ASSESSMENT OF HEAVY METALS IN CHROMOLAENA ODORATA (L.) AROUND A DUMPSITE IN IBADAN, SOUTH WESTERN NIGERIA

Abstract

Heavy metal contamination has become a critical environmental concern and poses a serious threat to the environment leading to hazardous health effect as they enter food chain. One of the main processes of human exposure to heavy metal through the food chain is transfer of nutrients from the soil to the plants. This study assessed heavy metal concentrations in Chromolaena odorata and the soils around Lapite dumpsite in Ibadan. Five C. Odorata samples (root, stem, leaf) each were taken from control, contaminated and waste dump sites considered in this study. Composite soil samples were collected from the topsoil (0-20m) around each of the
site. Inductively Coupled Plasma- Atomic Emission Spectrometry (ICP-AES) instrumentation technique was used to determine the heavy metals (iron (Fe), zinc (Zn), lead (Pb), copper (Cu), nickel (Ni), cadmium (Cd), chromium (Cr), cobalt (Co) and Arsenic (AS) in soil samples and C. odorata tissues. These results showed that C. odorata and soil samples had significantly high levels of heavy metals in waste dump and contaminated sites than control site. Heavy metal concentrations in C. odorata and soil samples showed decreasing order of
Fe> Zn> Cu> Pb> Ni> Co> Cr>Cd>As. The ability of C. Odorata to accumulate the metals was consistent with the high translocation ratio values of more than 1 and the low transfer factor values of less than 1.Heavy metals in soils showed positive correlation coefficient of 0.46-0.99 with the levels in C. Odorata plants. This study has shown the ability of C. Odorata plant to bio-accumulate translocate heavy metals.