Table 2.
Environmental variables of water samples with different pollutant levels.
| Mild | Moderate | Severe | Standard (mg/L)a | |
|---|---|---|---|---|
| pH | 7.10 ± 0.06A | 8.16 ± 0.18B | 7.69 ± 0.18AB | 6~9 |
| NH3-N | 3.39 ± 0.81A | 41.79 ± 8.09B | 451.33 ± 27.53C | 2.0 |
| TP | 9.64 ± 2.52A | 38.63 ± 7.47B | 72.23 ± 7.61C | 0.4 |
| COD | 634.78 ± 264.52A | 422.25 ± 72.57A | 1186.67 ± 455.81A | 40 |
| TN | 76.04 ± 34.00A | 97.11 ± 13.06A | 687.67 ± 142.54B | 2.0 |
| comprehensive pollution index range | 11.63–24.87 | 33.00–37.95 | 156.12 |
a environmental quality standards for surface water (GB3838-2002). Environmental variables were presented as mean ± standard error (SE). A and B indicate significant changes among three groups of ponds. The significance of difference was analyzed by least significant difference (LSD).