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

有证据表明，在上一个冰河时期，更多的二氧化碳储存在深海中，随着地球变暖，二氧化碳被释放到大气中。这有几种可能发生的方式。在最后一个冰河时代之后，当海水中的藻类总量减少时，二氧化碳就会被释放出来。或者，深海中储存的二氧化碳量可能会随着深海洋流的不同路径而改变。最近的研究表明，印度洋可能在其中一个或两个过程中发挥重要作用。从印度洋收集的新沉积物岩心将被用于研究化学成分的细微变化，这将为科学家提供一种记录二氧化碳在海洋和大气之间长期移动的方法。美国自然历史博物馆的社交媒体平台将用于制作海洋环流和气候的短视频片段和可视化，与教育工作者和公众分享。经过几十年的研究，冰川海洋中二氧化碳封存的物理控制与生物控制的问题仍未得到解决。在冰期，温盐环流、南大洋通风和养分利用的变化都被认为对大气CO2的减少发挥了重要作用。为了更好地了解二氧化碳的生物转移与物理转移的不同作用，需要检查多个海洋盆地中的多个水团。科学目标是通过确定末次冰期-间冰期过渡期间印度洋内部水体中Delta14C和氧合的时间演化和垂直分布（使用定量代理：delta - delta13cuel -globo和烯酮保存），重建南印度洋碳储量的大小和驱动机制。选择这些指标是为了区分水团循环速率和呼吸驱动的CO2积累速率，以评估这些机制在CO2固存中所起的作用。跨纬度和经度使用多个沉积物岩心是确定大西洋和太平洋中海洋二氧化碳储存的关键指标（δ - 14c和氧合）随着时间的推移存在很大差异的基础。这里提出的工作将利用近30年来南印度洋的第一个新核心材料，填补我们在知识方面的实质性空白。我们从深度（1118到3164米）选择了三个合适的岩心，这些岩心被主要的内部水体所沐浴，这些水体反映了该地区今天呼吸和循环驱动的二氧化碳储存。这里产生的结果将是该地区首次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。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.