Chesapeake Bay Nitrogen Fluxes Derived From a Land-Estuarine Ocean Biogeochemical Modeling System: Model Description, Evaluation, and Nitrogen Budgets

Authors

Yang Feng, Virginia Institute of Marine ScienceFollow
Marjorie A.M. Friedrichs, Virginia Institute of Marine ScienceFollow
John Wilkin, Rutgers University–New Brunswick
Hanqin Tian, Auburn UniversityFollow
Qichun Yang, Auburn University
Eileen E. Hofmann, Old Dominion UniversityFollow
Jerry D. Wiggert, University of Southern MississippiFollow
Raleigh R. Hood, University of Maryland Center for Environmental ScienceFollow

Document Type

Article

Publication Date

8-1-2015

Department

Marine Science

School

Ocean Science and Engineering

Abstract

The Chesapeake Bay plays an important role in transforming riverine nutrients before they are exported to the adjacent continental shelf. Although the mean nitrogen budget of the Chesapeake Bay has been previously estimated from observations, uncertainties associated with interannually varying hydrological conditions remain. In this study, a land-estuarine-ocean biogeochemical modeling system is developed to quantify Chesapeake riverine nitrogen inputs, within-estuary nitrogen transformation processes and the ultimate export of nitrogen to the coastal ocean. Model skill was evaluated using extensive in situ and satellite-derived data, and a simulation using environmental conditions for 2001–2005 was conducted to quantify the Chesapeake Bay nitrogen budget. The 5 year simulation was characterized by large riverine inputs of nitrogen (154 × 10⁹ g N yr⁻¹) split roughly 60:40 between inorganic:organic components. Much of this was denitrified (34 × 10⁹ g N yr⁻¹) and buried (46 × 10⁹ g N yr⁻¹) within the estuarine system. A positive net annual ecosystem production for the bay further contributed to a large advective export of organic nitrogen to the shelf (91 × 10⁹ g N yr⁻¹) and negligible inorganic nitrogen export. Interannual variability was strong, particularly for the riverine nitrogen fluxes. In years with higher than average riverine nitrogen inputs, most of this excess nitrogen (50–60%) was exported from the bay as organic nitrogen, with the remaining split between burial, denitrification, and inorganic export to the coastal ocean. In comparison to previous simulations using generic shelf biogeochemical model formulations inside the estuary, the estuarine biogeochemical model described here produced more realistic and significantly greater exports of organic nitrogen and lower exports of inorganic nitrogen to the shelf.

Publication Title

Journal of Geophysical Research G: Biogeosciences

Volume

120

Issue

8

First Page

1666

Last Page

1695

Recommended Citation

Feng, Y., Friedrichs, M., Wilkin, J., Tian, H., Yang, Q., Hofmann, E., Wiggert, J., Hood, R. (2015). Chesapeake Bay Nitrogen Fluxes Derived From a Land-Estuarine Ocean Biogeochemical Modeling System: Model Description, Evaluation, and Nitrogen Budgets. Journal of Geophysical Research G: Biogeosciences, 120(8), 1666-1695.
Available at: https://aquila.usm.edu/fac_pubs/18543