Comparative Assessment of Heavy Metals Loads in the Shoot of Selected Tree Plants and their Accumulation Potential in Kazaure, Jigawa Nigeria

The environment is often beautified by the presence of tree plants which consist of the shoot and the root. These plants contain organs often referred to as above ground organs (shoot) and below ground organ (root). In this study, the plant organs of five different plants including Adansoniadigitata, Anacardiumoccidentale, Azadirachtaindica, Eucalyptus globulus, and Parkiabiglobosa were sampled to investigate the levels of cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb) and zinc (Zn). The sampled parts were transported in polythene bags to the laboratory where they were sorted, pretreated, stored and digestedwith10 cm3 of 6M nitric acid. The digested samples were subjected to analysis using atomic absorption spectrophotometry to determine the heavy metals (HMs). The results revealed that all the above ground organs of these plants accumulated HMs at varying levels. The leaf samples of the all tree plants accumulated higher concentrations of the HMs than the bark samples except in P. big lobosa (7.07 ± 0.42 mg/Kg, Co [leaf]; 14.10 ± 0.62 mg/Kg, Co [bark]). The results revealed that the leaves portion contained more of the essential heavy metals (EHMs) than the bark samples of the tree plants. A. indica has the highest bio-indication potential while E. globulus exhibited the least potential based on the above ground organs analysis. The translocation factors of the NHMs (Cr and Pb) were below unity. The translocation factors well above unity suggest better phytoextraction capability of the tree plants. All the plants potentially accumulated the metals at varying levels irrespective of the different geographical locations, morphological and biomass variations of the tree plants.