Okeke et al. 2024 - Spent-engine-oil and palm-oil-mill-effluent soil metals

Okeke and colleagues compared heavy-metal concentrations in soils affected by palm oil mill effluent, spent engine oil effluent, and an uncontaminated control site in Ebonyi State, Nigeria. This is in-scope a3 source-attribution and soil-pathway evidence for agro-industrial and automotive effluents, not palm oil occurrence.

Key numbers

Table 1 reports mean soil concentrations as mg/kg:

The authors state that soil contaminated with spent engine oil had higher mean Zn, Ni, Mn, Fe, Cu, Co, Cr, and Cd than the palm oil mill effluent and control sites. They report Hg as higher in palm oil mill effluent soil than in spent-engine-oil or control soil. Pb was highest in the control soil, and the authors describe this as a site-specific exception to the broader trend.

The paper reports all listed mean concentrations as below the WHO reference values printed in Table 1. These are source-reported comparison values, not HMTc standards.

Methods (brief)

The study was conducted at Ebonyi State University’s Presco Campus in Abakaliki, Nigeria. The paper says it assessed soil metal concentrations across palm oil mill effluent, spent engine oil effluent, and control sites. The methods section also contains insect-assessment language that does not explain the soil-metal analytical workflow; this page therefore treats Table 1 as measured soil-context evidence but does not infer unreported digestion, instrument, or sampling details.

Implications

Certification: Do not use these values as palm oil product occurrence or edible-ingredient occurrence. They are soil and effluent-source values.

Courses: Useful source-attribution example because it compares two industrial effluent contexts side by side and shows that different activities load different metals into soil.

App: Context only. The source can support upstream due-diligence questions about palm oil mill effluent or spent-engine-oil contamination near production landscapes, not finished-product scoring.

Wiki pages this source may touch

• soil-to-plant-transfer
• source-attribution-environmental-burden-apportionment
• irrigation-and-soil-amendments
• nickel
• lead
• cadmium
• mercury-total
• chromium

Verification notes

Recovered from skip:not-food-occurrence under the 2026-06-10 inclusion-by-default rule. The old skip treated the paper as out of scope because it measured soil affected by spent engine oil and palm oil mill effluent rather than palm oil occurrence. On reading, it is in-scope a3 source-attribution/pathway evidence.

Numbers were checked against the abstract, Table 1, results, discussion, and conclusion in the extracted PDF. Hg is recorded as tHg and Cr as total Cr because the paper does not report mercury or chromium speciation. Products and ingredients are intentionally empty. The paired file ing-palm-oil-pb_2024_10-54517-ssd-v2i2-2410.pdf has the same SHA-256 hash and is treated as a duplicate of this source page.

Page history

The five most recent substantive edits to this page. The full version history lives in git; when DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.