Bowen, J. L. Boston University Marine Program, Marine Biological Laboratory, jlbowen@bio.bu.edu
Kroeger, K. D. Boston University Marine Program, Marine Biological Laboratory, kroeger@bio.bu.edu
Valiela, I. Boston University Marine Program, Marine Biological Laboratory, valiela@bio.bu.edu

 
HISTORICAL CHANGES IN ATMOSPHERIC NITROGEN DEPOSITION, AND ITS IMPACT ON COASTAL SYSTEMS
 
We reviewed existing literature to calculate rates of atmospheric nitrogen deposition to Waquoit Bay from 1900 to the present. In the Waquoit Bay estuary on the south coast of Cape Cod, MA, atmospheric deposition, waste water disposal, and fertilizer use are the main sources of nitrogen to the estuary. Nitrogen deposition to the watershed contributes 46% of the land derived nitrogen load to the estuary. Direct atmospheric deposition to the water surface comprises 31% to the total N load, so total atmospheric deposition contributes 51% to the nitrogen load of Waquoit Bay. The relative importance of atmospheric deposition has changed over time, as has the composition of ions in that deposition. The amount of total dissolved nitrogen has remained relatively constant over time, but there has been a shift from ammonium to nitrate as the dominant constituent in deposition, with nitrate exceeding ammonium around 1940. Most literature values are for wet dissolved inorganic nitrogen. We adjusted these values to include dry deposition, and dissolved organic nitrogen to both the watershed and the estuary. The relative importance of atmospheric deposition to watershed plus open water depend on watershed area, but in any case deliveries of atmospheric nitrogen are particularly important.
 
Day: Wednesday, Feb. 3
Time: 09:45 - 10:00am
Location: Sweeney Center
 
Code: SS50WE0945S