Microbial Community, Functioning, and Its Relationship with Heavy Metals in an Urban Brownfield
Date of Award
Doctor of Philosophy (PhD)
College of Science and Mathematics
Earth and Environmental Studies
Thesis Sponsor/Dissertation Chair/Project Chair
Jennifer Adams Krumins
The ubiquity of urban brownfields presents a challenge for environmental managers for managing degraded ecosystems that are in close contact with human habitation. Presence of metal contaminants in brownfields further complicate the matters as it cannot be degraded and hence pose a high risk to human and environmental health, and well-being of the local community. However, previous studies indicate that management and restoration of brownfields are possible through the use of low input longer term and sustainable remediation approaches. These sustainable approaches include the use of plants, fungi, and bacteria to increase soil function and mitigate risks from the contaminants. To improve soil function at brownfields, a thorough understanding of their microbial community composition and their responses to metal contamination is required. This understanding is even more critical in brownfields because each brownfield is different from one another. Brownfields differ not only in contaminants but also soil types and climatic context. Therefore, for any restoration and reclamation efforts in brownfields to materialize, it is essential to study the microbial community composition and understand how they respond to contaminants.
Against this backdrop, this dissertation explores the potential of gentle remediation option by understanding the relationship between the microbial community composition and function at Liberty State Park, a unique urban brownfield. LSP is a unique site because of the abundant growth of under-story and over-story vegetation since its abandonment five decades ago. Since vegetation at this site has flourished well, it provides an opportunity to learn more about this ecosystem, which is in the process of natural restoration. We characterized the microbial community, analyzed phosphatase activity, and quantified the metal contamination. Further, we examined the relationship soil heavy metal concentrations, microbial community, soil organic carbon content, bacterial density, and extracellular phosphatase activity as a proxy of ecosystem functioning.
We also investigated the relative importance of biotic factors (inoculum) and abiotic factors (soil base) on the extracellular enzymatic activities in a reciprocal microbial inoculation experiment. To this end, we cross-inoculated microbial communities between two heavy metal-contaminated soils, with high and low extracellular enzyme activities, respectively. We measured extracellular phosphatase activity, a proxy for soil function, after self- and cross-inoculation of microbial communities into sterilized soils. We also analyzed the microbial community composition and explored its relationship with phosphatase activity.
Finally, we studied the effect of bioaugmentation in chromium spiked, autoclaved soil on plant productivity and soil enzyme function. We also examined the translocation of metal from the soil system to belowground biomass and aboveground biomass. We also analyzed the phosphatase activity to investigate the relationship between soil function and plant-microbe interaction. The dissertation sheds light on the composition and functioning of urban brownfield soils. A deeper understanding of these unique ecosystems can mediate successful remediation, restoration and urban sustainability.
Singh, Jay Prakash, "Microbial Community, Functioning, and Its Relationship with Heavy Metals in an Urban Brownfield" (2019). Theses, Dissertations and Culminating Projects. 312.