My current research focus involves coal mine passive remediation systems and the microbial communities that live within them. I currently study four passive systems (see Field Sites for more information) built to treat circumneutral mine drainage (two) and acidic mine drainage (two). I seek to not only understand how bacterial communities influence mine drainage remediation, but also how these contaminated systems influence change in the bacterial communities (i.e. community composition shifts, growth adaptations, metal resistance acquisition, etc.)
DISSERTATION RESEARCH IN DR. NANCY TRUNS LAB (DUQUESNE UNIVERSITY) My dissertation work was completed in Dr. Nancy Trun's lab at Duquesne University (Pittsburgh, PA), where the lab focuses on the microbial communities present in passive remediation and their impact (positive and negative) on the system. The lab uses both classical microbiology and Next-generation sequencing to test hypotheses.
My first aim was to identify the spatiotemporal changes acting on Passive remediation systems designed to treat abandoned mine drainage. I completed four seasonal studies at Passive Remediation sites in Pennsylvania (Wingfield Pines, Lowber, Middle Branch, and Boyce Park). These studies determined that there were seasonal impacts on both the water quality and microbial communities living within the system (Read More Here).
My second aim looked at the differences between abiotic (geochemical) and biotic (microbial) influences on passive remediation systems through a series of lab based studies. The overarching goal of my research was to identify the impacts bacterial communities have on passive remediation systems. This was accomplished by studying iron and sulfur cycling occurring in these systems, which is understudied in passive remediation systems. My research confirmed that the iron oxidation occurring in the acidic passive systems was a result of biotic processes. Furthermore more, my research revealed that nitrate-dependent iron oxidation was occurring. This work identified symbiotic relationships between bacterial partners that couple nitrate reduction with iron oxidation. A better understanding of the biogeochemical cycling happening in passive remediation systems will provide insight on optimization and long-term efficiency of these systems.
While passive systems have great success at removing metal contamination from the system, sulfate remediation is often eluted in these systems. The third aim of my dissertation investigated the lack of sulfate reduction occurring in circumneutral passive systems and the potential for driving sulfate reduction. My work showed that there was a high relative abundance of sulfate reducing and sulfur oxidizing bacteria present in these systems despite no net change is sulfate levels. Further investigation revealed that that sulfate reducing bacteria were not only present, but metabolically capable of complete sulfate reduction when supplemented with a viable carbon source in 5 circumneutral mine drainage systems in southwestern Pennsylvania. This suggests that even in high aeration systems, sulfate reduction may easily be driven through the addition of compost, leading to an overall more efficient system.