Abstract
To explain the lower atmospheric CO2 concentrations during glacial periods, it has been suggested that the productivity of marine phytoplankton was stimulated by an increased flux of iron-bearing dust to the oceans1,2. One component of this theory is that iron—an essential element/nutrient for nitrogen-fixing organisms—will increase the rate of marine nitrogen fixation, fuelling the growth of other marine phytoplankton and increasing CO2 uptake. Here we present data that questions this hypothesis. From a sediment core off the northwestern continental margin of Mexico, we show that denitrification and phosphorite formation—processes that occur in oxygen-deficient upwelling regions, removing respectively nitrogen and phosphorus from the ocean—declined in glacial periods, thus increasing marine inventories of nitrogen and phosphorus. But increases in phosphorus were smaller and less rapid, leading to increased N/P ratios in the oceans. Acknowledging that phytoplankton require nitrogen and phosphorus in constant proportions, the Redfield ratio3, and that N/P ratios greater than the Redfield ratio are likely to suppress nitrogen fixation4,5, we suggest therefore that marine productivity did not increase in glacial periods in response to either increased nutrient inventories or greater iron supply.
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References
Falkowski, P. G. Evolution of nitrogen cycle and its influence on the biological pump in the ocean. Nature 342, 637–642 (1997).
Broecker, W. S. & Henderson, G. M. The sequence of events surrounding Termination II and their implications for the cause of glacial-interglacial CO2 changes. Paleoceanography 13, 352–364 (1998).
Redfield, A. C., Ketchum, B. H. & Richards, F. A. in The Sea Vol. 2 (ed. Hill, M. N.) 36–77 (McGraw Hill, London, 1963).
Tyrrell, T. The relative influences of nitrogen and phosphorus on oceanic primary production. Nature 400, 525–531 (1999).
Hood, R. R. et al. Answers sought to the enigma of marine nitrogen fixation. Eos 81, 1–3 (2000).
Ganeshram, R. S., Pedersen, T. F., Calvert, S. E., McNeil, G. W. & Fontugne, M. R. Glacial-interglacial variability in denitrification in the world's oceans: Causes and consequences. Paleoceanography 15, 361–376 (2000).
Codispoti, L. A. & Christensen, J. P. Nitrification, denitrification and nitrous oxide cycling in the eastern tropical South Pacific Ocean. Mar. Chem. 16, 277–300 (1985).
Codispoti, L. A. in Productivity in the Ocean: Past and Present (eds Berger, W. H., Smetacek, V. S. & Wefer, G.) 377–394 (Wiley & Sons, Chichester, UK, 1989).
Delaney, M. L. Phosphorus accumulation in the marine sediments and the oceanic phosphorus cycle. Glob. Biogeochem. Cycles 12, 563–572 (1998).
Brandes, J. A., Devol, A. H., Yoshinari, T., Jayakumar, D. A. & Naqvi, S. W. A. Isotopic composition of nitrate in the central Arabian Sea and eastern tropical North Pacific: a tracer for mixing and nitrogen cycles. Limnol. Oceanogr. 43, 1680–1689 (1998).
Ganeshram, R. S., Pedersen, T. F., Calvert, S. E. & Murray, J. W. Large changes in oceanic nutrient inventories from glacial to interglacial periods. Nature 376, 755–758 (1995).
Jahnke, R. A., Emerson, S. R., Roe, K. V. & Burnett, W. C. Present day formation of apatite on the Mexican continental margin. Geochim. Cosmochim. Acta 47, 259–266 (1983).
Froelich, P. N. et al. Early diagenesis of organic matter in Peru continental margin sediments: Phosphorite precipitation. Mar. Geol. 80, 309–343 (1988).
Schuffert, J. D., Kastner, M. & Jahnke, R. A. Carbon and phosphorus burial associated with modern phosphorite formation. Mar. Geol. 146, 21–23 (1998).
Schenau, S. J., Slomp, C. P. & De Lange, G. Phosphogenesis and active phosphorite formation in sediments from the Arabian Sea oxygen minimum zone. Mar. Geol. 169, 1–19 (2000).
Ganeshram, R. S. & Pedersen, T. F. Glacial-interglacial variability in upwelling and bioproductivity off N. W. Mexico. Paleoceanography 13, 634–645 (1998).
Burnett, W. C. Apatite-glauconite associations off Peru and Chile: palaeo-oceanograpic implications. J. Geol. Soc. Lond. 137, 757–764 (1980).
Garrison, R. E. & Kastner, M. Phosphatic sediments and rocks recovered from Peru margin during ODP Leg 112. Proc. ODP Sci. Res. 112, 111–134 (1990).
Shimmield, G. B. & Mowbray, S. R. The inorganic geochemical record of the Northwest Arabian Sea. Proc. ODP Sci. Res. 117, 409–429 (1991).
Altabet, M. A., François, R., Murray, D. W. & Prell, W. L. Climate-related variations in denitrification in the Arabian Sea from 15N/14N ratios. Nature 373, 506–509 (1995).
Ruttenberg, K. C. Reassessment of the oceanic residence time of phosphorus. Chem. Geol. 107, 405–409 (1993).
Sañudo-Wilhelmy, S. A. et al. Phosphorus limitation of nitrogen fixation by Trichodesmium in the central Atlantic Ocean. Nature 411, 66–69 (2001).
Filippelli, G. M. Controls on phosphorus concentrations and accumulation in oceanic sediments. Mar. Geol. 139, 231–240 (1997).
O'Brien, G. W. & Heggie, D. East Australian continental margin phosphorites. Eos 69, 2 (1988).
Lambourn, L. D., Devol., A. H. & Murray, J. W. R/V New Horizon 90-5 Cruise: Water Column and Porewater Data (Special report no. 110, School of Oceanography, University of Washington, 1991).
Price, N. B. & Calvert, S. E. The geochemistry of phosphorites from the Nambian Shelf. Chem. Geol. 23, 151–170 (1978).
Acknowledgements
We thank A. Devol and J. Murray for the opportunity to collect sediment cores during the NSF-supported voyage 90-5 of RV New Horizon to the Mexican margin. We thank M. Soon and B. Nielsen for carrying out elemental and isotopic determinations, and J. Brandes for permission to use his water column nitrogen isotope data. This work was supported by the Natural Sciences and Engineering Research Council of Canada and the Natural Environment Research Council of the UK.
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Ganeshram, R., Pedersen, T., Calvert, S. et al. Reduced nitrogen fixation in the glacial ocean inferred from changes in marine nitrogen and phosphorus inventories. Nature 415, 156–159 (2002). https://doi.org/10.1038/415156a
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DOI: https://doi.org/10.1038/415156a
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