Tissues Accumulation of Heavy Metals by Maize (Zea maize L.) Cultivated on Soil Collected from Selected Dumpsites in Ekiti State, Nigeria

Aims: The study examined the levels of heavy metals in tissues of maize (Zea mays L.), cultivated on four selected dumpsites in Ekiti State, Nigeria; with a view to discouraging constant cultivation of abandoned dumpsites.

Study Design: It is an analytical study.

Place and Duration of Study: The study was carried out in 2012 on selected dumpsites located in Ekiti State, Nigeria.

Methodology: Representative soil samples collected from four dumpsites located in Ekiti State were analyzed for pH, organic matter and heavy metals, prior to plant cultivation. After maturity, heavy metals concentrations were determined in various sections of plant, using flame absorption spectrophotometer. All determinations were carried out in triplicates using standard analytical procedures. The results obtained were subjected to statistical analyses.

Results: The results showed that these dumpsites were grossly polluted with heavy metals when compared with control sites in the range: Cd (21.9-138.0), Co (11.1-60.8), Cr (9.0-29.8), Cu (7.0-18.0), Fe (125.0-752.0), Pb (35.0-60.0), Mn (11.0-47.1), Ni (15.0-29.8), Sn (3.5-9.6) and Zn (63.0-80.2), all in mg/kg. Moderate values of soil pH and organic matter content revealed that maize could thrive well on mentioned dumpsites. However, the plant accumulated elevated concentrations of heavy metals in their shoot, when compared with the root, with Cr and Pb having higher concentration range of 101-104 mg/kg and 109.9-158.2 mg/kg respectively in its shoot at all dumpsites investigated.

Conclusion: Therefore, cultivation of arable crops on dumpsites should be discouraged as constant environmental monitoring is imperative.