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

南太平洋沙尘供应的冰期和间冰期变化

• 批准号: 412785502
• 负责人: Dr. Torben Struve
• 金额: --
• 依托单位: Lamont-Doherty Earth Observatory
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/412785502?language=en
• 关键词: Glacial; Interglacial; Changes; Dust; Supply

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.

该项目旨在揭示南太平洋尘埃来源变化在过去南半球气候变化中的作用。据推测，冰川时期向缺铁的南大洋提供的粉尘增加，促进了初级生产力的增强，导致大气中二氧化碳的净减少。然而，这一重要的反馈机制被认为迫使气候系统走向完全冰期状态，这取决于南半球沙尘循环的冰期-间冰期变化在纬向上基本同步的假设。初步研究表明，在全新世晚期和末次盛冰期（LGM）期间，澳大利亚的来源对南太平洋的粉尘沉积有很大贡献。然而，横跨LGM南太平洋的沙尘沉积的特点是中南美洲来源的大量贡献在亚南极区占主导地位，而它们在南极区的影响则大大减少。南太平洋地区沙尘来源的这种异质性表明，在各自的沙尘来源地区，沙尘动员可能被抵消，这可能影响了冰川南大洋大气CO2生物减少的效率。为了确定尘埃来源的过去时间变化，本项目采用多代理方法，包括分析从南太平洋沉积物岩心PS75/056-1和PS75/083-1中提取的尘埃分数（<5微米）的稀土元素含量、铅、钕和锶同位素。这两个分别来自亚南极和南极带的记录，将使我们能够重建过去~26万年南太平洋内沙尘来源的变化，并将其与南大西洋的演变时间进行比较。国家和国际项目伙伴将使用相同的岩心来诊断补充参数，包括岩石成因和生物成因颗粒通量的量化，以及重建粉尘源区域的环境条件。与该领域主要专家的共同努力将首次使人们能够全面评估南半球沙尘循环与南大洋生物地球化学之间的联系及其对冰期-间冰期气候变化的意义。