Hannah Veldhuizen

I am working on two different topics that involve answering basic science questions of antimony isotopes and a more applied project looking at leaching of coal ash.

Antimony Isotopes: My research focuses on the use of antimony stable isotopes to determine the fractionation associated with geomicrobiological cycling of Sb(V) and Sb(III). Despite Sb’s increasing use, a limited number of studies exist on its mobility, toxicity, and geochemical reactions. Given that Sb isotopes have not been developed until recently, isotope fractionation factors for most processes of Sb are still unknown. Improving our knowledge of Sb isotope shifts expected in natural systems may lead to successful use of δ¹²³Sb to track immobilization of toxic Sb via reduction reactions. For example, Sb isotope data could provide evidence for Sb(V) reduction in an Sb-contaminated groundwater plume. Similarly, Sb isotope shifts in ancient rocks may provide evidence for changes in the global Sb redox cycle caused by evolving atmospheric O₂, marine anoxic or euxinic events. 

Coal Ash Leaching: Coal ash is a waste product of burning coal that is stored in landfills or coal ash waste ponds. When coal ash comes into contact with water by infiltration of rainwater or direct contact with groundwater, toxic elements such as As, Cr, and Se leach from the coal ash into water. When these toxic elements are released into the environment, they impact humans and wildlife by often exceeding standards for drinking water and surface water. The amount of toxic elements leached from coal ash is dependent on a variety of properties such as pH and redox conditions. Variation in redox conditions is driven by the presence of oxygen in natural environments where oxygen-rich (oxic) and oxygen-poor (anoxic) both exist. The objective of my study is to determine the influence that repeated oscillations of oxic and anoxic conditions have on dissolved redox active elements in a flow-through column simulated coal ash pond. During this experiment, the concentrations of dissolved redox active elements will be monitored to see if the repeated oscillations cause changes to the element’s mobility.