Nicolas Stephens

Max-Planck-Institut für Biogeochemie
Hans-Knöll-Str. 10
07745 Jena
Phone: +49 (3641) 576221
Email: stephens -atnospam- bgc.mpg.de

Postal Address:
Max-Planck-Institut für Biogeochemie
Postfach 10 01 64
07701 Jena

current research | curriculum vitae | publications | carrer development plan (internal)

Current Research: Including the Nitrogen Cycle and Diazotrophs in a Dynamic Green Ocean Model

The Dynamic Green Ocean Model that is being developed, provides the ability to simulate ocean carbon cycling in terms of a physical (OPA) model. Although rapidly advancing the models being developed here, and as part of other research efforts are still relatively primitive. Often the all important biologically mediated feedback cycles are poorly understood and inadequately represented. In conjunction with other studies designed to better understand and implement the more important ocean processes, this study concentrates on the interaction of the nitrogen cycle on potential feedback regulation of the the nitrogen biogeochemistry on sources and sinks of carbon as exerted through marine based biology.
The current version of the model describes the main sources and sinks of nitrogen metabolism in the marine ocean with an enthuses on accounting for the processes of nitrogen fixation in the open ocean. Presently a model that can account for nitrogen fixation as represented by a functional planktonic type (PFT) should provide the ability to better describe fluxes of nitrogen and carbon, and provide a better understanding of the feedback processes exerted through diazotrophic (N2-fixing) growth. In developing the model components to describe N2 fixation in a marine ecosystem, the aim is also to better represent and understand the other fundamental nitrogen assimilatory/ dis-assimilatory processes such as denitrification and the relationship to the availability of other growth limiting nutrients like phosphorus and iron.

For more information please go to www.bgc.mpg.de/~stephens

This project (ER 4) contributes to the science objective 1 (Quantify feedbacks in the global carbon cycle) of GREENCYCLES and has links to the projects of Maciej (ESR IV) and Meike (ESR V).

Publications

Stephens N, Flynn KJ and Gallon JR (2003) The interrelationships between the pathways of inorganic nitrogen assimilation in the cyanobacterium Gloeothece can be described using a mechanistic model. New Phytologist 160: 545-555.