Geosciences-Scholarly Publications

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Browsing Geosciences-Scholarly Publications by Author "Abimbola, A.F"

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  • Item
    Open Access
    Biogeochemical and engineering characteristics of soils and groundwater around a dumpsite
    (Earth Sciences Research Journal, 2013) Odukoya, A.M; Oresanya, O; Abimbola, A.F
    An active dumpsite in Lagos south-western Nigeria was monitored to test natural attenuation efficiency in reducing contaminants by determining soil and groundwater biogeochemical and engineering properties within and around the site. From the Casagrande Plasticity Chart, the soil could be classified as clay or silt having intermediate to high plasticity; unsaturated zone thickness was 10-20m and permeability was low (1.96x10-5 to 41.8x10-5 m/s). Appropriate microorganisms, such as bacteria, viruses and fungi which are required for natural attenuation, were naturally present. Nutrients such as calcium, copper, magnesium, manganese, potassium, sodium and zinc, as well as electron donor (organic carbon) and electron acceptor (oxygen, nitrate, sulphate and iron), were also present in various amounts for effective natural attenuation. All the parameters analysed in water samples came within Environmental Protection Agency standards, except Fe, Na, Cl, NO3 , Al, Ba, Ni, total bacteria and total fungi. Phenol and total viral count were not detected in the two boreholes studied, but they showed values as high as 10,000 MPN/100ml and 230 CFU/100ml, respectively, in leachate. The concentration of contaminants in the soil was very high and inversely proportional to depth.
  • Item
    Open Access
    Contamination assessment of surface and groundwater within and around two dumpsites
    (International Journal of Environmental Science & Technology, 2010) Odukoya, A.M; Abimbola, A.F
    Geochemical analyses of groundwater and streams flowing around abandoned and active dumpsites in Lagos, Southwestern Nigeria were carried out. Results show that water samples have generally low total dissolved solids with average values of 163.75 and 153.4 for abandoned and active dumpsites, respectively. pH ranges from 3.96- 8.34 while total hardness varies from 10-220 mg/L calcium carbonate (soft to slightly hard). Average concentrations of the dominant ions for abandoned and active dumpsites were 57.8 and 25.86 mg/L (Na) representing 40.7 and 46.3 % of the total cations respectively and Nitrate (av. 96.89 and 61.51 mg/L) representing 49.1 % and 40 %, respectively of the total anions. The pH, coliform count and concentrations of nitrate iron, manganese and sodium in most of the water samples were above the national drinking water standards proposed by the United States Environmental Protection Agency. Trace elements like silver, arsenic, beryllium, bismuth, cerium, cobalt, chromium, lithium selenium, tellurium, titanium, uranium, vanadium, tin and yttrium were below detection level for all the water samples while tungsten, thallium, molybdenum and lead were only present in surface and groundwater close to the dumpsites and also display values higher than recommended standards while cupper, zinc, aluminum, barium and strontium were present in most of the samples. The pollution index among all sites varied from 0.009 to 1.26 and 0.106 to 6.25 for abandoned and active dumpsites, respectively while the water around most of the dumpsite areas exceeded the acute and chronic effect levels proposed by the United States Environmental Protection Agency in 2007.
  • Item
    Open Access
    Geochemical characterization of soils, sediments and waters around active and abandoned dumpsites in Lagos.
    (Chinese Journal of Geochemistry, 2006) Abimbola, A.F; Odukoya, A.M
    In developing countries, large amounts of wastes are dumped daily in open dumping sites without proper management. This practice usually causes enhanced concentration of metallic ions in environmental media within and beyond the vicinity of such dumps with attendant adverse environmental and health risks. Hence the aim of this study is to assess and elucidate the physico- and metallic ions concentrations in three environmental media (soils, sediments and waters) around active (Ojota) and abandoned (Isolo) dumpsites in Lagos and also to do a comparative study with reference to possible environmental and health impacts. A total of eighty samples comprising water, sediments and topsoils were collected around the two dumpsites. The soil and sediment were dried, disaggregated and sieved to <75 ~tm fraction for analysis of the metallic ions using aqua-regia digestion technique and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The analysis of metallic ions and cations in water was carded out using Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) while unacidified water samples were analyzed for anions concentrations using the DIONEX DX-120 Ion Chromatography techniques. Analytical results show that pH, NO3, Fe, Mn and Na in most of the water samples are above WHO and EPA standards. Also there are relatively strong correlations between NO3 and C1, SO4, Coliform, TDS and EC which are an indicator of water contamination especially in the direction of groundwater flow. The mean values of the significant metallic ions present in the water samples include Cu (16.29 and 38.0), Zn (535.71 and 667.0), A1 (0.27 and 0.19), Ba (42.86 and 55.0), Sr (80.0 and 136.0) and B (118.7 and 160.2) for active (Ojota) and abandoned (Isolo) dumpsites respectively. Soil samples revealed varied concentrations with the estimated average contamination factors of 3.86 and 5.71 (As), 1.60 and 1.93 (Mo), 3.41 and 4.24 (Zn), 0.93 and 2.23 (Cu), 7.71 and 12.64 (Pb), 8.71 and 9.21(Cd) for both active and abandoned sites respectively. All these metals with Ag are also significant and follow the same trend in the sediments. Ag, Bi, Sb, Ga, Sc, M_n, Ga and La in soil samples are only significant for samples close to the dumpsites while Bi, Be, Sb, Co, Cu, La and Cr are significant for sediments taken downstream. Most of the metallic ions show significant enrichment in both soil and sediments while A1, B, Ba and Sr are only significant in water. These may be attributed to the adsorption characteristics of the soil and sediments, and relatively high mobility and solubility of the metals in water, respectively. The overall contamination degrees for both active and abandoned dumpsites are 23 and 34 for water, 40 and 30 for soil, 62 and 25 for sediments, respectively, which indicate a very high degree of contamination and a considerable degree of contamination, respectively. It can be concluded that samples around the abandoned dumpsite show higher level of contamination than those of active dumpsite. This may be the result of total decomposition and chemical reactions of wastes within the abandoned dumpsite as a result of its abandonment for a long time without any treatment measure, thus resulting in leachates plume that migrated from the dumpsite to the soil, surface water, sediments and eventually to the groundwater within and beyond the vicinity of the dnmpsite.