleum Institute (°API) gravity determined using the measurement of specific gravity (S.G.) of the crude oil samples range from 47.80 to 55.50. This suggests that the samples fall into one category of crude oil classification which in this case is light crude.
This paper examines the relative permittivity of irradiated and non-irradiated crude oil samples in the frequency range 0.1 – 100.0MHz and room temperature regulated at 25 ± 1oC. Samples of crude oil of mean specific gravity 0.780 ± 0.015 were irradiated for periods of two, four, six, eight and ten months respectively using a gamma radiation source (Cobalt 60) at a dose rate of 0.65mSv per hour. Dielectric measurements were made by using a Boonton RX meter type 250A admittance bridge manufactured by central research Laboratories, Inc, Red, Wing, Minnesota. Analysis of the resulting dielectric data revealed that both the irradiated and non-irradiated samples exhibited dielectric dispersion over the frequency range investigated. However, the relative permittivity values of the irradiated samples were found to be higher than those of the non-irradiated sample. This difference is understandable as it can be attributed to the ionization of atoms and weakening of molecular bonds in the irradiated samples. The increase in relative permittivity for the irradiated samples was observed to be time dependent as the longer the time of irradiation of sample the higher the value of its relative permittivity. Also, in this study, it was observed that the non-irradiated crude oil sample has longer relaxation time than the irradiated ones. The relaxation time decreases gradually with increasing irradiation time. This has physical significance on the basis of the molecular theory of matter and the fact that relaxation time is inversely proportional to relaxation frequency. These results are comparable with the work of other researchers for which similar trends have been observed.
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