Assessment of Potentially Toxic Elements in Egbetua Stream Sediments, South-Western Nigeria

Abstract

The study area is located in Egbetua area in Akoko Edo Local Government Area of Edo State, southwestern Nigeria. the aim of the study is to assess the concentrations of potentially toxic elements in sediments from the study area. Ten samples collected from various locations in Egbetua stream were subjected to standard geochemical analysis using energy dispersive x-ray fluorescence spectrometer model “Minipal 4”. The average concentrations of six elements are V (26.89 ppm), Cr (32.33 ppm), Co (6.13 ppm), Ni (16.10 ppm), Au (21.13 ppm), and Zr (1,285.20 ppm) and they were compared to those of upper continental crust baseline values. V, Cr, Co, and Ni have extremely low concentrations, while Au and Zr have very high concentrations. Moreover, V, Cr, Co, and Ni have average enrichment ratios of 0.28, 0.35, 0.35 and 0.34, respectively, which are < 1 implying their depletion in relation to their average crustal baseline concentrations. On the other hand, Au and Zr are highly enriched in the study area. Au has average geoaccumulation index (Igeo) values of 4.40 indicative of strongly to extremely polluted, while Cr, Co, Ni and Zr have average Igeo values of 10.95, 6.14, 9.98 and 17.34, respectively, indicative of sediments that are extremely polluted. The potentially toxic elements pose very serious environmental geochemical pollution threat in the study area. It is recommended that urgent action should be taken to mitigate and clean the study area of these potentially toxic elements.