Department Of Chemistry

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Browsing Department Of Chemistry by Author "Abayomi, A.A."

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    Open Access
    [PDF] from researchgate.net Urban highway runoff in Nigeria I. Heavy metals in sheet flow from the main expressway in Lagos metropolis
    (Journal of Applied Sciences, 2007-12) Alo, B.I.; Abayomi, A.A.; Osuntogun, B.A.; Olayinka, K.O.
    Whole-unfiltered-water samples were collected from the runoff of a major highway in Lagos metropolis at four different points along the road and at the receiving stream through which the runoff eventually discharges into the lagoon. The study was conducted to characterize the types and levels of pollutants on a typical Nigerian road and was carried out during three different rainy days between the months of February and May, 2004. The collected samples were analysed for the presence of heavy metals; Cd, Cr, Cu, Pb and Zn. Pollution-indicating …
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    Open Access
    Sequential injection analysis for the monitoring of riverine phosphorus and iron inputs into the lagos lagoon sediments
    (J. Flow Injection Analysis, 2016-04) Oladosu, N.O.; Zhao, K.; Abayomi, A.A.; Olayinka, K.O.; Alo, B.O.; Deng, A.
    Sequential injection analysis (SIA) protocols for the determination of phosphorus and mineral iron (Fe) in the Lagos Lagoon sediment were developed by optimizing some existing standard methods. Sandwiched sample was found to offer higher sensitivity than a 2-zone stack for P SIA. The injection volumes of sample and reagent for P analysis were 40 µL and 20 µL (split into two 10-µL zones) respectively while 150 µL of sample and 10 µL of reagent were injected in Fe analysis. The sampling rates were 31 h-1 and 75 h-1 for P and Fe SIA protocols respectively. Quantitative digestion of total P was achieved by a sediment-to-persulfate ratio of 1:3 by mass in 2.0 mL of 0.3 M NaOH. Average recovery of bioavailable P in matrix samples was 91.7 % and average recoveries of total P were 111.5 % and 96.6 % in matrix samples and blanks respectively. Average recovery of mineral iron in matrix samples was 94.3 % while average recovery in blanks was 97.4 %. The method detection limits were 1.4 mg P kg-1 and 2.6 mg P kg-1 for bioavailable-P and total-P methods respectively while the method detection limit for mineral iron method was 0.44 mg Fe kg-1. The combination of neutralization and dilution of bicarbonate extract prevented CO2 interference during SI absorbance scanning. The performance of these methods indicated their suitability for sediment P and Fe monitoring of the Lagos Lagoon system.
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    Open Access
    Studies and transactions on pollution assessment of the Lagos Lagoon System, Nigeria
    (2014) Alo, B.I.; Olayinka, K.O.; Oyeyiola, A.O.; Oluseyi, T.O.; Alani, R.A.; Abayomi, A.A.
    The Lagos Lagoon system is a brackish coastal lagoon—the largest in the West African coast with a large series of estuaries—located between longitude 3o23′ and 3o40′E and between latitude 6o27′ and 6o48′N. It is a shallow expanse of water (0.3–3 m deep), 50 km long and 3–13 km wide and separated from the Atlantic Ocean by a narrow strip of barrier bar complex. This report is on the levels of pollution and nutrients status of the Lagos Lagoon system including physicochemical properties, pesticides organochlorines (OC), polyaromatic hydrocarbons (PAHs), heavy metal species and nutrients observed between 2002 and 2008. Watersheds of the highways on the lagoon had higher concentrations of nutrients (phosphorus and nitrates) relative to other locations on the Lagoon. The western part of the Lagoon was found to have higher concentrations of Cd, Cu, Pb and Zn than the other points. Lagos Lagoon and the adjoining creeks show high anthropogenic input of PAHs and other persistent organic pollutants (POPs). The major hydrocarbon index in most samples was at C29, C31 and C27, indicating vascular plants sources. Mean PBT levels in water and in sediment increased with time between 2004 and 2007. PBT distribution in the lagoon followed the pattern, sediment > biota > water, though some exceptions occurred where the biota bioaccumulated more PBTs than are found in both sediment and water. The Lagoon biota bioaccumulated organochlorine pesticides above allowable limits and thus pose a high risk to human health. The levels of some pollutants in the Lagoon have negatively impacted on the environmental quality which has indirectly affected the social and economic activities of the dependants and this requires improved management strategies to ameliorate. Indeed with the high population that the estuary/lagoon system supports, consideration for its designation as an international waterbody and its concomitant attention is now paramount.