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Zinc isotopes as tracers of nutrient cycling and carbon uptake by the past oceans

Project information

Grant agreement ID: 41562

  • Start date

    1 January 2007

  • End date

    31 December 2008

Funded under:

FP6-MOBILITY

Coordinated by:

UNIVERSITY OF BRISTOL

United Kingdom

Objective

Changes in atmospheric CO2 concentrations, recorded in ice-cores, may force up to 50% of the temperature change during Quaternary climate change. The 'biological pump', by which carbon is sequestered from the atmosphere and transferred to the deep ocean, is one of the key processes that control atmospheric carbon dioxide concentrations on these timescales. Variation in the strength of this pump is one of the most popular hypotheses to explain the ice-core data.

A strengthened biological pump during glacial periods requires higher primary productivity in the surface ocean and increased trace metal supply to certain key regions of the ocean is a potential mechanism to achieve this. We have no robust proxies for the past trace metal content of the surface ocean. The host institution for this proposal has been pioneering a new approach involving the isotopes of zinc (Zn). Early findings show, firstly, that the light Zn isotopes are preferentially taken up by marine primary producers.

Secondly, the Zn isotopic composition of dissolved Zn in trace-metal limited zones of the surface ocean show that surface waters are enriched in heavy isotopes relative to continental input. These observations suggest that Zn isotopes could provide a record of the degree of trace metal limitation in the past surface ocean, and hence the efficiency with which the surface ocean takes up atmospheric carbon dioxide.

The objectives of this proposal are to apply this tracer, using diatom opal as a substrate, to the past oceans, specifically to regions of the present surface ocean that are trace metal limited (S. Ocean and N. Pacific) but which have been suggested to have been released from it during glacial periods.

Leaflet | Map data © OpenStreetMap contributors, Credit: EC-GISCO, © EuroGeographics for the administrative boundaries

Coordinator

UNIVERSITY OF BRISTOL

Address

Senate House, Tyndall Avenue
N/A Bristol

United Kingdom

Project information

Grant agreement ID: 41562

  • Start date

    1 January 2007

  • End date

    31 December 2008

Funded under:

FP6-MOBILITY

Coordinated by:

UNIVERSITY OF BRISTOL

United Kingdom