Photosynthesis by phytoplankton reduces partial pressure of CO2 at the surface of the ocean and is therefore a potential means of action for a marine CO2 removal technology. Here we study how glacial rock flour may influence photosynthesis in the open ocean. Glacial rock flour is a fine-grained silicate mineral from the bedrock grinded by the Greenland Ice Sheet and enters the ocean via fjords and coastal waters. It is therefore a natural source of nutrients and trace metals to the ocean. It is easily accessible in large quantities and could be a suitable source for large-scale CO2 removal. The impact of suspended glacial rock flour was analyzed through 14 incubation experiments with natural phytoplankton communities sampled in the subtropical Atlantic. A significant increase in photosynthesis was found in 12 experiments where variable fluorescence Fv/Fm increased 12% and the average concentration of chlorophyll a increased significantly in comparison with control treatments during a 6-day period. Incubations with glacial rock flour showed a significant uptake of phosphorus whereas the average concentrations of silicate and dissolved inorganic nitrogen increased. Nutrient changes could be explained by increasing phytoplankton and microbial biomass, remineralization of organic matter, and weathering (mobilization) of glacial rock flour. These short time experiments indicated that trace metals from glacial rock flour stimulated phytoplankton growth. Thus, glacial rock flour has the potential to increase photosynthesis and phytoplankton growth, and therefore may be a potential means of action for marine CO2 removal.

中文翻译：

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冰川岩粉增加亚热带地表水域天然浮游植物群落的光合作用和生物量：去除海洋二氧化碳的潜在行动手段


浮游植物的光合作用降低了海洋表面二氧化碳的分压，因此是海洋二氧化碳去除技术的潜在行动手段。在这里，我们研究冰川岩粉如何影响公海的光合作用。冰川岩粉是一种细粒硅酸盐矿物，来自格陵兰冰盖磨碎的基岩，通过峡湾和沿海水域进入海洋。因此，它是海洋营养物质和微量金属的天然来源。它易于大量获取，并且可能是大规模去除二氧化碳的合适来源。通过对亚热带大西洋天然浮游植物群落进行 14 次孵化实验，分析了悬浮冰川岩粉的影响。在 12 个实验中发现光合作用显着增加，在 6 天的时间内，与对照处理相比，可变荧光 Fv/Fm 增加了 12%，叶绿素 a 的平均浓度显着增加。与冰川岩粉一起孵育显示出磷的显着吸收，而硅酸盐和溶解的无机氮的平均浓度增加。营养物质的变化可以通过浮游植物和微生物生物量的增加、有机物的再矿化以及冰川岩粉的风化（动员）来解释。这些短时间的实验表明，冰川岩粉中的微量金属刺激了浮游植物的生长。因此，冰川岩粉具有增加光合作用和浮游植物生长的潜力，因此可能是去除海洋二氧化碳的潜在行动手段。