Data Description

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Citation:
Ziveri, P et al. (2012): Experimental data of CO2, CO3, Omega calcite saturation, pH values, alpha and epsilon fractionation factors, and Dd18O calctite-water. doi:10.1594/PANGAEA.808168,
Supplement to: Ziveri, Patrizia; Thoms, Silke; Probert, Ian; Geisen, Markus; Langer, Gerald (2012): A universal carbonate ion effect on stable oxygen isotope ratios in unicellular planktonic calcifying organisms. Biogeosciences, 9, 1025-1032, doi:10.5194/bg-9-1025-2012
Abstract:
The oxygen isotopic composition (d18O) of calcium carbonate of planktonic calcifying organisms is a key tool for reconstructing both past seawater temperature and salinity. The calibration of paloeceanographic proxies relies in general on empirical relationships derived from field experiments on extant species. Laboratory experiments have more often than not revealed that variables other than the target parameter influence the proxy signal, which makes proxy calibration a challenging task. Understanding these secondary or "vital" effects is crucial for increasing proxy accuracy. We present data from laboratory experiments showing that oxygen isotope fractionation during calcification in the coccolithophore Calcidiscus leptoporus and the calcareous dinoflagellate Thoracosphaera heimii is dependent on carbonate chemistry of seawater in addition to its dependence on temperature. A similar result has previously been reported for planktonic foraminifera, supporting the idea that the [CO3]2- effect on d18O is universal for unicellular calcifying planktonic organisms. The slopes of the d18O/[CO3]2- relationships range between -0.0243 per mil/(µmol/kg) (calcareous dinoflagellate T. heimii) and the previously published -0.0022 per mil/(µmol/kg) (non-symbiotic planktonic foramifera Orbulina universa), while C. leptoporus has a slope of -0.0048 per mil/(µmol/kg). We present a simple conceptual model, based on the contribution of d18O-enriched [HCO3]- to the [CO3]2- pool in the calcifying vesicle, which can explain the [CO3]2- effect on d18O for the different unicellular calcifiers. This approach provides a new insight into biological fractionation in calcifying organisms. The large range in d18O/[CO3]2- slopes should possibly be explored as a means for paleoreconstruction of surface [CO3]2-, particularly through comparison of the response in ecologically similar planktonic organisms.
Project(s):
Mediterranean Sea Acidification in a Changing Climate (MedSeA) *
Parameter(s):
#NameShort NameUnitPrincipal InvestigatorMethodComment
1Species *SpeciesZiveri, Patrizia *
2Carbon dioxide, partial pressure *pCO2µatmZiveri, Patrizia *
3Carbonate ion concentration *CO3**2-µmol/kgZiveri, Patrizia *
4Calcite saturation state *SI CalZiveri, Patrizia *Omega calcite
5pH *pHZiveri, Patrizia *total scale
6Fractionation factor *Frac FactorZiveri, Patrizia *alpha(chi-H2O), calcite-water
7Fractionation factor *Frac FactorZiveri, Patrizia *epsilon(chi-H2O), calcite-water
8Delta delta 18O *Dd18Oper milZiveri, Patrizia *d18Ocalcite - d18Owater vs. PDB
License:
CC-BY Creative Commons Attribution 3.0 Unported
Size:
192 data points

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