Development and application of geochemical tracers for paleo and modern oceanography

人为二氧化碳的增加可能会改变未来的气候，我们必须提高我们的预测能力，以决定最佳的社会反应。海洋通过控制大气二氧化碳和重新分配到来的太阳热量，在调节地球气候方面发挥着关键作用。海水中两种天然放射性同位素(230和231pa)的分布为现代海洋中的颗粒动力学、碳通量和深水循环提供了重要信息，可用于更好地量化对气候变化重要的海洋过程。此外，这些同位素在沉积记录中的结合，提供了一种评估这些海洋过程与过去气候变化有关的时间演变的手段，并提供了所需的时间背景，以区分人为活动引起的气候趋势和反复出现的自然周期。我将测量溶解于海水中并与东北和赤道太平洋的海洋颗粒有关的230和231Pa值的详细水柱剖面，这将补充正在进行的大西洋西北部的工作。这些剖面将提供关于深水通风(大西洋)和上升流(太平洋)速率的定量信息，以及关于控制海洋颗粒下沉速率和碳向深海固存的因素的信息。这些信息将被置于更大的时间背景下，利用230和231Pa的沉积记录，进一步记录与第四纪晚期和全新世气候变化有关的碳通量和深水环流的变化。大西洋沉积物提供了对过去深水形成的变化及其在引发气候突然变化中的作用的洞察(由中科院资助的工作)。我将通过整合第230、231Pa和有孔虫的镁/钙比来补充这项研究，这是一项关于太平洋过去环流和生产力变化的多PI、多代理研究。

The rise in anthropogenic CO2 may alter future climate and we must improve our predictive capabilities to decide on optimal societal responses. The ocean plays a critical role in regulating Earth's climate by controlling atmospheric CO2 and by redistributing incoming solar heat. The distribution of two natural radioisotopes (230Th and 231Pa) in seawater provides important information on particle dynamics, carbon fluxes and deep-water circulation in the modern ocean, which can be used to better quantify oceanic processes important for climate change. In addition, the incorporation of these isotopes in the sedimentary record provides a means of assessing the temporal evolution of these oceanic processes in relation to past climate changes and provides the needed temporal context to distinguish between climatic trends induced by anthropogenic activities and recurring natural cycles.I will measure detailed water column profiles of 230Th and 231Pa dissolved in seawater and associated with marine particles in the northeastern and equatorial Pacific which will complement on-going work in the northwestern Atlantic. These profiles will bring quantitative information on ventilation (Atlantic) and upwelling (Pacific) rates of deep water, and on the factors controlling the sinking rates of marine particles and the sequestration of carbon into the deep sea.This information will be placed in a larger temporal context using the sedimentary record of 230Th and 231Pa to further document changes in carbon flux and deep-water circulation associated with climatic shifts during the late Quaternary and the Holocene. Atlantic sediments provide insights into past changes in deep water formation and their role in triggering abrupt climate changes (work funded by CFCAS). I will complement this study by integrating the 230Th, 231Pa, and foraminifera Mg/Ca in a multi-PIs, multiproxy study of past changes in the circulation and productivity of the Pacific Ocean.