Impacts of land cover and land use change on the nitrogen dynamics of the Chesapeake Bay over the past 100 years

Cathy Feng, Virginia Institute of Marine Science, cyfeng@vims.edu
Marjorie Friedrichs, Virginia Institute of Marine Science, marjy@vims.edu (Presenter)
Hanqin Tian, Auburn University, tianhan@auburn.edu
Qichun Yang, Auburn University, qzy0001@tigermail.auburn.edu
Raymond Najjar, The Pennsylvania State University, rgn1@psu.edu

Land cover and land use (LCLU) in the Chesapeake Bay watershed has greatly changed over the past century due to population growth. To quantify how these changes have modified the nitrogen dynamics of the Chesapeake Bay, a land-estuarine-ocean biogeochemical modeling system (DLEM-ROMS-ECB) has been applied to the Chesapeake Bay for the first five years of the 20th century and the first 5 years of the 21st century. These two time periods were characterized by similar riverine inputs of fresh water, but very different inputs of inorganic nitrogen. Over this time period, population growth increased by ~230% and urban land development increased by ~260%. Although cropland decreased over this time period (by ~50%), fertilizer usage increased significantly, resulting in a ~50% increase in riverine dissolved inorganic nitrogen input and a smaller ~15% increase in riverine total organic nitrogen input. Our DLEM-ROMS-ECB simulations indicate that these population growth and LCLU changes resulted in a ~50% increase in net ecosystem production and denitrification, a ~30% increase in burial loss, and a ~60% increase in ocean export of total organic nitrogen. The transport of inorganic nitrogen to the shelf was small in both time periods, but was directed out of the Bay in the early 20th century and into the Bay in the early 21st century.

Presentation Type:  Poster

Session:  Theme 2: Landscapes to coasts: understanding Earth system connections   (Mon 1:30 PM)

Associated Project(s): 

• Friedrichs, Marjy: U.S. Eastern Continential Shelf Carbon Cycling (USECoS): modeling, data assimilation and analysis ...details

Poster Location ID: 80