HR: 0830h
AN: B21D-0743    [PDF]
TI: Changes on a glacial-interglacial timescale in the oceanic inventory of phosphorus and its relation to climate change
AU: * Tamburini, F
EM: federica.tamburini@erdw.ethz.ch
AF: Geological Institute, ETH-Zentrum, Sonneggstrasse 5, Z\"{u}rich, CH-8092 Switzerland
AU: F\"{o}llmi, K B
EM: karl.foellmi@unine.ch karl.foellmi@unine.ch
AF: Geological Institute, University of Neuch\^{a}tel, Rue Emile-Argand 11, Neuch\^{a}tel, CH-2007 Switzerland
AB: Phosphorus (P) is an important nutrient, which, along with other macro- and micronutrients, limits productivity in oceans. On a glacial-interglacial timescale, potential variations in the oceanic inventory of P, which are invoked by changes in the continental weathering regime, may have an impact on global primary production, on CO$_{2}$ drawdown from the atmosphere, and on climate. It is crucial, therefore, to constrain P inventory changes throughout glacial and interglacial periods. We present new data that illustrate how P is distributed in marine sediments and how its inventory changed during the last 150,000 years. We have applied the SEDEX techinique (Ruttenberg, 1992) on sediments from eight different Ocean Drilling Program (ODP) Sites (Northeastern Atlantic; Peru margin; Oman margin; Japan Sea; Ontong Java plateau; North Atlantic; South China Sea). Authigenic and Fe-bound minerals, and organic material represent the principal sinks of reactive P in oceanic sediments. Regardless of the environmental setting and type of sediment, P phases have been detected at all sites. Moreover, average reactive P concentrations are in the same range of values, between 0.3 and 0.6 mg/g. Only concentrations at the Oman and the Peru margin sites fall outside this interval, showing concentrations characteristic of phosphogenesis. Average concentrations calculated over glacial and interglacial periods do not show any significant difference. Changes in P distribution and concentrations in the sediments, and mass accumulation rates seem closely linked to local climatic and oceanographic conditions, but still reflect global processes (i.e., oceanic circulation and climate). On a global average, P accumulation rates in the sediments increased during the last glacial, suggesting a positive relationship between cold climate, increased physical weathering and P sink in the ocean sediments. Reactive P inventory variations seem paced by the precessional cycle (23 kyr), pointing at the ultimate control of low latitude processes on the oceanic P cycle. Ruttenberg, K. C., 1992 - Development of a sequential extraction method for different forms of phosphorus in marine sediments. Limnology and Oceanography, 37(7), 140-1482.
DE: 1030 Geochemical cycles (0330)
DE: 3344 Paleoclimatology
DE: 4835 Inorganic marine chemistry
DE: 4845 Nutrients and nutrient cycling
SC: Biogeosciences [B]
MN: 2003 Fall Meeting