O. I. Asubiojo

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.

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.

Environmental impact of vehicular traffic in Nigeria: health aspects

Blood lead levels were analysed and pulmonary function tests were performed on Nigerian traffic wardens, comprising sixty from Lagos (ages 24-52 years; 27 +/- 6), thirteen from the sparsely populated university town of Ile-Ife (ages 22-40 years; 27 +/- 8) and a control group of twenty-four subjects (age 19-55 years; 31 +/- 8). Perkin-Elmer Zeeman 3030/HGA 600 AAS was used for blood analysis. The mean lead level in Lagos wardens was 18.1 +/- 6.4 micrograms/dl, which was significantly higher than the level of 10.2 +/- 2.7 micrograms/dl in Ife wardens and 12.9 +/- 7.0 micrograms/dl obtained in the controls (P < 0.001). However, there was no significant difference between the levels of blood lead in Ife traffic wardens and normal controls. Significant differences (P < 0.0005) in spirometric measurements--peak flow rate (PEFR), forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC)--were observed between traffic wardens and control subjects. The noise levels measured along traffic roads exceeded the threshold for hearing damage.

Elemental composition of Nigerian harmattan dust

Six samples of harmattan dust collected over three seasons of harmattan in Nigeria were analyzed for 29 elements by instrumental neutron activation analysis. The mean concentrations are (in μg/g): Al, 61100; As, 6.59; Au, 0.16; Ba, 695; Br, 195; Ce, 122; Cl, 6200; Co, 20.9; Cr, 119; Cs, 2.72; Eu, 1.31; Fe, 43 1000; Ga, 21.9; Hf, 8.05; K, 15700; La, 53.9; Mg, 8700; Mn, 825; Na, 6400; Rb, 82.4; Sb, 32.7; Sc, 10.3; Se, 6.61; Sm, 6.50; Th, 14.0; Ti, 4900; U, 6.28; V, 81.6; Zn, 2200. The results are compared to similar recent studies in the German Democratic Republic.

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).

Determination of elemental composition of TSP from cement industries in Nigeria using EDXRF technique

Abstract Suspended dust particulates within and around cement industries in Nigeria were sampled and analyzed using EDXRF technique. The TSP concentrations ranged from 500 μg/m 3 to 1300 μg/m 3 within the factory, while outside the factory the range is from 100 μg/m 3 to 370 μg/m 3 . In major shop floors, particulate matter concentrations as high as 10 4 μg/m 3 were recorded. Elements detected include Na, Al, Si, K, Ca, Ti, V, Cr, Mn, Fe, Co, Zn, S, Cu and Pb. Highly enriched elements were Ca, S, Zn, Cu and Pb with enrichment factors 30–350, 75–200, 100–14 700 and 20–700 respectively. Elements such as Al, Fe, Mn, Na, V and Cr were moderately enriched. Source apportionment of the pollutants by chemical mass balance (CMB) and factor analysis methods revealed cement contributions up to 60% within the factory and 30% around the residential neighbourhoods. Control measures like electrostatic precipitators have been strongly suggested to these factories.

A trace element study of commercial infant milk and cereal formulas

Three commercial infant milk formulas, one commercial infant cereal formula and one locally grown cereal used for infant feeding in Nigeria were analyzed for 17 trace elements, viz: Al, As, Br, Ca, Ce, Cl, Co, Cr, Fe, K, Mg, Mn, Na, Rb, Sb, Se and Zn. The commercial milk formulas contain adequate amounts of Ca, Cl, Co, Fe, K, Mg, Mn, Na and Zn, the locally grown cereal contains adequate amounts of Co, K, Mg, Mn and Zn and low in Ca, Cl, Fe and Na while the commercial cereal has adequate amounts of Ca, Cl, Co, K, Mg, Na and Zn. None of the samples analyzed was found to contain any elements up to threshold toxicity limits of concentrations.

The complementarity of PIXE and PIGE techniques: A case study of size segregated airborne particulates collected from a Nigeria city

The Proton Induced X-ray Emission (PIXE) technique is a reliable ion beam analytical tool for the characterization of thin aerosol samples, but it can underestimate the lightest measurable elements (such as Na, Mg, Al and Si) owing to the absorption of their X-rays inside the sample. The Proton Induced Gamma-ray Emission (PIGE) technique could be employed as avalid means to determine corrections for such an effect. Hence, in this study, Fine (PM(2.5)) and Coarse (PM(10-2.5)) particulate matter samples collected at Ikeja, Lagos-Nigeria, using a double staged Gent stacked sampler were analyzed for their elemental concentrations using an external beam set-up for simultaneous PIXE and PIGE measurements. The measured PIXE concentrations as well as the PIGE correction factors for Na and Al detected in the PM(10-2.5) samples (collected on polycarbonate Nuclepore membranes) are reported. The concentrations of 24 elements (Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Se, Br, Rb, Sr, Zr, Cs and Pb) detected in both fractions were displayed, discussed and likely sources of these elements were also identified.