Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Journal topic
Volume 6, issue 4
Biogeosciences, 6, 501-513, 2009
https://doi.org/10.5194/bg-6-501-2009
© Author(s) 2009. This work is distributed under
the Creative Commons Attribution 3.0 License.
Biogeosciences, 6, 501-513, 2009
https://doi.org/10.5194/bg-6-501-2009
© Author(s) 2009. This work is distributed under
the Creative Commons Attribution 3.0 License.

  02 Apr 2009

02 Apr 2009

Phosphorus burial in the ocean over glacial-interglacial time scales

F. Tamburini*,1 and K. B. Föllmi2,** F. Tamburini and K. B. Föllmi
  • 1Geological Institute, D-ERDW, ETH Zürich, Zürich, Switzerland
  • 2Institut de Géologie, Université de Neuchâtel, Neuchâtel, Switzerland
  • *now at: Group of Plant Nutrition, D-AGRL, ETH Zürich, Zürich, Switzerland
  • **now at: Institut de Géologie et Paléontologie, IGP, Université de Lausanne, Lausanne, Switzerland

Abstract. The role of nutrients, such as phosphorus (P), and their impact on primary productivity and the fluctuations in atmospheric CO2 over glacial-interglacial periods are intensely debated. Suggestions as to the importance of P evolved from an earlier proposal that P actively participated in changing productivity rates and therefore climate change, to most recent ones that changes in the glacial ocean inventory of phosphorus were important but not influential if compared to other macronutrients, such as nitrate. Using new data coming from a selection of ODP sites, we analyzed the distribution of oceanic P sedimentary phases and calculate reactive P burial fluxes, and we show how P burial fluxes changed over the last glacial-interglacial period at these sites. Concentrations of reactive P are generally lower during glacial times, while mass accumulation rates (MAR) of reactive P show higher variability. If we extrapolate for the analyzed sites, we may assume that in general glacial burial fluxes of reactive P are lower than those during interglacial periods by about 8%, because the lack of burial of reactive P on the glacial shelf reduced in size, was apparently not compensated by burial in other regions of the ocean. Using the calculated changes in P burial, we evaluate their possible impact on the phosphate inventory in the world oceans. Using a simple mathematical approach, we find that these changes alone could have increased the phosphate inventory of glacial ocean waters by 17–40% compared to interglacial stages. Variations in the distribution of sedimentary P phases at the investigated sites seem to indicate that at the onset of interglacial stages, shallower sites experienced an increase in reactive P concentrations, which seems to point to P-richer waters at glacial terminations. All these findings would support the Shelf-Nutrient Hypothesis, which assumes that during glacial low stands nutrients are transferred from shallow sites to deep sea with possible feedback on the carbon cycle.

Publications Copernicus
Download
Citation
Share