Description:
<jats:title>Abstract</jats:title><jats:p>A flue dust originaly enriched in metal sulfides evolved as a by‐product of Cu smelting. The dust was deposited as slurry in unsealed heaps. It is characterized by very high contents of toxic metals such as Pb and Zn. The slurry is a source of soil, sediment, and water contamination. We studied a Technosol profile developed from deposited flue‐dust slurry by means of chemical and mineralogical characterization (SEM‐EDX, XRD, FTIR, DTA‐MS, XRF, Pb isotopes), by open‐flow and closed‐flow column experiments on contaminant release under water‐saturated conditions, and by geochemical modeling to evaluate release processes and to quantify aqueous contaminant concentrations. Besides ash particles and quartz, the flue‐dust slurry contains Fe oxides, silicates, sulfates, and sulfides (in varying states of weathering). In both column approaches, metal concentrations exceed inspection values. The concentration patterns in both experimental column approaches indicate near‐equilibrium mineral dissolution. Geochemical modeling reveals partial dissolution of sulfates and precipitation of secondary carbonates. Their precipitation prevents complete sulfate dissolution, which would have led to even higher aqueous metal concentrations and contaminant export. The combination of detailed material characterization, column experiments, and modeling allows for quantitative and qualitative estimation of contaminant release into the soil solution.</jats:p>