Bio-Indication of Potentially Toxic Metals Utilizing Barks of Different Species of Tree Plants in Urban Centre of Kazaure, Jigawa State

The food chain of area like Kazuare is bound to be unarguably affected by the entry of large sums of potentially toxic metals, PTMs into the green environment courtesy the activities of the construction companies and vehicular emissions that took over the atmospheric environment of the studied area. These man-made factors uphold upper hand over the natural factors that include topography of the chosen area of study. Selected portion of Kazaure was therefore chosen for the investigation of the PTMs fallouts using the barks of common tree plant species (Cassia acutifolia, Casuarina equisetifolia, Dalbergia nigra Mangifera indica and Terminalia catappa) in the region as bioindicators. The findings unveiled the availability of all the assayed PTMs and the good potential of bioindicating status of all the barks of tree plants so considered. The following trends were revealed by this study; C. acutifolia (Fe > Co > Pb > Zn > Ni > Mn > Cu > Cr); C. equisetifolia (Fe > Mn > Co > Zn > Cr > Ni > Pb > Cu); D. nigra (Fe > Cr > Mn > Pb > Zn > Co > Ni > Cu); M. indica (Fe > Cr > Co > Mn > Pb > Zn > Ni > Cu); T. cattapa (Fe > Co > Mn > Pb > Cr > Zn > Cu > Ni). All the PTMs were significantly bioaccumulated with the exception of Pb in C. equisetifolia and M. indica as statistically deduced by two-way ANOVA. None of the plant species are hyperaccumulator but are good bioindicators and could serve as phytoremediators if the chance arises. There are no significant differences in the levels of PTMs among the topographic positions of the plant species. Land use practices, however, differed significantly indicating anthropogenic interference as a predominant determinant of PTMs enrichment of soil-plant systems. Metal tolerant dominant plants in Kazaure LGA could be classified as metallophytes. Indigenous species, accumulators and excluders, showed prospects for phytoremediation and rehabilitation of metal contaminated areas, respectively. Concentrations of Cr, Ni and Pb in assayed tree plant barks exceeded the international permissible limits, which highlighted the necessity to estimate human health risks for PTMs in disturbed regions.