Collaborative Research: Disentangling physical and biological controls on Indian Ocean carbon storage during the last glacial-interglacial transition

有证据表明，在上一个冰河时代，更多的二氧化碳储存在深海水域，并随着地球变暖而释放到大气中。有几种方式可以实现这一点。在上一次冰河时代之后，当海水中的藻类总量减少时，二氧化碳可能会释放出来。或者，储存在较深海水中的二氧化碳的数量可能会随着深水洋流的不同路径而变化。最近的研究表明，印度洋可能在这两个过程中的一个或两个过程中发挥重要作用。从印度洋新收集的沉积物岩心将被检查化学成分的细微变化，这将为科学家提供一种方法来记录二氧化碳如何在很长一段时间内在海洋和大气之间移动。美国自然历史博物馆的社交媒体平台将被用来制作海洋环流和气候的短视频片段和可视化，与教育工作者和普通公众分享。经过几十年的研究，冰川海洋二氧化碳封存的物理控制与生物控制的问题仍然没有得到解决。在冰川期间，温盐环流的变化、南大洋的通风和养分的利用都被认为在减少大气二氧化碳方面发挥了重要作用。要更好地理解二氧化碳的生物转移和物理转移的不同作用，就需要研究多个海洋盆地中的多个水团。科学目标是通过确定最后一次冰川-间冰期过渡期间印度洋内部水团中Delta14C和氧合(使用Delta-Delta13Cwuel-Globo和烯酮保存)的时间演变和垂直分布，重建驱动南印度洋碳储存的规模和机制。选择这些指标来区分水质量循环和呼吸驱动的二氧化碳积累的速度，以评估这些机制在二氧化碳封存中所起的作用。在确定海洋二氧化碳储存的关键指标(Delta14C和氧合作用)在大西洋和太平洋随着时间的推移有很大不同方面，使用了横跨纬度和经度的多个沉积物岩芯。这里提出的工作将利用南印度洋近30年来的第一批新的核心材料，填补我们知识上的一大空白。我们从深度(1,118至3,164米)选择了一套三个合适的岩芯，这些岩芯沐浴在主要的内部水团中，反映了当今该地区由呼吸和循环驱动的二氧化碳储存。在这里创建的结果将是第一个使用这些技术来确定南印度洋二氧化碳储存的规模和机制的领域。该奖项反映了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。

Evidence suggests more carbon dioxide was stored in deep ocean waters during the last ice age and released to the atmosphere as the Earth warmed. There are several ways that this might happen. Carbon dioxide could be released when the total amount of algae in ocean waters decreases after the last ice age. Or the amount of carbon dioxide stored in the deeper ocean waters could change with differing pathways of deep currents. Recent work suggest the Indian Ocean might play an important role in one or both of these processes. Newly collected sediment cores collected from the Indian Ocean will be examined for subtle changes in the chemistry that will provide scientists a way to document how carbon dioxide moves between the oceans and atmosphere over long periods of time. The social media platform of the American Museum of Natural History will be used to produce short video segments and visualizations of ocean circulation and climate to share with educators and the general public. The question of physical versus biological controls of CO2 sequestration in the glacial ocean remains unresolved after decades of research. During glaciations, changes in thermohaline circulation, Southern Ocean ventilation, and nutrient utilization are all believed to have played an important role in reducing atmospheric CO2. An improved understanding of the different roles of biological transfer versus physical transfer of CO2 requires examining multiple water masses in multiple ocean basins. The scientific objective is to reconstruct the magnitude and mechanisms driving carbon storage in the southern Indian Ocean by determining the temporal evolution and vertical distribution of Delta14C and oxygenation (using quantitative proxies: Delta-delta13Cwuel-globo, and alkenone preservation) in Indian Ocean interior water masses across the last glacial-interglacial transition. These proxies have been chosen to distinguish between the rate of water mass circulation and respiration-driven CO2 accumulation to assess the roles these mechanisms played in CO2 sequestration. The use of multiple sediment cores across latitude and longitude has been fundamental in determining that critical indicators of oceanic CO2 storage (Delta14C and oxygenation) differed substantially in the Atlantic and Pacific through time. Work proposed here will fill a substantial gap in our knowledge by making use of the first new core material from the Southern Indian Ocean in nearly 30 years. We have selected a suite of three suitable cores from depths (1,118 to 3,164 m) that are bathed by the major interior water masses that reflect both respiration and circulation driven CO2 storage in the region today. Results created here will be the first from this area using these techniques to determine the magnitude and mechanisms of Southern Indian Ocean CO2 storage.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.