| T value and significance | ||||||
| Hg | As | Pb | Cd | Zn | Cu | Cr |
January | 18.01*** | 1.48 NS | 1.97 NS | 3.48*** | 7.55*** | 8.06*** | 4.08*** |
April | 5.14*** | 9.82*** | 2.5* | 3.15** | 2.95** | 6.98*** | 5.73*** |
July | 6.23*** | 4.89*** | 2.21* | 2.37* | 4.37*** | 6.64*** | 8.59*** |