The calcification process of planktic foraminifers and its implication for the incorporation of paleo-oceanographic signals to their shells

在海洋沉积物中发现的浮游有孔虫的外壳经常被用于古海洋学的重建。拟议项目的重点是南极有孔虫的生态学和外壳地球化学。要准确可靠地解释沉积记录中的有孔虫同位素特征，就需要在应用代用品之前详细了解生物物种在其环境中的现代行为。我们的目标是解开和理解和量化的深度依赖钙化的南极有孔虫壳，通过使用最近开发的氧同位素质量平衡模型南极有孔虫壳生长。该模型将使用浮游生物拖和沉积物陷阱收集有孔虫在非洲西北部地区关闭进行测试。将使用一种新技术（二次离子质谱法）进行稳定同位素测定，该技术可对有孔虫方解石试验的连续室进行分析。物种特定的深度栖息地的详细量化，使我们能够进一步调查海水碳酸盐化学（[CO 3 2-]）控制的碳和氧同位素的结合有孔虫方解石在深度集成壳生长过程中垂直整个水柱在非洲西北部地区。在校准特定物种的δ 13 Cshell/[CO 3 2-]关系后，古海洋学家将能够通过应用特定物种的校正因子来估计古记录中的δ 13 CDIC。此外，从水柱和从核心顶部沉积物的有孔虫δ 13 C数据的比较提供了潜在的信息，人为CO2入侵到海洋表层水。量化[CO 3 2-]对氧同位素的影响可能会改善古温度的估计。

The shells of planktic foraminifers found in ocean-sediments are frequently used for paleooceanographic reconstruction. The proposed project focuses on the ecology and shell geochemistry of planktic foraminifers. An accurate and reliable interpretation of foraminiferal isotopic signature in the sedimentary record requires a detailed knowledge of the modern behavior of living species with regard to their environment prior to proxy application. We aim to unravel and understand and quantify the depth dependent calcification of planktic foraminiferal shells by using a recently developed oxygen isotope mass balance model for planktic foraminiferal shell growth. The model will be tested using plankton tow and sediment trap collected foraminifers in the region off NW Africa. Stable isotope determination will be carried out using a new technique (Secondary Ion Mass Spectrometry) which allows analyses of successive chambers of foraminiferal calcite tests. Detailed quantification of species-specific depth habitat allows us further to investigate how the seawater carbonate chemistry ([CO3 2-]) controls the incorporation of carbon and oxygen isotopes into foraminiferal calcite during the depth-integrated shell growth process vertically throughout the water column in the region of NW Africa. After the calibration of the species-specific δ13Cshell/[CO3 2-] relationship, paleo-oceanographers will be able to estimate the δ13CDIC from the paleo-record by applying a species-specific correction factor. Additionally, the comparison of foraminiferal δ13C data from the water column and from core top sediments gives potentially information about invasion of anthropogenic CO2 into the surface ocean water. Quantifying an effect of [CO3 2-] on oxygen isotopes may improve estimation of paleo-temperatures.