Geology Club Seminar

At the intersection of both terrestrial and aquatic environments, floodplains are hotspots for microbial diversity and biogeochemical reactions which influence surface-groundwater water quality and regional land-water interactions for more than 1 in 10 Americans. Despite their importance, little is known about the structure and function of the microbial communities in these environments. Furthermore, past studies have primarily examined bacterial and archaeal communities with 16S rRNA primer sets that separately target each domain, thereby limiting holistic interpretations of the overall microbial communities. Thus, depth-resolved knowledge of microbial community diversity and distribution within the terrestrial subsurface is extremely limited, but is needed to understand biogeochemical perturbations initiated by the water cycle.

Applying complementary molecular approaches to field-based and laboratory studies, this work explores the net effect of microbial ecology and geochemistry on key biogeochemical cycles below-ground. This talk explores how the position and behavior of sediment-groundwater interfaces drive spatio-temporal trends in microbial diversity and metabolic function. High-throughput sequencing results for 250+ samples from five sites (down to 6 m depth) revealed the simultaneous detection of diverse, rare archaeal and bacterial taxa, reflecting microbial diversity observed worldwide. Pairing depth-resolved genomics with detailed geochemical measurements over drought-to-flood conditions, hydrologic transition regimes are the primary driver for microbial niche partitioning in the terrestrial subsurface and hold possible implications for water quality.