65 Journal of Environmental & Earth Sciences | Volume 05 | Issue 01 | April 2023 Journal of Environmental & Earth Sciences https://journals.bilpubgroup.com/index.php/jees *CORRESPONDING AUTHOR: Sunday Ojochogwu Idakwo, Department of Geology and Mining, Ibrahim Badamasi Babangida University, Lapai, Niger State, 740005, Nigeria; Email: idakwo@ibbu.edu.ng ARTICLE INFO Received: 12 September 2022 | Revised: 18 March 2023 | Accepted: 21 March 2023 | Published Online: 13 April 2023 DOI: https://doi.org/10.30564/jees.v5i1.5060 CITATION Okonkwo, S.I., Idakwo, S.O., Kolawole, M.S., et al., 2023. Source, Contamination Assessment and Risk Evaluation of Heavy Met- als in the Stream Sediments of Rivers around Olode Area SW, Nigeria. Journal of Environmental & Earth Sciences. 5(1): 65-84. DOI: https://doi.org/10.30564/jees.v5i1.5060 COPYRIGHT Copyright © 2023 by the author(s). Published by Bilingual Publishing Group. This is an open access article under the Creative Commons Attribu- tion-NonCommercial 4.0 International (CC BY-NC 4.0) License. (https://creativecommons.org/licenses/by-nc/4.0/). ARTICLE Source, Contamination Assessment and Risk Evaluation of Heavy Metals in the Stream Sediments of Rivers around Olode Area SW, Nigeria Stellamaris Isioma Okonkwo 1 , Sunday Ojochogwu Idakwo 2* , Mofolorunsho Samuel Kolawole 3 , Olufemi Faloye 4 , Anthony Azubuike Elueze 4 1 Department of Geology, Federal University of Technology, Owerri, Owerri, Imo State, 460114, Nigeria 2 Department of Geology and Mining, Ibrahim Badamasi Babangida University, Lapai, Niger State, 740005, Nigeria 3 Department of Geology, Federal University, Oye-Ekiti, Ekiti State, 360001, Nigeria 4 Department of Geology, University of Ibadan, Ibadan, 200005, Nigeria ABSTRACT In order to investigate the source, contamination, and risk of heavy metals such as Pb, Zn, Cu, Ni, Co, Fe, Mn, and Cr, twelve (12) stream sediments and ten (10) rock samples were collected from pegmatite mining sites at Olode and its environs inside Ibadan, Southwestern Nigeria. The average values and order of abundance obtained followed the pattern: Mn (595.09) > Ba (80) > Cr (50.82) > V (45.09) > Zn (29.73) > Cu (13.82) > Co (13.82) > Sr (10.46) > Ni (9.73) > Pb (9.09) > Fe (1.59). These were greater than the background values, indicating that mining has a negative impact on the study area, as indicated by the high coeffcient of variation and correlation values (> 0.6) for Copper-Lead (0.929), Copper-Vanadium (0.970), Copper-Chromium (0.815), Lead-Vanadium (0.884), and others. On the basis of the enrichment factor (EF), the Olode sediments show extremely high enrichment for Mn and Ba in the research region. Cu and Ni are most likely to blame for the elevated contamination levels, according to CF values. The degree of contamination (CD), pollution load index (PLI), pollution index (PI), and modifed pollution index (MPI) all revealed high levels of contamination in all stream sediment samples, whereas Igeo shows that the Olode stream sediments are “practically uncontaminated to extremely contaminated by Ni, Co, and Mn”. Ni and Cu are the major regulating factors that are most likely causing the possible Er i . As a result, these fndings give important information for conducting appropriate ecological management research. Keywords: Olode; Heavy metals; Stream sediments; Risk assessment; Contamination indices