Response of the Southern Ocean biological carbon pump to climate-related changes in iron supply

南大洋生物碳泵对气候相关铁供应变化的响应

• 批准号: 522414107
• 负责人: Dr. Ying Ye
• 金额: --
• 依托单位: Alfred-Wegener-Institut (AWI) Helmholtz-Zentrum für Polar- und Meeresforschung
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/522414107?language=en
• 关键词: Response; Southern; Ocean; biological; carbon

The Southern Ocean (SO) plays a fundamental role in regulating the oceanic carbon uptake and thus the Earth's climate. Higher dust deposition during glacial periods was hypothesised to have alleviated iron limitation in the SO and contributed to the drawdown of atmospheric CO2. Observations of natural iron fertilisation events in the SO and modern artificial ocean iron fertilisation experiments (OIFs) confirmed the positive response of phytoplankton growth to iron addition. It is however debatable if such an increase of primary production leads to an increase of carbon export and storage, and how the response of the marine carbon pump to changes in iron supply is affected by climate change. EIFEX (the European Iron Fertilisation Experiment, carried out in 2004 in the SO) is the only OIF during which a significant increase in carbon export in the fertilised waters was detected. This increased export flux was attributed to the formation of aggregates by diatom species and mass sinking during the bloom termination. The previous modelling study however, failed to reproduce the observed changes in carbon export, indicating that the model parameterisations of iron supply and utilisation, particle dynamics and of processes controlling phytoplankton bloom evolution need to be revised. Further, a significant contribution to carbon export in naturally fertilised regions is made by diatom resting spores, which is so far completely ignored in global modelling of the marine carbon cycle. The proposed project will determine the key drivers of the SO biological carbon pump (e.g. phytoplankton community composition, particle and nutrient dynamics) based on EIFEX observations during EIFEX and of natural iron fertilisation events, improve the model representation of these key drivers, reassess the impact of iron fertilisation in the SO on carbon sequestration and predict responses of marine carbon cycle to future changes in iron supply.

南大洋（SO）在调节海洋碳吸收和地球气候方面发挥着重要作用。据推测，在冰川期更高的灰尘沉积减轻了SO中的铁限制，并有助于大气CO2的下降。在SO和现代人工海洋铁施肥实验（OIFs）的自然铁施肥事件的观察证实了浮游植物生长的积极反应，铁的添加。然而，这种初级生产的增加是否会导致碳出口和储存的增加，以及海洋碳泵对铁供应变化的反应如何受到气候变化的影响，这是有争议的。EIFEX（欧洲铁施肥实验，2004年在SO进行）是唯一的OIF，在此期间，在施肥沃茨中的碳输出显着增加。这种增加的出口通量是由于硅藻物种和质量下沉的水华终止期间形成的聚集体。然而，以前的建模研究，未能再现所观察到的碳输出的变化，表明模型参数化的铁的供应和利用，粒子动力学和控制浮游植物水华演变的过程需要修改。此外，硅藻休眠孢子对自然施肥区的碳输出做出了重大贡献，但迄今为止，在海洋碳循环的全球建模中，这一点完全被忽视。拟议项目将根据EIFEX期间的EIFEX观测和自然铁施肥事件确定SO生物碳泵的关键驱动因素（例如浮游植物群落组成，颗粒和营养物动态），改进这些关键驱动因素的模型表示，重新评估SO中铁施肥对碳封存的影响，并预测海洋碳循环对未来铁供应变化的响应。