Validation of the B/Ca proxy for surface seawater pH and application to measure anthropogenic ocean acidification

可以说，更好地了解地球过去的自然波动？美国的气候及其与温室气体的关系将增强限制未来对海洋和大气化学的影响的能力，从而限制与人为增加二氧化碳有关的全球气候变化。海洋酸化对海洋钙化生物，如珊瑚、翼足类、有孔虫和钙质藻类的潜在影响尤其令人关切。自工业革命以来，海洋酸化的实际程度仍然难以量化。在这个项目中，哥伦比亚大学Lamont Doherty地球观测站的研究人员将通过实验实验室培养和墨西哥湾高分辨率沉积物岩心的结合，研究提出的B/Ca古代用物的稳健性。一项初步研究表明，这一代用物有可能反映冰期/间冰期表层海水pH和大气co2分压的变化。然而，硼在浮游有孔虫壳中的掺入似乎也受到温度的影响，盐度的变化改变了海水硼的浓度。由于海洋中pH、温度和盐度的变化是一致的，因此量化各自对B/Ca的影响只能在实验室中量化，只有在这些参数可以单独列出的情况下才能量化。因此，拟议研究的第一步是在实验室受控条件下进行代理验证。如果B/Ca代用品的质量在实验室培养中得到证实，并且可以量化效果，B/Ca可能比硼同位素/古ph代用品有几个优势：B/Ca分析速度快得多，需要的样品材料少，代用品可能不受沉积物溶解的影响。就更广泛的影响而言，很明显，海水的酸碱状态对海洋学的所有分支学科和各种各样的全球环境研究学科都具有根本的重要性。该项目将以多个机构间合作为特色，并将为研究生提供培训和支持。

Arguably, a better knowledge of past natural fluctuations in the earth?s climate and its relation to greenhouse gases will enhance the ability to constrain future impacts on ocean and atmospheric chemistry, and thus global climate change related to anthropogenic additions of CO2. Particular concern exists regarding the potential impact of ocean acidification on marine calcifiers such as corals, pteropods, foraminifers and calcareous algae. The actual extent of ocean acidification since the industrial revolution is still poorly quantified. In this project, researchers at the Lamont Doherty Earth Observatory of Columbia University will study the robustness of a proposed B/Ca paleoproxy through a combination of experimental laboratory cultures and a high-resolution sediment core from the Gulf of Mexico. A pilot study has shown that this proxy has the potential to reflect glacial/interglacial changes of surface seawater pH and atmospheric pCO2. However, the incorporation of boron into planktonic foraminifer shells also seems to be affected by temperature, and salinity variations change the seawater boron concentration. Because pH, temperature and salinity change in unison in the ocean, quantification of the respective effects on B/Ca can only be quantified in the laboratory, were parameters can be singled out. The first step of the proposed research is therefore the proxy validation under controlled conditions in the laboratory. If the quality of the B/Ca proxy is confirmed in laboratory culture and effects can be quantified, B/Ca could have several advantages over the boron isotope/paleo-pH proxy: B/Ca analyses are much faster, require less sample material, and the proxy may not be affected by dissolution in the sediment. In terms of broader impacts, it is clear that the acid-base state of seawater is of fundamental importance to all subdisciplines of oceanography and to a wide variety of global environmental research disciplines. The project will feature multiple inter-institutional collaborations and will provide for the training and support of a graduate student.