摘要
This study investigated the accumulation of heavy metals in the above-ground vegetation and soil around an iron smelting factory located at the Fashina Area, Ile-Ife, Osun State, southwestern Nigeria. This was with a view to establish baseline data which can be used for assessing the impact of the steel processing industry in the area. Samples of the two most common herbaceous species （Chromolaena odorata and Aspilia africana） around the factory were randomly collected at 10 m away from the wall of the factory, and soil samples were randomly collected at 0-15 cm depths in the same area. The plant species were oven-dried, put through a mixed acid digestion procedure, and, along with soil samples, were analyzed for N, P, K, C, Zn, Pb, Cd, Ni, and Cr using an atomic absorption spectrophotometer. The data obtained were subjected to appropriate descriptive and inferential statistical analyses. The results revealed that the soils were slightly acidic, with pH values of 6.23±0.24 in the dry season and 6.10±0.16 in the rainy season. There was a significant difference （P 〈0.05） in the percentage content of total N, total P, K, and organic matter values in the soil samples collected in the two seasons. The Cd, Pb, and Cr contents in the soil samples from the rainy season were significantly higher （P 〈0.05） than those of the dry season. The analyzed plant species showed a progressive decrease in the concentration of the elements tested, with percentage content of C 〉 P 〉 N in both Aspilia africana and Chromolaena odorata. In the dry season, C percentage concentration was higher in Aspilia africana, while the other elements followed the trend observed in the rainy season. The concentration of Zn was higher in Aspilia af- ricana in both the polluted site and the control site in the rainy season, while the concentrations of the other heavy metals were higher in Chromolaena odorata in the dry season. This study revealed that the heavy metal concentration varied with the plant species and also with the prevailing seasonal conditions. Also, the accumulation and concentration of heavy metals in both plant species and in the soil indicated a potential hazard of the factory to the local environment.
This study investigated the accumulation of heavy metals in the above-ground vegetation and soil around an iron smelting factory located at the Fashina Area, Ile-Ife, Osun State, southwestern Nigeria. This was with a view to establish baseline data which can be used for assessing the impact of the steel processing industry in the area. Samples of the two most common herbaceous species （Chromolaena odorata and Aspilia africana） around the factory were randomly collected at 10 m away from the wall of the factory, and soil samples were randomly collected at 0-15 cm depths in the same area. The plant species were oven-dried, put through a mixed acid digestion procedure, and, along with soil samples, were analyzed for N, P, K, C, Zn, Pb, Cd, Ni, and Cr using an atomic absorption spectrophotometer. The data obtained were subjected to appropriate descriptive and inferential statistical analyses. The results revealed that the soils were slightly acidic, with pH values of 6.23±0.24 in the dry season and 6.10±0.16 in the rainy season. There was a significant difference （P 〈0.05） in the percentage content of total N, total P, K, and organic matter values in the soil samples collected in the two seasons. The Cd, Pb, and Cr contents in the soil samples from the rainy season were significantly higher （P 〈0.05） than those of the dry season. The analyzed plant species showed a progressive decrease in the concentration of the elements tested, with percentage content of C 〉 P 〉 N in both Aspilia africana and Chromolaena odorata. In the dry season, C percentage concentration was higher in Aspilia africana, while the other elements followed the trend observed in the rainy season. The concentration of Zn was higher in Aspilia af- ricana in both the polluted site and the control site in the rainy season, while the concentrations of the other heavy metals were higher in Chromolaena odorata in the dry season. This study revealed that the heavy metal concentration varied with the plant species and also with the prevailing seasonal conditions. Also, the accumulation and concentration of heavy metals in both plant species and in the soil indicated a potential hazard of the factory to the local environment.
