Heavy Metal Loading in Agricultural Soils; Contribution of Tobacco Wastes. A Case Study of Morogoro Municipality, Tanzania

The concentration of heavy metals (Cu, Zn, Fe, Mn and Pb) in soil and tobacco wastes from Mwele and Kichangani in Morogoro Municipality were analyzed using X-Ray Fluorescent (XRF) technique. The mean levels in the soil in mg/kg dry mass at Mwele garden were Cu (54.62), Zn (119.37), Fe (49211.93), Mn (989.89) and Pb (14.41), that of Kichangani were Cu (13.39), Zn (15.12), Fe (7657.11), Mn (154.65) and Pb (6.20), that of tobacco wastes piles were Cu (11.30), Zn (27.33), Fe (2272.10), Mn (280.02) and Pb (0.69). The concentrations at the three sites displayed a similar trend, Fe greater thanMn greater than Zn greater thanCu greater thanPb while among the sites levels were in the trend Mwele greater than Kichangani greater thantobacco waste piles. The higher levels of residues at Mwele compared to Kichangani suggested significant contribution from the wastes piles. The higher residue levels at Mwele garden than at the piles suggested the high accumulation over years at Mwele gardens. The levels were within the permissible levels (TBS) but suggesting a long term environmental pollution risk due to continuing piling up of the residues. The study suggested thorough study of the routes of metal cycling on the area and hence carry out environmental impact and risk assessment.