Tracking rare earth elements in an acid mine drainage stream: Lion Creek, Empire, Colorado

Undergraduate Honors Thesis

Citations

Citeable URL: https://scholar.colorado.edu/concern/undergraduate_honors_theses/nc580p28v

Abstract

Acid mine drainage, or acid rock drainage, poses a significant threat to both ecosystems and human communities due to boosted levels of acidity and toxic metal concentrations. Within these systems, dissolved rare earth elements are often found in elevated concentrations, potentially to an economic level. To better understand the mobility and fate of rare earth elements within acid mine drainage systems, Empire, Colorado was chosen as a study site for trace metal analysis. Both in-situ and laboratory measurements were conducted, revealing a strong dependence on Fe and Al concentrations for the sorption of rare earth elements onto the riverbed at this site. More specifically, Al-precipitates present a strong forcing on rare earth element sorption onto the riverbed, while Fe-precipitates don’t, and the formation of these precipitates are largely dependent on the pH of the water. At pH levels greater than 3, the Al-precipitates dominate, leading to much higher concentrations of rare earth elements found sorbed onto the riverbed. This is consistent with previous laboratory experiments and provides more data to an ever-expanding catalog of study in acid mine drainage systems.

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