 |
| Titel |
Lack of Southern Ocean paleoproductivity changes in biogenic aerosol records in the EPICA ice cores |
| VerfasserIn |
P. Kaufmann, F. Fundel, H. Fischer, E. Wolff, M. Hansson, R. Udisti, J. P. Steffensen, M. De Angelis, D. Wagenbach |
| Konferenz |
EGU General Assembly 2009
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250026982
|
|
|
|
|
|
| Zusammenfassung |
| The Southern Ocean (SO) has been recognized as a key player in explaining glacial/interglacial
carbon dioxide changes. In general two principal hypotheses have been put forward to explain
a glacial drawdown of carbon dioxide in the SO: a) changes in SO overturning circulation and
b) an enhanced biological export production in the SO due to iron fertilization. The latter is
suggested by the 20 times higher glacial dust flux found in Antarctic ice cores. However,
observational evidence for an enhanced biological productivity in the glacial SO is
controversial and modeling studies show only a limited capacity of additional carbon uptake
by iron fertilization.
Here we present the first high-precision records of biogenic ammonium from the
two EPICA ice cores reflecting biomass production in the SO. These records show
essential no glacial/interglacial change in ammonium deposition fluxes indicating no
change in atmospheric ammonium concentrations and, thus, also little change in the
biological productivity in SO surface waters in the glacial. The result from the
ammonium record is corroborated by the lack of glacial/interglacial changes in biogenic
sulfate, essentially reflecting DMS producing plankton species in the seasonal sea ice
zone.
Both ammonium and sulfate fluxes show secondary changes on the order of 20-30%,
which are within the uncertainty of the accumulation rate estimate used to calculate
deposition fluxes. Nevertheless we investigate in how far these minor changes may be related
to dust deposition, sea ice coverage as well as aerosol transport. |
|
|
|
|
|
|