Women Advancing River Research: Audrey Sawyer

The recording for this seminar is now available

ABSTRACT:

Streambed tapestries: Stream-groundwater mixing and relationships with morphology, metals, and microbes
Mountain streams are under pressure from changing climate, land use, and water demand. These pressures influence the natural hydrologic connection between streams and aquifers and the biogeochemistry of both surface water and groundwater. In order to understand these connections in the bed of one mountain stream—East River, Colorado—we mapped stream-groundwater (hyporheic) exchange, water chemistry, and microbial communities at high spatial resolution during summertime baseflow conditions. We found elevated dissolved manganese concentrations and more recalcitrant dissolved organic carbon (DOC) in regions of groundwater upwelling. These regions also had distinct microbial assemblages. In seasonal observations and numerical models, the spring snowmelt season introduced DOC to the streambed that stimulated respiration of manganese-oxides. During the baseflow season, upwelling groundwater delivered dissolved manganese that reacted with oxygen from surface water to form manganese-oxide precipitates. These manganese-oxides can act as important sorption sites for contaminant metals, and their seasonal occurrence will likely change with surface water-groundwater interactions in a warming climate.

BIOGRAPHY: 

Audrey Sawyer is an associate professor of earth sciences at The Ohio State University. The focus of her research is surface water-groundwater interaction in rivers and coastal waters. She is the recipient of a U.S. National Science Foundation CAREER Award and the Kohout Early Career Award in Hydrogeology from the Geological Society of America. Sawyer earned a bachelor's degree in geology and environmental engineering from Rice University in 2004, a master's degree in geoscience from the Pennsylvania State University in 2007, and a doctoral degree in geological sciences from the University of Texas-Austin. 

Additional Information:

Lecture begins at 11 a.m. U.S. Eastern time (New York) and will be followed by a question and answer session. Registration is required prior to the free event.