Determination of the sources of heavy metals pollution using neem tree (azadirachtaindica) stem barks in Maiduguri, Borno State, Nigeria

Determining the sources of heavy metals pollution in the environment is very important in other to provide solution to the problem. Plants are important indicators of heavy metals in Environmental Pollution. Neem trees is used for shade lining the streets or in most people's back yards in Maiduguri. This study was aimed at determining the concentration (µg/g) of Mn, Ni, Co, Cr, Cd, Cu, Fe, Zn and Pb in barks of Neem tree at various distances away from the main roads of Maiduguri Metropolitan council, Borno State, Nigeria. Samples (stem barks) were collected monthly for three months from three different locations (Bama station, Bulumkutu and Post office areas designated as S1, S2 and S3 respectively) at distances of 50 m and 100 m each from the main roads, and 250 m to serve as control. The samples were collected monthly from the designated and control points for a period of three months. The concentrations of heavy metals in the samples were determined using Perkin-Elmer Analyst 200 Atomic Absorption Spectroscopy (AAS). The results showed that the mean concentrations (μg/g) of the heavy metals in the various locations varied for Zn (0.115±0.007 - 0.719 ± 0.003), Mn (0.234±0.07 - 1.413 ± 0.134), Cu (0.013±0.001 - 0.151 ± 0.003), Co (0.010±0.004 - 0.043 ± 0.013), Fe (1.412±0.028 - 7.681 ± 0.123) and Pb (0.003±0.003 - 0.245 ± 0.147). Analysis of Variance (ANOVA) confirmed significant differences (p<0.05) among the levels of the heavy metals from the three locations. Generally, the concentrations of the heavy metals decrease with increase in distance from 50 m to 100 m and then decrease at 250 m (control) from the main roads at locations S1 and S2. However, the concentrations of the heavy metals increase with increase in distance from 50 m to 100 m and then increase at 250 m (control) from the main roads at locations S3. Hence, the pollution in S1 (bama station area) and S2 (Bulumkutu area) are due to both vehicular traffic and other anthropogenic activities while the pollution in S3 (Post office area) is due vehicular traffic activities. Therefore, the Neem tree bark can be used to determine the sources of heavy metals pollution in Maiduguri