Experimental investigation of the impact of pH on colloid-associated metal mobility in mine-impacted wetland sediment

Metal mining operations generate waste rock that is affected by mineral weathering reactions and can produce acidic metal-rich leachate. Leachate pH can have direct impacts on metal mobility by changing metal solubility, and through colloid-facilitated metal transport, potentially increasing metal transport downgradient of the waste rock. This work presents a set of laboratory column experiments that study the effect of colloids on metal mobility in wetland sediment impacted by the drainage from a sulfide-bearing abandoned waste-rock pile. The fully-saturated experiments investigate pH conditions ranging from 2.5 to 7, varying flow rates 45 to 90 m/yr, and measured metal concentrations in leachate filtered at 10 μm, 1 μm, 0.1 μm, and 0.01 μm. Results indicate that metal mobility is higher at lower pHs for Al, Mn, Fe, Cu, Cd, and Zn, but the impact of the smallest colloids studied (i.e., <0.01 μm) is reduced as the pH decreases and metal transport is dominated by the dissolved phase. ..., , # Experimental investigation of the impact of pH on colloid-associated metal mobility in mine-impacted wetland sediment

Dataset DOI: [10.5061/dryad.tb2rbp0h7](https://doi.org/10.5061/dryad.tb2rbp0h7)

## Description of the data and file structure

Saturated column experiments were used to study the impact of pH on the association of metal contaminants (Al, Mn, Fe, Cu, Pb, Cd, and Zn) with colloids in mine-impacted wetland sediment. Columns were leached with metal- and colloid-containing solutions that had pH values of 2.5, 4, 5.5, and 7, were then filtered through filter pore sizes of 10, 1, 0.1, and 0.01 micrometers. Unfiltered samples were used to determine total colloid concentrations and pH, and filtered samples were analyzed with Inductively Coupled Plasma Mass Spectrometry (ICP-MS) for metal and major element (Na, Mg, K, Ca) concentrations. In all files, empty cells indicate elements that were below detection limits (for all ICP-MS data) or were not measured due to equipment avai..., ,