Glacial – Interglacial Changes in Dust Supply to the Pacific Southern Ocean

该项目旨在揭示过去南半球气候变化期间南太平洋尘埃来源变化的作用。据推测，冰川增加粉尘供应到铁缺乏的南大洋促进提高初级生产力，导致大气CO2的净下降。这一重要的反馈机制被认为迫使气候系统走向完整的冰川状态，然而，这一假设是基于南半球尘埃循环中的冰川-间冰期变化在很大程度上是同步发生的。初步工作表明，澳大利亚的来源大大有助于在南太平洋的灰尘沉积，在晚全新世和末次冰期最大（LGM）。然而，横跨末次盛期南太平洋的尘埃沉降的特点是来自南美洲中部的主要贡献在亚南极带，而他们的影响在南极区大大减少。南太平洋沙尘源区的这种异质性意味着沙尘活动在各自源区被抵消的可能性，这可能影响了冰川南大洋大气CO2的生物下降效率。从南太平洋沉积物岩心PS 75/056-1和PS 75/083-1中提取的尘埃部分（<5微米）的钕和锶同位素。这两个记录分别来自亚南极带和南极带，将能够重建过去26万年来南太平洋地区的尘埃来源变化，并将其时间与南大西洋的演变进行比较。国家和国际项目合作伙伴将使用相同的岩心诊断补充参数，包括量化岩石和生物颗粒通量以及重建粉尘源区的环境条件。与该领域主要专家的协调努力将首次全面评估南半球尘埃循环与南大洋地球化学的联系及其对冰川-间冰期气候变化的重要性。

This project is designed to unravel the role of changes in South Pacific dust provenance during past Southern Hemisphere climate variations. It has been hypothesized that the glacial increase in dust supply to the Fe-deficient Southern Ocean fostered enhanced primary productivity resulting in a net drawdown of atmospheric CO2. This important feedback mechanism was suggested to have forced the climate system towards full glacial states relying, however, on the assumption that glacial-interglacial changes in the Southern Hemisphere dust cycle occurred zonally largely synchronized. Preliminary work suggests that Australian sources contributed substantially to the dust deposition in the South Pacific, both during the late Holocene and the Last Glacial Maximum (LGM). However, the dust deposition across the LGM South Pacific was characterized by substantial contributions from central South American sources dominating in the Subantarctic Zone whereas their influence in the Antarctic Zone was considerably reduced. Such heterogeneity in dust provenance across the South Pacific implies the possibility that dust mobilization was offset in the respective source areas, which could have influenced the efficiency of biological drawdown of atmospheric CO2 in the glacial Southern Ocean.In order to identify past temporal variations in dust provenance, this project follows a multi-proxy approach comprising the analysis of rare earth element content, lead, neodymium and strontium isotopes of the dust fraction (<5 micrometer) extracted from South Pacific sediment cores PS75/056-1 and PS75/083-1. These two records from the Subantarctic and Antarctic Zone, respectively, will enable the reconstruction of dust provenance changes within the South Pacific across the past ~260,000 years, and to compare their timing with the evolution in the South Atlantic. The same cores will be used by national and international project partners to diagnose complementary parameters including the quantification of lithogenic and biogenic particle fluxes as well as reconstructions of environmental conditions in the dust source regions. The concerted effort with leading experts in the field will, for the first time, allow to comprehensively assess the link of the Southern Hemisphere dust cycle with Southern Ocean biogeochemistry and their significance for glacial-interglacial climate variations.