Geochemical Speciation and Environmental Implications of Heavy Metal Mobility in Okporowo-Ekpeye Farmlands Impacted by Artisanal Oil Refining
Main Article Content
Abstract
Oil spills in agricultural lands pose significant threats to soil quality and food security, especially in the Niger Delta. This study investigates the speciation and mobility of five heavy metals—arsenic (As), cadmium (Cd), chromium (Cr), manganese (Mn), and lead (Pb)—in soils from oil-impacted farmlands in Okporowo-Ekpeye, using the modified Tessier sequential extraction method. Results showed that cadmium was predominantly found in the exchangeable fraction (F2) at 52.8%, indicating high mobility and bioavailability. Lead followed closely with 37.2% in F2, suggesting a substantial ecological risk. Arsenic was mostly in the reducible fraction (F4), accounting for 48.6% of its total concentration, pointing to potential release under reducing conditions. Chromium and manganese were primarily found in the residual fraction (F6) at 61.3% and 58.7%, respectively, suggesting a lithogenic origin and lower bioavailability. Based on the Risk Assessment Code (RAC), cadmium and lead were classified as high-risk (RAC > 30%), while arsenic showed moderate risk. Chromium and manganese posed low ecological risk with RAC values below 10%. These findings highlight the need for urgent remediation efforts and the development of sustainable land management practices in oil-contaminated farmlands to protect both ecological and human health.
Article Details
References
Adewumi, G.O., & Osobamiro, M.T. (2016). Chemical speciation and potential mobility of some toxic metals in tropical agricultural soil. Research Journal of Environmental Toxicology, 10, 159-165. DOI: https://doi.org/10.3923/rjet.2016.159.165
Akinmoladun, F.I., & Ajayi, A.A. (2019). Impact of heavy metal contamination on soil quality in oil impacted areas of Nigeria. Ecotoxicology and Environmental Safety, 170, 1-9.
Akinnawo, S.O. (2021). Evaluation study on the sequential extraction and eco-toxicological profile of heavy metals in sediment along the coastline of Nigeria. Communication: Faculty of Science University Ankara Series B Chemistry and Chemical Engineering, 63(1), 1-26. https://dergipark.org.tr/en/pub/communb/issue/64811/904608
Akinwale, O.O., Nneji, P.O., Nkwocha, S.T., Chikhuare, F., Nkwocha, J.E., Remilekun, I.T., & Idowu, A.R. (2024). Evaluation and risk assessment of heavy metals in wetland soils in the University of Lagos. World Journal of Advanced Research and Reviews, 24(1), 857-869. DOI: https://doi.org/10.30574/wjarr.2024.24.1.3094
American Academy of Pediatrics. (2022). Low-level lead exposure and its effects on neurodevelopment. Pediatrics, 149(2), e20220012. doi:10.1542/peds.2022-0012
Azizi, M., Faz, A., Zornoza, R., Martinez-Martinez, S., & Acosta, J. A. (2023). Phytoremediation potential of native plant species in mine soils polluted by metal(loid)s and rare earth elements. Plants, 12(6), 219-230. https://doi.org/10.3390/plants12061219 DOI: https://doi.org/10.3390/plants12061219
Balogun, M.A., Money, M.O., Omosigho, H.N., & Ataikiru, H.O. (2019). Pollution level determination using chemical speciation in the vicinity of petroleum prospecting areas in Southern Niger Delta. Journal of Chemical Society of Nigeria, 44(5), 825 -831.
Cao, J., Sun, Z., Wang, Y., & Liu, Z. (2020). Heavy metal contamination in agricultural soils and its impact on food safety: A review. Science of the Total Environment, 712, 136415.
Center for Disease Control and Prevention. (2023). Lead exposure: Health effects and prevention. https://www.cdc.gov/nceh/lead/
Ekpete, O. A., & Festus, C. (2013). Heavy metal distribution in soil along Iwofe-Rumuolumeni Road. International Journal of Science and Technology, 8(1), 450-455.
Ekpete, O. A., Edori, O. S., & Iyama, W. A. (2019). Concentrations of polycyclic aromatic hydrocarbons from selected dumpsites within Port Harcourt Metropolis, Rivers State, Nigeria. International Journal of Environmental Sciences & Natural Resources, 21(4), 56-66 DOI: https://doi.org/10.19080/IJESNR.2019.21.556066
Farkas, A., Rada, E., Cusimano, G., Istrate, I.A., & Ragazzi, M. (2021). Toxicological effects of lead exposure on human health and environment. Environmental Pollution, 268, 115822 DOI: https://doi.org/10.1016/j.envpol.2020.115822
Jadhav, M. S., & Singh, S. P. (2020). Speciation of heavy metals in contaminated soils and their environmental risk assessment. Environmental Toxicology and Chemistry, 39(7), 1789-1804.
Kalagbor, I. A. Dibofori-Orji, A. N., & Ekpete, O. A. (2019). Exposure to heavy metals in soot samples and cancer risk assessment in Port Harcourt, Nigeria. Journal of Health and Pollution, 9(24), 191-211. DOI: https://doi.org/10.5696/2156-9614-9.24.191211
Kumar, V., Sharma, A., Kaur, P., Singh Sidhu, G. P., Bali, A. S., Bhardwaj, R., Thukral, A. K., & Cerda, A. (2019). Pollution assessment of heavy metals in soils of India and ecological risk assessment: A state-of-the-art. Chemosphere, 216, 449–462. https://doi.org/10.1016/j.chemosphere.2018.10.066 DOI: https://doi.org/10.1016/j.chemosphere.2018.10.066
Lahori, A. H., Mierzwa-Hersztek, M., Demiraj, E., Idir, R., Bui, T. T. X., Vu, D. D., Channa, A., Samoon, N. A., & Zhang, Z. (2020). Clays, limestone and biochar affect the bioavailability and geochemical fractions of cadmium and zinc from Zn-Smelter polluted soils. Sustainability, 12(20), 8606. https://doi.org/10.3390/su12208606 DOI: https://doi.org/10.3390/su12208606
Ochiagha, K. E., Okoye, P. C., & Eboagu, N. C. (2020). Chemical speciation and potential mobility of heavy metals in the soils of Onitsha South Local Government Area Anambra Nigeria. American Journal of Applied Chemistry, 8(3), 74-81. doi: 10.11648/j.ajac.20200803.12 DOI: https://doi.org/10.11648/j.ajac.20200803.12
Otones, V., Álvarez-Ayuso, E., García-Sánchez, A., Santa Regina, I., & Murciego, A. (2011). Arsenic distribution in soils and plants of an arsenic impacted former mining area. Environmental Pollution, 159(10), 2637-2647. https://doi.org/10.1016/j.envpol.2011.05.027 DOI: https://doi.org/10.1016/j.envpol.2011.05.027
Rehman, M. Z. U., Khan, S., Qin, K., Brusseau, M. L., Shah, M. T., & Din, I. (2019). Cadmium in soils and groundwater: A review. Applied Geochemistry, 108, 104388. https://doi.org/10.1016/j.apgeochem.2019.104388 DOI: https://doi.org/10.1016/j.apgeochem.2019.104388
Sikdar, A., Arockiam Jeyasundar, P. G. S., Debnath, B., Hossain, M. S., Islam, M. A., & Ahammed, G. J. (2022). Cadmium contamination in the soil environment: Impact on plant growth and human health. Agrochemicals in Soil and Environment, 367–408. Springer. https://link.springer.com/chapter/10.1007/978-981-16-9310-6_16 DOI: https://doi.org/10.1007/978-981-16-9310-6_16
Tessier, A., Campbell, P.G.C., & Bisson, M. (1979). Sequential extraction procedure for the speciation of particulate trace metals. Analytical Chemistry 51 (7), 844-851. DOI: https://doi.org/10.1021/ac50043a017
Thuy, N.T., Vuong, T.X., Nguyen, T.L., & Tu, B.M. (2022). Chemical Speciation, Risk Assessment, and Pollution Level of Lead Metals in Road Dust of some Industry Zones and Urban Areas in Northern Vietnam. Vietnam Nguyen University (VNU). Journal of Science: Natural Sciences and Technology, 38(1), 98-103. DOI: https://doi.org/10.25073/2588-1140/vnunst.5322
Wang, X., Sato, T., Xing, B., & Tao, S. (2005). Health risks of heavy metals to the general public in Tianjin, China via consumption of vegetables and fish. Science of the Total Environment, 350(1-3), 28-37. https://doi.org/10.1016/j.scitotenv.2004.09.044 DOI: https://doi.org/10.1016/j.scitotenv.2004.09.044