Ecological Risk Assessment of the Soil around Odo Iya-Alaro (Iya Alaro River) at Ojota, Lagos States, Nigeria

Human developmental activities always result to waste generation; that invariably pollute the environment, if not properly managed. The aim of this study is to determine soil quality around Odo Iya-Alaro at Ojota, Lagos. A total of 12 soil samples were collected from 0 -15 cm and 15- 30 cm at three different spots of 100 and 500 m (control) away from the bank of the river. Samples were analysed for pH, EC, NO3, TOC; Zn, Na, K, Ca, Mg, Cu, Fe, Cd, Cr, Ni, and Pb using standard analytical methods. The results were subjected to both differential and inferential statistics using statistical package (SPSS 22.0 version). Subsequently, the data were compared with Earth crust values. The soil pollution was evaluated using pollution, ecological risk, and geo-accumulation index. Cr (50.43), Ni (29.47), and Cu (104.10) mg/kg at 100 m were higher than their controls; (12.09), (8.14), and (86.06) mg/kg respectively, but lower than their respective Earth crusts; (100), (80) except (50) mg/kg. The soil was moderately polluted with pH (1.15), Na (3.00), K (2.11), Mg (1.87), Ca (1.26) and Cu (1.21); considerably polluted with EC (3.82), TOC (3.39), and Ni (3.62); and very highly polluted with Fe (8.26). Fe (711.73) had a very high ecological risk.  The Geo – accumulation index was moderately - strongly polluted with Zn (2.61), and very strongly polluted with pH (5.37), EC (14.90), NO3 (9.66), Na (15.41), K (11.31), Mg (9.51), Ca (17.08), Fe (15.32), Cu (12.54), Cr (8.67), and Ni (7.32). The soil was polluted. and urgently needs reclamation for Garden Park (relaxation).