Oyediran K. Owoade

Characterization and source identification of airborne particulate loadings at receptor site-classes of Lagos Mega-City, Nigeria

Size segregated suspended particulate matter (PM2.5 and PM2.5-10) were collected using Gent low-volume air sampler at four different receptor site-classes in Lagos Mega City, Nigeria. The particulate mass loading was quantified and the concentration was analyzed to examine the pattern and variation from one receptor site-class to another. The PM2.5/PM10 ratio varied among the site-classes with the residential and marine sites having the least and highest ratio of 0.31± 0.13 and 0.49 ± 0.17 respectively. Particulate loading was higher on weekdays than on weekends (by a factor of about 1.5) in all but the marine site-class.The mean PM2.5/PM10 ratio is 0.41 ± 0.15, which suggests that traffic emission is not the principal source of the Particulate Matter (PM). The INAA assay of the particulates detected ten elements: As, Br, Ce, K, La, Mo, Na, Sb, Sm and Zn. Except for Br, Mo and Sb, the detected elements were more pronounced in the coarse-fractioned filter. Principal Component Factor Analysis (PCFA) of the detected elements identified some common sources (traffic-related, traffic emission, sea-salt and industrial emission) for both PM fractions at the four receptor site-classes. Implications: An assessment of the ambient air quality of the study area has been carried out. Some residential areas can have high particulate matter (PM) loading even more than industrial areas due to contributions from local and transport from neighboring sites. The site-classes have common PM sources and PM loadings are generally lower on weekends than on weekdays, with the coarse fraction being dominant. Measures should be put in place to reduce contributions to PM loading by biomass burning, traffic-related, and industrial emissions, as they have been identified as common and prominent anthropogenic sources of PM.

A complimentary tool in the determination of activity concentrations of naturally occurring radionuclides.

The determination of activity concentrations of radionuclides requires a reliable gamma spectrometry system, which also depends on the compulsory attainment of secular equilibrium amongst the progenies of the radionuclide of interest. This is often difficult to attain and hence a helium particle induced x-ray emission technique, not requiring the compulsory attainment of secular equilibrium, was used to determine the actual concentrations of the elemental content of tailings from the high background radiation tin mining area, Jos, Nigeria. The activity concentrations of the radionuclides of (40)K, (232)Th and (238)U were also calculated based on their elemental analyses, providing reliable information about the heads of uranium ((238)U) and thorium ((232)Th) series on the study area.

Source identification and apportionment of PM2.5 and PM2.5−10 in iron and steel scrap smelting factory environment using PMF, PCFA and UNMIX receptor models

To identify the potential sources responsible for the particulate matter emission from secondary iron and steel smelting factory environment, PM2.5 and PM2.5−10 particles were collected using the low-volume air samplers twice a week for a year. The samples were analyzed for the elemental and black carbon content using x-ray fluorescence spectrometer and optical transmissometer, respectively. The average mass concentrations were 216.26, 151.68, and 138. 62 μg/m3 for PM2.5 and 331.36, 190.01, and 184.60 μg/m3 for PM2.5−10 for the production, outside M1 and outside M2 sites, respectively. The same size resolved data set were used as input for the positive matrix factorization (PMF), principal component factor analysis (PCFA), and Unmix (UNMIX) receptor modeling in order to identify the possible sources of particulate matter and their contribution. The PMF resolved four sources with their respective contributions were metal processing (33 %), e-waste (33 %), diesel emission (22 %) and soil (12 %) for PM2.5, and coking (50 %), soil (29 %), metal processing (16 %) and diesel combustion (5 %) for PM2.5−10. PCFA identified soil, metal processing, Pb source, and diesel combustion contributing 45, 41, 9, and 5 %, respectively to PM2.5 while metal processing, soil, coal combustion and open burning contributed 43, 38, 12, and 7 %, respectively to the PM2.5−10. Also, UNMIX identified metal processing, soil, and diesel emission with 43, 42 and 15 % contributions, respectively for the fine fraction, and metal processing (71 %), soil (21 %) and unidentified source (1 %) for the coarse fraction. The study concluded that metal processing and e-waste are the major sources contributing to the fine fraction while coking and soil contributed to the coarse fraction within the factory environment. The application of PMF, PCFA and UNMIX receptor models improved the source identification and apportionment of particulate matter drive in the study area.

An optimization of PIXE procedure for high-Z species in a lower Z matrix.

Singly charged helium ((4)He(+)) induced PIXE technique was used for the elemental analysis of tin mining tailings. The procedure gave very good results especially when a correction was implemented for X-ray absorption in the low-Z region of the spectrum. The use of helium ions to induce X-ray emission was found to be adequate, especially in the case of the intermediate light elements (12<Z<21) where the nuclear reaction sensitivity decreases. Consequently, helium-induced X-ray emission analysis can be usefully applied for trace element detection of low-Z species in a higher Z matrix as well as high-Z species in a lower Z matrix.

Spatial and temporal variations of the particulate size distribution and chemical composition over Ibadan, Nigeria

Spatial and temporal variation of suspended particulate matter was measured in Ibadan, Nigeria during the raining and dry months of 2013 and 2014, respectively. Six different locations were considered, reflecting city-spread, population density, lifestyle, and vehicular- and industrial-related activities. Elemental characterisation of the samples were carried out using energy dispersive x-ray fluorescence (ED-XRF) spectroscopy, while the black carbon content was determined using an optical transmissometer. Backward trajectory analysis indicated that most air mass was of maritime origin except on few occasions that suggested the Sahara desert origin. Average PM2.5/PM10 ratio for the entire sampling period was 0.32 ± 0.04. This is slightly lower than the reported values in the coastal city of Lagos, partly because of more adequately paved and better road networks resulting in lower dust re-suspension and/or there are relatively finer fraction particulates from other sources, which might include marine, industrial, and secondary emission-related sources. Black carbon showed predominance in the fine fractions and was, majorly, of traffic origin. Major enriched elements of concern are S, Zn, As, and Pb aside from those of sea origin. Refuse burning was observed to be the principal source of Pb and Zn in all the sites except one, which showed major industrial-related activities source. This study will provide data for future measurement and modelling works as well as providing a benchmark for relevant agencies for policy making on setting emission standards for the country.

Heavy metals in industrially emitted particulate matter in Ile-Ife, Nigeria

ABSTRACT Iron and steel smelting facilities generate large quantities of airborne particulate matter (PM) through their various activities and production processes. The resulting PM that contains a variety of heavy metals has potentially detrimental impacts on human health and the environment. This study was conducted to assess the potential health effects of the pollution from the heavy metals in the airborne PM sampled in the vicinity of secondary smelting operations in Ile‐Ife, Nigeria. X‐ray fluorescence (XRF) was used to determine the elemental concentration of Pb, Cr, Cd, Zn, Mn, As, Fe, Cu, and Ni in the size‐segregated PM samples. Pollution Indices (PI) consisting of Contamination Factor (CF), Degree of Contamination (DC) and Pollution Index Load (PLI) and Target Hazard Quotient (THQ) were employed to assess the pollution risk associated with the heavy metals in the PM. CF, DC and PLI values were 3< CF <6, >32 and >1, respectively for the three sites, indicating deterioration of the ambient air quality in the vicinity of the smelter. The heavy metals in the airborne PM pose a severe health risk to people living in vicinity of the facility and to its workers. The diminished air quality with the associated health risks directly depends on the industrial emissions from steel production and control measures are recommended to mitigate the likely risks. HighlightsHighly polluting industries operate in developing countries.Heavy metals in particulate pollution from a secondary steel facility were measured.Pollution indexes were used to quantify the likely resulting human health risks.There is a high probability of adverse effects in workers and nearby inhabitants.

Radiological indices of technologically enhanced naturally occurring radionuclides: a PIXE approach

This paper reports an assessment of the level of the radionuclides (40)K, (232)Th and (238)U in environmental soil samples (process waste), and hence their calculated dose rates. For this purpose, the radioactivity from three natural radionuclides was determined in tin process-waste samples in Jos, Nigeria. This work is based on the particle induced x-ray emission (PIXE) approach, devoid of the secular equilibrium, and most of the resolution, interference, self-absorption, geometrical and density correction problems inherent in gamma spectrometry. Many potential environmental hazards have been observed and the data would be of use to the government in its remediation plan for the study area. The high hazard indices require taking adequate measures to check exposures, and an underground lining in the waste ponds to prevent direct contact with the waste pile is recommended. The use of the wastes as building materials should be stopped and use of soils around this area in any development projects should be discouraged until detailed studies on indoor radiation doses and the effects on the inhabitants of prolonged exposures have been carried out.

An ICP-OES, TXRF, and EDXRF analysis of airborne particulate samples in an iron and steel smelter environment

Elemental concentrations of air particulates collected by gravimetric method in a scrap iron and steel smelter industry were determined using a combination of four different techniques: total reflection X-ray fluorescence (TXRF), the conventional energy dispersive X-ray fluorescence (EDXRF), the modified (polarized) energy dispersive X-ray fluorescence ED(P)XRF, and the inductively coupled plasma optical emission spectroscopy (ICP-OES) analytical techniques. A number of elements were detected by all the techniques, some by one or two while some are better detected by a particular technique. The ICP-OES and TXRF techniques have low detection limits worth of consideration despite the risk of contamination possible during sample preparation. The techniques are observed to be adequate for analytes above K except for Br and Pb, which are significantly lost during digestion of samples. The Mo-target EDXRF, just like ICP-OES and TXRF, cannot detect elements below K but substitute well for them in the analysis of volatile elements like Br and Pb despite its higher detection limits for the said elements. The Mo-target EDXRF is also observed to be inadequate for rare earth elements with energies close to that of Mo as a result of possible poor resolution of the energy peaks. The ED(P)XRF is more adequate in the analysis of low Z elements as well as volatile ones. Where volatile elements like Cl, Br, and Pb and/or low Z elements are of primary interest, the use of techniques involving no elaborate sample preparation should be considered.

Composition and Source Identification of Chemical Species in Dust from Selected Indoor Environments in Ile-Ife, Nigeria

This study presents the elemental compositions and concentrations of indoor dust and identifies the major sources in some selected indoor environments in Ile-Ife, Nigeria. The dust samples were collected from 16 indoor environments comprising offices, churches, residential and staff quarters using a cyclonic high power vacuum cleaner. The dust samples were analyzed for elemental concentrations using x-ray fluorescences. The data sets were analyzed for the possible sources and their contributions using Principal Component Factor Analysis (PCFA). The result showed that dust samples contained several elements: K, Ca, Ti, Mn, Fe, Ni, Cu, Zn, Ga, As, Rb, Sr, Se, Zr, V, and Sc. The PCFA identified three factors with the percentage variance of 92, 77, 71 and 68%, for the office, church, residential, and staff quarters, respectively, for the combined elemental data of each of the site classes. The identified sources were track-in-soil, road and windblown soil dust, paint debris, household dust from personal care materials, cooking, and cleaning activities. The unintentional track-in-soil due to mobility of the occupants, structural materials, and outdoor air was the major sources contributing to the indoor dust.