| from decades of heavy pollution | 3 | cause |
| highly | 2 | degree |
| seriously | 2 | degree |
| river → be → toxic | 14 |
| river → be contaminated with → toxin | 4 |
| negative | neutral | positive |
| 0.918 | 0.076 | 0.005 |
| Raw frequency | 18 |
| Normalized frequency | 0.311 |
| Modifier score | 0.500 |
| Perplexity | 326.581 |