| Atmospheric Nitrogen Inputs to the Ocean and their Impact
T Jickells (1), K. Altieri (2), D. Capone (3), E. Buitenhuis (1), R. Duce (4), F. Dentener (5), K. Fennel (6), J. Galloway (7), M. Kanakidou (8), J. LaRoche (9), K. Lee (10), P. Liss (1), J. Middleburg (11), K. Moore (12), S. Nickovic (13), G. Okin (14), A. Oschilies (15), J. Prospero (16), M. Sarin (17), S. Seitzinger (18), J. Scharples (19), P. Suntharalingram (1), M. Uematsu (20), L. Zamora (21)
Atmospheric nitrogen inputs to the ocean have been identified as an important source of nitrogen to the oceans which has increased greatly as a result of human activity. The significance of atmospheric inputs for ocean biogeochemistry were evaluated in a seminal paper by Duce et al., 2008 (Science 320, 893-7).
In this presentation we will update the Duce et al 2008 study estimating the impact of atmospheric deposition on the oceans. We will summarise the latest model estimates of total atmospheric nitrogen deposition to the ocean, their chemical form (nitrate, ammonium and organic nitrogen) and spatial distribution from the TM4 model. The model estimates are somewhat smaller than the Duce et al estimate, but with similar spatial distributions. We will compare these flux estimates with a new estimate of the impact of fluvial nitrogen inputs on the open ocean (Sharples submitted) which estimates some transfer of fluvial nitrogen to the open ocean, particularly at low latitudes, compared to the complete trapping of fluvial inputs on the continental shelf assumed by Duce et al. We will then estimate the impact of atmospheric deposition on ocean primary productivity and N2O emissions from the oceans using the PlankTOM10 model.
The impacts of atmospheric deposition we estimate on ocean productivity here are smaller than those predicted by Duce et al impacts, consistent with the smaller atmospheric deposition estimates. However, the atmospheric input is still larger than the estimated fluvial inputs to the open ocean, even with the increased transport across shelf to the open ocean from low latitude fluvial systems identified.
1. School of Environmental Science University of East Anglia UK
2. Energy Research Centre University of Cape Town SA
3. Department of Biological Sciences University of S California USA
4. Departments of Oceanography and Atmospheric Sciences
Texas A&M University USA
5. JRC Ispra Italy
6. Department of Oceanography Dalhousie University Canada
7. Department of Environmental Sciences U. Virginia USA
8. Department of Chemistry, University of Crete, Greece
9. Department of Biology Dalhousie University, Canada
10. School of Environmental Science and Engineering Pohang University S Korea.
11. Faculty of Geosciences University of Utrecht Netherlands
12. Department of Earth System Science University of California at Irvine USA
13. WMO Geneva
14. Department of Geography University of California USA
15. GEOMAR Keil Germany
16. Department of Atmospheric Sciences, University of Miami, USA
17. Geosciences Division at Physical Research Laboratory, Ahmedabad, India
18. Department of Environmental Studies, University of Victoria, Canada
19. School of Environmentak Sciences, U Liverpool UK
20. Center for International Collaboration, Atmosphere and Ocean Research Institute, The University of Tokyo Japan
21. Oak Ridge Associated Universities USA |