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No abstract

 Users may download and print one copy of any publication from the public portal for the purpose of private study or research.  You may not further distribute the material or use it for any profit-making activity or commercial gain  You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.

No abstract

No abstract

The dissolution of sulfide minerals can lead to hazardous arsenic levels in groundwater. This study investigates the oxidative dissolution of natural As-bearing sulfide minerals and the related release of arsenic under flow-through conditions. Column experiments were performed using reactive As-bearing sulfide minerals (arsenopyrite and lollingite) embedded in a sandy matrix and injecting oxic solutions into the initially anoxic porous media to trigger the mineral dissolution. Noninvasive oxygen measurements, analyses of ionic species at the outlet, and scanning electron microscopy allowed tracking the propagation of the oxidative dissolution fronts, the mineral dissolution progress, and the change in mineral surface composition. Process-based reactive transport simulations were performed to quantitatively interpret the geochemical processes. The experimental and modeling outcomes show that porewater acidity exerts a key control on the dissolution of sulfide minerals and arsenic release since it determines the precipitation of secondary mineral phases causing the sequestration of arsenic and the passivation of the reactive mineral surfaces. The impact of surface passivation strongly depends on the flow velocity and on the spatial distribution of the reactive minerals. These results highlight the fundamental interplay of reactive mineral distribution and hydrochemical and hydrodynamic conditions on the mobilization of arsenic from sulfide minerals in flow-through systems.

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A dispersion-advection model was used to simulate the Elk river chemical spill 2014. The numerical and analytical solutions were used to predict the concentrations of 4-methylcyclohexane methanol (MCHM) at the water treatment plants located along the Elk and Kanawha rivers. The results are of similar magnitude as measured concentrations although a time-lag was found between modeled and measured plume arrival likely due to accumulation of systematic errors. Considering MCHM guidelines for drinking water, the spill represented a serious health threat through the water up taken by the treatment plant located on the Elk river and it also constituted a risk of contamination for the drinking water produced by treatment plants located on the Kanawha river.