G. E. OGBEIDE

This study was carried out to determine the concentrations of some heavy metals, such as nickel, cadmium, mercury, and oxidative stress status of tomatoes sold in local markets in Benin City, Edo State, Nigeria. Fresh tomato samples were brought from Uselu and Ikpoba Hill market in Benin City. The samples were oven-dried at 105°C for 24 hours and grinded to powder. The powdered samples were dissolved in deionized water, filtered through Whatman filter paper, and the volume was made up to 25 ml using 10 ml of 98% nitric acid. The resulting solution was analysed for the presence of heavy metals using an Atomic Absorption Spectrophotometer
(AAS, Perkin Elmer model 2130). The results showed that the nickel concentration present fresh tomato samples obtained from the two markets ranged from 0.13 mg/kg to 0.16 mg/kg, while
the cadmium concentration ranged from 0.11 mg/kg to 0.13 mg/kg. However, when compared to
W.H.O standard, the heavy metal concentration was slightly above the recommended value of
0.10 mg/kg. Also, oxidative stress analysis showed that the superoxide dismutase (SOD) value
ranged from 3.02 U/g to 3.48 U/g, Catalase (CAT) value ranged from 0.08 U/g to 0.10 U/g, the glutathione peroxidase (GPx) value ranged from 4.96 U/g to 5.73 U/g, while the malondialdehyde (MDA) value ranged from 0.50 U/g to 0.64 U/g respectively. These findings were indicative of environmental pollution due to industrial and vehicular emissions and also the mode of handing and processing of the samples. Although the heavy metals detected in this study are not beneficial to man and plant, low concentration can prove detrimental to health.

This study was carried out to determine the concentrations of some heavy metals such as nickel, cadmium, mercury and oxidative stress status of tomatoes sold in local markets in Benin City, Edo State, Nigeria. Fresh tomatoes samples were brought from Uselu and Ikpoba hill market in Benin City. The samples were oven-dried at 105°C for 24 hour and grinded to powder. The powdered samples were dissolved in deionized water, filter through whatman filter paper and the volume was made up to 25 ml using 10 ml of 98% nitric acid. The resulting solution was analysed for the presences of heavy metal using using Atomic Absorption Spectrophotometer (AAS, Perkin Elmer model 2130). The results showed that the nickel concentration present fresh tomatoes samples obtained from the two markets ranged from 0.13 mg/kg to 0.16 mg/kg, while the cadmium concentration ranged from 0.11 mg/kg to 0.13 mg/kg. However when compared to W.H.O standard the heavy metal concentration were slightly above the recommended value of 0.10 mg/kg. Also oxidative stress analysis showed that the superoxide dismutase (SOD) value ranged from 3.02 U/g to 3.48 U/g, Catalase (CAT) value ranged from 0.08 U/g to 0.10 U/g , Glutathione peroxidase (GPx) value ranged from 4.96 U/g to 5.73 U/g, while Malondialdehyde (MDA) value ranged from 0.50 U/g to 0.64 U/g respectively. These findings were indicative of environmental pollution due to industrial and vehicular emissions and also the mode of handing and processing of the samples. Although the heavy metals detected in this study are not beneficial to man and plant, low concentration can prove detrimental to health.

Environmental pollution from heavy metals in mechanic workshop soils poses serious threat to soil fertility, microbial health and groundwater quality. This study evaluated the bioremediation potential of phosphate solubilizing bacteria (Pseudomonas sp.) and hydroxyapatite in reducing heavy metal concentrations in contaminated soil. The study was carried out in a mechanic workshop in Osasogie, Ugbowo, Benin city, Edo state, Nigeria with four treatments: soil only (O1), soil + phosphate solubilizing bacteria (O2), soil + hydroxyapatite (O3) and soil + phosphate solubilizing bacteria + hydroxyapatite (O4). Microbial count and heavy metal concentrations (iron, copper and arsenic) were tested after 14 days. According to results hydroxyapatite was most effective in increasing the growth of Pseudomonas sp. and in the remediation of soil contaminated with copper and iron while phosphate solubilizing bacteria was the least effective due to the short period of remediation. In conclusion, Pseudomonas sp. and hydroxyapatite showed great promise in cleaning up heavy metal contaminated soil from a mechanic workshop.