J. O. Ojo

Neutron activation analysis of Nigerian crude oils

A total of 40 crude oils from 10 different oil fields in Nigeria were analysed for 39 elements by Instrumental Neutron Activation Analysis (INAA). Significant correlations were found between Ni and V concentrations and Ni versus Se concentrations. The American Petroleum Institute (API) gravities are inversely correlated with total transition metal concentration of the oils but there is no obvious correlation of the V/Ni ratio with the age of the oil fields. The oils are very similar to North Alaska Type B oils in key transition metal parameters and cluster analysis results using the transition metals as variables indicate that the oils might have been formed from two closely related sources.

Elemental Composition of Head Hair and Fingernails of Some Nigerian Subjects

In this article, we present the elemental concentrations determined by INAA for 30 elements measured in some or all head hair samples of 100 Nigerian subjects and 20 elements in the fingernails of some of the same subjects. Measurements of the skewness of the distribution of each element in both tissues confirm previous reports that many tend toward a log-normal distribution. Thus, their concentrations in the tissues may not be under any homeostatic control. The ranges of elemental concentrations together with the medians, and the arithmetic and geometric means, with their respective standard deviations are presented and compared with literature values for other populations. Correlations between elements detected in hair are also sought.

OCCURRENCE OF NATURAL RADIONUCLIDES AND FALLOUT CESIUM-137 IN DRY-SEASON AGRICULTURAL LAND OF SOUTH WESTERN NIGERIA

The radioactivity of the Opa river — irrigated farmlands in the south western Nigeria was determined using an HpGe based, low-level passive gamma-counting system. With the exception of two isotopes, the main radionuclides analysed in the sample were the progenies of238U and232Th. The other two isotopes were the naturally occurring40K and the anthropogenic137Cs. The result obtained showed elevated levels of radioactivity from all detected radionuclides compared to the published data for this area. Enhanced levels of naturally occurring radionuclides is attributed to the use of phosphatic fertilizers for dry season vegetable cultivation along this river banks. The presence of the fission product137Cs could be traced to the fallouts occasioned by the various French nuclear tests in the Sahara desert, and probably, some effect of the more recent nuclear reactor accident at Chernobyl in 1986.

INAA in the determination of the elemental constituents of a natural fluorite

A complementary use of the comparative and the semi-absolute variations of instrumental neutron activation analysis (INAA) has enabled us to determine 22 different elements in a sample of natural fluorite originating from the younger granite province of Nigeria. The mineral has a brownish purple appearance with some veinlets having a deep purple coloration. Of all the 22 elements measured, Fe (851.36 ppm), Sb (7.69 ppm), Ag (87.4 ppm), Hg (2.71 ppm) and Se (1.97 ppm) are found to be exclusive to the veinlets while Au (109.15 ppm), Co (2.15 ppm) and W (173.20 ppm) are concentrated in the main matrix of the fluorite. With the aid of the semi-absolute method, it was possible to measure the Au concentration in the IAEA Soil-7 reference material to be 56.83±5.87% ppm. A qualitative electron microprobe analysis (EMA) showed that the bulk of the matrix is composed mainly of Ca and F, as expected.

Trace elements in sickle cell disease

Instrumental Neutron Activation Analysis (INAA) and Proton-Induced X-ray Emission (PIXE) analysis (employed as a complementary technique) have been used to determine the concentration of 11 elements in blood samples and its components erythrocytes and plasma obtained, from three groups of subjects in Nigeria viz: sickle cell anaemia (SCA) subjects, subjects with sickle cell trait and normal control subjects. The results suggest that SCA subjects have significantly higher concentrations of Na, Cl, Ca and Cu in their whole blood and erythrocytes and a higher concentration, of Cl and Cu in their plasma relative to the control subjects. Furthermore, a significantly lower concentration of K, Fe, Zn, Se, Br and Rb were found in the whole blood and erythrocytes of the SCA subjects as compared to the controls while the concentration of K and Fe in the plasma of the SCA subjects were however, found to be significantly higher than that of the control group. The study also shows that there was no significant differences between the concentration of these 11 elements in the group with sickle cell trait and the normal control group.

Correlations Between Trace Element Levels in Head Hair and Blood Components of Nigerian Subjects

Elemental concentrations in head hair and blood (whole-blood, erythrocytes and plasma) of 28 Nigerian subjects were determined using instrumental neutron activation analysis (INAA) and proton-induced X-ray emission (PIXE) techniques. Correlations found between different elements in hair and blood are reported. Hair levels of both zinc and chlorine were found to be significantly correlated with their levels in erythrocytes.

Characterization of pollutants around tin mining and smelting operations using EDXRF

Abstract Energy dispersive X-ray fluorescence (EDXRF) in combination with HpGe based passive gamma spectrometry is used to measure the concentration of toxic heavy metals and radionuclides in the soils around a lead/tin smelter and also air particulates and mining wastes collected from some tin mines and a tin mill. Toxic heavy metals like Sn, Pb, As, Zn, Bi and Ni were detected and found to be highly enriched in the soils, air particulates and mine wastes. The concentrations of Th and U ranged between 0.01 and 2.94%, and 0.002 and 0.11% in the tailings and between 2.25 and 9.09%, and 0.25 and 0.56% in the monazites respectively. The radiological waste management implications are discussed.

Influence of pre-irradiation annealing and Lix–Co(1−x)–O thin film deposition on the TL response of soda lime glass

Abstract Effects of pre-irradiation annealing and deposition of a thin film of Li x –Co (1− x ) –O on soda lime glass substrate are studied using the thermoluminescence technique, at low gamma radiation doses. Simple but similar glow curves were obtained with a single glow peak in all cases. Glow peaks occurred within the temperature range of 266 and 288 °C depending on sample treatment and gamma dosage. Within the studied gamma radiation dose range of 0.86–4.29 mGy, the heated soda lime glass consistently showed the highest TL response, while that from the film deposited sample was the least. At a dose of 0.86 mGy, a 41.8% enhancement and a 56.7% loss in signal over those from ordinary soda lime glass were recorded for annealed and film deposited samples respectively. Peak shift to higher temperatures were also observed in the two treated samples, relative to blank. These we have attributed to the increased diffusion of alkali ions in the annealed glass and exchange of impurity ions between the Li x –Co (1− x ) –O thin film and the soda lime glass substrate, at high temperatures, resulting in increased formation of points and complex defects that could be either killer or radiative traps.

Studies in the compartmentalization of trace elements in the blood of patients with sickle cell anaemia using PIXE technique

Abstract Concentrations of trace elements in the whole blood, plasma and erythrocytes of 77 individuals (20 carrying the HbSS genotype, 21 with HbAS and 36 with HbAA) were determined using a PIXE facility employing a 2 MeV proton beam. Up to 16 elements were detected in some or all of the samples. The skewness of elemental distribution was measured for each element in the three bloodflow compartments. Most of the essential elements, apart from selenium were distinctly packed in either the erythrocytes or the plasma. Results of the t -test employed to compare elemental values between sickle cell subjects and matched controls show similar patterns in the three compartments for some of the elements. The results are compared with previous work using INAA.

Regulation of elemental ratios in affective disorders: A study using PIXE

Abstract The biochemical aetiology of affective disorders includes possible derangement of trace-elements metabolism. It is however becoming clear that rather than individual elements, ratios of critical elements might be more important parameters to study. In this work, we have employed a 2 MeV proton beam PIXE facility to determine the concentrations of up to 9 elements, K, Ca, Fe, Cu, Zn, Br, Rb, S and P, in freeze-dried plasma and erythrocytes obtained from 21 patients suffering from affective disorders. The regulation of some important ratios in terms of dispersion about mean values were studied as well as correlations between these elements. There were very marked close regulations of elemental ratios in affective disorders when the results are compared with those obtained from normal subjects used as controls.