Concentration of heavy metals and petroleum hydrocarbons in previously remediated sites in Niger Delta, Nigeria

Abstract

This study was aimed at assessing the soil conditions of previously remediated oil spill sites in the Niger Delta region. Ninety-six (96) soil samples were collected over two seasons from remediated sites from three states (Rivers, Abia, and Imo). Gas Chromatographic (GC) Analysis was used in analyzing for Total Petroleum Hydrocarbon (TPH) content while heavy metals analysis for Lead (Pb), Zinc (Zn), Copper (Cu), Chromium (Cr) and Iron (Fe) was done using absorptive spectrophotometric analyses. The data generated was subjected to ANOVA and multiple comparisons, Post-Hoc Tukey HSD test using IBM SPSS version 26.0. Results showed TPH range of 0.85±0.72mg/kg to 1.76±0.42mg/kg in samples from Owaza site in Abia state. Concentration of heavy metals in soil samples was below the standard permissible levels of the World Health Organization and other regulatory bodies such as Department of Petroleum Resources (DPR) intervention values, United States Environmental Protection Agency (USEPA), and Environmental Guidelines and Standards for Petroleum Industry in Nigeria (EGASPIN 2002), accepted values for soil samples. There were no effects of season variation observed. Enrichment factor of (323.20- 508.64) and (298.37-567.26) indicates anthropogenic activities as sources of pollution. The result of the current studies signifies that, the soils of previously remediated sites have safe levels of the contaminants; however, werecommended a regular routine check on the levels of contaminants.