O. A. Akanle

Trace elements in drinking and groundwater samples in southern Nigeria.

The levels of Al, Sn, Cs, Rb, Sr, Br, Cr, Mo, Co, Ba, Cu, Zn, Cd, Pb, Mn, Se, As, V and Ni were determined in drinking water supplies (public taps, domestic taps and treated water from public water sources) and groundwater supplies (boreholes and shallow wells) in some parts of Southern Nigeria. The water samples were analysed using inductively coupled plasma mass-spectrometry (ICP-MS). The mean levels (microgram/l) of all the elements ranged between 0.35 microgram/l for Cs and 87.3 micrograms/l for Zn in the drinking waters and between 0.54 microgram/l for Co and 420.3 micrograms/l for Ba in the groundwaters. A comparison of the elemental concentrations with WHO guidelines showed that with the exception of violations of Cd, Cr and Se limits in some of the drinking water samples, the levels of all the other elements investigated were below the WHO maximum allowable concentrations.

Traffic pollution: preliminary elemental characterisation of roadside dust in Lagos, Nigeria

Roadside dust collected from different parts of Lagos metropolis were analysed for heavy metals and other trace elements using a combination of instrumental neutron activation analysis (INAA), inductively coupled plasma-optical emission spectrometry (ICP-OES), and flame atomic absorption spectrometry (FAAS). The results show a positive correlation of the concentration of Pb and some other vehicular emission-related elements with the traffic density. Automotive emission was also found to be the main contributor to Pb concentration in the roadside dust but some elements which hitherto have been linked with automotive emission, such as cadmium and nickel, did not show any strong correlation with traffic density.

The atmospheric deposition of major, minor and trace elements within and around three cement factories

Total atmospheric deposits of particulate matter within the premises of three Nigerian cement factories were collected and characterised for about 25 elements using a combination of Energy Dispersive X-ray Fluorescence Spectrometry (EDXRF) and Instrumental Neutron Activation Analysis (NAA). Some toxic heavy metals like As, Pb, Ni, Co, Zn, Cu, Cr, as well as S, Ca, P were found to be highly enriched in the neighbourhood compared to the control sites. Deposition rates of the cement marker element, Ca, decreased exponentially with increasing distance from the factories.

Effects of cement production on the elemental composition of soils in the neighborhood of two cement factories

The effects of cement production on the elemental composition of soils in the neighborhood of two cement factories in Nigeria have been investigated using the XRF and PIXE/RBS techniques. The concentration of 21 elements viz:-Mg, Al, Si, P, S, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Sr, Pb, As, Zr, Rb and Br, were determined in about 30 samples. Calcium, P, S, Cr, Ni, Cu and Zn, were found to be relatively enriched in the soils of the cement factory premises. Calcium, a cement marker element, was found to be well correlated with Mg, S, Fe, Ni and Cu in the soils, and inversely proportional to the Si and Ti concentrations. From Ca/Si ratios and enrichment factors of the marker elements, it was found that soil contamination due to cement drops sharply with distance from the factories, and with increasing depth from the surface.

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.

Analysis of suspended air particulates along some motorways in Nigeria by PIXE and EDXRF

Elemental concentrations of air particulates collected by a gravimetric method were determined using proton induced X-ray emission (PIXE) and energy dispersive X-ray fluorescence (EDXRF) analytical techniques. Air particulate samples were collected over a six-month period at three positions (middle and two opposite sides) across a road at different locations. Total suspended particulate (TSP) matter concentrations were between 100 and 2000 μg/m3 in Lagos and between 120 and 720 μg/m3 at Ile-Ife; traffic densities were 1000–10000 vehicles per hour and 450–1500 vehicles per hour respectively. Preliminary results show that Pb, Br and Zn were highly enriched relative to the Earths crust and the Pb concentration exceeded the threshold limit value (TLV) prescribed by the Nigerian Federal Environmental Protection Agency (FEPA) for over 50% of the sampling times. Furthermore, the lead to bromine ratios in both cities were found to be within the range of those emanating from vehicular exhaust (i.e. 2.57).

Investigation of elemental models in senile dementia and depressives using neutron activation analysis

Instrumental neutron activation analysis has been used to determine the concentration of a range of elements in hair and blood samples, separated into erythrocytes and plasma, obtained from two groups of women, senile demented (9) and depressives (16), and their respective controls (17 and 9). The results suggest that the senile dementia group has significantly higher Al concentrations in erythrocytes and hair relative to the controls but no significant correlation between the aluminium content of hair and that of blood exists. Further, Zn concentrations determined in the erythrocytes and plasma of these subjects were lower compared to the control values. Vanadium levels above our detection limit for the element were found in seven cases out of a total of sixteen in the depressive group. Vanadium was also found to be at higher concentration in the hair of the depressive group compared to the controls. Again no significant correlation was found to exist between the concentration of vanadium in hair and in erythrocyte sample for these seven subjects.

Elemental characterization of airborne particulates at two Nigerian locations during the Harmattan season

Airborne particulate matter collected during the Harmattan season at Kano in the northern part, and Ile-Ife in the southern part of Nigeria was analyzed for about 30 elements by a combination of instrumental neutron activation analysis and X-ray fluorescence analysis. Although the total suspended particulate concentration (ng/m3) is much higher in Kano than Ife, the elemental composition at both locations is very similar and cluster analysis shows a strong correlation between the two, indicating a common origin for particulates. Particle-size distribution studies show that Kano dust is mainly coarse while Ife dust is mainly fine. The crustal-type elements are mainly concentrated in the coarse particles (≥3 μm) at both locations while the conventional anthropogenic elements are hosted mainly by the fine particles (0.49 μm and below).

Fluorine determination in diet samples using cyclic INAA and PIGE analysis

Fluorine is an important trace element for life and human well-being. Food, in general, provides about 40 percent of the fluorine intake in the human body. In order to measure fluorine levels in human diet samples, Instrumental Neutron Activation Analysis (INAA) and Proton Induced Gamma-ray Emission (PIGE) analysis were used. Reactions19F(n,γ)20F and19F(n, p)19O were employed for determination of the fluorine concentration using a reactor neutron spectrum and epithermal neutrons. Corrections were made for the sodium matrix interference caused by the23Na(n, α)20F threshold reaction in the case of reactor neutron cyclic activation analysis and for the oxygen interference via18O(n, γ)19O reaction when using the epithermal cyclic NAA method. The fluorine content of the diet samples was also determined by PIGE analysis making use of the resonance reaction19F(p, αγ)16O at 872 keV. Cyclic Neutron Activation Analysis (CNAA) when combined with mass fractionation was found to be the most suitable for determination of low concentration of fluorine, through the19F(n, γ)20F reaction with a detection limit of 2.2 ppm in Bowens Kale elemental standard.

A COMPARATIVE STUDY OF ELEMENTAL COMPOSITION OF HUMAN BREAST MILK AND INFANT MILK SUBSTITUTES

Instrumental neutron activation analysis (INAA) and protoninduced X-ray emission (PIXE) analysis have been employed to determine the concentration of 13 elements in human breast milk, various infant formulas, and locally produced cereals from Nigeria, as well as from various infant formulas and natural cow and goat milk available in the UK. The study shows that if the locally produced cereal is to be used on a regular basis for babies in Nigeria, then their diet must be supplemented with essential trace elements. Furthermore, parents should be discouraged from giving their infants cow and goat milk because of the high concentration of major elements compared to human breast milk.