Abstract

Soil, vegetation and atmospheric pollution have been a serious problem in recent years in Lafia, especially among the communities living along the major highways due to increase in industrialization and vehicular movements. The level of heavy metals (Cd, Cr, Ni, Pb and Zn) in Neem tree leaves, bark and soil along major roads in Lafia were determined using digestion and atomic absorption spectrophotometer methods. The leaves, trunk bark and soil samples were collected along Makurdi road (Tudun Kauri), Jos road (National Supply), Nasarawa state polytechnic site and Obi road (Maraba Akunza). The aim was to assess the level of the metals in the samples. The mean concentration of metals in the various locations along roads varied between Pb (0.028 to 0.570 mg/kg), Zn (0.061 to 1.326 mg/kg), Ni (0.028 to 0.261 mg/kg), Cr (0.013 to 0.201 mg/kg). Samples from Makurdi road (Tudun Kauri) indicated higher level of Zn, while sample from Jos road indicated the highest level of Pb. Levels of Cr and Ni in the various locations were obtained in minute quantities and were largely undetected in most of the samples. However, levels of all the metals obtained from the various locations along the major roads were below the WHO/FDA maximum permissible levels of heavy metals in plants. The Neem plant (Azadirachta indica) could be a good bioindicator of Pb and Zn.

Key words: Heavy metal, neam leaves, bark, soil, digestion, atomic absorption spectrophotometer.