Heavy metals | Not polluted | Moderately polluted | Heavily polluted | Present study | Shell value | Continental crust value |
Mn | <300 | 300 - 500 | >500 | 478 - 2211 | 850 | 750 |
Fe | ND | ND | ND | 14,787 - 95,464 | 47,200 | 35,900 |
Cr | <25 | 25 - 75 | >75 | 99 - 290 | 90 | 71 |
Cu | <25 | 25 - 50 | >50 | 23 - 133 | 45 | 32 |
Ni | <20 | 20 - 50 | >50 | 23 - 65 | 68 | 49 |
As | <3 | 3 - 8 | >8 | 55 - 105 | 13 | 10 |
Zn | <300 | 300 - 600 | >600 | 44 - 205 | 95 | 129 |
Pb | <40 | 40 - 60 | >60 | 4 | 20 | 0.3 |
Cd | - | <6 | >6 | BDL | 0.3 | 16 |