The concentrations of metals (Ca, Cd, Fe, Mn, Pb and Zn) were determined by flame atomic absorption spectrophotometry in water, sediments and fish samples in the Ogun river catchments, Ketu, Lagos, which is an important bird nesting, fishing and drinking water source. The results show that the southern tip bothering the Lagos lagoon is where the highest metal concentrations are found in the fish species (Tilapia sp. and Chrysichthys sp.), whereas the Agboyi creek segment near the lagoon with higher surrounding human population density recorded higher levels of metals in sediments and water samples. The two fish species accumulated different amounts of metals. However, the differences were not statistically different at p < 0.05. There is a significant correlation (p < 0.05) for Cd concentration in water. The concentrations of Pb in sampling points 3 and 4 as well as Cd, Mn and Fe in all six sampling points exceeds the World Health Organization (WHO) limits for drinking water. Levels of metals obtained for sediments are within the range reported for Nigeria's river sediments. Based on this study, the human risks for heavy metals in the harvested fish species from the Ogun river catchments, Ketu, are low for now as the concentrations were below the recommended Food and Agriculture Organization (FAO) maximum limits for Pb (0.5 mg/Kg), Cd (0.5 mg/Kg), and Zn (30 mg/Kg) in fish.

The detection and quantification of four phthalate esters-dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), and diethylhexyl phthalate (DEHP)-in water, sediment, and some fish species were carried out using flame ionization gas chromatography. The samples were collected from the Ogun river catchments, Ketu, Lagos. The DMP was not detected in the water and fish samples but was detected in sediments collected from four of the six sampling sites. The concentration of DEP, DBP, and DEHP in the fish species ranged from 320.0-810.0, 380.0-1,080.0, and 40.0-150.0 μg/kg in Tilapia sp.; 310.0-860.0, 400.0-1,170.0, and 40.0-110.0 μg/kg in Chrysichthys sp.; and 320.0-810.0, 400.0-3,970.0, and 30.0-300.0 μg/kg (DEHP) in Synodontis sp.,respectively. The differences in fish phthalate levels are not statistically significant at p < 0.05, an indication that phthalate esters accumulation is not fish species dependent. The DEP, DBP, and DEHP values recorded are considerably higher than the maximum allowed concentrations for drinking water prescribed by the US Environmental Protection Agency. The phthalate pollution index and biosediment accumulation factor values were also calculated.

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The level of heavy metals in crabs and prawns was investigated using Atomic Absorption Spectrophotometer. The mean concentration of copper in the crab was 1.56±0.87 µg/g; the mean concentration of zinc in the crab was also 0.64±1.96 ܖg/g. Chromium had the highest mean concentration of 8.936±35.4 µg/g while cadmium had the lowest mean of 1.66±1.82 µg/g lead was not detected. The mean concentration of heavy metals in prawn samples were follows: copper: 1.04±0.6 µg/g, cadmium: 0.07±0.08 µg/g, chromium: 4.06±7.00 µg/g and Zn 0.64±0.45 µg/g. Lead was not detected in prawn. The mean concentration of copper, cadmium and zinc in prawn was observed to be within the range NAFDAC standard for water and aquatic foods while crabs have higher mean concentration of heavy metals with the exception of zinc and copper are within the limit.

The industrial activities remain a major source of pollution to environment. The impact assessment of Cement productions on the environmental media: soils, groundwater and tree barks was thus investigated. Forty (40) composite soils, ten (10) groundwater and six (6) tree barks samples were collected around Dangote Cement, Ibese, and West African Portland Cement Company (WAPCO), Sagamu, Nigeria, and were analysed of trace metals following standard procedure. The concentration of Fe, Cr and Pb in top soils (sub soil) around Dangote ranged from 79.5-393 (85.2-830), 7.50-26.0 (12.0-25.0) and 2.5-68.5 (2.50-11.0) (mg/kg) respectively, while values around WAPCO ranged from 75.0-232 (49.6-194), 16.0-31.0 (7.50-28.5) and 18.5-78.5 (7.50-66.5) (mg/kg) respectively. Reduction in metal concentrations with distance from the factories was observed. The order of trace metals in tree bark samples was Fe > Pd > Ni > Cd > Cr > Co. Although, the levels of metals observed are within the normal range found in soil, measures to avoid build-up of trace metals must be in place, to ensure a sustainable environment.

Environmental quality deterioration resulting from increase in the level of potentially toxic metals is becoming more pronounced, thus raising the question on safety status of our environment. Impact assessment and characterization of trace metals in the environmental media including groundwater, top soils, and tree barks in the vicinities of West African Portland Cement Company factory mill, Ewekoro, Ogun State, Nigeria was undertaken. The environmental samples were analysed for trace metals employing flame atomic absorption spectrometry (FAAS). The concentration of Cu, Cd and Fe detected in the groundwater ranged between 0.026 -0.082, 0.0038 -0.004 and 0.003-0.035 (mg/L) respectively. A decrease order in the level of metals level observed in the top soil is Fe > Pb >Ni > Cr > Cu > Cd, while that of tree barks samples is Fe > Cu > Cr > Pb > Ni > Cd. The saturated index (SI) obtained (through phreqC model) of the groundwater samples showed saturated to undersaturated with respect to CdSO 4 and FeSO 4 :7H 2 O, while SI was saturated to supersaturate with respect to CdCO 3 and FeCO 3 . Quality indices employed in analyzing soil data include enrichment factor, contamination factor and pollution load index. There is a buildup of trace metals in the environment (soil) particularly Pb. The levels of metals investigated are within the threshold limit set by the WHO health-based guideline for drinking water. Significant correlations were found to exist between Cd and Ni, Cr and Fe both in the tree bark and top soil samples, suggesting common source.