Nonequilibrium leaching behavior of metallic elements (Cu, Zn, As, Cd, and Pb) from soils collected from long-term abandoned mine sites
[Display omitted] •Leachate concentration of As and Pb is controlled by recalcitrant pool while other metals by readily leachable pool.•Both batch and column experiments exhibit the initial flush export followed by lower steady-state export.•Steady-state leaching is perturbed by initial seepage and...
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Veröffentlicht in: | Chemosphere (Oxford) 2015-09, Vol.134, p.150-158 |
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Sprache: | eng |
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•Leachate concentration of As and Pb is controlled by recalcitrant pool while other metals by readily leachable pool.•Both batch and column experiments exhibit the initial flush export followed by lower steady-state export.•Steady-state leaching is perturbed by initial seepage and more likely by repeated drying–wetting cycle.•The nonequilibrium leaching is likely due to conversion between recalcitrant and leachable forms.
Leaching of metallic elements (Cu, Zn, As, Cd, and Pb) from two mine-impacted soils (DY and BS) was evaluated by batch decant-refill and seepage flow experiments. During eight consecutive leaching steps, aqueous As concentrations remained relatively constant (approx. 1.6 and 0.1mgL−1 for DY and BS, respectively), while Cu (0.01–3.2mgL−1), Zn (0.2–42mgL−1), and Cd (0.004–0.3mgL−1) were quickly reduced. The reduction of Pb concentration (0.007–0.02mgL−1 and 0.2–0.9mgL−1 for DY and BS, respectively) was much lesser. This pattern was well-explained by the biphasic leaching model by allocating a large fast leaching fraction (ffast>0.2) for Cu, Zn, and Cd while a negligible ffast for As and Pb ( |
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ISSN: | 0045-6535 1879-1298 |
DOI: | 10.1016/j.chemosphere.2015.04.018 |