Table 1.
Physicochemical characteristics of samples from three sites in Bulgaria polluted by uranium mining activities, expressed as means ± standard deviation (n = 15).
| Parameter | D | BC | BuhC | BuhD | Sliv |
|---|---|---|---|---|---|
| pH | — | — | 6.9 ± 0.3 | 6.6 ± 0.2 | 7.5 ± 0.3 |
| OM | % | — | 2.8 ± 1.3 | 1.6 ± 1.0 | 0.3 ± 0.1 |
| NO3-N | mg/kg | — | 21.6 ± 12.9 | 9.4 ± 6.6 | 19.9 ± 11.0 |
| SO4 | mg/kg | — | 786 ± 95.0 | 1300 ± 142.0 | 151 ± 14.0 |
| As | mg/kg | 3.84 | 274 ± 13.01 | 72.4 ± 2.81 | 412 ± 22.01 |
| Cd | mg/kg | 0.15 | 2.4 ± 1.31 | 1.1 ± 1.2 | 2.7 ± 1.81 |
| Co | mg/kg | ND | 29.5 ± 1.2 | 27.2 ± 1.2 | 22.4 ± 1.4 |
| Cr | mg/kg | 51.00 | 89.6 ± 2.6 | 95.2 ± 7.4 | 8.6 ± 1.9 |
| Cu | mg/kg | 47.34 | 236 ± 11.41 | 101 ± 21.0 | 3410 ± 87.01 |
| Ni | mg/kg | 36.41 | 75.2 ± 13.4 | 98.4 ± 8.91 | 37.0 ± 11.0 |
| Pb | mg/kg | 19.19 | 674 ± 39.41 | 126 ± 16.3 | 5160 ± 49.91 |
| Zn | mg/kg | 54.98 | 448 ± 52.01 | 464 ± 23.11 | 1270 ± 98.41 |
| U | mg/kg | 0.3–11* | 200 ± 21.2 | 78.4 ± 8.7 | 374 ± 11.2 |
| TIAs | — | — | 1.63 ± 0.08 | 0.43 ± 0.02 | 2.45 ± 0.13 |
| TICd | — | — | 0.03 ± 0.01 | 0.01 ± 0.00 | 0.03 ± 0.02 |
| TICo | — | — | 0.05 ± 0.00 | 0.05 ± 0.00 | 0.04 ± 0.00 |
| TICr | — | — | 1.26 ± 0.03 | 1.34 ± 0.1 | 0.12 ± 0.02 |
| TICu | — | — | 6.74 ± 0.32 | 2.88 ± 0.60 | 97.43 ± 2.50 |
| TINi | — | — | 0.75 ± 0.13 | 0.98 ± 0.09 | 0.37 ± 0.11 |
| TIPb | — | — | 1.03 ± 0.06 | 0.19 ± 0.02 | 7.90 ± 0.08 |
| TIZn | — | — | 3.89 ± 0.45 | 4.03 ± 0.00 | 11.04 ± 0.86 |
| TIsum | — | — | 15.38 | 9.91 | 119.38 |
1Value above the maximum allowable concentration referring to Bulgarian legislation [47]. *Values according to UNSCEAR [48]. ND: no data; n: number of samples; D: dimension; BC: background concentrations referring to Bulgarian legislation [47]; TIsum: sum of toxicity indices of heavy metals (except U) and metalloid As.