ABSTRACT

Exploration, production, maintenance, transportation, storage, vandalization and accidental discharge oil of crude oil causes contamination of soil and water bodies, thereby altering their physicochemical properties and nutrient cycle. Crude oil contamination ofsoil has also been reported to cause anatomical changes in most plants. This study assessed the phytoremediation potential, growth and anatomy of Axonopus compressus, Eleusine indica and Ipomoea batatas grown on crude oil contaminated soil. The experiment was a factorial arrangement (3x4) in a completely randomized design (CRD). The treatment levels were 0%, 1%, 2%, 3% and 4% crude oil concentration (Volume/ weight) in the soil. The study observed a significant (P<0.05) reduction in plant height, number of leaves, stem girth and fresh and dry weight ofthe three plants grown on the crude oil treated soils (1%, 2%, 3% and 4%). Some anatomical changes were observed in the treated leaf, root and stem samples (l%-4% v/w). Disorder in the arrangement of epidermal cells in the leaves and distortion of cells of roots and leaves were observed. The heavy metals contents ofthe treated soil, roots and leaves were significantly (P<0.05) higher than those of the untreated ones. These effects as observed, increased with increase in level of contamination. Iron was observed to have the highest content in soil at Oweek (7.42mg/kg in 0% and 11.89mg/kg in 4%) while Nickel had the least content (0.03mg/kg in 0% and 0.38 mg/kg in 4%). Cadmium had the highest percentage reduction by the three plants (55% in A. compressus, 65% in E. indica and 60% in I. batatas). The metal contents in the plant parts (leaf and root) differed among the plant species studied. A. compressus had more accumulation of heavy metals on the roots than on the leaves. Whereas the leaves of E. indica was observed to accumulate more heavy metals than its roots. The observed differences in the heavy metal content ofthe soil and plant parts, as well as the observed anatomical changes in plants are suggested as possible tool in phytoremediation and phytomonitoring. The results ofthe study were presented in tables and charts. However, in order to avoid the reintroduction ofthe heavy metals into the soil or plants, caution should be applied in the disposal of experimental soils and plants.