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Geology Seminar Series - Kaitlyn Crawford, MSc student - An Investigation into the Microbiology and Geochemistry of Kinetic Tests

Wed., Mar. 29, 2023 4:00 p.m. - Wed., Mar. 29, 2023 5:00 p.m.

Location: CW 237.1 and Zoom

Please join us for a graduate student seminar, all are welcome!

Topic: An Investigation into the Microbiology and Geochemistry of Kinetic Tests

Date and Time: Wednesday, March 29, 2023 at 4:00 PM

Location: College West Room 237.1

Zoom Link:

( Meeting ID: 959 6926 1627- - - - Passcode: 617922)

Presenter: Kaitlyn Crawford, Master Student, Dept. of Geology, University of Regina


Laboratory-scale kinetic tests are often used to predict the onset of acid mine drainage (AMD) or contaminated neutral drainage (CND) by evaluating the release rates of metals and ions from mine waste materials. This information guides costly decisions on mine waste management and water treatment. However, there are still gaps in our understanding and interpretation of scaling-up effects in kinetic tests. Humidity cell tests are repeated cycles of wetting and drying tailings samples to accelerate weathering processes and determine drainage characteristics over time. Due to the known role of microorganisms in AMD metal cycling and sulfur oxidation, the objective of the present study is to examine changes in drainage chemistry and the microbial communities present in the tailings, and their relationship to one another during humidity cell experiments. In previous studies, culture-based work has been done on humidity cell tests; however, culture-based work does not capture the full picture in terms of diversity and temporal changes in the microbial communities present. Thus, we are using high-throughput amplicon sequencing at timepoints throughout our study to gain further insight on microbial community changes during the tests. Eight humidity cells were constructed with four tailings samples from two sites in northern Quebec. The humidity cells were operated for 42 weeks, with one set of four cells at 4 °C and the other at room temperature (~22 °C). Preliminary geochemical analyses suggest that the leachates differ in key ion loadings between 4 °C and ambient lab temperatures. As well, some of the typical metal cycling genera of bacteria were found including Thiobacillus, Leptospirillium and other metal resistant bacteria. Understanding the impact of temperature and microbiology on these tests can help to improve our understanding of scale effects. The results of this study will help to guide practitioners in interpreting the results of humidity cell tests, with the overall goal of better informed mine site planning.