Evolution of South Pacific Oxygen and Preformed Nutrient Changes over the Deglaciation

深海中的氧浓度，再加上对营养物质和海水温度的测量，为理解海洋中碳的循环和大气中二氧化碳的数量提供了强有力的制约。这项研究使用深海沉积物岩心作为这些关键环境变量自上一个冰期高峰期以来的变化的记录器，这一时期包括地球气候系统的根本性转变。资金用于培训一名研究生，以及一名K-12教师和她的两名高中生。培训活动还将包括对海洋科学表现出兴趣的代表性不足群体的成员参加。这些数据将提供给社区，并将引起那些试图了解海洋中碳循环的人们的广泛兴趣。更具体地说，这项研究将进一步开发一种有希望的方法来定量重建深海中的氧--底栖有孔虫和深海有孔虫(Dd13C)的碳同位素值之间的差异。使用这项技术，研究小组将产生过去25,000年来南太平洋氧气浓度的记录。这段时间涵盖了一个重大的气候过渡时期，当时大气中的二氧化碳浓度从冰川时代的低水平上升到工业化前的较高水平。估计底水磷酸盐(底栖有孔虫中使用Cd/Ca)和底水温度(底栖有孔虫中使用Mg/Ca和Li/Ca)将在相同的沉积岩心中使用。结合氧气重建，磷酸盐和温度信息将被用来估计深水离开水面的区域的营养物质含量(预制营养物质)。氧气和预制营养物质变化的时间和幅度将有助于理解海洋生物和循环的变化如何有助于在上一个冰期降低二氧化碳。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Oxygen concentrations in the deep ocean, in combination with measurements of nutrients and seawater temperature, provide a powerful constraint for the understanding cycling of carbon in the ocean and the amount of atmospheric carbon dioxide. This research uses deep sea sediment cores as recorders of changes in these key environmental variables since the peak of the last ice age, a period encompassing a fundamental shift in the Earth's climate system. Funding supports training of a graduate student, along with a K-12 teacher and two of her high school students. The training activities will also include the participation of members of under-represented groups who have demonstrated interest in the Ocean Sciences. The data will be made available to the community and will be of broad interest to those seeking to understand the cycling of carbon in the ocean.More specifically, this research will further develop a promising method for the quantitative reconstruction of oxygen in the deep ocean-- the difference between carbon isotope values of epibenthic and deep infaunal foraminifera (Dd13C). Using this technique, the research team will generate records of oxygen concentrations in the South Pacific over the last 25,000 years. This time period covers a major climatic transition when atmospheric carbon dioxide concentrations rose from the low levels of glacial times to the higher values of the pre-industrial present. Estimates bottom water phosphate (using Cd/Ca in benthic foraminifera) and bottom water temperature (using Mg/Ca and Li/Ca in benthic foraminifera) will be made using in the same sediment cores. Combined with the oxygen reconstructions, phosphate and temperature information will be used to estimate the nutrient content in the regions where the deep water left the surface (preformed nutrients). The timing and magnitude of the changes in oxygen and preformed nutrients will help to understand how changes in ocean biology and circulation contributed to the lowering in carbon dioxide during the last ice age.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.