Geology Seminar Series - Kaitlyn Crawford: Humidity Cell Testing: The who, what, when, where, and why

Laboratory-scale kinetic tests are often used to predict the onset of AMD and evaluate the release rates of metals and anions from mine waste materials. This information guides decisions on mine waste management and water treatment. However, there are still gaps in our understanding and interpretation of kinetic tests. The objective of the present study is to examine changes in the chemistry of the leachates produced by the humidity cell experiments and the relationships to the microbial communities in the tailings through time. The Joutel and Eleonore mine sites (QC, Canada) host tailings that are rich in iron and sulfur minerals and have the potential to or already produce harmful acid mine drainage (AMD). Eight humidity cells will be constructed using four samples from each site and will be run for 40-60 weeks or until geochemical equilibrium is attained. Leachates will be tested every week for pH, ORP/Eh, alkalinity, acidity, and electrical conductivity as well as metal and anion concentrations. High-throughput sequencing of the 16s rRNA gene will be performed on DNA from solid and liquid samples to monitor changes in microbial communities over time. Once equilibrium has been reached, the humidity cells will be deconstructed and recharacterized; these results will be compared to the in-situ environments. The results of this study will help to improve prediction techniques to prevent and counter AMD at contaminated sites, as well as for improved mine site planning.