Dataset belonging to "Impact of seawater inorganic carbon chemistry on element incorporation in foraminiferal shell carbonate" Version 3

Reconstruction of the marine inorganic carbon system relies on proxy signal carriers, such as element / calcium (El/Ca) ratios in foraminiferal shells. Concentrations of boron, lithium, strontium, and sulfur have been shown to vary with carbonate system parameters, but when comparing individual proxy reconstructions based on these elements they are rarely in complete agreement. This is likely caused by the simultaneous effects of multiple environmental factors on element incorporation. Culture experiments with benthic foraminifera have revealed that the shell’s S/Ca reflects the carbon chemistry and can potentially be used as a proxy for seawater [CO32-]. Aiming to investigate the application potential of sulfur incorporation for carbonate speciation reconstruction, we present S/Ca ratios in five planktonic foraminiferal species, namely G. bulloides, G. ruber albus, G. ruber ruber, T. sacculifer, and N. incompta from core-top sediments in regions with contrasting [CO32-], [HCO3-], temperature, and salinity. Analyses of B/Ca and Mg/Ca ratios are included here since these elements have been shown to depend to a certain degree on carbon system parameters (e.g. calcite saturation state and pH, respectively) as well. Moreover, foraminiferal Mg/Ca values are covarying with S/Ca values and thereby might compromise its proxy application. In contrast to previously published results, this new dataset shows a positive correlation between the incorporation of sulfur in the foraminifer’s shell and seawater [CO32-]. As the incorporation of sulfur and magnesium are positively correlated, S/Mg values of the same foraminifer may be used to improve inorganic carbon system reconstructions.