Denitrification in Permeable Continental Shelf Sediments on the South Atlantic BightEPA Grant Number: FP916364
Title: Denitrification in Permeable Continental Shelf Sediments on the South Atlantic Bight
Investigators: Rao, Alexandra M.F.
Institution: Duke University
EPA Project Officer: Just, Theodore J.
Project Period: January 1, 2004 through December 31, 2006
Project Amount: $79,609
RFA: STAR Graduate Fellowships (2004) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Fellowship - Oceanography and Coastal Processes , Aquatic Ecosystems
Denitrification rates and pathways are being investigated in continental shelf sediments of the South Atlantic Bight (SAB). This region, covering 90,600 km2 on the southeastern U.S. seaboard, is dominated by permeable, nonaccumulating medium- to coarse-grained sands. Despite low organic carbon content, recent measurements have demonstrated the presence of significant metabolic activity presumably supported by filtration of organic matter advectively transported into the seabed. The objective of this study is to contribute to our understanding of the fate of fixed nitrogen in permeable shelf sediments and the potential role of continental shelves in the marine nitrogen cycle.
Sediment flow-through reactor experiments have been conducted with unamended seawater and 15N-labelled nitrate additions to constrain the nitrogen budget for these sediments. Preliminary results indicate that denitrification occurs in the presence of oxygen, probably within suboxic microenvironments and closely coupled to in situ nitrification. Coupled nitrification-denitrification may quantitatively consume regenerated nitrogen within the upper oxic zone of SAB sediments.