Master of Philosophy (M.Phil.) Theses and Dissertations

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Browsing Master of Philosophy (M.Phil.) Theses and Dissertations by Author "ASEPERI, Dare Joseph"

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    Assesement of Heavy Metal Content and Health Impact of Classroom Dusts on Lower Level Primary School Children in Southwestern Nigeria
    (Department of Chemistry, Falculty of science, Obafemi Awolowo University, ile-ife Niigeria., 2023) ASEPERI, Dare Joseph
    This study determined the bioavailable concentration of heavy metals in deposited classroom dust, evaluated the potential sources of the heavy metals. It further estimated the possible health risk of exposure to heavy metals in classroom dust. These were with a view to providing information on the health issues that could be associated with exposure of school children to heavy metals. A total of 36 composite dust samples were collected from classrooms of nursery and lower-level primary schools in Ondo and Ile-Ife towns, and their environs in Southwestern part of Nigeria. The samples were subjected to a four-stage sequential extraction protocols in order to extract the bioavailable metals from the dust samples. All the samples were analyzed for total metals and bioavailable metals using Energy .Dispersive X-Ray Fluorescence (EDXRF) Spectrometer. The effectiveness of the sequential extraction procedure was determined by recovery analyses based on comparison of the sequential analysis results with the total metal concentration in the samples. The accuracy of the instrument was determined with analysis of a standard reference soil sample (SRM 1646a) while precision was assessed using replicate sample analysis. The average percentage recovery (%R) values were done by comparing the sum of the fractions (F1 – F4) to total metal concentrations. The results showed %R values that ranged from 85.77% Cd to 98.52% Cu. Also, the values of the reference soil material for the metals agreed well with the obtained values. The overall mean concentration of total metal was in the order Fe > Al > Co > Zn > Mn > Pb > Cu > Ni > As > Ag > V > Cr > Cd with Fe having the highest concentration (166,875.37 ± 43,550.60 mgkg-1) and Cd with the lowest concentration (3.34 ± 5.49 mgkg-1). The distribution of metals in the sequential extraction showed the prominence of Cd (32.61%) and Ag (25.29%) in the soluble exchangeable fraction (F1), Mn (44.28%), and Zn (30.19%) in the carbonates, oxides, and a reducible fraction (F2). Elements Cd, Ag, Zn, Mn, Cu, and Pb had better spread in the four fractions (F1-F4). The Bioavailability Index showed that Mn, Ni, Ag and Cd were potentially bioavailable from the three traffic volume categories while Al, V, Cr, Co, Fe, Cu, Zn, As and Pb were biounavailable (<0.2). The hazard index indicated possibility for non-cancer risk for elements Fe, Ni, Cu, Zn, As, Pb, Ag and Cd while Al would pose no threat. There was indication for the possibility of cancer risk for Ni, Pb and Cd. The contamination factor showed that the dust samples were highly contaminated. The geoaccumulation index showed intense pollution caused by Ni, Cu, Zn and Pb. The receptor model (PMF 5.0) identified two major possible sources which include the vehicular emissions and mixed sources to indicate high anthropogenic activities. This study concluded that there was a possibility of human health problems considering the contribution of bioavailable heavy metals in the polluted classroom environment, hence the need to minimize contact to heavy metals carried by dust.