Earth Science Department Seminar

Monday, April 1, 2019 2:00 pm - 2:00 pm EDT

Life in the critical zone: microbial interactions and biogeochemical cycling on the edge

Dr. Allyson Brady
School of Geography and Earth Sciences
McMaster University

Microorganisms play a crucial role in the underlying biogeochemical processes that occur within the Critical Zone where the geosphere, atmosphere, hydrosphere, and biosphere intersect. Yet, how these physical, chemical, and biological processes are coupled and at what spatial and temporal scales is not well constrained. Microbial activity and interactions governing the transport of nutrients and pollutants, biogeochemical cycling and weathering are still not well understood and largely remain a black box. Key questions persist regarding, for example, how microbial diversity changes throughout Critical Zone profiles and what environmental factors impact biotic weathering processes.

Extreme environments are model systems in which to investigate these fundamental interactions and to identify biosignatures that may be used to study microbial activity. These environments offer a glimpse into often extensive biogeochemical cycling that can occur as well as into the distinctive communities that drive these interactions. My research applies organic biomarker and natural abundance isotope analysis (13C, 14C) to investigate biogeochemical processes in dynamic microbial ecosystems. Past and current projects include cycling of carbon in Antarctica, linking habitability and weathering of terrestrial basalts in Hawaii, and microbial ecology of terrestrial geothermal springs. Studying microbial interactions and biogeochemical cycling within the Critical Zone has important implications for understanding processes that shape the surface of the Earth and support life, including impacts of climate change on soil health and freshwater resources.