Modeling the impact of iron and phosphorus limitations on nitrogen fixation in the Atlantic Ocean

• Main Authors: Coles, V. J., Hood, R. R.
• Other Authors: Horn Point Laboratory, University of Maryland Center for Environmental Science (UMCES), University of Maryland System-University of Maryland System
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2006
• Subjects: [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO]; [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph]; [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces; environment; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Sarmiento; North Atlantic
• Online Access: https://hal.science/hal-00297846; https://hal.science/hal-00297846/document; https://hal.science/hal-00297846/file/bgd-3-1391-2006.pdf

International audience The overarching goal of this study is to simulate subsurface N* (sensu, Gruber and Sarmiento, 1997) anomaly patterns in the North Atlantic Ocean and determine the basin wide rates of N 2 fixation that are required to do so. We present results from an Atlantic implementation of a coupled physical-biogeochemical model that includes an explicit, dynamic representation of N 2 fixation with light, nitrogen, phosphorus and iron limitations, and variable stoichiometric ratios. The model is able to reproduce nitrogen, phosphorus and iron concentration variability to first order. The latter is achieved by incorporating iron deposition directly into the model's detritus compartment which allows the model to reproduce sharp near surface gradients in dissolved iron concentration off the west coast of Africa and deep dissolved iron concentrations that have been observed in recent observational studies. The model can reproduce the large scale N* anomaly patterns but requires relatively high rates of surface nitrogen fixation to do so (1.8×10 12 moles N yr ?1 from 10° N?30° N, 3.4×10 12 moles N yr