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Articles by J.P. Essien
Total Records ( 4 ) for J.P. Essien
  M.G. Ekpenyong , S.P. Antai , J.P. Essien and G.D. Iwatt
  The influence of pH (5.5, 7.0 and 8.5) on the response patterns of species of Penicillium and Rhodotorula to increasing concentrations of zinc during biodegradation of Nigerian light crude oil was assessed by the carbon dioxide (CO2) evolution technique, over a 16-day period. Mean rates of CO2 evolution decreased with increasing pH in control cultures of Penicillium sp., but increased with increasing pH in cultures containing 1000 mg L-1 of zinc. However, analysis of variance of data revealed that there was no statistically significant (p>0.05) difference among the metal concentrations, suggesting tolerance of this species of Penicillium to high levels of zinc. In contrast, mean rates of CO2 evolved in cultures containing Rhodotorula sp. decreased with increasing pH in both control and test cultures containing zinc. Efficiency of inhibition was minimal at pH 8.5 in cultures containing Penicillium sp., but maximal at the same pH in those containing Rhodotorula sp. Interestingly, low concentrations of zinc (≤10 mg L-1) stimulated CO2 evolution in Rhodotorula sp. at pH 5.5 and 7.0, but not 8.5, suggesting pH-dependent low level zinc requirement of the oil biodegradative enzymes of the organism.
  E.D. Udosen , N.U. Benson , J.P. Essien and G.A. Ebong
  The relation between aqua-regia extractable heavy metals in Manihot utilissima grown in a municipal dumpsite in Nigeria was investigated. Analysis has revealed significantly higher levels of Cd, Cr, Fe, Mg and Pb in the crop plant and soil from the dumpsite than values recorded fro the background soil (control). Arsenic, which was absent in the soil and plant from the background soil, was detected in soil samples from the dumpsite but not accumulated by the cassava plant cultured in the waste-dump. Heavy metals levels in soil and plants also varied with the sampling grids (locations). However, there was no clear relationship in heavy metals concentration between the cultured plants and corresponding soil from the dumpsite. Although, the levels of (Cd, Cr, Pb) detected in soil and Manihot utilissima are within the regulated limits, the deterioration of the dumpsite soil and environs ecoquality is desirable due to daily input of wastes and sludge. Therefore consumption of crop plants grown in dumpsites may be of serious health risk with the presence and plausible accumulation of metals such as Pb, Cr, Cd and As in the soil and plant. The frequency distribution characteristics and relative standard deviations were studied.
  N.U. Benson , M.U. Etesin , J.P. Essien , I.U. Umoren and M.A. Umoh
  Fishes are important bioindicators of the integrity of aquatic ecosystems and were used to evaluate the status of heavy metal pollution in an oil impacted aquatic ecosystem (Imo River) located within the Niger Delta region of Nigeria. The concentrations of Cd, Cr, Cu, Fe, Pb, Mg, Mn, Ni and Zn were determined using inductively coupled plasma spectrometer (Optima 3000-Perkin Elmer). The metal concentrations in liver and muscle tissues of Ethmalosa fimbriata (bonga fish), Chrysichthyes nigrodigitatus (catfish), Lutiana ava (pink snapper), Stellifer lancelatus (croaker) and Tilapia guineensis (Tilapia) were consistently higher in the livers than in the muscle tissues of all the five fishes. Magnesium concentration was anomalously higher in the muscle tissue than liver of C. nigrodigitatus, E. fimbriata and L. ava but not in S. lancelatus and T. guineensis. Muscle-liver ratios (MLRs) of the respective heavy metals ranged between 0.089 (CuM:CuL) and 1.299 (MgM:MgL) for C. nigrodigitatus, 0.186 (CrM:CrL) and 1.401 (MgM:MgL) for E. fimbriata, 0.194 (CuM:CuL) and 1.498 (MgM:MgL) for L. ava, 0.131 (CuM:CuL) and 0.646 (NiM:NiL) for S. lancelatus, 0.009 (CuM:CuL) and 0.916 (MgM:MgL) for T. guineensis. Interestingly, copper indicated least MLR in almost all the investigated fishes except in E. fimbriata. Magnesium showed the highest MLR in all fish species except in S. lancelatus. On the other hand, the cadmium/zinc ratios were higher in the muscle tissues than livers of all the fishes analyzed except in E. fimbriata. The threshold contamination value for human dietary risk was however, not exceeded.
  M.G. Ekpenyong , S.P. Antai and J.P. Essien
  The number (quantity) and nature (quality) of hydrocarbon-degrading bacteria and fungi in Qua Iboe estuary, Nigeria and their biodegradation potentials were assessed in this study to ascertain the estuary’s inherent capacity for natural attenuation following an oil spill. Water and sediment samples collected 9 months after a minor oil spill revealed, upon analysis that the fraction of total heterotrophic microorganisms that could utilize crude oil as sole source of carbon and energy was up to 64% in sediments and 15% in near shore waters. There was significant correlation (r = 0.78; p<0.05) between total hydrocarbon content (THC) and percentage abundance of hydrocarbon utilizers in the samples. Different taxonomic and physiological groups of bacteria, yeast and mold were identified. Their carbon dioxide evolution potentials as groups, in terms of rate and extent of evolution, were only marginally better than those from their constituent pure culture studies. A pH-dependent periodic succession of these groups and their species was observed during the study. From the foregoing therefore, Qua Iboe estuary has a great capacity to self-purify in the event of an oil spill and such natural attenuation might even be more environment-friendly than other remediation protocols particularly bioaugmentation.
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