Managed Aquifer Recharge (MAR) is a key strategy for meeting increased groundwater demands. However, previous studies have revealed that MAR operations can oxidize arsenic-bearing sulfide minerals such as arsenopyrite and mobilize arsenic. Arsenopyrite oxidation can also form ferrihydrite, which attenuates arsenic. It is therefore vital to characterize MAR-induced redox changes to better predict arsenic fate and transport. In this study, we probed the effects of injected water constituents on redox equilibrium, focusing on arsenic mobilization and secondary mineral precipitation, using a combination of inductively coupled plasma-mass spectrometry and solid phase characterization, including atomic force microscopy, X-ray absorption spectroscopy, and X-ray photoelectron spectroscopy. We found the formation of oxidized iron overlayers in systems equilibrated with atmospheric oxygen. Additionally, chloride presence in reclaimed water and model systems inhibited near-surface iron oxidation, increasing arsenic mobility. This study provides valuable insight into redox processes influencing arsenic mobilization during MAR.

Redox processes influencing arsenic mobilization and attenuation at mineral-water interfaces during managed aquifer recharge

245th National Meeting (2013)

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