Table 3 Grading of potential ecological hazard indices for single heavy metals/multiple heavy metals.
Level | Single/multiple heavy metal threshold intervals | Risk level |
|---|---|---|
I | Ei<40/RI<150 | Low risk |
II | 40 ≤ Ei<80/150 ≤ RI<300 | Medium risk |
III | 80 ≤ Ei<160/300 ≤ RI<600 | Medium to high risk |
IV | 160 ≤ Ei<320/RI>600 | High risk |
V | Ei>320 | Very high risk |
