Table 1 Nemerow multi-factor pollution, potential and comprehensive ecological indices.
Nemerow multi-factor pollution index, NIPI | ||
|---|---|---|
NIPI ranges | Pollution grades | |
≤0.7 | Clean | |
0.7 < NIPI ≤ 1 | Cautionary | |
1 < NIPI ≤ 2 | Light pollution | |
2 < NIPI ≤ 3 | Medium pollution | |
NIPI > 3 | Heavy pollution | |
Potential (\(E_{\text{r}}^{i}\)) and comprehensive (RI) ecological harm indices rating for the heavy metal | ||
|---|---|---|
\(E_{\text{r}}^{i}\) range | RI range | Ecological pollution grades |
<40 | <150 | Light ecological risk |
40–79 | 150–299 | Middle ecological risk |
80–159 | 300–600 | Strong ecological risk |
160–320 | >600 | Very strong ecological risk |
>320 | <150 | Extremely strong ecological risk |