This study investigated the chemical speciation of Cd, Cr, Cu, Ni and Pb and their contamination/ pollution indices in the sediment of River Ala in Akure, Nigeria. Sediment samples taken along the course of the river were subjected to Sequential Extraction Technique and the heavy metals were quantified using atomic absorption spectrophotometer. Varied distribution of metals among the chemical fractions was recorded, with contribution from both anthropogenic and geogenic sources to the total heavy metals concentration in the sediment. Pollution/contamination index evaluation showed that the sediment fall within the "very slight and "moderate contamination" range with respect to Cr, Cu, Ni and Pb and in the moderate pollution range with Cd.

Ondo State being the highest producer of Cocoa in Nigeria constitutes the most probable area with the highest use of chemical pesticides to enhance cocoa production. As effective as these chemicals may be in achieving this goal, the incidence of their residues on non-targeted substances and the total environment, with the attendant adverse effects have being of serious concerns. Our objective in this paper is to assess contamination of farm soils by organochlorine pesticides applied on cocoa farms within the Central Senatorial District of Ondo State, Nigeria. Soil samples were collected from selected cocoa farms and analysed for organochlorine pesticides residues using GC-MS. Some soil physicochemical properties including pH, particle size and organic matter that may influence the dynamics of the pollutants were also determined. Organochlorine compounds detected at varied concentrations include Endosulfan I and Endosulfan II occurring most frequently with highest concentrations of 350.10 mg/kg and 3.55 mg/kg respectively. Other organochlorine compounds detected were Heptachlor, Heptachlor epoxide, Aldrin, Deldrin,, isomers of Benzene hexachloride: α-BHC, β-BHC, δ-BHC, and Ƴ-BHC (lindane). The concentrations of the organochlorine pesticides (mg/kg) measured in the soil samples showed significant (p<0.05) correlation with the total organic matter contents of the soil. Findings from this research thus, provide information on the current and health risk residue levels of organochlorine pesticides in soil from this region with which future environmental performance on the use of pesticides on cocoa farms could be progressively monitored.

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Composite water samples taken from Owena Multi-purpose Dam in six sampling campaigns covering the wet and dry seasons were analyzed for physico-chemical and microbial characteristics using standard methods for the examination of water and wastewater jointly published by the American Public Health Association, American Water Works Association and Water Pollution Control Federation. Results showed significant (p < 0.05) seasonal variations in most measured parameters with few showing significant spatial variation. The characteristics of the water from the dam lake revealed an acceptable quality for most measured parameters with low chemical pollutants burden when compared with drinking water standards and water quality for aquaculture. However, high values of turbidity, colour, iron, manganese and microbial load were recorded compared with drinking water standards, which call for proper treatment of the water before distribution for public consumption

Indiscriminate disposal of solid waste in unauthorized places has become an increasing problem for most cities in Nigeria, especially Benin-City, Edo state. Benin-City one of the largest city in Nigerian is experiencing the problem of solid waste management despite the best attempt of waste avoidance, reduction, reuse and recovery. Use of dumpsites is still the ultimate disposal method of domestic and industrial wastes in Benin-City. Three dumpsites in Benin-City and environs were selected randomly to evaluate their leachates characteristics. Leachate samples were collected from the dumpsites at three months interval and were assessed for their quality through physico-chemical and elemental examination using standard methods for examination of water and wastewater. Physicochemical analysis result showed pH range of 6.76±0.08-7.49±0.

We report on the speciation study of five toxic metals in the floodplain alluvial soils of Onukun river of Okitipupa, Ondo State, Nigeria. The bulk metal concentrations in the soil samples were in the order: Fe > Cr > Zn > Cu > Pb > Cd. Speciation analysis via sequential extraction was used to fractionate the metals into five operationally defined pools: exchangeable, carbonate, easily reducible, organic, and residual fractions. Generally, the organic, residual, and reducible fractions were the most abundant pools for Cu, Cr and Fe, Pb and Zn, respectively, whereas Cd was undetected. The soils were loamy sand, with pH and organic matter content ranging from 4.71% to 7.00% and 1.92% to– 4.62%, respectively. Furthermore, three pollution indices viz. geoaccumulation index, enrichment factor, and mobility/bioavailability evinced the trends: Fe > Cr > Zn > Cu > Pb, Cr > Zn > Cu > Fe > Pb, and Zn > Pb > Cu > Fe > Cr, respectively, with the pollution load index highest of 0.39. Conclusively, the floodplains’ soils are considered contaminated with the target toxic metals, necessitating their periodic monitoring and remediation.