Analysis of sediment quality in the oil-reach Bayelsa state, Niger delta region of Nigeria

Sediments are a dire part of the aquatic ecosystems, and their contamination is a global concern. Therefore, this study evaluates sediment quality in the Niger Delta region of Nigeria based on heavy metal-contamination. To achieve this, three set of sediment samples were collected, two were sampled from areas with history of crude oil spills, and a control sample was collected from an area with no history of crude oil spills. Sediment sampling covered three different sites. For site 1, the mean concentrations of heavy metal were 0.49, 14.70, 7.35, 8.72, 13.92, and 38.06 mg/kg for cadmium, chromium, copper, nickel, lead, and zinc, respectively. These concentrations were below the threshold effect concentration, and probable effect concentration. These are both environment risk guidelines. Similarly, for site 2, the mean concentrations of heavy metals were 1.92, 30.61, 19.41, 20.05, 22.99, and 102.28 mg/kg for the heavy metal order above. The concentration of cadmium (1.92) is above the threshold effect concentration value (0.99 mg/kg), which implies adverse effect is expected to occur. The concentration values of the rest heavy metals were below both the threshold effect concentration and probable effect concentration guideline values. For site 3, the mean concentration values following the heavy metal order were 0.29, 36.45, 20.20, 16.25, 21.51, and 62.14 mg/kg, respectively. These values are all below the two specified guideline values. The control samples all had concentrations below the guideline values of the two specified guidelines, indicating that the high concentration values were due to crude oil spills in the area. However, since heavy metals are known for their bioaccumulation and biomagnifications potentials, and degradation resistance, there is need for sediment quality analysis in the region to safeguard our aquatic ecosystems.