Assessment of the Impact of Local Crude Oil Refineries on Soil Quality in Selected Island Communities in Niger Delta, Nigeria

Abstract

In the last few years, there has been an ongoing effort to combat illegal oil bunkering, including the dismantling of artisanal refining activities in the Niger Delta. This study assessed the level of heavy metals and hydrocarbons concentration in former artisanal sites. Surface soil sample were collected in triplicates from nine island communifies along the Escravos Estuary and analysed for nutrients, heavy metals and hydrocarbons using standard laboratory procedures. The mean values of heavy metals and hydrocarbons were above the regulatory limits in soil. A one-way analysis of variance (ANOVA) showed significant differences (P< 0.05) in Mn, Fe, Zn, Cu, Pb, Ni, Mb, Cr, Ag, B, V and Au. Significant differences (P< 0.05) were also reported for TPH, PAH and THC. The mean concentrafion of metals in soil in decreasing order includes Fe> Zn> Mn> Cu> B> Ag> Mo> Au> V> Ni Cr> Be> Hg> Co> Pb> Se> Cd> Al> As, while for hydrocarbons it was TPH> PAH> THC. For communifies, Okerenkoko-gbene (52.74±6.3) and Ikpokpo (52.36±3.9) had the highest metal distribution. The same trend was observed for PAH (Okerenkoko-gbene 149.61±37.1 and Ikpokpo 143.32±18), while the reverse was the case for TPH (Ikpokpo 310.71±79 and Okerenkoko-gbene (291.56±87.1) and THC (Ikpokpo 19.13±0.4 and Okerenkoko-gbene 18.34±0.9). The elevated concentration of metals and hydrocarbons in soil requires remediation to prevent leaching into the estuary thereby affecting fisheries and seafood for human consumpfion.