| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 6335390 | Applied Geochemistry | 2012 | 9 Pages |
Potentially toxic metals, such as Cu, Pb and Zn, are leached from weathered rocks at many closed mine sites due to the acidic environments and mineralogical modifications. The mobilized toxic metals may cause contamination of surrounding water bodies. In this study, both laboratory column experiments and field observations at a former mine located in the north of Japan were carried out to compare the leaching behavior of Cu, Pb and Zn. The thickness of the surface weathered rock was varied (10, 20 and 30Â cm) for the columns experiments while porous cups for porewater sampling were set up at different depths (GL-15, -45, -70, and -95Â cm) for the field observations. Deionized water was added once a week over 75Â weeks to the columns to simulate rainfall while porewater was extracted by a vacuum pump in several sampling campaigns (over 18Â months). Similar low pH and leaching behavior of potentially toxic metals were observed for column experiments and field observations. A moderate increase in concentration with depth was observed for Cu and Zn. However, no increase in concentration was observed for Pb. This suggests that the leaching of Cu and Zn is enhanced by the length of the flow pathway through the weathered rock layer while Pb concentration is restricted by the precipitation of insoluble Pb sulfate. Thus, the thickness of the weathered rock layer is an important parameter that should be taken into consideration to estimate the loads of some potentially toxic metals, which is important when designing remediation schemes.
⺠Copper, Pb, and Zn leaching from weathered rocks from a former mine were compared. ⺠Potentially toxic metals leaching from columns and field observations were similar. ⺠The pH was acidic and did not fluctuate significantly over the experiments. ⺠Copper and Zn concentrations increased with depth. ⺠Lead concentrations remained unchanged since Pb-Sulfate restricted its solubility.
