Assessment of Levels and Ecological Risks of Some Selected Potentially Toxic Metals in Soils around Onne Dumpsite, Rivers State, Nigeria

The concentrations of selected potentially toxic metals and other soil physico-chemical variables in soil receptacles of a solid waste dumpsite at Onne, Nigeria were assessed to ascertain the levels of contamination and ecological risks. Surface soils (0 – 20 cm depth) from four sampling areas (north, south, east and west) of the dumpsite were analyzed for Cd, Pb, Ni, As and Cr, using atomic absorption spectroscopy. Single and integrated ecological risks indices were calculated using established models. Results revealed the mean values (mg/kg) of Cd (1.00 – 3.09), Pb (125.37 – 285.48), Ni (10.37 – 16.17), As (0.26 – 0.87), Cr (52.16 – 77.17). Assessment of ecological risk indices for north, south, east and west showed {PLI (2.38, 1.27, 1.17 and 1.33), EF (1.01, 16.0, 13.90 and 56.0), Cd (21.50, 11.10, 9.49 and 10.90), PERI (392.0, 132.0, 148.0 and 157.0), PIAvg (5.17, 2.55, 2.27 and 2.56), PINemerow (7.75, 3.80, 3.18 and 3.38) } respectively. These implied that the soils around the dumpsite area were polluted due to enrichment of the selected metals and therefore of low quality. Ecological risk reduction strategies were also recommended.