Ojekunle et al. 2015 - Mechanic-village soil and tree-bark metal uptake

Ojekunle and colleagues measured Cd, Pb, and Cu in soil and tree bark around a mechanic village in Abeokuta, Nigeria, comparing the results with a farmland control. This is in-scope supply-chain and mitigation evidence because it documents a source-attribution pathway from mechanic activity to soil and plant tissue, not cashew-nut occurrence.

Key numbers

Table 1 reports mean soil metal concentrations in mg/kg:

Table 2 reports soil concentration ranges and regulatory limits:

The text states that the maximum statistical value for Pb in mechanic-village soil was 24.34 mg/kg at a high-activity point. The authors interpret this as evidence of higher mechanic activity at that location, while still below the soil guideline they cite.

Table 3 reports mean concentrations in plant bark, compared with source-cited food/heavy-metal standards:

Table 4 reports percentage uptake efficiency:

The conclusion states that heavy-metal uptake efficiency in the three species followed Mango > Cashew > Neem. The authors recommend mango where copper pollution is the main target and neem where multiple metals occur in similar proportions.

Methods (brief)

Soil was collected 10 m from the base of sampled trees at 0-15 cm and 15-30 cm depths, air dried, sieved, digested with concentrated sulphuric acid/selenium solution and hydrogen peroxide, and analyzed by Thermo S4 AAS. Bark was cut from the top, middle, and bottom of trunks with a nitric-acid-washed stainless knife, oven dried at 105 degrees C, digested with sulphuric, perchloric, and nitric acids, and analyzed by AAS. Samples were run in triplicate and reported as mean values.

Implications

Certification: Do not use these values as cashew-nut, mango fruit, or neem-derived product occurrence. They are contaminated-soil, tree-bark, and phytoremediation/source-attribution values.

Courses: Useful example of a non-food upstream pathway where an industrial activity increases Pb, Cd, and Cu in soil and plant bark around a food-relevant tree species without directly measuring the edible commodity.

App: Context only. The source can inform supply-chain due-diligence questions around mechanic-village or workshop contamination near orchards; it does not score cashew products.

Wiki pages this source may touch

• soil-to-plant-transfer
• source-attribution-environmental-burden-apportionment
• remediation-evidence
• lead
• cadmium
• copper

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 and tree bark rather than cashew food occurrence. On reading, it is in-scope a2/a3 evidence: it reports phytoremediation uptake percentages and a mechanic-activity soil contamination pathway.

Numbers were checked against the abstract, Tables 1-4, results discussion, methods, and conclusion in the extracted PDF. Products and ingredients are intentionally empty because no edible cashew, mango, neem product, or other consumer product was measured.

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.