Seasonal Variation of Heavy Metal Concentrations in Soils and Cocoyam Tubers Around Selected Municipal Dumpsites: Assessment Using Translocation Factor and Contamination Indices

Municipal open dumpsites are major sources of heavy metal contamination, posing significant risks to agricultural soils and food safety in developing countries. This study evaluated the seasonal distribution, soil to tuber translocation, contamination indices and human health risks of Pb, Zn, Ni, Cu, Cr and Cd in soils and cocoyam (Colocasia esculenta) cultivated around three municipal dumpsites in Akwa Ibom State, Nigeria. Composite soil samples were collected at three depths (0–10, 10–20, 20–30 cm) from each dumpsite and a control site, in both dry and wet seasons, to assess vertical and seasonal metal variation. Cocoyam tubers were also harvested at each location. Metals were determined by Atomic Absorption Spectrophotometry after digestion. Transfer factor (TF), contamination factor (CF), degree of contamination (Cdeg), hazard quotient (HQ) and hazard index (HI) were computed to assess metal mobility and health risk. Metal concentrations generally decreased with soil depth, showing surface accumulation from waste deposition. The highest concentrations occurred at Ikot Ekpene (13.50 and 88.50 mg/kg in Pb and Zn, dry season), while Pb increased to 37.50 mg/kg in wet season. Transfer factors exceeded unity for Pb at Eket (TF = 1.22, dry season), and for Pb at Uyo (TF = 1.27) and Cr at Eket (TF = 1.43) in the wet season, indicating high translocation into tubers. Soil contamination was highest at Ikot Ekpene (Cdeg = 18.36 dry season; 37.77 wet season), while tubers recorded Cdeg values of 22.40–24.67 (dry season). Hazard indices exceeded the US EPA threshold (HI > 1.0) at all dumpsites, peaking at 11.29 (Ikot Ekpene, wet season), with Pb the major contributor to risk. Cocoyam cultivated around municipal dumpsites carries a high heavy metal exposure risk. Improved waste management and restrictions on food crop cultivation in contaminated areas are recommended.

Heavy metals, Cocoyam (Colocasia esculenta), Municipal dumpsites, Translocation, Contamination indices

1. Ajah, K. C., Ademiluyi, J. & Nnaji, C. C. (2015). Spatiality, seasonality and ecological risks of heavy metals in the vicinity of a degenerate municipal central dumpsite in Enugu, Nigeria. Journal of Environmental Health Science Engineer 13, 15. https://doi.org/10.1186/s40201-015-0168-0 [Google Scholar] [Crossref]

2. Akpan, A. D., Okori, B. S. & Ekpechi, D. C. (2022). Human Health Risk Assessment of Polycyclic Aromatic Hydrocarbons in water samples around Eket Metropolis, Akwa Ibom State, Nigeria. Asian Journal of Environment and Ecology, 19(4), 58-71. [Google Scholar] [Crossref]

3. Ali, H., Khan, E., & Ilahi, I. (2019). Environmental chemistry and ecotoxicology of hazardous heavy metals: Environmental persistence, toxicity, and bioaccumulation. Journal of Chemistry, 2019, Article 6730305. https://doi.org/10.1155/2019/6730305 [Google Scholar] [Crossref]

4. Alloway, B. J. (2013). Heavy metals in soils: Trace metals and metalloids in soils and their bioavailability (3rd ed.). Springer. https://doi.org/10.1007/978-94-007-4470-7 [Google Scholar] [Crossref]

5. Amusan, A. A., Ige, D. V., & Olawale, R. A. (2005). Characteristics of Soils and Crops’ Uptake of Metals in Municipal Waste Dump Sites in Nigeria. Journal of Human Ecology, 17, 167 - 171. https://doi.org/10.1080/09709274.2005.11905775 [Google Scholar] [Crossref]

6. Baguma, G., Bamanya, G., Twinomuhwezi, H., Gonzaga, A., Omara, T., Onen, P., Ocakacon, S., Angiro, C., Waibale, W., & Ntuwa, R. (2025). Bioaccumulation and transfer of potentially toxic elements in the yam-soil system and associated health risks in Kampala’s Luzira Industrial Area. Journal of Xenobiotics, 15(6), 193. https://doi.org/10.3390/jox15060193 [Google Scholar] [Crossref]

7. Bortey-Sam, N., Nakayama, S. M., Akoto, O., Ikenaka, Y., Fobil, J. N., Baidoo, E., Mizukawa, H., & Ishizuka, M. (2015). Accumulation of Heavy Metals and Metalloid in Foodstuffs from Agricultural Soils around Tarkwa Area in Ghana, and Associated Human Health Risks. International journal of environmental research and public health, 12(8), 8811–8827. https://doi.org/10.3390/ijerph120808811 [Google Scholar] [Crossref]

8. Ebong, G. A., Etuk, H. S., & Johnson, A. S. (2007). Heavy metals accumulation by Talinum triangulare grown on waste dumpsites in Uyo metropolis, Akwa Ibom State, Nigeria. Journal of Applied Sciences, 7(10), 1404–1409. [Google Scholar] [Crossref]

9. Ebong, G. A., Akpan, M. M., & Mkpenie, V. N. (2008). Heavy metal contents of municipal and rural dumpsite soils and rate of accumulation by Carica papaya and Talinum triangulare in Uyo, Nigeria. E-Journal of Chemistry, 5(2), 281-290. https://doi.org/10.1155/2008/854103 [Google Scholar] [Crossref]

10. Ebong, G. A., Offiong, O. E. & Ekpo, B. O. (2015). Pollution Indices of Trace Metals in Urban Dumpsite Soils within Akwa Ibom State, Nigeria. International Research Journal of Pure & Applied Chemistry, 6(2), 84-94. https://doi.org/10.9734/IRJPAC/2015/15331 [Google Scholar] [Crossref]

11. Ebong, G. A., Etuk, H. S., & Dan, E. U. (2019). Multivariate Statistical Evaluation of Ecological Risks Associated with the Uncontrolled Tipping Method of Urban Wastes at Uyo Village Road, Akwa Ibom State, Nigeria. Singapore Journal of Scientific Research, 9(1), 1-12. [Google Scholar] [Crossref]

12. Ekanem, A. N (2015). Relations between metal levels in Plant and Soil from waste dumpsite in Uyo metropolis. Elixir Applied Chemistry, 78, 29829-29832. [Google Scholar] [Crossref]

13. Ekere, N. R., Ugbor, M. C. J., Ihedioha, J. N., Ukwueze, N. N., & Abugu, H. O. (2020). Ecological and potential health risk assessment of heavy metals in soils and food crops grown in abandoned urban open waste dumpsite. Journal of environmental health science & engineering, 18(2), 711–721. https://doi.org/10.1007/s40201-020-00497-6 [Google Scholar] [Crossref]

14. Ferronato, N., & Torretta, V. (2019). Waste Mismanagement in Developing Countries: A Review of Global Issues. International Journal of Environmental Research and Public Health, 16, 1060. https://doi.org/10.3390/ijerph16061060 [Google Scholar] [Crossref]

15. Genchi, G., Sinicropi, M. S., Lauria, G., Carocci, A., & Catalano, A. (2020). The Effects of Cadmium Toxicity. International journal of environmental research and public health, 17(11), 3782. https://doi.org/10.3390/ijerph17113782 [Google Scholar] [Crossref]

16. Hakanson, L. (1980). An ecological risk index for aquatic pollution control: A sedimentological approach. Water Research, 14(8), 975–1001. https://doi.org/10.1016/0043-1354(80)90143-8 [Google Scholar] [Crossref]

17. Ihedioha, J. N., Ukoha, P. O., & Ekere, N. R. (2017). Ecological and human health risk assessment of heavy metal contamination in soil of a municipal solid waste dump in Uyo, Nigeria. Environmental geochemistry and health, 39(3), 497–515. https://doi.org/10.1007/s10653-016-9830-4 [Google Scholar] [Crossref]

18. Ita, R. E., & Anwana, E. D. (2017). Geochemical Assessment of Heavy Metal Contamination in Rural and Urban Wetlands in Akwa Ibom State, Nigeria. New York Science Journal, 10, 43-51. [Google Scholar] [Crossref]

19. Ite, A. E., Harry, T. A., Obadimu C. O., Ekwere, I. O. (2019). Comparison of Indoor Air Quality in Schools: Urban vs. Industrial 'Oil & Gas' Zones in Akwa Ibom State, Nigeria. Journal of Environment Pollution and Human Health, 7(1), 15-26. https://doi.org/doi:10.12691/jephh-7-1-3 [Google Scholar] [Crossref]

20. Monechot, W., Nicholas, E. O., S., & Onyekachi, C. I. (2014). Heavy metal characteristics of soils at the municipal solid wastes dumpsite at Uyo metropolis, Akwa Ibom State, South-South, Nigeria. Chemistry and Materials Research, 6(7), 49-60. [Google Scholar] [Crossref]

21. Rahimzadeh, M. R., Rahimzadeh, M. R., Kazemi, S. & Moghadamnia, A. A. (2017). Cadmium toxicity and treatment: An update. Caspian Journal of Internal Medicine, 8(3):135–145. https://doi.org/0.22088/cjim.8.3.135. [Google Scholar] [Crossref]

22. Rahimzadeh, M. R., Rahimzadeh, M. R., Kazemi, S., & Moghodamia, A. A. (2024). Copper poisoning with emphasis on its clinical manifestations and treatment of intoxication. Advances in Public Health, 1, 6001014. https://doi.org/10.1155/2024/6001014. [Google Scholar] [Crossref]

23. Tchounwou, P. B., Yedjou, C. G., Patlolla, A. K., & Sutton, D. J. (2012). Heavy metal toxicity and the environment. In A. Luch (Ed.), Molecular, clinical and environmental toxicology. Springer, pp. 133-164. https://doi.org/10.1007/978-3-7643-8340-4_6 [Google Scholar] [Crossref]

24. Ubong, U. U., Ikpe, E. E. Ekanem, A. N., Jacob, J. N. & Archibong, U. D. (2023a). Heavy Metals, profile of the proposed Dump-site at Ntak-Inyang Itam, Akwa Ibom State, Nigeria. Journal of Geography, Environment and Earth Science international, 27(2), 17-28. [Google Scholar] [Crossref]

25. Ubong, U. U., Ekwere, I. O., Akpan, A. D. & Ite, A. E. (2023b). Human Health Risk Assessment of Cadmium (Cd), Lead (Pb) and Mercury (Hg) levels in organs of fish obtained from Iko River, Eastern Obolo Local Government Area, Akwa Ibom State, Nigeria. Journal of Materials and Environmental Science, 14(20), 384-394 [Google Scholar] [Crossref]

26. Ukpong, E. C. (2013). Assessment of heavy metal content in soils and plants around waste dumpsites in Uyo metropolis, Akwa Ibom State. The International Journal of Engineering and Science, 2(7), 75–86. [Google Scholar] [Crossref]

27. Umoh, S. D. & Etim, E. E. (2013). Determination of Heavy Metal Contents from Dumpsites within Ikot Ekpene, Akwa Ibom State, Nigeria using Atomic Absorption Spectrophotometer. The International Journal of Engineering and Science, 2(2), 123-129 [Google Scholar] [Crossref]

28. Wang, F., Guan, Q., Tian, J., Lin, J., Yang, Y., Yang, L., & Pan, N. (2020). Contamination characteristics, source apportionment, and health risk assessment of heavy metals in agricultural soil in the Hexi Corridor. CATENA. 191, 104573. https://doi.org/10.1016/j.catena.2020.104573. [Google Scholar] [Crossref]

29. Zhu, D., Asnani, P. U., Zurbrugg, C., Anapolsky, S., & Mani, S. (2008). Improving solid waste management in India: A sourcebook for policy makers and practitioners. Washington, DC: The World Bank. [Google Scholar] [Crossref]

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