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LIST OF VOLUME TWO, NUMBER ONE ARTICLES
VOL. 2, No. 1 , ARTICLE 1 Ecological risk assessment of heavy metals in Great Kwa River Estuary, South Eastern coast of Nigeria by Ogri O. R., Ibok U. J. & Offem J. O.
Abstract In this study, heavy metal was monitored quarterly in Great Kwa river estuary for a period of one year. Heavy metal results together with physicochemical parameters including nutrients were used to estimate the potential risk of heavy metals in this ecosystem. The results indicated that Cd and Zn were the most hazardous metals in this estuary. The ecological risk was higher in the rainy than the dry season (84.4 and 78.3 respectively). Generally, the ecological risk posed by heavy metals in this estuary (80.2) is considered low. FOR FULL ARTICLE: SEND E-MAIL TO ekomrob@yahoo.com
VOL. 2, No. 1 , ARTICLE 2 Bioremediation potential of Bacillus species in oil-polluted soil from auto-mechanic workshops in Calabar, Nigeria. by Eja M. E., Udo S. M. & Asikong B. E.
Abstract Biodegradation potential of indigenous Bacillus species on auto-mechanic waste-oil-polluted soils was investigated. Total hydrocarbon levels ranged from 1,160.6 – 6,130.1 mg/kg and 6-11 mg/kg in the contaminated and uncontaminated (control) soil samples taken at a depth of 15 cm, respectively. The observed THC levels exceeding 100 mg/kg which is the maximum level recommended by the Department of Petroleum Resources (DPR), indicated highly contaminated soils. Bacillus subtilis showed the highest level of biodegradation. B. cereus, B. cereus var. mycoides and B. megaterium showed relatively lower biodegradation potential. The highest incidence of Bacillus species (68%) coincided with the C:N ratio of 8.4:1, indicating that optimum utilization of hydrocarbon by Bacillus in these soils would require 1 gram of N per 9.4 gram of its biomass. FOR FULL ARTICLE: SEND E-MAIL TO ekomrob@yahoo.com
VOL. 2, No. 1 , ARTICLE 3 Silver uptake by green alga Chlorella emersonii. by Arikpo G. E. & Eja M. E.
Abstract Investigations were carried out on the uptake of silver by the green alga Chlorella emersonii. Uptake of silver by Chlorella over time showed a logarithmic profile, with a rapid initial uptake over the first five minutes, which then slowed down. After 30 minutes little or no further uptake occurred. Uptake of silver by chlorella showed a direct relationship to the amount of metal present, suggesting ‘equilibrium conditions’ being responsible for amount of metal removed from solution rather than just number of binding sites available. There was a direct relationship between amount of Chlorella present and amount of metal removed from solution. There was a direct relationship between uptake of silver and the temperature of the solution, over the temperatures tested (10oC – 70oC). Absence of metabolic involvement in the uptake process was observed as there was no effect on final uptake of silver in investigations carried out with either dead or living cells. It is concluded that living or dead Chlorella biomass has a high biosorption potential for silver, especially at elevated temperatures which characterize wastewater discharges, and thus its attractive application in biosorption technology. FOR FULL ARTICLE: SEND E-MAIL TO ekomrob@yahoo.com
VOL. 2, No. 1 , ARTICLE 4 The life history cycle of the brackish river prawn (Macrobrachium macrobrachion Herklots 1851) in the Cross River Estuary, Nigeria. by Enin U. I.
Abstract The life history cycle of Macrobrachium macrobrachion in the Cross River Estuary, Nigeria, was analyzed based on catch samples collected from the landings of the artisanal fishery between October 1991 and December 1993 (27 months). An all year round spawning was observed with two peak periods, the major one between July and September and a secondary one in January. Recruitment showed a similar cycle with the major peak between December and January, and a smaller peak in May. Catch rates were highest between July and November coinciding with the main spawning season of the shrimp, suggesting that exploitation was based mainly on the spawning population. It was argued that the interference of the artisanal fishing operations with the spawning population, may be detrimental to the conservation and hence, the health of the shrimp stock. The preliminary life-cycle pattern proposed has a generation time of 12 months and a maximum longevity of 24 months. The observed life history cycle was apparently linked to the seasonal fluctuations of some environmental factors in the estuary. FOR FULL ARTICLE: SEND E-MAIL TO ekomrob@yahoo.com
VOL. 2, No. 1 , ARTICLE 5 Effect of water-soluble fraction of crude oil on development and hatching success of Heterobranchus longifilis eggs. by Eni G. E., Obiekezie A. I. & Akpan E. R.
Abstract Concentration–response relationships were evaluated for some indices such as fertilization success, hatching success and post – fertilization mortality in eggs of Heterobranchus longifilis exposed to sub-lethal concentrations of water soluble fractions of Nigerian light crude oil. Eggs and embroyonic materials of H. longifilis exposed to 0.00, 2.50, 5.00, 10.00, 15.00 and 20.00ppm water-soluble fraction (WSF) of Nigerian Light crude oil recorded significant differences (p<0.05) in fertilization success in the different exposure concentrations such as 74.67% > 73.33% > 70.67% > 69.33% > 66.00 % > 60.00%, respectively, with fertilization success decreasing with increasing toxicant concentration. Post-fertilization egg mortality increased with increase in concentration of WSF of crude oil yielding 5.00, 9.33, 18.00, 21.33, 24.00 and 25.33 percent respectively, for 0.00, 2.50, 5.00, 10.00, 15.00, and 20.00ppm WSF of crude oil. Hatching success also decreased with increasing concentration of WSF of crude oil yielding mean percent hatching of 70.00%, 64.00%, 52.67%, 48.00%, 44.00%, and 34.67% respectively for 0.00ppm (control) 2.50, 5.00, 10.00,15.00 and 20.00ppm. Hence, Nigerian light crude oil significantly reduced fertilization and hatching success, increased fertilization failure and post fertilization egg-death of treated H. longifilis eggs compared to control. The present findings show that the 10.00ppm permissible limit of hydrocarbons in our inland waters, as set by Directorate of Petroleum Resources (DPR) may be too high and require downward revision. FOR FULL ARTICLE: SEND E-MAIL TO ekomrob@yahoo.com
VOL. 2, No. 1 , ARTICLE 6 Bacterial carbon production and subsequent losses to heterotrophic microflagellates in a tropical estuarine ecosystem. by Antai E. E., Esin A. A. & Udo S. M.
Abstract Bacterial growth, production and losses to heterotrophic mircroflagellate were investigated in the lower Cross River estuary from February 1999 to December 1999. Bacterial and microflagellate numbers were relatively high, varing from 4.1to 14.9 x 109 cells l-1 and 3.3 to 14.9 x 106 cells l-1 respectively during the study period. The plankton community was uncoupled experimentally by differential filtration and changes in numbers of bacteria and predator microflagellates were measured over several days. Bacterial biomass grazed range from4.6 to 20 µgCl-1. Results show that bacteria and microflagellates have a coupled relationship (r2 = 72.5) and the microbial ecology of the lower Cross River is primary regenerative.FOR FULL ARTICLE: SEND E-MAIL TO ekomrob@yahoo.com
VOL. 2, No. 1 , ARTICLE 7 Environmental effects of radiographic developer effluent. by Egbe N. O., Eduwem D. U., Inyang S. O., Nneoyi-Egbe A. F., Olisemeke B. F., Inah G. B., Chiaghanam N. O. & Ikamaise V. C.
Abstract Radiographic developers are widely used in the photographic and X-ray film processing. Results of present studies has shown that over 16,000 litres of developer is used annually by the major companies in Calabar, the Capital of Cross River State in Nigeria. Presently there is no legislation on the management of the associated effluents in Nigeria. Environmental impact of the developer effluent was studied by comparison of soil conditions and plant growth before and after treatment with the effluent. Results showed a significant modification of soil constitution, and retardation of plant growth at relatively low concentrations of effluent. Observed impacts are attributed to effluent components including heavy metals, salts and organics. The environmental hazard of radiographic developer effluent disposal and the need for legislation on it are discussed. FOR FULL ARTICLE: SEND E-MAIL TO ekomrob@yahoo.com
VOL. 2, No. 1 , ARTICLE 8 The effects of water-soluble fractions of crude oil and crude oil-dispersant mixtures on the hatchability of eggs of Clarias gariepinus. by Douglas A. F., Ikweozor I. K. E. & Daka E. R.
Abstract Hatching success and time taken to hatch were determined in laboratory-fertilized eggs of Clarias gariepinus exposed to different concentrations of water-soluble fraction (WSF) of crude oil and to mixtures of crude oil and the dispersant Corexit 9527. Initial tests were carried out over a wide range of concentrations and in subsequent experiments five replicates of each concentration were used. Controls with no toxicant added were also set up. Hatching success was found to be significantly higher in controls (71.2 + 5.2 %) than at all concentrations of WSF (p<0.05); with hatching success in the treatments ranging from 24.6 + 1.4 % (at 10 % WSF) to 52.2 + 2.9 % (at 2.5 % WSF). There was an inverse relationship between hatching success and time taken to hatch as delayed hatching occurred in the solutions containing petroleum hydrocarbons. No hatching took place in all treatments containing crude oil + dispersant. FOR FULL ARTICLE: SEND E-MAIL TO ekomrob@yahoo.com
VOL. 2, No. 1 , ARTICLE 9 Water quality status of the Qua-Iboe River Estuary, Nigeria: Baseline studies. by Akpan E. R.
Abstract Water quality parameters, temperature, dissolved oxygen, pH, conductivity, salinity, sulphate, calcium, magnessium, turbidity, total suspended matter, ammonium, nitrite, nitrate, bicarbonate, silicate and total hydrocarbons were determined in the Qua Iboe River Estuary and Creeks from November 1985 to September, 1986. Meteorological parameters such as air temperature and relative humidity were are also collected. Water temperature ranged from 24.6 to 31.8 oC; total hydrocarbons from 1.40 to 10.44 ppm; salinity, from 0.07 to 33.69 ppt; dissolve oxygen from 3.7 to 8.2 mg/l and pH from 6 to 10.29. Observed variations are mainly attributed to tidal and seasonal regimes of salt water intrussion and freshwater discharge. All parameters measured are within ranges considered usual for pristine tropical estuaries. The results therefore represent baseline conditions and will serve for the comparison of future measurements in the system. It will also be of great value in environmental impact studies for projects in the area. FOR FULL ARTICLE: SEND E-MAIL TO ekomrob@yahoo.com
VOL. 2, No. 1 , ARTICLE 10 Performance evaluation of a compact sewage treatment plant in Port Harcourt, Nigeria. by Leton T. G, & Clement C. M.
Abstract Nigeria is a fast growing economy with concomitant increase in urban population which has resulted in increased food/materials consumption and disposal of wastes. Consequently, waste disposal is a major public health concern. Wastes are generally discharged into the environment without adequate treatment. This study was initiated to determine the effectiveness of a sewage treatment plant in Port-Harcourt, Nigeria. The wastewater treatment plant installed capacity is 30 m3/d and serves 20 duplex housing units with boys quarters, an office block, a staff canteen and a club house. It is situated in an oil company residential estate, Rumuogba, Port Harcourt and the effluent is discharged into a system of inter-connected surface drains to the Woji River in Port Harcourt. The parameters used for the study include flowrate, BOD, COD, TS, SS, DS, TP, TN, and NH3, obtained in 2002. In terms of the influent and final effluent quality, the plant is operating within the national effluent guidelines (FEPA, 1995). Total solids (TS), BOD and COD removal rate of 90, 91 and 88 % respectively were recorded, resulting in the final effluent values of 59, 25.3 and 38.2 mg/l; these results are all below the FEPA guidelines levels of 2500, 50 and 100 mg/l respectively. Similarly, although a moderate reduction of 40, 30 and 36 % were recorded for total nitrogen (TN), total phosphorus (TP) and NH3, the final values of 0.3, 6, and 0.38 mg/l are still within acceptable guidelines levels of <5, <10 and <0.5 mg/l respectively. FOR FULL ARTICLE: SEND E-MAIL TO ekomrob@yahoo.com |
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