Three Dimensional Velocity Distribution Modelling of Nun River in Nigeria | Chapter 04 | Emerging Issues in Science and Technology Vol. 2

In this study, hydrodynamics and sediment concentration equations of partial differential in 3-dimensions were solved using finite difference methods, the Crank Nicolson procedure to predict both sediment concentration and velocity profile of Nun River. The computer software (EKU2.8) which is a modification of the Navier Stoke’s equations was employed for discretization of Nun River stretch of 2,000 m into 2,245 rectangular meshes and simulation of the river’s flow velocity distribution. The code was validated by using the field water current measurements obtained from a selected stretch of the river. Average predicted velocities of 0.85 m/s, 1.542 m/s and 0m/s compared favorably with 0.8m/s, 1.475 m/s and 0.09m/s obtained from field measurement for upstream, midstream and downstream boundaries. The predicted results have approximate correlation coefficients of 0.96 for velocity distribution using Pearson product-moment method. The model proved very useful in predicting the velocity distribution of Nun River; higher versus lower velocities at inner and outer bends, with resultant effect of erosion and sediment deposition accordingly. The result of this study may be considered an important contribution to the improvement of sediment and erosion risk management.

Author(s) Details

Desmond U. Nwoko
Centre for Occupational Health, Safety and Environment, University of Port Harcourt, Nigeria.

Ify L. Nwaogazie
Department of Civil and Environmental Engineering, University of Port Harcourt, Nigeria.

Charles C. Dike
Centre for Occupational Health, Safety and Environment, University of Port Harcourt, Nigeria.

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Speciation of Some Heavy Metals in Sediments of the Pennington River, Bayelsa State, Nigeria | Chapter 8 | Theory and Applications of Chemistry Vol. 2

Speciation helps in the identifications and quantification of the defined geochemical fractions, forms or phases  in  which  an  element  exists  in  the  environment.  Speciation  in  sediment  compartment  is  a significant step to understand the potential environmental risk, distribution, mobility and bioavailability of pollutants. The total heavy metal concentrations of some environmentally toxic metals in sediments of the Pennington River System, Bayelsa state, Nigeria was examined. The concentrations of heavy metals  in  each  fraction  were  determined  using  a  ANALYST  400  Perkin-Elmer  AAS.  The  mean concentrations  (mg/kg)  for  the  six  metals  in  dry  season  sediment  samples  were:  0.14±0.17(As), 0.39±0.55(Co), 2.43±5.06(Cu), 26.82±22.19(Fe), 0.69±1.10(Pb), and 1.22±1.19(Zn), while the mean metal   concentrations   (mg/kg)   in   wet   season   samples   were:0.11±0.18(As),0.37±0.6(Co), 2.07±4.35(Cu),  26.65±24.79(Fe),  0.61±1.08(Pb),  and  1.11±1.00(Zn)  respectively.  Speciation  study applying  the  five-stage  sequential  extraction  scheme  revealed  that  As,  Co,  and  Pb  in  sediment prevails mostly in exchangeable fraction. Cu and Zn were more prevalent in residual fraction, while Fe was found more in residual and Fe/Mn-Oxide fractions. In an attempt to infer anthropogenic input from natural input, comparison with sediment quality guideline (SQGs) and ecotoxicological sense of heavy metal  contamination  was  employed.  The  concentration  of  the  studied  heavy  metals  in  Pennington River  System  does  not pose  a  threat  to  the  sediment  dwelling  fauna  and  anyone  who  consumes aquatic animals, particularly fish, from the Pennington River. According to SQGs, the studied heavy metals of the Pennington River sediments were under the category of non-polluted. Speciation is a powerful and versatile technique for predicting the degree of contamination risk of a river system. In this  present  study,  all  heavy  metals  investigated  are  relatively  stable  under  normal  conditions  of Pennington River system. This means that there is a low source of pollution arriving to the Pennington River  system.  Iron  was  found  to  be  the  highest  occurring  heavy  metal  and  arsenic  was  the  least occurring  heavy  metal in  this  study.  Furthermore,  there  is  no heavy  metal pollution threat pose  to sediments  dwelling  fauna  and  anyone  who  consume  aquatic  animals,  particularly  fish  from  the Pennington River system.  To preserve the unpolluted state of the Pennington River system it remains important that allochthonous inputs are devoid of heavy metals.

Author(s) Details

Kaywood E. Leizou, Ph. D
Department of Chemical Sciences, Niger Delta University, Wilberforce Island, Nigeria.

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