| C. | Average | The standard deviation | The average standard deviation | 95% Confidence interval of the difference | t | Df | Sig. (2-tailed) | ||
| Lower | Upper | ||||||||
| 1 Pair | Lead and cadmium summer | −0.0043915 | 0.0071065 | 0.0005025 | −0.0053824 | −0.0034006 | −8 | 199 | 0.000 |
| Pair 2 | Cadmium and cadmium spring summer | 0.0001810 | 0.0010817 | 0.0001082 | −0.0000336 | 0.0003956 | 1 | 99 | 0.097 |
| Pair 2 | Lead and lead spring summer | 0.0033740 | 0.0048634 | 0.0004863 | 0.0024090 | 0.0043390 | 6 | 99 | 0.000 |