Decoupling of iron and phosphate in the global ocean

Iron (Fe) is an essential micronutrient for marine phytoplankton often limiting phytoplankton growth due to its low concentration in the ocean and thus playing a role in modulating the ocean's biological pump. In order to understand controls on global Fe distribution, the decoupling between Fe and P04 and the sensitivity of surface nutrient concentrations to changes in aeolian iron supply, I use a hierarchy of ocean circulation and biogeochemistry models. I formulate a mechanistic model of iron cycling which includes scavenging onto sinking particles and complexation with an organic ligand. The iron cycle is coupled to a model of the phosphorus cycle. The aeolian source of iron is prescribed. This system is examined in the context of a highly idealized box model. With appropriate choice of parameter values, the model can be brought into consistency with the relatively sparse ocean observations of iron in the oceans. I implement this biogeochemical scheme in a coarse resolution ocean general circulation model, guided by the box model sensitivity studies. This model is also able to reproduce the broad regional patterns of iron and phosphorus. In particular, the high macro-nutrient concentrations of the Southern Oceans result from iron limitation in the model. I define a tracer, Fe* that quantifies the degree to which a water mass is iron limited. Surface waters in high nutrient, low chlorophyll regions have negative Fe* values, indicating Fe limitation, because aeolian surface dust flux is not sufficient to

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Earth, Atmospheric, and Planetary Sciences.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2003

Author dc:creator

• Parekh, Payal

Advisor dc:contributor.advisor

• John C. Marshall and Edward A. Boyle.

• Earth, Atmospheric, and Planetary Sciences.
• Joint Program in Oceanography/Applied Ocean Science and Engineering.
• Woods Hole Oceanographic Institution.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/59512

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/59512