Acid mine lakes are the final product of open cut mining operations, and microbial driven biogeochemical processes can significantly influence water quality in these lakes. I investigated the physicochemistry and microbiology of Batman Pit, an acid mine lake located at Mount Todd mine in northern Australia. There were significantly higher levels of metals and lower pH in the Pit water for the wet season sampling compared to the dry season sampling. There was also a significant increase in Fe+3 in the wet season. Microbial abundance and diversity was assessed through the water column to a depth of 90 meters during both the wet and dry seasons. Large-scale 16S rRNA gene sequencing was used to characterise the bacteria and archaea communities. For eukaryotes the 18S rRNA gene was targeted. The archaea community was not influenced by the changes in chemistry and did not change between the wet and dry season. In contrast, the bacteria community changed with season and was influenced by the physicochemical parameters of the water/drainage in the Pit. Bacteria that can cycle iron were detected in both seasons, and Acidiphilium and Leptospirillum dominated this community. In contrast to archaea, the eukaryotic community changed with season and this community shift was partially due to chemistry and possibly also influenced by bacterial diversity and abundance. A metagenomics approach was used as a step towards understanding metabolic processes in this pit lake. Surface water was sampled during the wet season and shotgun sequenced to determine whether iron cycling was a dominant process in the Batman Pit. Iron cycling genes were not recovered, however I gained insight into bacterial processes possibly associated with the detoxification of heavy metals, ammonia oxidation, and carbon fixation. The data suggest that bacteria are key players in Batman Pit and may drive the differences in water quality between the wet and dry season. Any remediation strategies will therefore need to take into account seasonal changes in the water quality that arise due to microbial activity and increased runoff into the Pit.
|Date of Award||Mar 2015|
|Supervisor||Karen Gibb (Supervisor), David Parry (Supervisor) & Claire Streten (Supervisor)|