ISC2010

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Presented at the 2nd International Sclerochronology Conference, July 2010, Mainz Germanny.

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ISC2010

  1. 1. The application of bivalve sclerochemistry in reconstructing past Greenland meltwater runoff Emma A. A. Versteegh 1 Martin E. Blicher 2 , Simon R. Troelstra 3 , Frank Dehairs 1 1 Vrije Universiteit Brussels, Belgium; CALMARs project 2 Greenland Climate Research Centre, Nuuk, Greenland 3 VU University Amsterdam, the Netherlands or The quest for a meltwater proxy in Arctic bivalves
  2. 2. Greenland ice cap <ul><li>Sigificantly rising runoff since 1990s </li></ul><ul><li>Ice volume loss: ~80 km 3 /y </li></ul><ul><li>Sea level rise: 0.15 - 0.20 mm/y </li></ul><ul><li>Runoff only known for the last decades  How was this in the past? </li></ul><ul><li> Meltwater proxy? </li></ul>
  3. 3. Mytilus trossulus (Bay mussel) <ul><li>Arctic Mytilus species </li></ul><ul><li>Subtidal (?) </li></ul><ul><li>Recorder of SST (Mg/Ca),  18 O w </li></ul><ul><li>Lives > 22 years </li></ul><ul><li>Present in shell middens </li></ul><ul><li>Can we use  18 O and Mg/Ca of M. trossulus to reconstruct past meltwater fluxes? </li></ul>
  4. 4. Klein et al., (1996)
  5. 5. <ul><li>T(°C) = 2.50 * [(Mg/Ca) * 1000] - 2.07 </li></ul>Klein et al., (1996)
  6. 6. 2008 (3 shells) 1933 2008
  7. 7. Methods <ul><li>Stable isotopes: Micromill, GasBench-II & Finnigan Delta+ </li></ul><ul><li>Trace elements: New Wave UP-193 & Thermo XSeries 2 ICP-MS </li></ul>
  8. 8.  18 O temperature Freshwater
  9. 9. Mg/Ca Mg/Ca (mmol/mol)
  10. 11. Mg/Ca temperature 2008 2006 2004 2003 2002 2001 2000 1999 1998 2005 2007
  11. 12. 2005 2007
  12. 13. 2005 2007
  13. 14. Conclusions <ul><li>Meltwater is visible in  18 O values of, but is not (yet) quantifiable. </li></ul><ul><li>Mg/Ca appears to be related to T, but not like previously described. </li></ul><ul><li>B/Ca and Li/Ca correlate with Mg/Ca (temperature?). </li></ul><ul><li>Ba/Ca shows peaks, typical for marine bivalves. </li></ul><ul><li>Better constrained instrumental (and shell growth) data are needed </li></ul><ul><li> Monitoring experiment. </li></ul>
  14. 15. Chlamys islandica <ul><li>Lifespan > 21 y </li></ul><ul><li>Present in fossil shell assemblages. </li></ul><ul><li>Monitoring experiment, suspended culture at 15 m depth. </li></ul><ul><li>Can we find a meltwater proxy in C. islandica ? </li></ul><ul><li>Salinity? </li></ul><ul><li>Temperature? </li></ul><ul><li>Primary productivity? </li></ul>
  15. 17. Shell growth & T
  16. 18. Shell growth & phytoplankton
  17. 19. Ba/Ca and phytoplankton
  18. 22. Conclusions <ul><li>Growth and Ba/Ca appear to be influenced by phytoplankton / food abundance. </li></ul><ul><li>Several elements show periodic features. Temperature? Organic matrix? </li></ul>
  19. 23. Future work <ul><li> 18 O! </li></ul><ul><li>Look again at conversion distance axis  time axis </li></ul><ul><li>Investigate possible relationship between Ba/Ca / growth / phytoplankton and meltwater amounts / sea ice cover. </li></ul><ul><li>M. trossulus specimens from other Greenland locations (Godthåbsfjord & Nipisat Sound). </li></ul><ul><li>Modelled runoff data for specific shell collection sites </li></ul>
  20. 24. Thank you! Questions?

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