Faculty of Science

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Browsing Faculty of Science by Author "Abayomi, A. A."

Now showing 1 - 7 of 7
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    Open Access
    Assessment of nitrogen and phosphorus loading by atmospheric dry deposition to the Lagos Lagoon, Nigeria
    (Springer Nature Switzerland AG. Part of Springer Nature, 2016-07) Olayinka, K. O.; Oladosu, N. O.; Abayomi, A. A.; Alo, B. I.
    Surface water pollution has been found to be considerably driven by the contributions of airborne particles, open-air waste burning and fossil fuel combustion, ammonia volatilization from excreta, fertilizer and derivatives from explosive factories. Atmospheric deposition into the Lagos Lagoon is suspected to be a major contributor to the nutrient levels of the lagoon. Atmospheric dry nutrient deposition was monitored at six stations around the Lagos Lagoon from January to June 2012 in order to estimate the contribution of atmospheric deposits into the lagoon’s nutrient cycles. Species of phosphorus (P) and nitrogen (N) in the lagoon water were analyzed by colorimetric methods. Mean [NO− 3 + NO− 2]-N was 3.08 ± 2.10 mg m−2 day−1 (0.55–8.73 mg m−2 day−1). The (NO− 3 + NO− 2)-N was only about 2 % of total N but [NH+ 4 + organic]-N was approximately 38 % of total N. Particulate N was about 60 % of total N. Average total N was 144 ± 94.9 mg m−2 day−1 (48.0–285 mg m−2 day−1). Average soluble reactive P was significantly lower than [NO− 3 + NO− 2]-N averaging about 0.12 ± 0.12 mg m−2 day−1. Soluble reactive P (SRP) was less than 2 % of total P but soluble organic P was about 86 % of total P. Particulate P accounted for about 12 % of total P. Average total P was 4.56 ± 10.1 mg m−2 day−1 (0.48–31.6 mg m−2 day−1). This study shows that atmospheric deposition of nutrients into the Lagos Lagoon is taking place and this may represent a considerable proportion of the total nutrient loading of the lagoon.
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    Open Access
    Assessment of nitrogen and phosphorus loading by atmospheric dry deposition to the Lagos Lagoon, Nigeria
    (Springer, 2016-05-25) Olayinka, K. O.; Oladosu, N. O.; Abayomi, A. A.; Alo, B. I.
    Surface water pollution has been found to be considerably driven by the contributions of airborne parti- cles, open-air waste burning and fossil fuel combustion, ammonia volatilization from excreta, fertilizer and deriva- tives from explosive factories. Atmospheric deposition into the Lagos Lagoon is suspected to be a major contributor to the nutrient levels of the lagoon. Atmospheric dry nutrient deposition was monitored at six stations around the Lagos Lagoon from January to June 2012 in order to estimate the contribution of atmospheric deposits into the lagoon’s nutrient cycles. Species of phosphorus (P) and nitrogen (N) in the lagoon water were analyzed by colorimetric methods. Mean [NO − 3 + NO − 2 ]-N was 3.08 ± 2.10 mg m−2 day−1 (0.55–8.73 mg m−2 day−1 ). The (NO− 3 + NO− 2)-N was only about 2 % of total N but [NH+ 4 + organic]-N was approximately 38 % of total N. Particulate N was about 60 % of total N. Average total N was 144 ± 94.9 mg m−2 day−1 (48.0–285 mg m−2 day−1 ). Average soluble reactive P was significantly lower than [NO − 3 + NO − 2 ]-N averaging about 0.12 ± 0.12 mg m−2 day−1 . Soluble reactive P (SRP) was less than 2 % of total P but soluble organic P was about 86 % of total P. Particulate P accounted for about 12 % of total P. Average total P was 4.56 ± 10.1 mg m−2 day−1 (0.48–31.6 mg m−2 day−1 ). This study shows that atmo- spheric deposition of nutrients into the Lagos Lagoon is taking place and this may represent a considerable propor- tion of the total nutrient loading of the lagoon.
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    Open Access
    The contribution of roadside soil to phosphorus loading in the eutrophic Lagos Lagoon, Nigeria
    (pubs.rsc.org, 2011-05-11) Abayomi, A. A.; Nimmo, M.; Williams, C.; Olayinka, K. O.; Osuntogun, B. A.; Alo, B. I.; Worsfold, P. J.
    Roadside soils were sampled from the Lagos Lagoon catchment during the wet and dry seasons over the period 2005–2009. Lagoon sediment samples were also collected within the same period. All samples were digested with aqua regia to determine total phosphorus and extracted with 0.5 M sodium bicarbonate to determine the bioavailable fraction (Olsen-P). A segmented flow analyser method was used for analysis and good accuracy was demonstrated for two reference soils (SO-2 from CCMET and SRM 2711 from NIST). The Lagos Lagoon is a hypereutrophic water body (1270 1170 mgPL 1 ), with significant areas of anoxia and water hyacinth growth. The total phosphorus concentrations in roadside soils (16 sites; mean 2 S.D.) were 285 279 mg kg 1 in the wet season and 424 629 mg kg 1 in the dry season, indicating that rainwater leaching is a major source of phosphorus in the lagoon. The bioavailable fractions were 5.17 3.47 mg kg 1 (2.1 1.5% of the total) in the wet season and 13.0 8.7 mg kg 1 (4.3 4.5% of the total) in the dry season.
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    Open Access
    Online zinc reduction-sequential injection analysis for the determination of nitrogen species in extracts of riverine sediment
    (Springer, 2017-04-07) Oladosu, N. O.; Abayomi, A. A.; Zhang, X.; Olayinka, K. O.; Alo, B. I.; Deng, A.
    The substitution of hazardous analytical reagents such as Cd with benign alternatives for chemical determination is one of the principles of green chemistry. An eco-friendly Zn reduction method for nitrate determination was developed to achieve this end. Online zinc reduction-sequential injection analysis (ZnR-SIA) protocol was developed for the determination of nitrogen (N) species in the Lagos Lagoon sediments by modification of some standard methods. The novel application of boric acid-borate buffer employed in borate-buffered granular Zn reduction suppressed gas evolution from the Zn micro-column, making the Zn reduction adaptable to online use, unlike the frequently used ammonia-ammonium buffer. Further results showed that the sampling rate for the two-zone stack was 65 h−1. The boric acid-borate buffer offered 5.9-fold and 1.3-fold of the instrument response given by the ammonia-ammonium buffer at 0.50 and 5.0 mg N L−1 respectively. The method detection limits of the ZnR-SIA for the three matrices studied were 24.6 μg N L−1 for reagent water, 0.383 mg N kg−1 for KCl-extractable nitrate, and 3.18 mg N kg−1 for total nitrogen. The average recovery of nitrate-N in matrix samples was 94.7%, and its precision was 4.52%. The average recoveries of total N in blanks and matrix samples were 97.9 and 93.2% respectively. The method accuracies demonstrated the suitability of the ZnR-SIA for sediment N determination. Zn reduction is recommended where sustainable development is desired and is a potential substitute for the standard Cd reduction owing to Cd toxicity.
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    Open Access
    Studies and transactions on pollution assessment of the Lagos Lagoon System, Nigeria
    (Springer, 2014-06-03) Alo, B. I.; Olayinka, K. O.; Oyeyiola, O. A.; Oluseyi, T. O.; Alani, R. A.; Abayomi, A. A.
    Abstract 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 3o 230 and 3o 400 E and between latitude 6o 270 and 6o 480 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.
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    Open Access
    Urban highway runoff in Nigeria I. Heavy metals in sheet flow from the main expressway in Lagos metropolis
    (researchgate.net, 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 indices such as dissolved oxygen, BOD5, total solids, conductivity, chlorides, hardness, alkalinity and acidity were also determined. The results of the analyses showed that Zn was most prominent in the sampled runoffs with mean concentrations of 68.7±3.0, 119.7±58.3 and 33.1±24.0 ppb in the three sampled events. Cd -at a concentration of 0.6 ppb was only detected in one of the samples. The concentrations of these metals were shown to vary with the time of sampling during the precipitation. Levels were generally higher in first flush samples
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    Open Access
    Wet nitrogen and phosphorus deposition in the eutrophication of the Lagos Lagoon, Nigeria
    (Springer, 2017-01-18) Oladosu, N. O.; Abayomi, A. A.; Olayinka, K. O.; Alo, B. I.
    Air pollution is influenced by wind-aided particu- late suspension, open-air waste burning, and fossil fuel combustion. The pollutants from these sources eventually deposit on ambient surfaces. Atmospheric wet deposition into Lagos Lagoon may be significant additions to the nutrient levels of the eutrophic lagoon. Precipitation was monitored at three stations in the Lagos Lagoon basin from May to November, 2012, in order to estimate the contribution of wet deposition to the nutrient cycles of the lagoon. Water samples were digested with potassium persulfate, and the species of phosphorus (P) and nitrogen (N) were analyzed by colorimetric methods. The mean [NO3− +NO2−]-N level was 0.39 ± 0.51 kg ha−1 month−1. The average total N was 3.16 ± 6.39 kg ha−1 month−1. The mean soluble reactive P was lower than the [NO3− + NO2−]-N averaging 0.06 ± 0.09 (at control site S2) to 0.24 ± 0.10 kg ha−1 month−1 (at site S1). Average total P was 1.25 ± 0.82 kg ha−1 month−1 . The annual total N (May–September) was 4.55 (at S2) to 32.4 kg ha−1 year−1 (at S3). The annual total P (May–November) over Lagos Lagoon basin was 5.06 kg ha−1 year−1 (at S2). This study demonstrated that wet deposition of anthropogenically derived nutrients to the Lagos Lagoon is ongoing and may represent a considerable proportion of the total nutrient load- ing to it. The increased P availability in the wet deposition is likely responsible for the water hyacinths, which usually blossom on Lagos Lagoon during the late rainy season, and the reported harmattan-season bottom water hypoxia.