洋流向海洋沉积物输送的风成土、浮冰碎片（IRD）和被侵蚀的大陆碎屑，为了解地球系统过程和气候提供了重要的见解。
这项研究使用过去15万年来自非洲西南部亚南极南大洋的深海岩芯TN057-6中，大陆衍生（岩性）馏分的Sr-Nd-Pb同位素比率，利用贝叶斯框架中的混合模型集来确定源区域并量化其相对贡献和通量。研究人员将这些数据与平行核心海洋钻探计划站点1090的代用数据，和来自潜在南美洲气流尘源区（PSAs）的新呈现数据进行比较，以便对大气、海洋和冰层动力学进行综合调查。
在冰川/间冰期时间尺度上，PSA的输入量各不相同，寒冷期，南美洲南部的来源占岩性分数的88%（主要是Patagonia，提供高达68%），而在间冰期，南部非洲的来源更重要。
在末次冰期较暖的海洋同位素阶段(MIS) 3，岩石生成通量有时是较冷的MIS2和MIS4的两倍，并且显示出独特的同位素比率，可用南极衍生的可能来自Weddell海的浮冰碎片来解释。浮冰碎片的输入有时贡献高达41%，随后是南极千年变暖事件，气温升高，导致冰原边缘不稳定。高浮冰碎片与提高生物可利用铁、养分利用率、高生物生产力和降低大气CO2同步。
总体而言，TN057-6沉积物记录了南半球系统的气候变化和冰冻圈变化，这些变化在冰期/间冰期和冰下时间尺度上影响了生物地球化学循环。
附：英文原文
Title: Patagonian dust, Agulhas Current, and Antarctic ice-rafted debris contributions to the South Atlantic Ocean over the past 150,000 years
Author: Barkley, Anne E., Winckler, Gisela, Recasens, Cristina, Kaplan, Michael R., Koffman, Bess G., Calabozo, Fernando, Middleton, Jennifer L., Anderson, Robert F., Cai, Yue, Bolge, Louise, Longman, Jack, Goldstein, Steven L.
Issue&Volume: 2024-7-23
Abstract: Disentangling inputs of aeolian dust, ice-rafted debris (IRD), and eroded continental detritus delivered by ocean currents to marine sediments provide important insights into Earth System processes and climate. This study uses Sr-Nd-Pb isotope ratios of the continent-derived (lithogenic) fraction in deep-sea core TN057-6 from the subantarctic Southern Ocean southwest of Africa over the past 150,000 y to identify source regions and quantify their relative contributions and fluxes utilizing a mixing model set in a Bayesian framework. The data are compared with proxies from parallel core Ocean Drilling Program Site 1090 and newly presented data from potential South America aeolian dust source areas (PSAs), allowing for an integrated investigation into atmospheric, oceanic, and cryospheric dynamics. PSA inputs varied on glacial/interglacial timescales, with southern South American sources dominating up to 88% of the lithogenic fraction (mainly Patagonia, which provided up to 68%) during cold periods, while southern African sources were more important during interglacials. During the warmer Marine Isotope Stage (MIS) 3 of the last glacial period, lithogenic fluxes were twice that of colder MIS2 and MIS4 at times, and showed unique isotope ratios best explained by Antarctic-derived IRD, likely from the Weddell Sea. The IRD intrusions contributed up to 41% at times and followed Antarctic millennial warming events that raised temperatures, causing instability of icesheet margins. High IRD was synchronous with increased bioavailable iron, nutrient utilization, high biological productivity, and decreased atmospheric CO2. Overall, TN057-6 sediments record systematic Southern Hemisphere climate shifts and cryospheric changes that impacted biogeochemical cycling on both glacial/interglacial and subglacial timescales.
DOI: 10.1073/pnas.2402120121
Source: https://www.pnas.org/doi/abs/10.1073/pnas.2402120121