The effect of pH on heavy metals availability on crude oil remediated and non-remediated soil, Nkeleoken Community Eleme, Rivers State, Nigeria

Abstract

This study was aimed at examining the influence of pH on heavy metals availability in polluted and non-polluted soils. The findings showed that metal availability depends on soil solution which is pH dependent. The values of pH in Nkeleoken remediated soil (RSENa, RSENb, RSENc) in dry season were 6.01, 5.87, 5.78 and 6.64, 5.77, 5.68 in wet season with mean values of 5.89±0.05 and 6.03±0.53 while the pH of the contaminated soil ranged between 4.31 – 4.41. The mean values of heavy metals in Nkeleoken remediated soil are; Se (318±9.88; 326±11.6 mg/kg), Cd (3.65; 3.82±1.09 mg/kg), V (1095±71.05; 1189±149 mg/kg), Ba (8.98±1.53; 9.40±1.89 mg/kg), Cu (8.19±0.08; 8.84±0.14 mg/kg), Ni (0.02±0.01 mg/kg), As (5.52±2.35; 10.3±2.38mg/kg), Pb (1.73±0.32; 2.70±1.38 mg/kg) and Cr (23.1±4.05; 23.1±4.05 mg/kg). The results revealed that V and Se had the highest concentration level followed by As while the least concentrations were observed in Cd, Ba, Pb and Cr in both dry and wet season. The concentrations of heavy metals in the non-remediated soil ranged from 866 – 868 mg/kg, 1356 – 6332 mg/kg, 211 – 218 mg/kg, 73.6 – 79.0, and 866 – 868 mg/kg for Se, V, Ba Pb and as in dry and wet seasons. However, Cr concentrations ranged from 6.03 – 7.02 mg/kg. The concentrations of V and Se in the non-remediated soils (NRSENx - NRSENz) during dry and wet seasons were higher than their corresponding in the remediated soils likewise the recommended values set by DPR (2012).