Table 5.
Contribution (in %) of the individual heavy metals to the ecological risk index (RI), hazard index (HI), and lifetime cancer risk (LCR) at specific sampling areas. Since there is a negligible difference in the contribution by age group (<±0.2%), the values are presented as averages. Distinctly high values that contribute significantly to the risk indices are highlighted in bold. LCR from Ba, Cu, Hg, Mn, Sb, V and Zn were not calculated because these metals are not carcinogenic. Some locations are abbreviated as follows: Tagburos river (Tb river), surrounding soils and sediments (SA), and other rivers (Others). Please refer to Fig. 1A–C for their relative locations.
| Heavy metal | Location | Potential Ecological Risk Index (RI) | Hazard Index (HI) | Lifetime Cancer Risk (LCR) |
|---|---|---|---|---|
| As | PQMI | 0.31 | 2.16 | 1.92 |
| Tb river | 0.48 | 4.06 | 3.44 | |
| Wharf | 2.28 | 9.52 | 14.02 | |
| Honda Bay | 5.16 | 32.95 | 22.96 | |
| SA | 0.38 | 3.54 | 2.09 | |
| Others | 0.40 | 5.09 | 4.01 | |
| Ba | PQMI | 0.03 | ||
| Tb river | 0.17 | |||
| Wharf | 0.02 | |||
| Honda Bay | 0.06 | |||
| SA | 0.12 | |||
| Others | 0.16 | |||
| Cd | PQMI | 0.03 | 0.02 | 0.00 |
| Tb river | 0.08 | 0.07 | 0.00 | |
| Wharf | 0.05 | 0.02 | 0.00 | |
| Honda Bay | 0.20 | 0.14 | 0.00 | |
| SA | 0.04 | 0.04 | 0.00 | |
| Others | 0.04 | 0.05 | 0.00 | |
| Co | PQMI | 0.43 | 0.02 | |
| Tb river | 1.02 | 0.05 | ||
| Wharf | 0.06 | 0.01 | ||
| Honda Bay | 0.84 | 0.03 | ||
| SA | 1.17 | 0.04 | ||
| Others | 1.31 | 0.06 | ||
| Cr | PQMI | 11.84 | 39.07 | 98.00 |
| Tb river | 10.03 | 40.40 | 96.36 | |
| Wharf | 10.50 | 20.73 | 85.92 | |
| Honda Bay | 12.95 | 39.22 | 76.91 | |
| SA | 13.32 | 58.86 | 97.80 | |
| Others | 7.21 | 43.18 | 95.81 | |
| Cu | PQMI | 1.17 | 0.10 | |
| Tb river | 4.09 | 0.42 | ||
| Wharf | 2.63 | 0.13 | ||
| Honda Bay | 9.52 | 0.74 | ||
| SA | 2.31 | 0.26 | ||
| Others | 2.36 | 0.36 | ||
| Hg | PQMI | 31.00 | 45.35 | |
| Tb river | 10.32 | 18.43 | ||
| Wharf | 71.63 | 62.71 | ||
| Honda Bay | 1.97 | 2.65 | ||
| SA | 1.84 | 3.60 | ||
| Others | 2.84 | 7.54 | ||
| Mn | PQMI | 3.44 | 1.89 | |
| Tb river | 25.00 | 16.72 | ||
| Wharf | 1.21 | 0.40 | ||
| Honda Bay | 8.55 | 4.30 | ||
| SA | 15.94 | 11.70 | ||
| Others | 13.47 | 13.39 | ||
| Ni | PQMI | 50.62 | 8.58 | 0.04 |
| Tb river | 44.17 | 9.14 | 0.04 | |
| Wharf | 9.35 | 0.95 | 0.01 | |
| Honda Bay | 57.10 | 8.89 | 0.03 | |
| SA | 62.59 | 14.21 | 0.04 | |
| Others | 70.72 | 21.76 | 0.08 | |
| Pb | PQMI | 0.37 | 0.36 | 0.02 |
| Tb river | 1.64 | 1.96 | 0.11 | |
| Wharf | 0.82 | 0.48 | 0.05 | |
| Honda Bay | 1.66 | 1.49 | 0.07 | |
| SA | 0.54 | 0.71 | 0.03 | |
| Others | 0.38 | 0.68 | 0.04 | |
| Sb | PQMI | 0.66 | ||
| Tb river | 1.44 | |||
| Wharf | 3.98 | |||
| Honda Bay | 6.13 | |||
| SA | 0.46 | |||
| Others | 0.72 | |||
| V | PQMI | 0.82 | 1.32 | |
| Tb river | 3.12 | 6.10 | ||
| Wharf | 1.02 | 0.97 | ||
| Honda Bay | 1.74 | 2.55 | ||
| SA | 2.47 | 5.28 | ||
| Others | 1.96 | 5.69 | ||
| Zn | PQMI | 0.40 | 0.02 | |
| Tb river | 1.07 | 0.07 | ||
| Wharf | 0.51 | 0.02 | ||
| Honda Bay | 1.17 | 0.06 | ||
| SA | 0.58 | 0.04 | ||
| Others | 0.62 | 0.06 |