No abstract

The study focused on development of mathematical modeling and numerical simulation technique for selected heavy metal transport in Uyo municipal solid waste dumpsite in Akwa Ibom State to investigate the level in depth to which leachate from the dumpsite extends and the quantity of leachate at various depth of the dumpsite soil. Uyo waste dumpsite is operating open dumping system where provisions are not made for preservation and conservation of soil and water quality, hence, the need for this study. Three monitoring pits within Uyo waste dumpsite were constructed and infiltration runs were measured, and soil samples were collected beside infiltration points from nine designated depths ranging from 0 to 0.9 m for modeling heavy metal transport in the soil. Data collected were subjected to descriptive and inferential statistics while the COMSOL Multiphysics software 6.0 was used to simulate the movement of pollutants in the soil. It was observed that heavy metal contaminant transport in soil of the study area is in the power functional form. The transport of heavy metals in the dumpsite can be described by a power model from linear regression and a numerical model based on finite element. Their validation equations showed that the predicted and the observed concentrations yielded a very high R2 value of over 95%. The power model and the COMSOL finite element model show very strong correlation for all selected heavy metals. Findings from the study has identified level in depth to which leachate from the dumpsite extends and the quantity of leachate at various depth of the dumpsite soil which can be accurately predicted using leachate transport model of this study.

Land degradation is a major challenge to agriculture in Nigeria. Soil conservation practices have been put in place to reclaim degraded landscapes. The effectiveness of these measures in improving soil properties have not been really studied in Nigeria, particularly in Uyo, Akwa Ibom State. This research assessed the effect of soil and water conservation structures (Gabions and Mattresses) in Ikot Akpan ravine on selected soil properties. A total of 12 soil samples were collected from the conserved (plots treated with gabions and mattresses) and non-conserved (plots with no treatment). Soil tests to determine soil properties were done. A one-way analysis of variance (ANOVA) statistics using a general linear model at a=0.05 was used to show significant difference exists between the two landscapes. The results showed that sand (80.84 ± 1.26%, 81.07 ± 1.90%), silt (13.70 ±3.30%, 11.41 ± 2.53%), and pH (6.51 ± 0.26) were positively affected by the conservation structure. However, bulk density (2.33± 0.27g/cc, 2.38 ± 0.16g/cc) and electrical conductivity (00.12 ± 0.02ds/m) were negatively impacted by the conservation structure. Other soil properties such as clay (7.71 ±2.54%, 7.79 ± 1.02%), available phosphorus (30.12 ±4.55mg/kg, 44.81 ± 9.28mg/kg), total nitrogen (0.05 ±0.01%, 0.05±0.02), moisture content (5.48 ±0.96%, 5.68 ± 0.85%), organic carbon (1.97 ± 0.04%, 1.95 ± 0.11%), effective cation exchange capacity (ECEC) (13.85±4.30 cmol/kg, 15.76 ± 2.06 cmol/kg) and exchangeable bases were not affected by the conservation practice. The conservation structure was very effective in controlling soil erosion and reducing soil loss. Soil conservation practices should be encouraged.