| Trace element | The dredged sediments | The local aquifer sediments | ||||||
---|---|---|---|---|---|---|---|---|---|
 |  | Recent filling | Older | Deep | Shallow | ||||
 |  | No. 4 | No. 5 | No. 2 | No. 1 | No. 7 | No. 9 | No. 6 | No. 8 |
Total extractable fraction (%) | Ag | 69.68 | 33.12 | 31.06 | 11.29 | 4.20 | 4.81 | 2.53 | 6.70 |
 | Cd | 93.70 | 77.32 | 57.30 | 51.11 | 44.64 | 38.73 | 14.53 | 17.89 |
 | Sb | 8.02 | 5.36 | 9.10 | 5.33 | 1.95 | 2.57 | 1.72 | 1.70 |
 | Tl | 13.24 | 9.85 | 12.24 | 5.92 | 4.20 | 7.53 | 9.87 | 6.91 |
 | Pb | 93.55 | 89.68 | 84.89 | 68.65 | 52.06 | 51.83 | 59.93 | 63.40 |
 | Cr | 31.96 | 18.61 | 19.20 | 12.71 | 16.18 | 8.24 | 11.24 | 12.53 |
 | Fe | 34.84 | 32.79 | 32.55 | 26.79 | 23.18 | 27.08 | 18.89 | 26.03 |
 | Ni | 44.37 | 35.91 | 33.64 | 23.96 | 30.59 | 17.75 | 13.61 | 10.88 |
 | Cu | 75.29 | 47.72 | 50.10 | 38.59 | 56.77 | 32.74 | 19.50 | 18.53 |
 | Zn | 87.59 | 68.75 | 59.38 | 31.41 | 43.51 | 27.82 | 16.95 | 17.05 |
 | As | 45.96 | 30.64 | 29.35 | 23.47 | 19.51 | 5.40 | 1.64 | 2.34 |