Ocean Acidification- Category 1: Real time assessment of ocean acidification proxies and their incorporation in the marine sediment record

在过去两个世纪里，大量和迅速的二氧化碳释放到大气中，并由此被海洋吸收了其中的很大一部分，导致海洋化学发生了可测量的变化，最明显的是pH值和碳酸根离子浓度的下降。在过去的200年里，大气中二氧化碳的这种变化及其对海水化学的伴随影响并不是唯一的，而是在整个地质历史中经常发生的。量化海洋对大气CO2中这种自然发生的变化的响应，为模拟和预测与人为增加CO2相关的海洋化学未来变化提供了有价值的见解。这项工作探讨了三个碳酸盐离子和pH值代理（重量，B/Ca和硼同位素组成的浮游有孔虫壳）使用15年的时间序列的沉积物捕获样品和水柱化学测量收集每两周的Cariaco盆地海洋时间序列的一部分。这些结果将与在时间序列现场进行的上层水柱碳酸根离子和pH值的每月测量结果进行比较。高沉积速率，分层沉积物积累在Cariaco盆地将用于直接比较这三个有孔虫pH值代理和大气CO2记录在过去两个世纪，在此期间，CO2增加了约100 ppmv的变化。研究的最终产品将是对这些广泛使用的pH值代理进行深入的现场校准。资金支持研究生，并为本科生参与研究提供机会。

The large and rapid release of CO2 into the atmosphere over the past two centuries and resultant uptake of a significant fraction of this by the oceans have resulted in measurable changes in ocean chemistry, most notably decreases in both pH and carbonate ion concentration. This change in atmospheric CO2 during the last 200 years and its concomitant effect on seawater chemistry are not unique but rather have occurred frequently throughout geologic history. Quantifying the response of the oceans to such naturally occurring changes in atmospheric CO2 provides valuable insights for modeling and predicting future changes in ocean chemistry associated with anthropogenic increases in CO2. This work examines three carbonate ion and pH proxies (weight, B/Ca and boron isotope composition of planktonic foraminiferal shells) using the 15-year time series of sediment trap samples and water column chemistry measurements collected biweekly as part of the Cariaco Basin ocean time series. These results will be compared to monthly measurements of upper water column carbonate ion and pH made at the time series site. High deposition rate, laminated sediments accumulating in the Cariaco Basin will be used to make a direct comparison between changes in these three foraminiferal pH proxies and the atmospheric CO2 record for the last two centuries, a period during which CO2 has increased by ~100 ppmv. The end product of the research will be an in-depth field-calibration of these widely used pH proxies. Funding supports a graduate student, and provides opportunities for undergraduate involvement in research.