Résumé - Abstract
Acid mine drainage (AMD) is a significant environmental concern at many hard rock mines. Laboratory-based predictive tests are often used to determine whether AMD will be generated by mine wastes, but these tests generally do not explicitly examine the role of microbes in acid-generating processes. The present study proposes that given the flexibility of their design and operation, as well as their ability to reproduce field conditions more closely than other related tests, leaching columns are likely the best available apparatus for examining microbially-mediated weathering processes in mine wastes. This study extends the capabilities of the advanced customizable leach columns (ACLCs) developed by Okane Consultants to enable monitoring of microbial communities throughout the duration of the tests. The main objectives of this work are to: (1) track microbial community changes in the ACLCs and in the leachates over time; and (2) examine the relationship between community changes and the geochemical evolution of the system. In this study, typical geochemical and mineralogical characterizations will be performed alongside microbiological analyses. A combination of culture-dependent and culture-independent microbiological analyses will be used. Microbes will be enriched and/or isolated from the waste material and characterized using DNA analyses to identify key genera responsible for sulfur and iron oxidation. In addition, DNA will be extracted from solids and leachates at several timepoints to perform high-throughput sequencing of the 16S rRNA gene. This method provides a fingerprint of the composition and diversity of microbial communities. The results from this study will be used to improve methodologies for incorporating microbiological analyses into routine kinetic column testing.