Impact of temperature, salinity and [CO3 2-] on the Mg/Ca and Sr/Ca in benthic foraminifera (Ammonia tepida): results from culture experiments.


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Delphine.Dissard [ at ] awi.de

Abstract

The trace element composition of calcitic foraminiferal tests has become an important tool by which paleoceanographers reconstruct past oceanic conditions. On timescales much shorter than their residence time, the elements strontium and magnesium occur in seawater with nearly constant ratios to calcium. Variation in Sr/Ca and Mg/Ca in benthic foraminiferal tests can then be explained as a function of environmental parameters that control their incorporation into the tests. For benthic foraminifera, temperature appears to be the dominant parameter, however, a better understanding of the possible impact of other parameters such as pH or [CO32-], and salinity is needed to increase the accuracy of element ratio proxies. Towards this goal the benthic foraminifer Ammonia tepida was cultured under three different salinities (20, 33 and 40) and two different pCO2 conditions (120 and 2000ppm), both sets of experiment were run at two different temperatures (10 and 15°C). Weights and elemental composition were determined. Results indicate that both Mg and Sr incorporation are enhanced with increasing temperatures and increasing salinity. Changes in [CO32-] or total dissolved inorganic carbon do not affect the Mg partitioning coefficient. On the contrary, Sr incorporation is enhanced under increasing [CO32-]. Shell weights decrease with decreasing [CO32-], and increase with decreasing temperature.



Item Type
Conference (Poster)
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Not peer-reviewed
Publication Status
Published
Event Details
ASLO Conference, Nizza..
Eprint ID
21078
Cite as
Dissard, D. , Nehrke, G. , Reichart, G. J. and Bijma, J. (2009): Impact of temperature, salinity and [CO3 2-] on the Mg/Ca and Sr/Ca in benthic foraminifera (Ammonia tepida): results from culture experiments. , ASLO Conference, Nizza. .


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