Station number | Average concentration (µg/l) | |||
Winter | Spring | Summer | Autumn | |
1 | 8.76 | 4.80 | 3.08 | 4.56 |
2 | 6.55 | 3.86 | 2.13 | 3.32 |
3 | 0.076 | 0.028 | 0.008 | 0.022 |