First Assessment of Ecological Health, Human Health, and Public Health Implications of Site Specific Speciation of Heavy Metals in Ohaji-Egbema, Niger Delta, Nigeria
DOI:
https://doi.org/10.64229/aserx194Keywords:
Bioavailability, Chemometrics, Oil Pollution, Risk, Speciation, Toxic MetalsAbstract
Heavy metal contamination in oil-rich regions could be a source of multifaceted threats to human health. This study investigated the site-specific speciation, bioavailability, and associated ecological and human health risks heavy metals (Cd, Mn, Cu, Zn, Co) in surface soils of Ohaji-Egbema a prominent hub of oil and gas exploitation activities within the Niger Delta. After physiochemical charaterisation, the six composite soil samples from six distinct sites were analyzed through a detailed sequential extraction procedurefor concentrations of chemical species of metalusing Atomic Absorption Spectrometry (AAS). Appropriate chemometric tools were subsequently employed in identifying potential contamination sources and elucidate their linkages to critical soil properties.Results revealed elevated metal levels, often exceeding established WHO/FAO guideline thresholds for environmental safety. Notably, manganese (average 158.15 mg/kg) and cadmium (average 143.65 mg/kg) exhibited pronounced concentrations and high potential bioavailability, with site-specific ranges of 30.9-185.4 mg/kg for Mn and 10.8-109.4 mg/kg for Cd. Speciation analysis indicated that a significant proportion, often greater than 50%, of the studied metals resided in highly mobile and bioavailable fractions (F1-F3), signifying considerable ecological and human health risks. Key soil properties, particularly acidic pH (4.75-6.44) and high soil organic matter (50-64%), were found to significantly influence metal mobility and bioavailability. Calculated Hakanson Ecological Risk Indices indicated very high ecological risk, primarily driven by cadmium contamination. Human health risk assessment revealed that calculated Hazard Quotients (HQ) for cadmium (1.915) and cobalt (7.414) frequently exceeded unity (HQ ≥ 1) for children, indicating a significant potential for non-carcinogenic health risks to this vulnerable population via soil ingestion. Chemometric analysis provided insights into the likely anthropogenic sources of contamination, linking them to oil and gas activities. This study critically underscores the urgent need for targeted remediation strategies to mitigate heavy metal contamination and safeguard public health and ecological integrity in this heavily oil-impacted region.
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Copyright (c) 2025 Verla Evelyn Ngozi, Ugwulor Louis Oguchukwu, Verla Andrew Wirnkor (Author)
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