Isotopic constraints on declining oceanic nutrient inventories weakening the marine soft-tissue biological carbon pump during the last deglaciation

末次冰消期期间海洋营养物库存下降的同位素限制削弱了海洋软组织生物碳泵

• 批准号: 445549720
• 负责人: Dr. Christopher Somes, Ph.D.
• 金额: --
• 依托单位: Forschungseinheit Biogeochemische Modellierung
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/445549720?language=en
• 关键词: Isotopic; constraints; declining; oceanic; nutrient

Understanding the mechanisms controlling the nearly 80 ppm increase in atmospheric CO2 concentrations during the last deglaciation (19,000 to 9,000 years before present) remains a major challenge in paleoceanography. It has been suggested that up to half of the deglacial atmospheric CO2 rise may be driven by a reduction the marine biological carbon pump, i.e. the sequestration of CO2 in the deep ocean through primary production and vertical export of organic carbon. Even for the marine biological carbon pump, many mechanisms and nutrient cycles have been proposed to have driven these deglacial changes. This issue is extensively discussed and it remains largely unresolved since most studies focus only on single mechanisms and thus a coherent picture is lacking. In this project, we will use the Model of Ocean Biogeochemistry and Isotopes (MOBI) coupled within an Earth System Climate Model to estimate how declining marine nutrient inventories of nitrogen, iron, and dissolved organic carbon impacted the soft-tissue biological carbon pump in a transient simulation of the last deglaciation. The novel approach of our project will be utilizing the isotope tracers of carbon (13C and 14C) and nitrogen (15N) incorporated in our model. Direct comparisons of simulation results with isotopes measured in sedimentary records provide important quantitative constraints on processes controlling marine nutrient inventories and thus the strength of the soft-tissue biological pump. We will provide a comprehensive analysis on changes to key limiting nutrient inventories, as well as their individual and combined contribution to rising deglacial atmospheric CO2 using a coherent multi-proxy model-data comparison. This project will indicate the most important climate-sensitive marine nutrient cycle processes that need to be incorporated into global climate models to improve predictions of the future ocean and climate.

了解在最后一次冰川消融期间(距今19000至9000年)大气二氧化碳浓度增加近80ppm的机制仍然是古海洋学的主要挑战。有人提出，高达一半的退冰期大气二氧化碳上升可能是由于海洋生物碳泵的减少，即通过初级生产和有机碳的垂直出口将二氧化碳固定在深海中。即使对于海洋生物碳泵来说，也提出了许多机制和营养循环来驱动这些退冰期的变化。这个问题得到了广泛的讨论，但在很大程度上仍然没有得到解决，因为大多数研究只关注单一的机制，因此缺乏连贯的图景。在这个项目中，我们将使用地球系统气候模型中耦合的海洋生物地球化学和同位素模型(MOBI)来估计海洋营养物质氮、铁和溶解有机碳库存的下降如何影响软组织生物碳泵，在对最后一次冰川消融的瞬时模拟中。我们项目的新方法将利用我们模型中包含的碳(13C和14C)和氮(15N)的同位素示踪剂。模拟结果与沉积记录中测得的同位素的直接比较为控制海洋营养物质库存的过程提供了重要的数量限制，从而对软组织生物泵的强度进行了控制。我们将使用连贯的多代理模型-数据比较，全面分析关键限制营养物质清单的变化，以及它们对脱冰期大气二氧化碳上升的单独和综合贡献。该项目将指出最重要的对气候敏感的海洋营养循环过程，这些过程需要纳入全球气候模型，以改进对未来海洋和气候的预测。