Table 7.
Mean risk factor, Er, values for Ag, Cd and Sb with standard deviation; the RI for the sum of risk factors and the contribution, in percentage, of Ag, Cd and Sb to the RI in sediment from the five stormwater ponds
| Pond | Er-Ag1 | Er-Cd1 | Er-Sb1 | RI2 | % Ag of RI | % Cd of RI | % Sb of RI | % Ag + Cd + Sb of RI |
|---|---|---|---|---|---|---|---|---|
| A |
147 ± 11 Class 3 |
93 ± 16 Class 3 |
267 ± 75 Class 4 |
593 Class 3 |
25 | 16 | 45 | 86 |
| B |
421 ± 102 Class 5 |
182 ± 44 Class 4 |
528 ± 143 Class 5 |
1248 Class 4 |
34 | 15 | 42 | 91 |
| C |
18 ± 2 Class 1 |
31 ± 0 Class 1 |
22 ± 4 Class 1 |
134 Class 1 |
14 | 23 | 16 | 53 |
| D |
129 ± 66 Class 3 |
111 ± 54 Class 3 |
321 ± 150 Class 5 |
646 Class 4 |
20 | 17 | 50 | 86 |
| E |
17 ± 3 Class 1 |
25 ± 12 Class 1 |
48 ± 27 Class 2 |
117 Class 1 |
16 | 20 | 39 | 75 |
1The risk of single element was classified as according to Håkanson (1980), and here, for convenience, it has been given a numeric classification: Class 1 Low potential ecological risk Er < 40; Class 2 Moderate potential ecological risk 40 ≤ Er < 80; Class 3 Considerable ecological risk 80 ≤ Er < 160; Class 4 High potential ecological risk 160 ≤ Er < 320 and Class 5 Very high ecological risk Er > 320
2The RI, the sum of the risk factors, was classified according to Håkanson (1980), and here, for convenience, it has been given a numeric classification: Class 1 Low ecological risk RI < 150; Class 2 Moderate ecological risk 150 ≤ RI < 300; Class 3 Considerable ecological risk 300 ≤ RI < 600; Class 4 Very high ecological risk RI ≥ 600