Overview
Emmanuel measured cadmium (Cd), nickel (Ni), lead (Pb), Mn, and total chromium (Cr) in vegetables grown around Wudil, Nomans-Land, and Sharada in Kano State, Nigeria. Table 1 gives crop-by-site concentrations for pepper, lettuce, carrot, onion, beetroot, and spinach. Cadmium is the clearest occurrence concern in the table, reaching 0.36 mg/kg in Wudil carrot, while chromium reaches 0.42 mg/kg in Nomans-Land spinach and 0.41 mg/kg in Sharada onion.
Key numbers
All concentrations are source-reported mg/kg in the edible vegetable matrix.
| Site | Vegetable | Cd | Ni | Pb | Mn | Cr |
|---|---|---|---|---|---|---|
| Wudil | Pepper | 0.19 | 0.04 | 0.06 | 4.87 | 0.13 |
| Wudil | Lettuce | 0.27 | 0.06 | 0.02 | 9.28 | 0.10 |
| Wudil | Carrot | 0.36 | 0.03 | 0.12 | 0.97 | 0.12 |
| Wudil | Onion | 0.33 | 0.02 | 0.08 | 0.67 | 0.14 |
| Nomans-Land | Beetroot | 0.22 | 0.03 | 0.10 | 0.78 | 0.10 |
| Nomans-Land | Pepper | 0.25 | 0.03 | 0.10 | 0.79 | 0.10 |
| Nomans-Land | Spinach | 0.31 | 0.03 | 0.13 | 1.72 | 0.42 |
| Sharada | Onion | 0.23 | -0.01 | 0.15 | 0.82 | 0.41 |
| Sharada | Lettuce | 0.28 | -0.01 | 0.15 | 0.82 | 0.40 |
Table 2 reports an overall vegetable mean +/- SD of Cd 0.21 +/- 0.02 mg/kg, Ni 0.02 +/- 0.03 mg/kg, Pb 0.10 +/- 0.05 mg/kg, Mn 2.16 +/- 2.4 mg/kg, and Cr 0.21 +/- 0.17 mg/kg. The corresponding soil mean +/- SD values were Cd 0.29 +/- 0.70 mg/kg, Ni -0.15 +/- 0.04 mg/kg, Pb 1.41 +/- 1.58 mg/kg, Mn 6.12 +/- 4.001 mg/kg, and Cr 0.57 +/- 0.30 mg/kg.
The source also calculates estimated daily intake. Examples include Wudil carrot Cd 2.07E-03, Wudil lettuce Mn 5.33E-02, Sharada onion Cr 2.31E-03, and Nomans-Land spinach Cr 2.42E-03 in the paper’s EDI units.
Methods (brief)
Samples were collected during the January-March 2025 dry season from Wudil, Nomans-Land, and Sharada, representing peri-urban, residential, and industrial urban-agriculture settings. The study reports 64 total samples from eight sites, including soil and edible vegetable portions. Vegetable samples were prepared from edible tissue, digested using microwave-assisted acid digestion, and analyzed by microwave plasma atomic emission spectroscopy. Statistical comparisons used ANOVA and Pearson correlation.
Implications
- Certification: Adds Nigeria-market occurrence data for Cd, Pb, total Cr, Ni, and Mn across several raw vegetable matrices. This is not a US-market benchmark pool source unless a cross-market rationale is documented.
- Courses: Useful for showing how urban agriculture, soil contamination, and crop type create different heavy-metal patterns across vegetables.
- App: Supports both crop-specific pages and broad vegetable category pages with table-level occurrence values.
Related evidence
- Green bell pepper
- Lettuce
- Carrot
- Spinach
- Onions
- Beet
- Leafy Vegetables
- Root vegetables
- Non-root vegetables
- Vegetables Mixed
- Non-Root Vegetables
- Root and Tuber Vegetables
- Leafy / Green Vegetables, Other
- Spinach
- Cadmium
- Lead
- Nickel
- Chromium
- Manganese
Update history
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