Simultaneous measurement of boron isotopes and the boron/calcium ratio in biogenic marine carbonates as a tool to reconstruct the marine carbonate system

大约三分之一的人为排放的二氧化碳溶解在海洋中。这导致pH值下降，通常被称为“海洋酸化”。为了了解海洋，包括其生态系统，将如何对酸化作出反应，可以从地球过去历史中海洋碳酸盐化学的重建中学到很多东西。同时测量碳酸盐（如有孔虫或珊瑚）的硼同位素组成（11B）和硼钙比（B/Ca），可以确定海洋的“酸度”。在本研究中，我们建议同时使用无机沉淀实验和有孔虫培养实验来研究B的掺入，以建立对代理关系的机制理解。然后我们将把校准应用于化石记录。同时测量同一样本上的两个代用物（历时）将使我们能够重建季节性的变化，这是当今气候理解的最重要目标之一。我们将使用来自阿拉伯海的沉积物岩心来重建末次冰期-间冰期旋回期间碳酸盐体系（与季风活动有关）的季节性变化。

About one third of anthropogenically emitted CO2 dissolves in the oceans. This leads to a decrease in pH and is commonly termed “ocean acidification”. In order to understand how the ocean, including its eco-system, will respond to acidification, much can be learned from reconstructions of the ocean carbonate chemistry in the past history of the Earth. The simultaneous measurement of the boron isotopic composition ((11B) and of the boron to calcium ratio (B/Ca) on carbonates , such as foraminifera or corals, would allow to determine ocean “acidity”. In this study, we propose to, investigate the B incorporation using both, inorganic precipitation experiments and foraminiferal culture experiments in order to develop a mechanistic understanding of the proxy relationships. Then we will apply the calibrations to the fossil record. The simultaneous measurement of two proxies on the same sample (diachronous) will allow us to reconstruct changes in seasonality, which is one of the most important targets for present day climate understanding. We will use a sediment core from tha Arabian Sea to reconstruct changes in seasonality of the carbonate system (related to the monsoon activity) during the last glacial-interglacial cycle.