Heavy Metal Enrichment and Sediment Quality Assessment of Yewa Creek, Southwest Nigeria

Abstract

Surface sediment samples from the study area were analysed for their heavy metal contents, to determine level of enrichment, and assess sediment quality by employing the consensus based sediment quality guidelines. The mean probable effect concentration quotient (mPECQ), threshold effect and probable effect concentrations (TEC and PEC), and potential ecological risk index (RI) were used to evaluate the sediment quality. Pearson's correlation and cluster analyses were done to determine the interrelationship between heavy metals of concern and infer possible sources of these contaminants. In all the stations, sediments were not enriched in Cu, Pb, Co and Mn. The metals with significant enrichment are site-specific. Severe enrichment of Cd noticed at the uppermost reach of Yewa Creek has been adduced to contributions from untreated sewage sludge, mineral fertilizers and wastewater from agricultural activities. The Pearson's correlation matrix revealed that highly significant relationships exist between Co and Ni, As and Ni, As and Co, Cd and Ni, Cd and Co, and, Cd and As, implying that each of these pairs may have originated from the same contamination source(s). The result of hierarchical cluster analysis unveiled the association of Zn with Co, , As and Ni giving evidence of anthropogenic contribution, while its association with Cu, Pb and Mn also indicated , contribution from geogenic activities. The concentration of Cd in sediment from the second sampled station at the uppermost reach of Yewa Creek was below PEC, but its exceedance, based on comparison to PEL, suggested highly degraded sediments. Also, a very high risk index (RI) obtained in this station implied that sediment has been heavily impacted and harmful effects may be produced on vagrant and sessile organisms. Contrastingly, the calculated mPECQ values indicatedthat sediments in the study area are not toxic.

Publication Info:

Author: Philips, O.A. ; Adebayo, A.J. , and Falana, A.O.

Volume: 56

Issue: March

Published By: Journal of Mining and Geology, 2024-03-01