Assessment of Levels and Safe Factor Index of Heavy Metals in Soils Around Diobu, Port Harcourt, Nigeria

This study was aimed at determining the variations of some heavy metals in soil sample between Mile 3 (M3) and Mile 4 (M4), all in Diobu, which are both primarily business and residential areas when compared to the control represented by the Rivers State University (RSU), Port Harcourt. The Azuka Index (Ai) was used to determine the Safety Factor Index. The levels and distribution of seven heavy metals (Fe, Pb, Cu, Cd, Cr, Ni, As) in soil (0–25 cm depth) from the area using Atomic Absorption Spectrometer (AAS, Perkin Elmer 2380) were assessed. The results showed that in M3, Fe (1418.303), Cd (2.692), Pb (7.646), Ni (7.412) and M4, Fe (1162.011), Cd (1.436), Pb (7.372), Ni (5.384) were above WHO/FAO/FEPA recommended permissible limits for soils. High percentage variations occurred between the study stations and the controls, M3/RSU for Fe, Cd, Cr, Ni, As and M4/ RSU for Cd, Cr, Ni, As respectively. Though, the result of the ANOVA showed p-value of 0.2845 (α=0.05) meaning no significant difference within the M3, M4 and RSU stations was also corroborated by the t-test result for M3/ RSU control and M4/ RSU control which were 1.013 and 1.037 respectively at 0.05 significant levels. The mile 3 study station was observed to have more anthropic inputs which also showed in the variations from the Mile 4 results. The above results showed that only Cu in the Mile 4 study station certified a safe range while all the heavy metals exceeded safe limits especially Cd, As and Ni. The concentration distribution trend for the heavy metals studied were; M3 (Fe>Cr>Cu>Pb>Ni>As>Cd); M4 (Fe>Pb>Cr>Cu>Ni>As>Cd); RSU (Fe>Cu>Pb>Cr>Ni>As>Cd). The increasing concentrationss of these heavy metals in the soils of these areas stands a threat to health of the inhabitants; hence must be monitored and adequate measures taken by appropriate authorities of government