Colloids in abandoned mine drainage (AMD) likely play a role in the rate of deposition of iron to the streambed as reactive intermediates between the initial oxidation of Fe<sup>2+</sup> and the precipitation of macroscopic ferric oxyhydroxides. Additionally, as reactive surfaces for the adsorption or co-precipitation of trace metals, colloidal particles affect the fate and transport of other contaminants associated with AMD. In order to understand the chemical and hydrological variables that control the formation and stability of colloids in AMD, we compared water samples taken from several different locations in the Shamokin Creek Basin within the Western Middle Anthracite coalfield of Pennsylvania. Discharge sites with contrasting characteristics were chosen in order to explore the effects of variables such as dissolved Fe and sulfate concentrations, pH, and total metal loading. Colloidal samples were concentrated using tangential flow ultrafiltration and analyzed by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and x-ray diffraction (XRD) to identify mineralogy and organic composition and inductively coupled plasma mass spectrometry (ICP-MS) to determine trace metal composition. Analyses revealed differences in colloid composition between sites, providing preliminary data on the variables that affect the role of AMD colloids in metal transport.

Characterization of colloids in abandoned mine drainage

253rd National Meeting (2017)

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