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Modeling the impact of iron and phosphorus limitations on nitrogen fixation in the Atlantic Ocean
Horn Point Laboratory, University of Maryland Center for Environmental Science, P.O. Box 775, 2020 Horns Point Road, Cambridge, MD, 21613 USA
Abstract. 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 N2 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 N2 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 (1.8×1012 moles N yr−1 from 10° N–30° N, 3.4×1012 moles N yr
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Citation: Coles, V. J. and Hood, R. R.: Modeling the impact of iron and phosphorus limitations on nitrogen fixation in the Atlantic Ocean, Biogeosciences Discuss., 3, 1391-1451, 2006. Bibtex EndNote Reference Manager
