Carbon Export Buffering and CO2Drawdown by Flexible Phytoplankton C:N:P Under Glacial Conditions
Carbon Export Buffering and CO2Drawdown by Flexible Phytoplankton C:N:P Under Glacial Conditions
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DOI：
10.1029/2019pa003823
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发表时间：
2020-07-01
影响因子：
3.5
通讯作者：
Tanioka, Tatsuro
中科院分区：
文献类型：
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作者：
Matsumoto, Katsumi;Rickaby, Rosalind;Tanioka, Tatsuro
现代观测表明，海洋浮游植物化学计量的变化与主要表层沃茨的边界有关。例如，贫营养亚热带环流中的浮游植物通常具有高得多的C：N：P比率（即，高C：P和高N：P比值）高于富营养化上升流区和极地区。这种空间格局表明，养分供应是化学计量灵活性的一个关键环境驱动因素。浮游植物C：N：P的环境依赖性为在不同气候条件下修改生物泵的强度开辟了未探索的可能性。在这里，我们提出了一个幂律公式的C：N：P的灵活性，是由营养物质，温度和光驱动。我们嵌入配方在全球海洋碳循环模型与多种浮游植物类型，并探讨冰川条件下的地球化学影响。我们发现三个关键控制出口C：N：P比：浮游植物生理和群落结构，以及在全球范围内的区域生产的平衡。冰川输入的铁和海冰扩张是这三个控制的重要修改器。我们还发现，全球出口C：N：P在冰川条件下大幅增加，这有力地缓冲了全球碳出口的减少，并减少了约20亩大气CO2。这些结果指出，包括浮游植物的C：N：P的灵活性的混合机制，驱动大气CO（2）在冰川间冰期的时间尺度的重要性。最后，我们的模拟表明脱钩的营养物质，这可能会提供一个解决方案，长期以来的分歧，营养物质利用在冰川南大洋来自不同的营养物质代理。
Modern observations indicate that variations in marine phytoplankton stoichiometry correlate with the boundaries of major surface waters. For example, phytoplankton in the oligotrophic subtropical gyres typically have much higher C:N:P ratios (i.e., higher C:P and higher N:P ratios) than those in eutrophic upwelling regions and polar regions. Such a spatial pattern points to nutrient availability as a key environmental driver of stochiometric flexibility. Environmental dependence of phytoplankton C:N:P opens unexplored possibilities for modifying the strength of the biological pump under different climate conditions. Here we present a power law formulation of C:N:P flexibility that is driven by nutrients, temperature, and light. We embed the formulation in a global ocean carbon cycle model with multiple phytoplankton types and explore biogeochemical implications under glacial conditions. We find three key controls on export C:N:P ratio: phytoplankton physiology and community structure as well as the balance in regional production at the global level. Glacial inputs of iron and sea ice expansion are important modifiers of these three controls. We also find that global export C:N:P increases substantially under glacial conditions, and this strongly buffers global carbon export against decrease and draws down approximately 20 mu atm of atmospheric CO2. These results point to the importance of including phytoplankton C:N:P flexibility in a mix of mechanisms that drive atmospheric CO(2)over glacial-interglacial time scale. Finally, our simulations indicate decoupling of nutrients, which may provide a resolution to the longstanding disagreement regarding nutrient utilization in the glacial Southern Ocean derived from different nutrient proxies.