Wetlands are a vital landscape noted for water quality improvement and flood protection. They can be restored as riparian zones or imitated as seen in treatment wetlands which are used to treat wastewater, storm water, or acid mine drainage. Observations in treatment wetlands during storm events have shown mass export of copper (Cu), often correlated with high organic matter (OM) and/or iron oxides. However, our ability to predict these exports stems from our limited understanding of the interactions between Fe oxides, OM and Cu seen in binary phase sorption experiments conducted in the laboratory. Studying these interactions will provide insight on the retention and transport of Cu from wetland ecosystems. We hypothesize that as OM content increases, more colloidal phase ternary complexes will be present with higher Cu content. Stock solutions of OM, Fe(NO3)2, and Cu(NO3)2 were combined under fixed ionic strength and pH to mimic the <i>in-situ </i>formation of ternary phase complexes. The samples reacted with Cu for a period of 24 hours and were separated into bulk solid (&gt;0.22 μm), colloidal (&lt;0.22 μm and &gt; 300 Da), and dissolved phases via membrane filtration techniques. Cu isotherms representing partitioning to each size fraction for the range of pH and Fe:OM ratios were used to determine the likely transportable (dissolved and colloidal) Cu from wetlands and their characteristics with regard to relative Fe, Cu, and OM content.<br/>

Partitioning of Cu between size fractions in ferrihydrite and humic acid organominerals

256th National Meeting (2018)

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