Assessment of Heavy Metal Pollution Levels in Soils of Keffi, Landfill and Solid Waste Dumpsite and Its Ecological Risk

This study was carried out to quantitatively assess the heavy metal pollution level of soils collected from different landfill and solid waste dumpsite in keffi metropolis of Nasarawa State, Nigeria. Soil samples were collected from different landfill and dumpsites in Keffi metropolis at the depth of 0-30 cm. A total of 5 random samples per location and composited to obtain a laboratory sample. The collected soil sample were allowed to dry under normal temperature within soil sample preparation room of Department of Agronomy Nasarawa State University Shabu Lafia Campus. The analysis for heavy metal was conducted using Atomic Absorption Spectrometer (AAS). The levels of concentration these metals varied across soil among sampling point. The mean order of heavy metal concentration in Keffi is Zn>Fe>Mn>Pb>Al>Cu>Se>Ni>As>Hg respectively. The pollution indices such as Contamination factor (CF), Pollution load index (PLI), Contamination degree (Cd), Potential contamination index (Cp) and potential ecological risk index (RI) were used for the metal enrichment and contamination status was also calculated. The CF, Cd, Cp, PLI and RI values of the studied metals indicated that the study area does not posed risk to local environments. The concentration of heavy metal indicated that the study area does not posed high risk to local community but the odour from the land fill and dumping site pollute the air which causes respiratory problems. Hence, this open landfill should be closed from use in future and or properly managed by recycling in order to minimize future pollution problems. The mean order of heavy metal concentration in plant samples is Fe>Zn>Mn>AL>Pb>Cu>Cr>Ni >As>Hg respectively. The heavy metal (Fe and Zn) contents in the plants were higher compared to other metals analysed. The concentration of some metal was relatively high in the maize plant, but there were all below the WHO permissible limit except for Zn metal. The transfer factor (Tf) revealed that plants grown on dumpsite and landfill soils absorbed and accumulates heavy metals. The highest transfer factor value was obtained in Fe, followed by Cu, Pb, Zn, Al, Mn, Ni and As respectively.