Table 2.
Geo-accumulation Index (Igeo), Contamination Factor (CF) and Pollution Load Index (PLI) of Residential Settlements in Lagos and Ibadan, Nigeria
| Settlement type | Igeo | CF | Total | PLI | ||
|---|---|---|---|---|---|---|
| Lead | Cadmium | Lead | Cadmium | |||
| Lagos | ||||||
| Lagos old high income | −2.34 | 0.66 | 2.54 | 1.80 | 4.34 | 1.54 |
| Lagos new high income | −0.8 | 0.88 | 7.35 | 1.53 | 8.88 | 1.26 |
| Lagos average income | 1.41 | 1.08 | 28.3 | 2.07 | 30.4 | 1.97 |
| Lagos low income | 1.59 | 1.08 | 38.7 | 2.07 | 40.8 | 2.08 |
| Lagos suburban | −1.21 | −0.79 | 5.56 | 0.57 | 6.13 | 1.21 |
| Ibadan | ||||||
| Ibadan old high income | 0.59 | −0.73 | 19.3 | 0.74 | 20.0 | 1.52 |
| Ibadan new high income | 0.35 | −0.4 | 16.4 | 0.58 | 17.0 | 1.50 |
| Ibadan average income | 1.37 | −0.09 | 33.2 | 0.91 | 34.1 | 1.77 |
| Ibadan low income | 1.07 | −0.21 | 27.0 | 0.85 | 27.9 | 1.68 |
| Ibadan suburban | −0.36 | −2.17 | 10 | 0.22 | 10.2 | 1.14 |
Note: Four categories adapted to describe the extent of contamination are CF <1: very low contamination, CF 1–3: low contamination, CF 3–6: moderate contamination and CF > 6: considerable contamination; Igeo values are categorized as <0: uncontaminated, 0–1: uncontaminated-moderately contaminated, 1.00–1.99: moderately contaminated, 2.00–2.99: more contaminated and 3.00–3.99: highly contaminated; a PLI value of one indicates only baseline levels of pollutants present and values above one indicate progressive contamination of the soil.