Three green leafy vegetable samples of pumpkin leaves, spinach leaves, and sorrel leaves were collected from a farm in Akwanga and were tested for the presence of residues of organochlorine pesticides. The concentrations of all the pesticide residues in the vegetable samples were determined using GC/MS. Among the organochlorine pesticide p,p'-DDT was detected in pumpkin (0.75 mg/kg), spinach (0.319 mg/kg) and sorrel (0.219 mg/kg). ∂-BHC and ɣ-BHC were detected only in pumpkin leaves (0.359 mg/kg and 0.647 mg/kg respectively). Dieldrin was detected in spinach and sorrel (0.124 mg/kg and 0.053 mg/kg respectively). Endrin was detected in pumpkin (0.732 mg/kg) and Aldrin in sorrel (0.095 mg/kg). All these values were above the maximum residue limit (MRL) value of the pesticides. Endosulfan II was detected in sorrel (0.306 mg/kg) below the MRL. The levels of most of the pesticide residues found in vegetables were above the maximum residue limits (MRLs) that call for laws to regulate the use and circulation of such chemicals. Routine monitoring of pesticide residues in this study area is necessary for the prevention, control and reduction of environmental pollution, to minimize health risks.

Heavy metal species of water and bottom sediment samples from River Wujam in Chip district of Pankshin L.G.A. were investigated in the dry and wet seasons. The analysis was done using standard procedures. The results for the total metal concentration of the water samples ranges, thus, 0.02-0.03 mg/L for copper, 0.01-0.11 mg/L for lead, 0.02-0.07 mg/L for manganese, 0.01-0.06 mg/L for cadmium. But nickel and zinc were not detected within the limits used. The total metal concentration of metals analysed (Cu, Pb, Mn, Cd, Zn, and Ni) in the sediments revealed a generally higher concentration in the dry season except for cadmium which revealed a higher concentration in the wet season. Speciation of the metals was also carried out on the sediments using Tessier method to determine their distribution in the sediment of the river. The percentage ranges of the fractions for the dry season are, 12.24-46.09%, 15.80-24.01%, 11.47-21.91%, 10.83-22.80%, and 7.61-75.00% for exchangeable, carbonate, Fe-Mn oxide, organic, and residual fractions respectively. Ni was not detected within the limits used in the carbonate, Fe-Mn oxide and organic fractions. The range of fractions for the wet season are, 4.25-33.77%, 10.82-24.21%, 15.91-38.35%, 10.65-51.06%, and 19.01-26.77% for exchangeable, carbonate, Fe-Mn oxide, organic, and residual fractions respectively. Ni was not detected within the limits used in the carbonate and organic fractions. With change in the environmental conditions Cadmium and lead bound to such labile phases in both the dry and wet season, can easily remobilize in the water system. A moderate positive correlation existed in the total metal concentration of water samples between dry and wet seasons. A strong positive correlation existed in the total metal concentration in the sediments samples between dry and wet seasons. T-test results indicated that there is no significant variation in the concentrations between the seasons in both cases.

Soil from the vicinity of transformers installation in different locations in Jos, Plateau State was investigated for Polychlorinated Biphenyls (PCBs). The assessment was carried out for both total PCBs and congeners using Agilent 6975 GC-MS in ten different locations. The soil samples were extracted with 1:1 hexane- acetone in an ultrasonic bath, concentrated and cleaned with column chromatography using silica gel and hexane as eluting solvent. The result shows five locations were polluted with PCBs that exceed the maximum limit of 2.0mg/kg as permitted by the United States Toxic Substance Control Act (TSCA) with the following values NGS 1 (14.25), NGS 3 (4.47), NGS 6 (9.48), NGS 9 (8.21) and NGS 10 (5.05) while the others have NGS 2 (0.64), NGS 4 (1.85), NGS 5 (0.83), NGS 7 (0.95) in mg/kg respectively, NGS 8 value was below the instrument detection limit (0.0012mg/kg). The order for the total PCBs concentration in these selected locations are NGS 1 > NGS 6 > NGS 9 > NGS 10 > NGS 3 > NGS 4 > NGS 7 > NGS 5 > NGS 2. The carcinogenicity of the dioxin-like PCBs calculated as total toxicity equivalence concentration (TTEC) in these selected locations corresponds to NGS 1 (0.00001), NGS 2 (0.0000051), NGS 3 (0.0000054), NGS 4 (0.0000051), NGS 6 (0.0000063), NGS 7 (0.0000078), NGS 9 (0.0000051) and NGS 10 (0.0000051) respectively. The total cancer risk computed by addition of cancer risk due to ingestion, inhalation and dermal contact revealed that all the locations have very low to low cancer risk compared with the value recommended by the United State.

Water sample were collected from river Benue in five different locations: River MU (A), UAM water works (B), Coca-Cola/Brewery (C), River Agaba (D) and Wildlife Zoo (E). All the five sampling stations are located upstream of the river within Makurdi town. Six heavy metals: Pb, Zn, Mn, Fe, Cu, and Cd were analysed by Atomic Absorption Spectrometry (AAS). The concentration of Zn, Mn and Cu fall within the acceptable limit while that of Fe, Cd and Pb were found to be higher than the maximum accepted limit. The order was Fe>Pb>Cd, with Fe been highest in Coca-Cola Pb and Cd were highest in UAM water work.

Three green leafy vegetable samples of pumpkin leaves, spinach leaves, and sorrel leaves were collected from three different locations in a farm in Akwanga and were tested for the presence of organophosphorus (OP) compounds. The concentrations of all the pesticide residues in the vegetable samples were determined using gas chromatography with mass spectrometry (GC-MS). The organophosphorus pesticides detected include carbaryl (0.052 mg/kg) in pumpkin, this is below European maximum residues limit (EU MRL) of 0.1 mg/kg, Dimethoate was found in pumpkin (0.165 mg/kg), spinach (0.103 mg/kg) and sorrel (0.250 mg/kg) all above the EU MRL of 0.05 mg/kg. Dichlofenthion was detected in pumpkin (0.308 mg/kg), pirimiphos methyl was detected in pumpkin and spinach (0.428 mg/kg and 0.149 mg/kg respectively), all these were below the EU MRL of 0.5 mg/kg. Chlorpyrifos was found in spinach (0.230 mg/kg) and sorrel (0.192 mg/kg) only spinach was above the EU MRL of 0.2 mg/kg. The pesticide residue Bromophosethyl was detected in all vegetables, pumpkin leaves (0.501 mg/kg), sorrel (1.571 mg/kg) and spinach (7.981 mg/kg) all above the EU MRL of 0.5 mg/kg. The remaining pesticides detected were all below their EU MRL value; these are Ethion found in spinach (0.167 mg/kg), Methyl Parathion in spinach (0.103 mg/kg) and sorrel (0.335 mg/kg). The levels of some of the organophosphorus pesticide residues found in vegetables were above the maximum residue limits (MRLs) set by the European Union. This calls for laws to regulate the use and circulation of such chemicals. Based on the observation made in these studies,