SEDIMENT DENITRIFICATION

Denitrification, the conversion of oxidized forms of nitrogen to gaseous nitrous oxide or (mostly) dinitrogen (N₂), is a key removal process for nitrogen in aquatic ecosystems. The rate of such loss depends on many factors, including the rate of input of organic matter (mostly algae) to sediments, the oxygen concentration in water, the amount of nitrate in overlying water, the activity of benthic animals, and the presence of photosynthetic algae or submerged grasses. Understanding the balance of nitrogen inputs and losses is important for the management of coastal ecosystems such as the Chesapeake Bay. At HPL, a new approach to measurement using mass spectrometry was developed by Dr. Todd Kana; this approach is now widely used throughout the world. Applications of this new approach have included studies of denitrification and microbial diversity throughout the Chesapeake Bay, across the salinity gradient in the Patuxent River subestuary, in the Choptank River, in Chesapeake Bay shallow water ecosystems, and in the Potomac River. Other applications have included reservoirs, streams, Florida Bay, and Maryland’s coastal bays.