DOI: 10.1016/j.epsl.2018.06.004
Scopus记录号: 2-s2.0-85048702526
论文题名: Calibration of Na partitioning in the calcitic foraminifer Operculina ammonoides under variable Ca concentration: Toward reconstructing past seawater composition
作者: Hauzer H. ; Evans D. ; Müller W. ; Rosenthal Y. ; Erez J.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 497 起始页码: 80
结束页码: 91
语种: 英语
英文关键词: live-foraminifera
; Na/Ca calibration
; ocean paleochemistry
; seawater calcium proxy
Scopus关键词: Calcite
; Calibration
; Laser ablation
; Oceanography
; Residence time distribution
; Seawater
; Shells (structures)
; Sodium
; Strontium
; Submarine geophysics
; Uncertainty analysis
; Calcium concentration
; Distribution coefficient
; Experimental conditions
; Laser-ablation-ICP-MS
; live-foraminifera
; Major and minor elements
; Paleochemistry
; Seawater compositions
; Calcium
; calcite
; calcium
; calibration
; Cenozoic
; concentration (composition)
; foraminifera
; paleoceanography
; partitioning
; reconstruction
; seawater
; sodium
; water chemistry
; Foraminifera
; Nummulites
; Operculina ammonoides
英文摘要: Reconstructions of past changes in the seawater calcium concentration (Casw) are critical for understanding the long-term changes in ocean chemistry, the carbon cycle and for accurate application of elemental proxies (El/CaCaCO3) in foraminifera (e.g., Mg/Ca as proxy of temperature). Here we show that Na/Ca ratios in foraminiferal shells could be used for reconstructing Casw and Mg/Ca in the past oceans. Ca has a short residence time in the ocean (∼1 My), whereas Na in seawater has a residence time of ∼100 My. Hence it may be reasonably assumed that Nasw is invariant over the Cenozoic, enabling variations in oceanic Ca to be deduced from foraminiferal Na/Ca (Na/Cashell) if Na incorporation into foraminiferal shells depends on Na/Ca in seawater. Furthermore, the paleo-concentrations of other major and minor elements may then be calculated relative to the Ca in the shells, provided that other environmental or biological factors do not present a further complication. To evaluate this hypothesis, we cultured the benthic foraminifer Operculina ammonoides, an extant relative of the Eocene Nummulites, under varying Casw and temperature. The foraminifera grew well under the experimental conditions and increased their weight by 40–90%. The newly grown calcite (identified using a 135Ba labeling in the experimental seawater) was analyzed by Laser-Ablation ICP-MS for Li, Na, Mg and Sr to Ca ratios. The relationship between Na/Ca and Mg/Ca in the shell and their ratio in the solution are best described as a power function, where the instantaneous distribution coefficient is the derivative of the power fit to the El/Cashell versus El/Casw. In contrast, DSr and DLi are invariant with El/Casw. The influence of temperature on Li, Na and Sr incorporation was smaller than the uncertainty of our measurements. We conclude that Na/Ca in foraminiferal shells can be used to calculate paleo-calcium concentrations in the oceans and also other elements that may change relative to calcium (e.g., Mg, Sr, Li and others). © 2018 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/109777
Appears in Collections: 影响、适应和脆弱性 气候变化事实与影响
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作者单位: The Fredy & Nadine Herrmann, Institute of Earth Sciences, the Hebrew University of Jerusalem, Israel; Department of Geology and Geophysics, Yale University, New Haven, CT, United States; School of Earth and Environmental Sciences, University of St Andrews, St Andrews, United Kingdom; Department of Earth Sciences, Royal Holloway University of London, Egham, United Kingdom; Institute of Geosciences, Goethe University, Frankfurt, Germany; Department of Marine and Coastal Sciences, Department of Earth and Planetary Sciences, Rutgers University, New Brunswick, United States
Recommended Citation:
Hauzer H.,Evans D.,Müller W.,et al. Calibration of Na partitioning in the calcitic foraminifer Operculina ammonoides under variable Ca concentration: Toward reconstructing past seawater composition[J]. Earth and Planetary Science Letters,2018-01-01,497