Getting a Nitrogen Fix

Biogeochemist Karen Casciotti is working to understand how microorganisms affect the exchange of excess nutrients (principally nitrate) between groundwater and the coastal ocean. Casciotti and colleagues are using microbiological, molecular, and chemical techniques to understand which nitrogen-metabolizing microbes are present in the Waquoit Bay (Falmouth, Mass.) subterranean estuary and at what rate they are removing nitrogen from the system. (Photo by Tom Kleindinst, Woods Hole Oceanographic Institution)