Pollution

In this study, surface water and sediments were collected from twenty-four (24) different sites in four different locations along the longitudinal transect of the Lower Pra river and evaluated for their quality using several multivariate statistical methods including Principal Component Analysis and pollution index model. Environmental parameters such as heavy metals, water nutrients and physicochemical parameters were determined in the dry and wet periods. The PCA indicated that heavy metals Fe,-Mn,-Ni and-Zn were from predominantly natural sources, whilst Hg,-Cu and-Pb were from anthropogenic sources. Fe-Mn-Zn-Ni had an association with TSS whilst Hg-Se-Pb had an association with TDS.

Heat flow values were obtained from four boreholes located at Agbor, Delta State, Nigeria. The values obtained from the four wells, A, B, C and D was respectively 75, 68, 60 and 56mWm^-2. However, the average value of 64.75mWm^-2 is very close to the estimated value of 65mWm^-2 from the semi-empirical law of heat flow versus lithospheric age. The platinum resistance thermometer and the thermistor were used for the measurement of borehole temperature. From the measured temperature distribution, the temperature gradient was computed. The formation heat flow was obtained by multiplying the gradient by the mean thermal conductivity of the rocks. The interpretation of high and low values of heat flow in wells A and D respectively were explained.  However anomalous high heat flow values have been observed in well A.   The result reveals that a hot plate mobility of heat carrier through some structural boundary and chemical reactions of some organic matters are some specific causes of high heat flow anomaly in the area of the research.

Radon and its progenies are potential health hazards. The levels of radon concentration in homes and workplaces have been found to depend on meteorological and geological conditions, construction materials, and ventilation. The variation of radon concentration with ventilation conditions in ten offices at the campus of Ladoke Akintola University of Technology, Ogbomoso, Nigeria, has been studied in this work.The measurement of Radon-222 concentrations at each of the locations was done using an active electronic radon gas detector (pro series 3, model HS71512). The statistical variation of the five ventilation conditions with Radon-222 was determined at 0.05 level of significance, using analysis of variance. The Radon-222 concentrations for various ventilation conditions ranged from 20.0 to 51.8Bq m-3. The average concentration of indoor radon in the offices was measured to be 37.0 ± 8.39 Bq m-3. Natural mode of ventilation was discovered to be the most efficient way to lower the radon levels which were observed to depend significantly on the ventilation conditions. Despite the significant effect of ventilation on the indoor radon level, the radon concentration values in all the ventilation conditions investigated however were lower than the recommended intervention level of between 200 – 600 Bq m-3.

The maximum ground level air concentration from elevated point source over simple terrain is estimated using previous work by Essa et al. (2007). The eddy diffusivities in linear forms are used. The critical of the wind speed, plume height and downwind distance are estimated. The results of the maximum concentrations are applied using meteorological data of a plant stack located in, Inshas, Egypt.

Oil and grease removal process, through the use of fenton oxidation reaction on an oil polluted wastewater from a vegetable oil plant has been studied. The study was designed to assess the effectiveness of fenton oxidation reaction process in eliminating oil and grease contaminant in the wastewater. The raw wastewater was subjected to analysis through standard methods to determine BOD, Oil and grease, phenol, salinity and sodium batch oxidation process was adopted to remove the oil and grease in which four input parameters ; ph, Fe2+, temperature and hydrogen peroxide(H2O2) were considered. Four runs of experiment were performed where each parameter was varied while the other three remained constant. In each run, oil and grease removal was determined at ten minutes interval for 60 minutes through analysis. The results showed that the highest oil and grease removal efficiencies of 96.28% 98.74%, 99.02 and 93.03%were achieved at the optimum conditions of ph=3, fe2+=3.2 g/l, temp=450C and H2O2=4.5moles respectively and the oil and grease removal was progressive with time until at the point of inflection at 50 minutes where the removal appeared steady. Oil and grease removal efficiency was highly sensitive to the operating conditions. At excess values of the operating conditions, that is, at values beyond the optimum values, the rate of formation of the hydroxyl radical (OH•) became sluggish, impairing removal process. This also explained why the removal efficiency progressed to the plateau at the optimum condition values, and then declined as the values of the operating conditions increased.

The Densu River is a typical river used for drinking water source, flowing through agricultural areas in Southern Ghana. Surface water and sediment samples at 45 sampling sites from the river and its tributaries were collected and analyzed for pesticides residues using GC with ECD/FID. Sampling was over a period of 24 months covering both the wet and dry seasons of 2007 and 2008.  Pesticide residues and metabolites detected in water and sediment samples were organochlorines (dieldrin, DDT, DDE, endosulfan sulphate, ?-endosulfan, ?- HCH, ?- HCH, aldrin, ? - chlordane ,endrin, endrin ketone, endrin aldehyde, methoxychlor and  heptachlor). In an average of 13.69% of sediment and 3.30% of water samples, at least one pesticide residue was detected per sample. A total of 8 different pesticides residues were detected in water samples with concentrations ranging between 0.1µgL^-1 and 48.6µgL^-1 whiles in sediment samples 14 different types were detected with concentrations ranging between 0.10µgL^-1 and 163.00µgL^-1. The maximum levels of residues were found in downstream section of the basin. Aldrin and dieldrin levels detected were above the recommended limit of 0.03 µgL^-1 with endosulfan, endrin and chlordane registering levels above their recommended limits of 20.0µgL^-1, 0.6µgL^-1 and 0.2 µgL^-1 respectively for drinking water. The ratio of DDE/DDT  in environmental matrix were quite high indicating there old input of DDT and significant degradation. The results implicitly revealed that improper land use in the basin has led to poor water quality.

This study assessed the surface water quality of Qua Iboe River system in the coastal Niger Delta, Nigeria. A total of 7 sampling stations were selected for the study and results obtained using FAAS revealed the following mean trace element concentrations (molar): 3.65x10^–7 for Cd, 1.50x10^–7 for Pb, 3.89x10^–7 for Cr, 1.10x10^–6 for Cu, 2.50x10^–6 for Zn, 1.06x10^–6 for Ni and 9.34x10^–7 for Co. The ion association model based on Debye-Hückel theory using the llnl.dat database of the PHREEQCI computer program as well as the thermodynamic data was used for the chemical speciation studies. The distribution of solution species for the trace elements using the PHREEQCI model revealed that the predominant species in the river system was the free ions of Ni²⁺(97.6%), Co²⁺(97.7%), Zn²⁺(92.6%), Cu²⁺(70.2%), Cu⁺(81.2%) and Pb²⁺(62.0%) as well as the hydroxy species, CrOH₂⁺(58.7%) and chloride species, CdCl₂⁺(82.3%). From the model calculations, atacamite, CdCr₂O₇, CuCr₂O₇, PbHPO₄, ternorite and pyromorphite solubility showed positive values of the saturation indices (SI), indicating supersaturation which led to mineral precipitation condition of water.

Four stations were recently investigated at Abraka using Vertical Electrical Sounding (VES) for detailed studies for the analysis of the resistivity response of the earth due to buried cables (wires) in the ground. The cable is characterized by specified axial impedance and is assumed to be infinite in length. A configuration of a current point source in an infinite region was considered. The result shows that the metal conductor or cable channels a major portion of the current flow thereby leading to profound departures from the apparent resistivity curves calculated from idealized homogeneous and layered structures. It was observed that it is not advisable to carry out VES survey in an area where there are metallic conditions or pipes since they channel part of the current flow and distort the potential field distribution.

One of the most important concerns in arid and semi-arid areas of Iran is water erosion and sediment transport. Several experimental models were used for predicting the erosion severity and sediment yield in a sub-catchment area. These models are often developed for different regions than those in which they are applied. Therefore more field data should be gathered for model calibration and, ultimately, a better evaluation of method should be undertaken. However because of insufficient and less reliable sediment yield data in Iran the objective of this study is to evaluate the output results of PSIAC model in five small catchments, Semnan Province, Iran using reliable sediment yield data deposited in reservoir constructed in the outlet of these catchments. Correlation analysis showed that Upland erosion is closely related to Specific Sediment Yield (r2= 0.86). Comparison of the amount of PSIAC predicted and observed reservoir sediment SSY indicate that model was predicted lower than observed values in one catchment (Amrovan) and higher in four other catchments but these differences are not considerable in catchment scale.

The histopathological effects of 2,4- dichlorophenoxyacetic acid (2,4- D) intestine tissues of the Danio rerio were determined by light microscopy. The fish were experimentally exposed to sub-lethal concentrations (0,1 ppm, 0,5 ppm and 1 ppm) of 2,4-D for 5 days. Tissues were normal in the control group. In the intestine tissues of fish exposed to 2,4 dichlorophenoxyacetic acid, oedema, necrosis and atrophy of epithelial cells were observed. The present study proves its toxic potential in terms of the damages induced by 2,4- D in organ level.