Determination of heavy metals in neem tree (Azadirachta indica) stem bark along some major roads in maiduguri metropolis, nigeria

Neem tree samples (Azadirachta indica) were collected from Maiduguri metropolis, Borno State, Nigeria for the determination of trace elements. The concentrations of metals were observed lowest from the control sites. Concentrations of Pb, Zn, Mn and Fe were found to be highest from samples obtained at the Borno express motor park; Cr and Cd highest at West end junction; Ni highest at University gate while Polo road showed the lowest concentrations of all the metals. This deviation could be due to the volumeof vehicular movement in the afore-mentioned sampling points. However, the levels of the metals in the samples exceeded the World Health Organisation standard limits for medicinal plants. The traffic situation in the area of study might be regarded as a source of the variation in the metal concentration between the control sites and the four sampling points.